the uncertain consequences of nuclear weapons use

8/13/2019 The Uncertain Consequences of Nuclear Weapons Use

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JHU/APL NATIONALSECURITYPERSPECTIVE OCTOBER2013

Copyright 2013 James Scouras. All rights reserved. Printed in the United States of America.

INQUIRIES

Requests for permission to make copies of any part of this publication should be mailed to:

Dr. James ScourasNational Security Analysis DepartmentThe Johns Hopkins University Applied Physics Laboratory11100 Johns Hopkins RoadLaurel, Maryland 20723

DISCLAIMER

The views expressed in the paper represent a consensus among the authors. They should not be construed asthe views of the organizations with which the authors are affiliated.


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THEUNCERTAINCONSEQUENCESOFNUCLEARWEAPONSUSE

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CONTENTS

I. OVERVIEW ................................................................................................................................................... 1

II. HISTORICAL CONTEXT ................................................................................................................................2

SURPRISES .................................................................................................................................................................4

ENDURING UNCERTAINTIES AND WANING RESOURCES ....................................................................................10

III. PHYSICAL EFFECTS: WHAT WE KNOW, WHAT IS UNCERTAIN, AND TOOLS OF THE TRADE ................. 12

NUCLEAR WEAPONS EFFECTS PHENOMENA ........................................................................................................12

WEAPON DESIGN CONSIDERATIONS ...................................................................................................................19

PREDICTIVE TOOLS .................................................................................................................................................19

OTHER SOURCES OF KNOWLEDGE .......................................................................................................................20

IV. NON-PHYSICAL EFFECTS ........................................................................................................................... 22

V. SCENARIOS ................................................................................................................................................ 23

A SINGLE WEAPON DETONATED IN A CITY ..........................................................................................................23

CHINESE HIGH-ALTITUDE EMP ATTACK ON NAVAL FORCES ................................................................................25

REGIONAL NUCLEAR WAR BETWEEN INDIA AND PAKISTAN ...............................................................................26

U.S.-RUSSIAN UNCONSTRAINED NUCLEAR WAR ................................................................................................27

VI. TRENDS AND OTHER PATTERNS ............................................................................................................... 29

VII. CONCLUSIONS AND RECOMMENDATIONS ............................................................................................31

ACKNOWLEDGMENTS ........................................................................................................................................................35

ABOUT THE AUTHORS ........................................................................................................................................................35


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FIGURES

1. TRINITYFIREBALL .................................................................................................................................................3

2. THESTARFISHPRIMEHIGHALTITUDETEST. ...........................................................................................................5

3. TTAPS NUCLEARWINTERPREDICTIONS...............................................................................................................8

4. MT. GALUNGGUNGVOLCANICERUPTION.............................................................................................................9

5. DECADE X-RAYSIMULATORMODULE..............................................................................................................10

6. EMP COVERAGECONTOURS .............................................................................................................................13

7. ONEKILOTONISO-PRESSURECONTOURS...........................................................................................................14

8. THESEDANCRATER ...........................................................................................................................................15

9. OPERATIONCROSSROADS, EVENTBAKER.............................................................................................................16

10. HIROSHIMAFIREDAMAGE .................................................................................................................................17

11. HPAC FALLOUTPREDICTION.............................................................................................................................18

12. NUCLEARBOMBEFFECTSCOMPUTER..................................................................................................................20

SOURCES

We gratefully acknowledge the following institutions for providing the figures reproduced in this document.

Department of Defense: Figures 1, 5, 6, 7, 9, 10, and 11

Los Alamos National Laboratory: Figure 2

Science Magazine, American Association for the Advancement of Science: Figure 3

United States Geological Survey: Figure 4

Department of Energy National Nuclear Security Administration/Nevada Field Office: Figure 8

Oak Ridge Associated Universities: Figure 12


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out many significant damage mechanisms (e.g.fire), and thus more comprehensive consequenceassessments might support lower arsenal levels.

Contributing to forensics. With more and morestates, and potentially sub-state actors, acquiringnuclear weapons and delivery means other thanland-based missiles whose trajectories can betraced back to the country of origin, it may notbe clear just which actor was responsible fora nuclear detonation. The yield of the weaponand other information about its design can beestimated from the effects of the detonation andprovide a useful contribution to forensics, thescience of analyzing the physical evidence froma nuclear detonation, which provides a basis forattribution.

Avoiding unintended and unwanted effectsFinally, nuclear weapons have geographicallyextended effects that are generally unwanted andeven possibly catastrophic for belligerent andnon-belligerent alike. Policies and decisions onnuclear use must evaluate these, as well as theintended effects of nuclear use.

Clearly, the utility of a nuclear use consequenceassessment and the levels of uncertainties that can be

tolerated depend on the decisions that the assessmentis intended to supportThis paper attemptsto summarize thestate of knowledgeand correspondingstate of uncertaintywhich is presentlyavailable to supporsuch operational andpolicy choices.

I. OVERVIEW

Nuclear weapons were first developed in the 1940sOver the course of the subsequent decades, aconsiderable body of knowledge on the consequencesof their employment has accumulated through studyof the two instances of actual use and an extensive,

So long as the United States anticipates thepotential for nuclear weapon utilization, byeither its own action or hostile nuclear use against

U.S. interests, an understanding of the consequencesof employment will be needed to support critical

operational planning and policy choices. Theseinclude:

Developing and evaluating war plans.Estimatingthe damage that nuclear weapons will do to thevariety of targets in a war plan is necessary forefficient utilization of weapons and to ensure thatthe ability to meet damage goals is accuratelypredicted. Similarly, accurately predicting nucleareffects is necessary when minimizing casualties orcollateral damage is an important concern, as isincreasingly the case in the post-Cold War world.

Managing consequences. Developing conse-quence management plans requires some levelof understanding of nuclear effects to answerquestions such as: under what circumstancesshould people shelter in place or evacuate; whatevacuation routes are more likely to be free offallout; how long can first responders operatewhile exposed to radiation at various levels; howmany deaths and injuries of various types can beexpected; how far apart should critical government

and commercial backup systems be located; andwhat would bethe effective-ness of electro-magnetic pulse(EMP) hardeningmeasures?

Determining arsenalsize. The mantraof deterrence isthat threatening

unacceptabler e t a l i a t o r ydamage will prevent war. Clearly, whatever thecriterion for unacceptable damage, one needsto assess whether it is achievable with a specificarsenal. Thus, the question of how many nuclearweapons are enough depends critically on theability to assess consequences. In fact, as weshall see, traditional military assessments leave

The enormous investment of resourcesto understand the effects of nuclearweapons by the Department of Defensedoes not provide sufficient understandingto assess the consequences of nuclearuse for many significant scenarios.


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sustained, and costly national investment in bothtesting and analysis. The question addressed here iswhether the existing body of accumulated knowledgeon nuclear weapons effects is sufficient to support anuclear use consequence assessment, either as anintegral component of a nuclear deterrence failurerisk assessment or a stand-alone analysis informingspecific decisions.

It is the thesis of this paper that the answer tothis question is a resounding sometimes. We shallreview why the enormous investment of resourcesto understand the effects of nuclear weapons by theDepartment of Defense does not provide sufficientunderstanding to assess the consequences of nuclearuse for many significant scenarios. We then addresshow well we really must understand consequences

to enable a useful assessment. The answer will beseen to depend on the overall magnitude of theconsequences as well as the nature of the decisionthe assessment is intended to inform.

We begin with an overview of our nuclear weaponseffects experience, starting with the Trinity explosionand nuclear attacks on Japan and progressing toa discussion of the Cold War nuclear weapons testand analysis program. We emphasize a perspectivethat focuses on majorsurprises uncovered

by the tests them-selves, by analysesof non-Departmentof Defense scientists,and by observationsof analogous naturalphenomena. We thensummarize, effect byeffect, what we have learned from this experience,as well as the steady accumulation and refinementof knowledge through the weapons effects research

program, and what important uncertainties remain.Several potential scenarios of nuclear use areposed to provide a more holistic perspective onthe totality of nuclear effects. Looking beyond thecurrent knowledge base, we identify trends in factorsrelevant to our future ability to support a conse-quence assessment. We conclude with an evaluationof whether and under what circumstances the currentknowledge base can support a useful assessment and,

in light of current trends, provide several recommen-dations for the Department of Defense.

Before proceeding, an important caveat needsto be emphasized. Our discussion focuses on thephysical consequences of nuclear weapons use. Only

tangentially considered are those associated withnational security policy, social and psychologicaeffects, and other such intangibles. Whereas lackof such consideration reflects a serious gap in ourknowledge and methodological tools, physicaconsequences by themselves represent an importantcomponent of a more complete assessment andprovide the essential foundation for understandingnonphysical effects. Restricting attention to physicaconsequences thus provides a lower bound and firststep to any determination of the consequences of

nuclear weapons employment.

II. HISTORICAL CONTEXT

The worlds first nuclear test, code-named Trinity, tookplace on July 16, 1945 near Socorro, New Mexico, ata location that is now part of the White Sands MissileRange. Pre-test yield predictions1 varied widelyfrom a zero-yield fizzle to 45 kilotons2and it took

a number of yearsto converge to a

best-estimate of 21kilotons.3 The yieldof Little Boy, historyssecond nuclearexplosion detonatedover Hiroshima,remains a matter ofcontention to the

present day. Estimated yields have ranged from 6 to23 kilotons, converging to the current best-estimate of

1. Early concerns that a nuclear detonation might ignite theatmosphere were largely dismissed by the time of the test basedon a detailed analysis. See E. Konopinski, C. Marvin, and E. TellerIgnition of the Atmosphere with Nuclear Bombs, Los AlamosNational Laboratory Technical Report LA-602 (Los Alamos, NM: LosAlamos National Laboratory, 1946).2. K. T. Bainbridge, Trinity, Los Alamos Scientific Laboratory ReporLA-6300-H (Los Alamos, NM: Los Alamos National Laboratory1976).3. U.S. Department of Energy, United States Nuclear Tests: July1945 through September 1992, DOE/NV--209-REV 15 (Las VegasNV: U.S. Department of Energy Nevada Operations Office, 2000).

Extensive as nuclear weapons effectsresearch has been, it has accounted forless than 0.5% of the total cost of thenuclear weapons enterprise.


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15 kilotons.4In many ways, the uncertainty in yield ofthese first nuclear events is paradigmatic of the largeuncertainties that still attend nuclear phenomenologyand challenge our ability to perform a meaningfulconsequence assessment today.

Figure 1. Trinity Fireball. As the culmination of theManhattan Project, the Trinity atomic test was conductedin New Mexico on July 16, 1945. This photograph showsthe shape of the fireball with a radius of approximately400 feet at 16 milliseconds after detonation. Note the dustskirt traversing the terrain ahead of the main blast wave. 5

Employment of nuclear weapons by the United

States against Japan at the end of World War IIwas also accompanied by a number of surprisesand uncertainties. While the blast damage wasanticipated to result in massive destruction, no onehad predicted the development of catastrophicfirestorms subsequent to the explosion or theresulting black rain containing radioactive soot anddust that contaminated areas far from ground zero.6Post-war investigation now attributes the majority of

4. John Malik,The Yields of the Hiroshima and Nagasaki Explosions,Los Alamos National Laboratory Report LA-8819 (Los Alamos, NM:Los Alamos National Laboratory, 1985).5. The shape of the dust skirt is generally attributed to an obliqueprecursor shock propagating ahead of the main shock in a channelof hot (higher sound speed) air adjacent to the fireball-heatedsurface. Some have argued that for lower heights of burst, such asTrinity, the thermal layer has not yet formed at the time of shockreflection, and the scouring effect of the strong reflected shock wavealone is sufficient to create a supersonic dust jet that catches up andpropagates ahead of the main shock.6. C. R. Molenkamp, An Introduction to Self-Induced Rainout,Lawrence Livermore Laboratory Report UCRL-52669 (Livermore,CA: Lawrence Livermore Laboratory, 1979).

the estimated 200,000 casualties to inflicted burnsrather than the nuclear shock wave, as originallythought.7Additionally, large uncertainties in casualtyestimates resulted from the destruction of hospitalsand local government population records and slowerto-manifest health effects resulting from radiologicaexposure.

Since World War II, the United States has undertakenan extensive nuclear test and analysis program, withthe last atmospheric test conducted in 1962 and thelast underground test in 1992. During that period,the United States conducted over 1,000 nuclear testsfor purposes of warhead design and development,stockpile assurance and safety, and weapon effectswith the last category comprising approximately 10%of the total.8While difficult to assign a definitive figure,

the most authoritative estimate based on publiclyavailable information places a lower bound on thecost of development, deployment, and maintenanceof the U.S. nuclear arsenal from the Manhattanprogram through 1996 at about $8 trillion (adjustedto 2012 dollars).9

Most of this cost is attributed to building andmaintaining the variety of delivery platforms and thenuclear command and control system. Extensive asnuclear weapons effects research has been, it hasaccounted for less than 0.5% of the total cost of the

nuclear weapons enterprise.10

Our national investment in nuclear weapons effectsresearch developed out of Cold War exigency, withfocus on the damage expectancy projected for eachweapontarget combination. Such information servedas the basis for developing the Single IntegratedOperational Plan (SIOP) and a hypothetical RedIntegrated Strategic Offensive Plan (RISOP), whichtogether envisioned a strategic nuclear exchangebetween the United States and the Soviet Union

involving up to thousands of nuclear weapons

7. The Atomic Bombings of Hiroshima and Nagasaki, AtomicArchive, http://www.atomicarchive.com/Docs/MED/med_chp10shtml.8. U.S. Department of Energy, United States Nuclear Tests.9. Stephen I. Schwartz, ed., Atomic Audit: The Costs andConsequences of U.S. Nuclear Weapons Since 1940 (WashingtonDC: Brookings Institution Press, 1998). A factor of 1.44 was appliedto the 1996 cost estimate from this source to convert to 2012 dollars10. Authors estimate.


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aimed at nuclear forces, leadership, conventionalmilitary, and war-supporting industry targets.11Othermilitary applications produced manuals for groundcombatants, which established doctrine for tacticaloperations on a nuclear battlefield and protecting theforce from the effects of nuclear weapon detonations.

Left out of such developments were singlelow-yield (< 20 kiloton) weapons that might be partof a modern terrorist or rogue state threat today; theeffects of weapons with sophisticated designs thatmight be achieved by a technologically advancedadversary; and some known weapon effects, such asfire damage and electromagnetic pulse effects thatreceived a much lower level of attention becausethey were difficult to quantify and hence were neverincluded in the damage expectancy calculus. Blast

and shock effects,by contrast, wereunderstood to bethe primary damagemechanisms andalso considered moretractable, requiringless detailed infor-mation regarding thephysical features andoperational state of

the target. Accordingly, these effects enjoyed focusedattention and healthy funding and are thus relativelywell understood.

SURPRISES

Another persistent theme throughout the history ofthe nuclear effects knowledge acquisition experiencehas been the element of surprise. Many such surprisespertain to the response of military systems exposed toactual and simulated nuclear test environments forwhich open discussion is constrained by security andclassification restrictions. However, some of the largestsurprises are completely unclassified. Among theseare effects that had simply not previously occurredto Department of Defense scientists, including some

11. The SIOP evolved over time to provide greater flexibility (moreand smaller options), and later versions considered and attempted toreduce civilian casualties; however, the location of strategic targetsin and around cities made such attempts largely ineffectual.

that first became evident through observations ofnaturally occurring phenomena.

Radiation Belt Pumping and High-Altitude Electro-magnetic Pulse. Perhaps the most glaring examplesof surprise came during the 1962 high-altitude tes

series nicknamed Operation Fishbowl. In particular,the July 1962 exo-atmospheric detonation of Star-fish Prime, a 1.4 megaton nuclear test explosion ata height of burst of 400 kilometers over the PacificOcean, produced two significant and unwelcomesurprises. One surprise dawned only after a numberof months when Telstar 1, an AT&T telecommunica-tions satellite, which first demonstrated the feasibilityof transmitting television signals by space relay, diedprematurely after only a few months of successfuoperation.12The same fate befell other satellites,13and

within a short span oftime, all publiclya c k n o w l e d g e dspace assets hadbecome disabledThus was discoveredthe phenomenon opumping the belts,wherein naturaradiation belts encir-cling the Earth were

enhanced by bomb-generated electrons, creatingan unanticipated hazard for satellites that orbitedthrough the newly hostile environment. This obser-vation, along with known prompt radiation effectshelped to motivate a significant investment by theDepartment of Defense over the next 30 years inunderground nuclear testing, above-ground radiationsimulators, and computational approaches to betterunderstand the effects of the full complement ofionizing radiation on electronic systems and developappropriate hardening measures.

The other major surprise from Starfish Prime wasthe discovery of a high-altitude EMP as the streetlights in Honolulu, 800 nautical miles distant, went

12. Gilbert King, Going Nuclear Over the Pacific, Past Imperfec(blog), Smithsonian, August 15, 2012, http://blogs.smithsonianmagcom/history/2012/08/going-nuclear-over-the-pacific/.13. David M. Harland and Ralph D. Lorenz, Space SystemsFailures: Disasters and Rescues of Satellites, Rocket and SpaceProbes(Berlin: Springer and Praxis, 2005).

Another persistent theme throughout thehistory of the nuclear effects knowledgeacquisition experience has been theelement of surprise.


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dark at the time of the explosion and other instancesof electronic interference manifested themselves.14Within a few years of the test, a satisfactory physicsmodel had been developed that explained thelarge electromagnetic pulse observed.15 However,adherence of the United States to the terms of theAtmospheric Test Ban Treatysigned by PresidentKennedy in 1962 and ratified by the Senate in 1963precluded empirical validation of the theoreticalmodel.

Over the next two decades, a robust research anddevelopment effort executed by the Defense NuclearAgency greatly expanded understanding of thisphenomenon as the military scrambled to identifyvulnerabilities and develop hardening methodologiesto protect critical strategic military assets from the

threat of EMP exposure. Using pulse power sourcescoupled to suitable antennae, many key assets wereexposed to simulated environments, and damagethresholds of electronic systems to EMP exposurelevels were quantified. No comparable effort wasever expended to explore the vulnerabilities of thenations civil infrastructures to the potential perils ofan EMP attack.

In the 1990s, following the dissolution of the formerSoviet Union, the Department of Defense investmentin expanded understanding of all matters nuclear,

including EMP, declined precipitously as nucleareffects programs fell prey to the quest for the peacedividend. Meanwhile, the evolution of electronictechnology toward new generations of low-powerintegrated circuits with ever smaller feature sizestended to increase their inherent susceptibility toEMP-induced damage, and the ability to predictsurvivability to EMP environments becameincreasingly uncertain. At the same time, our militaryforces became increasingly reliant on potentiallyvulnerable electronic warfare systems. The late 1990s

also coincided with a push, still ongoing, to increase

14. John S. Foster, Earl Gjelde, William R. Graham, Robert J.Hermann, Henry (Hank) M. Kluepfel, Richard L. Lawson, GordonK. Soper, Lowell L. Wood Jr., and Joan B. Woodard, Report ofthe Commission to Assess the Threat to the United States fromElectromagnetic Pulse (EMP) Attack, Volume 1: Executive Report(McLean, VA: Commission to Assess the Threat to the United Statesfrom Electromagnetic Pulse [EMP] Attack, 2004).15. Conrad Longmire, Fifty Odd Years of EMP, NBC Report, Fall/Winter (2004): 4751.

Figure 2. The Starfish Prime High-Altitude Test. This1.4 megaton detonation at an altitude of 400 kilometers onJuly 9, 1962 created copious electrons from the beta decayof fission products. These electrons became trapped in theVan Allen radiation belts, creating a spectacular auroradisplay and a hazardous environment that led to the demiseof satellites orbiting near this altitude. Eight hundred nauticamiles away, an EMP from the blast turned off the street lightsin downtown Honolulu. Only five U.S. high-altitude testswere ever conducted, limiting our understanding of EMPand other high-altitude nuclear effects.

where possible reliance on commercial off-the-shelf(COTS) acquisition to complement the standardMilitary Specification (MILSPEC) approach. While aMILSPEC-focused acquisition system has delivered usthe 26-page MILSPEC for the chocolate brownie16

and the fabled $7,000 coffee pot,17 it also ensuredthat standards would be defined based on militaryrequirements, whereas an emphasis on COTS tended

to skew requirements in the direction of what wascommercially available.

As a result of these developments, by the late 1990sinvestment in EMP-related matters had declined, and

16. Cookies, Oatmeal; and Brownies; Chocolate CoveredMilitary Specification MIL-C-44072C, superseding MIL-C-44072B(Washington, DC: U.S. Department of Defense, 1987).17. Curtis R. Cook, Making Sense of Spare Parts Procurement,

Air Force Journal of LogisticsXIV, no. 2 (1990): 69.


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uncertainties had grown to such a degree that concernsinitially confined to a relatively ineffectual internalDepartment of Defense advocacy had attractedthe attention ofCongress. In 2001,Congress stood upthe Commission toAssess the Threat tothe United Statesfrom Electromag-netic Pulse Attack(hereinafter theEMP Commission)charged with devel-oping recommen-dations that addressed both military and hithertoneglected civilian infrastructures.18 The EMPCommissions final report, delivered in January 2009,highlights the potential for catastrophic, multi-yearEMP effects, which might cause irreparable harm tothe installed electrical infrastructure and ultimatelylead to a large number of deaths through the inabilityof critical infrastructures to sustain the population.19To date, there is scant evidence that the reportsrecommendations to protect these infrastructureshave resulted in concrete actions by the Departmentof Homeland Security.

The EMP Commission report also containsrecommendations to address classified deficienciesof both knowledge and practice related to thevulnerabilities and hardening of military systems. TheDepartment of Defenses response concurred withall the substantive recommendations, a classifiedAction Plan was promulgated by the Secretary ofDefense, and out-year funding was budgeted toaddress issues. Today, major systems EMP testinghas been reinstituted, the U.S. Strategic Command

18. Floyd D. Spence National Defense Authorization Act for FiscalYear 2001, Public Law 106-398 (Title XIV). One of the coauthorsof this paper (Frankel) served as the EMP Commissions ExecutiveDirector; another coauthor (Scouras) served as a Commission staffmember.19. John S. Foster, Earl Gjelde, William R. Graham, Robert J.Hermann, Henry (Hank) M. Kluepfel, Richard L. Lawson, GordonK. Soper, Lowell L. Wood Jr., and Joan B. Woodard, Report ofthe Commission to Assess the Threat to the United States fromElectromagnetic Pulse (EMP) Attack: Critical National Infrastructures(McLean, VA: Commission to Assess the Threat to the United Statesfrom Electromagnetic Pulse [EMP] Attack, 2008).

(USSTRATCOM) has reinvigorated an EMP facilityhardness testing certification program, a newpermanent Defense Science Board committee has

been stood up tofollow EMP mattersa special EMPaction officer hasbeen establishedin the Office of theAssistant Secretaryof Defense foNuclear, Chemicaland BiologicaMatters, and EMPsurvivability has

been incorporated in a new Department of DefenseSurvivability Instruction.20

The decline in funding has been reversed, andEMP is once again an important consideration insystem survivability. Notwithstanding these develop-ments, there is no guarantee that EMP will continueto receive the high-level interest needed to main-tain these developments indefinitely. Experience hasshown that without the sustained interest of the high-est levels of Department of Defense leadership, EMPresearch and hardness surveillance and maintenanceprograms will be at risk.

Ozone Depletion. In the 1970s, during theprolonged political-economic-scientific debate ovethe fate of the proposed U.S. Supersonic Transport(SST), a powerful argument contributing to its demisewas the notion that nitrogen oxides (NOx) producedin its exhaust would chemically combine to reducethe atmospheric layer of ozone protecting humanlife from harmful effects of solar ultraviolet (UV)radiation.21 Subsequently, similar concerns, notpreviously considered by Department of Defensescientists, were raised against the prospect of renewed

nuclear testing as models indicated nitrogen oxidesmight be produced as a product of the atmospheric

20. The CBRN Survivability Policy, DoD Instruction 3150.09incorporating change 1 (Washington, DC: U.S. Department oEnergy Nevada Operations Office, 2009).21. Harold S. Johnston, Photochemistry in the Stratosphere - withApplications to Supersonic Transport,Astra Astronautics1, no. 12(1974): 135156.

At present, with the reduced arsenals

and a perceived low likelihood of alarge-scale exchange on the scale ofCold War planning scenarios, officialconcern over nuclear ozone depletionhas essentially fallen off the table.


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chemistry catalyzed by the thermal environment of arising nuclear fireball.22

In 1982, in a highly emotive and publicly persuasivepresentation, Jonathan Schell painted the case againstnuclear waras if it wasnt already bad enough

as an apocalyptic scenario in which all human lifeon the face of the Earth might be extinguished as aresult of nuclear weapon-induced ozone depletion.In Schells hauntingly elegiac description, nuclearwar perpetrates asecond death, notmerely the extinctionof all that exists butthe extinction of allthat might ever havebeen with the death

of future generationsof the unborn,leaving behind onlyan empire of insectsand grass.23

However, a funny thing happened on the wayto ozone Armageddon. With the confluence ofboth changed external circumstances and eventualacceptance of prior contradictory scientificobservations, both officialdom and the publicstopped worrying about it. The changed external

circumstances were by far the most noticeable anddramatic. Arms control treaties and agreementsresulted in significant reductions in the numbers ofweapons in the nuclear arsenals of the United Statesand the Soviet Union. At the same time, accuracyimprovements in the missile delivered warheadsmeant that very large yields were no longer required toachieve high damage expectancy. As a result of thesechanges, the total yield calculated in a worst-casestrategic arsenal exchange between warring statesdecreased significantly from the 10,000-megaton

exchange, which underlays Schells lament. By2007, the total number of deployed warheads wasless than a quarter that available in 1982,24 while

22. Ozone Depletion, Atomic Archive, http://www.atomicarchive.com/Effects/effects22.shtml.23. Jonathan Schell, The Fate of the Earth (New York: Alfred A.Knopf, 1982).24. Nuclear Matters Handbook New Expanded Edition(Washington, DC: Office of the Assistant Secretary of Defense forNuclear, Chemical, and Biological Matters, 2011).

the total yield of the U.S. operational arsenal wasestimated at no more than 1,430 megatons.25Withthe probability of a full arsenal exchange recedingeven further after the collapse of the Soviet Unionand the continued reduction of numbers of warheadsearlier calculations predicting planetary-scale impactseemed increasingly irrelevant.

Scientific work based on real data, rather thanmodels, also cast some additional doubt on the basic

premise. Interest-ingly, publication oseveral contradic-tory papers basedon experimentaobservations actuallypredated Schell. In

1973, some 9 yearsbefore publica-tion of The Fate othe Earth, a report

was published that failed to find any ozone deple-tion during the peak period of atmospheric nucleartesting.26In another work published in 1976, attemptsto measure the actual ozone depletion associatedwith Russian megaton class detonations and Chinesenuclear tests were also unable to detect any significanteffect.27At present, with the reduced arsenals and a

perceived low likelihood of a large-scale exchangeon the scale of Cold War planning scenarios, officiaconcern over nuclear ozone depletion has essentiallyfallen off the table. Yet continuing scientific studies bya small dedicated community of researchers suggesthe potential for dire consequences, even for relativelysmall regional nuclear wars involving Hiroshima-sizebombs.28

25. U.S. Nuclear Weapon Enduring Stockpile, The NucleaWeapon Archive: A Guide to Nuclear Weapons, last updatedAugust 31, 2007, http://nuclearweaponarchive.org/Usa/WeaponsWpngall.html.26. P. Goldsmith, A. F. Tuck, J. S. Foot, E. L. Simmons, and R. LNewson, Nitrogen Oxides, Nuclear Weapon Testing, Concordeand Stratospheric Ozone, Nature244, no. 5418 (1973): 545551.27. J. K. Angell and J. Korshover, Global Analysis of Recent TotaOzone Fluctuations, Monthly Weather Review104, no. 1 (1976)6375.28. Michael J. Mills, Owen B. Toon, Richard P. Turco, DouglasE. Kinnison, and Rolando R. Garcia, Massive Global Ozone LossPredicted Following Regional Nuclear Conflict, Proceedings othe National Academy of Sciences of the USA105, no. 14 (2008)53075312.

Even a modest regional exchange ofnuclear weapons in an IndiaPakistanexchange scenario might yet producesignificant worldwide climate effects, ifnot the original full blown winter.


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Nuclear Winter. The possibility of catastrophicclimate changes came as yet another surprise toDepartment of Defense scientists. In 1982, Crutzenand Birks highlighted the potential effects ofhigh-altitude smoke on climate,29 while in 1983,Richard Turco, Owen Toon, Bruce Ackerman, BrianPollack, and Carl Sagan (TTAPS) suggested that a

Figure 3. TTAPS Nuclear Winter Predictions. Thesecalculations show the drop in surface land temperature levelsover time for various nuclear exchange scenarios. Note the

prediction of temperature drops for most of the exchangescenarios considered below the freezing point of water formonths. The scientific controversy over these results remainsunresolved.

5,000-megaton strategic exchange of weaponsbetween the United States and the Soviet Unioncould effectively mean national suicide for bothbelligerents.30They argued that following a massivenuclear exchange between the United States and theSoviet Union, copious amounts of soot, generated by

massive firestorms such as witnessed in Hiroshima,would be injected into the stratosphere, where it can

29. Paul J. Crutzen and John W. Birks, The Atmosphere After aNuclear War: Twilight at Noon,Ambio11, no. 23 (1982): 114125.30. Richard P. Turco, Owen B. Toon, Thomas P. Ackerman, JamesB. Pollack, and Carl Sagan, Nuclear Winter: Global Consequencesof Multiple Nuclear Explosions, Science 222, no. 4630 (1983):12831292.

reside indefinitely. Additionally, the soot would beaccompanied by dust swept up in the rising thermacolumn of the nuclear fireball. The combinationof dust and soot could scatter and absorb sunlighto such an extent that much of the Earth would beengulfed in darkness sufficient to cause cessationof photosynthesis. Unable to sustain agriculture foran extended period of time, much of the planetspopulation would be doomed to perish, andin itsmost extreme renditionhumanitys fate would beto follow the dinosaurs into extinction and by muchthe same mechanism.31 Subsequent refinementsby the TTAPS authorssuch as an extension ofcomputational efforts to three-dimensional modelscontinued to produce qualitatively similar results.

The TTAPS results were subjected to severe

criticism, and a lively scientific debate ensuedbetween passionate critics and defenders of the TTAPSanalysis. Some of the technical objections raisedincluded the neglect by TTAPS of the potentiallysignificant role of clouds;32lack of an accurate modeof coagulation and rainout;33 inaccurate capture ofeedback mechanisms;34fudge factor fits of micron-scale physical processes assumed to hold constantfor changed atmospheric chemistry conditions anduniformly averaged on a grid scale of hundreds ofkilometers;35 the dynamics of firestorm formation,

rise, and smoke injection;36

and estimates of the

31. Charles G. Wohl, Scientist as Detective: Luis Alvarez andthe Pyramid Burial Chambers, the JFK Assassination, and the Endof the Dinosaurs, American Journal of Physics75, no. 11 (2007)968977.32. Eugene F. Mallove, Lindzen Critical of Global WarmingPrediction, MIT Tech Talk, September 27, 1989, http://wwwfortfreedom.org/s46.htm.33. Michael C. MacCracken and John J. Walton, The Effects oInteractive Transport and Scavenging of Smoke on the CalculatedTemperature Change from Large Amounts of Smoke, in ThirdConference on Climate Variations and Symposium on ContemporaryClimate: 1850-2100,pp. 67, http://gate1.baaqmd.gov/pdf/2071_Third_Conference_Climate_Variations_Symposium_Contemporary_Climate_1850-2100_1985.pdf.34. Richard S. Lindzen, On the Scientific Basis for GlobaWarming Scenarios, Environmental Pollution83, no. 12 (1994)125134.35. Freeman Dyson, The Scientist as Rebel(New York: The NewYork Review of Books, 2006).36. J. E. Penner, L. C. Haselman, and L. L. Edwards, 1986: SmokePlume Distributions above Large-Scale Fires: Implications foSimulations of Nuclear Winter, Journal of Applied Meteorology25, no. 10 (1986): 14341444.


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optical properties and total amount of fuel availableto generate the assumed smoke loading. In particular,more careful analysis of the range of uncertaintiesassociated with the widely varying publishedestimates of fuel quantities and properties suggesteda possible range of outcomes encompassing muchmilder impacts than anything predicted by TTAPS.37

Aside from the technical issues raised by critics,the rapid decrease in number of weapons in nucleararsenals of the major powers along with decreasedaverage yields of the remaining weapons combinedto render the 5,000-megaton baseline exchangescenario envisioned by TTAPS obsolete. With thesubsequent demise of the Soviet Union, the nuclearwinter issue has pretty much fallen off the radar screenof Department of Defense scientists, which is not to

say that it completely disappeared from the scientificliterature. In the last few years, a number of analysts,including some of the original TTAPS authors, havesuggested that even a modest regional exchangeof nuclear weapons100 explosions of 15-kilotondevices in an IndiaPakistan exchange scenariomight yet produce significant worldwide climateeffects, if not the original full blown winter.38However, such concerns have failed to gain muchtraction in Department of Defense circles.

Impact of Dust and Debris on Aircraft. Some

natural phenomena can emulate certain effects ofnuclear explosions and are comparable in terms ofthe total energy release. They too have yieldedsurprising results. One such event was the 1982volcanic eruption of Mount Galunggung in Indonesia.This event lofted many millions of tons of volcanicash high into the atmospherean amount that wouldroughly correspond to that created by a nuclearsurface burst of several tens of megatons. A BritishAirways 747 accidentally traversed the ash cloudduring a night flight en route from Kuala Lumpur to

Perth. It promptly lost all four engines and descendedwithout power for 16 minutes from 38,000 to25,000 feet, when the crew was able to restart three

37. Joyce Penner, Uncertainties in the Smoke Source Term forNuclear Winter Studies, Nature324, no. 6094 (1986): 222226.38. O. B. Toon, R. P. Turco, A. Robock, C. Bardeen, L. Oman, andG. L. Stenchikov, Atmospheric Effects and Societal Consequencesof Regional Scale Nuclear Conflicts and Acts of individual NuclearTerrorism, Atmospheric Chemisty and Physics 7 (2007): 19732002.

Figure 4. Mt. Galunggung Volcanic Eruption, August 161982. Atmospheric particulates from this volcano, shownhere towering over Tasikmalaga, Indonesia, damagedcommercial aircraft traversing the plume and alertedscientists to the possibility of analogous effects produced bygeological particulates scoured by a nuclear blast and loftedto altitude in the iconic nuclear mushroom cloud.

of the four engines. During a diversion landing inJakarta the crew reported that the cockpit windscreenswere completely opaque, a result of sandblasting bythe highly erosive volcanic ash. By the same

mechanism, the glass lenses on the landing lights hadbeen so scoured that the light was barely visible.Subsequent inspection of the engines showed severeerosion of the compressor rotor blades and glass-likedeposits of fused volcanic ash on the high-pressurenozzle guide vanes and the turbine blades.39

39. B742, En-Route, Mount Galunggung Indonesia, 1982 (WXLOC), SKYbrary, http://www.skybrary.aero/index.php/B742,_enroute,_Mount_Galunggung_Indonesia,_1982_(WX_LOC)


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Recognizing the similarity of a nuclear surface burstto a volcanic event in terms of its dust-lofting potential,the Defense Nuclear Agency alerted the Strategic AirCommand (now STRATCOM) of the imminent hazardfacing strategic bombers entering airspace where

dust and debris clouds had already been created bythe preceding missile strikes. This was the start of amulti-year program to investigate the response ofstrategic aircraft engines to dust ingestion, leading tothe development of both technical and operationalmitigation measures.

ENDURINGUNCERTAINTIESANDWANINGRESOURCES

It is important not to conflate surprises withuncertainties. Surprises represent previouslyunanticipated phenomena uncovered in the course of

test activities or late-breaking insight. Once surprisehas been realized and the new phenomenologyunderstood, large residual uncertainties may still existbecause many of these unanticipated phenomenawere uncovered late in the test program, wereinadequately studied, or are inherently difficult tomodel. Moreover, the historical experience withnuclear weapons effects research imparts a naggingfeeling that there could be surprises yet to come thatwill be revealed only in the actual use of nuclearweapons.

While surprises helped to shape the nuclearweapons effects investments over the years, noteverything was learned as a result of surprises. Indeed,the Defense Nuclear Agency spent tens of millionsper annum up until the mid 1990s to maintain arobust research program in nuclear weapons effects,spanning computer modeling, simulator design,fabrication and operation, and large-scale fieldtesting (including underground nuclear tests up until1992). Such a sustained program was key to amassingthe extensive wealth of knowledge available to thecommunity today. However, the results of currentefforts to maintain and extend the existing knowledgebase on nuclear weapons effects are decidedly mixed.

The United States, in voluntary compliance withthe still unratified Comprehensive Test Ban Treaty,has not carried out a nuclear test since 1992, nor isthere any realistic prospect that such testing will beresumed in the foreseeable future. To compensate

for the lack of testing, the Department of Energyhas adopted a program known as Science-BasedStockpile Stewardship,40which advocates the use ofhigh-performance computing to better understandnuclear weapons physics along with heavy reliance

on highly specialized experimental facilities, suchas the National Ignition Facility, to validate keymodeling features. The National Laboratories havemade impressive strides in simulating the end-to-endperformance of nuclear warheads and the associatedweapon effects. However, critics argue that thevagaries of aging warheads and the complexityof the governing physics will always befuddle theconclusions drawn from such simulations.

Figure 5. DECADE X-Ray Simulator Module. Thisphotograph shows the first of four pulsed power modulesplanned for the DECADE simulator. The simulator was nevercompleted, a victim of post-Cold War apathy and budgetarydeclines visited upon all matters nuclear. A similar fateeventually befell many other nuclear effects simulators.

With the intense competition for resources in theDepartment of Defense, the prospects for establishingan analogous Nuclear Weapons Effects Stewardship

program remain dim. After the 1998 transition of theDefense Nuclear Agency41 to the Defense Threat

40. Raymond J. Juzaitis, Science-Based Stockpile Stewardship: AnOverview, Los Alamos Science28 (2003): 3237.41. In 1996, the Defense Nuclear Agency was renamed theDefense Special Weapons Agency with no change in missions. Pethe recommendations of the 1998 Defense Reform Initiative, theDefense Special Weapons Agency was combined with several othesmaller Department of Defense agencies to form the Defense ThreaReduction Agency.


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Reduction Agency (DTRA) with its considerablyexpanded mission portfolio, nuclear weapons effectsresearch has taken a back seat in both the experimentaland computational domains. No replacement for theloss of underground nuclear testing was ever

adequately developed or funded. DTRA no longerconducts large-scale, above-ground blast and shocksimulations, and radiation simulators have beenreduced to bare essentials. Despite several feebleattempts to do so, a meaningful revitalization ofscientific computing to help compensate for the lackof testing capabilities is still languishing.

A common affliction at both the Department ofEnergy and Department of Defense is the continuingbrain drain of nationalnuclear expertise

as nuclear expertsretire. They have notall been replaced byyounger scientists,who are less likelyto be attracted to afield where they canno longer aspire totest their creationsand where overallgovernment funding

has declined precipitously since the end of the ColdWar. None of these factors inspires much confidencethat persisting uncertainties in understanding nucleareffects are likely to be reduced any time soon.

The ongoing diminution of American nuclear expertiseis taking place against a backdrop of growth of nuclearexpertise in other countries. The spread of weaponsdesign sophistication from scientifically advancedcountries to less advanced nuclear aspirants is no longera threat but an accomplished fact. While these maynot yet include the most sophisticated yield-to-mass or

specially tailored output designs, there is little doubt thatcapabilities are spreading and, absent an effective treatyregime that prevents it, will continue to do so. Muchnuclear weapon information has diffused even into thepublic sphere, from the classic Los Alamos Primer42

42. Robert Serber, The Los Alamos Primer: The First Lectures onHow To Build an Atomic Bomb, LA-1 (Los Alamos, NM: Los AlamosNational Laboratory, 1943). This document was declassified in theearly 1960s.

and the Smyth Report43to the Department of DefensesThe Effects of Nuclear Weapons.44There are also manynon-governmental resources available on the web sitesof organizations such as Wikipedia, the Federation ofAmerican Scientists, the Union of Concerned Scientists

the Natural Resources Defense Council, and the NuclearWeapons Archive, which maintains Nuclear WeaponsFrequently Asked Questions.45

Recently, some additional increase in attentionand resources has been devoted to answering newquestions and reducing older uncertainties in thenuclear effects knowledge base. After going throughfunding cuts in the 1990s following the collapse of theSoviet Union and a deeper decline in the first decade

of the new century,the reality of a

continuing nucleaproliferation to rogueregimes and risingconcern over nucleaterrorism has spurreda modest revival ofinterest in nucleaeffects by militaryfunding agencies. Arising congressionainterest in the

vulnerability of our civilian infrastructures to bothnuclear and nuclear-like events, such as very largegeomagnetic solar storms, has also contributedto increased attentionalthough so far almost nofundingon the part of civilian funding agenciesHowever, the current status of nuclear effects researchremains dismal. Most notably, the newer questionsthat focus on more general societal consequences andwhich directly impact an ability to perform a credibleconsequence assessment have not been aggressivelypursued.

43. Henry DeWolf Smyth, Atomic Energy for Military Purposes(Princeton, NJ: Princeton University Press, 1945).44. Samuel Glasstone and Philip J. Dolan, Effects of NucleaWeapons, 3rd ed. (Washington, DC: U.S. Department of Defenseand United States Department of Energy, 1977).45. Carey Sublette, Nuclear Weapons Frequently AskedQuestions, The Nuclear Weapon Archive: A Guide to NuclearWeapons, last modified July 3, 2007, http://nuclearweaponarchiveorg/.

Newer questions that focus on moregeneral societal consequences andwhich directly impact an ability toperform a credible consequenceassessment have not been aggressivelypursued.


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III. PHYSICAL EFFECTS: WHAT WE KNOW,

WHAT IS UNCERTAIN, AND TOOLS OF THE

TRADE

While we have not likely exhausted potential occa-sions for surprise and uncertainties persist, afternearly seven decades of intensive investigation, thereis actually quite a bit that we do know. In this section,we first provide summaries of the state of our knowl-edge across a range of physical nuclear effects andoffer a qualitative characterization of the attendantuncertainties associated with each. These summa-ries are followed by a description of tools in currentuse for consequence prediction and other sources ofknowledge influential in shaping public perceptions.

NUCLEARWEAPONSEFFECTSPHENOMENA

In each of the summaries that follow, we haveendeavored to briefly describe the phenomenonand the nature of its effects and to characterize ourlevel of knowledge as well as lingering uncertaintiesthat may stem from an inaccurate prediction of thenuclear environment, errors in characterization ofsystem response, or both. We have attempted to limitthe technical complexity of our descriptions withoutsacrificing accuracy.

Prompt Radiation. A detonating weapon will emitionizing radiation in the form of high-energy particles(alpha, beta, neutron) and electromagnetic energy(gamma rays, x-rays, UV). Radioactive decay of thefission fragments will continue to release alpha,beta, and gamma radiation. The radiation from thefission event and the radioactive decay of the fissionfragments up to 1 minute after detonation togetherhave traditionally been defined as the promptradiation environment.

Ionizing radiation is highly injurious to personnel

and, at high dose levels, can lead to rapid incapacita-tion and death. Lower levels of exposure can increasea persons probability of contracting various cancers.

Gamma rays and neutrons can also penetratedeeply into electronic components and may damagethe materials and electronic devices that compriseintegrated circuits. Gamma rays induce stray currentsthat produce strong local electromagnetic fields;neutrons interact directly with semiconductor

materials and change their electrical propertiesX-rays and gamma rays may also darken optical fibersand damage optical elements. Additionally, for near-surface bursts, energetic neutrons will activate variouselements found in air, soil, structures, and other man-made infrastructure components. Activated elementswill subsequently undergo radioactive decay,releasing potentially harmful ionizing radiation.

At low altitudes, the atmosphere will absorb alx-rays within a few meters. This creates a hot firebalthat subsequently drives a strong airblast. In space,x-rays travel unimpeded and imperil satellites to greatdistances, damaging optics and distorting critical-tolerance structural components.

The physics of prompt ionizing radiation is welunderstood and uncertainties of the sort that would

preclude a consequence assessment might best becharacterized as low. However, greater emphasisneeds to be placed on three-dimensional calculationsto better understand the mitigating effects oshadowing for detonations in an urban landscapeSuch effects could significantly alter prompt radiationcasualty counts.

Electromagnetic Pulse. A high-altitude (ove40 kilometers) nuclear burst will, through aphoton-scattering process known as the Compton

effect, produce copious quantities of electronswhose interaction with Earths natural magneticfield will generate a massive electromagnetic fieldwith a terrestrial footprint extending over thousandsof square miles. For example, the EMP footprint ofa detonation at an altitude above approximately500 kilometers over Omaha, Nebraska wouldencompass the entire contiguous 48 states. Howeverbecause the intensity of the electrical disturbancegrows weaker as the distance from the detonationpoint increases, an EMP attack may more likely

be targeted at lower altitudes and closer to higherpopulation density areas of the country, i.e., abovethe east or west coasts or both.

The electromagnetic impulse itself includes a fastshock component (termed E1),46 whose durationmay last only billionths of a second but may coupledamaging energies into electronic components such

46. E1 is generated by gamma-scattered Compton electronsturning in the Earths magnetic field.


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as computers, switches, and short runs of electricalwires, andfor large energy yield weaponsalso aslow shock component (termed E3),47 which maylast milliseconds to seconds and impress damagingimpulses on long runs of conducting wires such as thetransmission lines that tie the power grid together.48

Figure 6. EMP Coverage Contours. EMP coverage areaon the ground increases with increased height of burst. Anuclear detonation at an altitude of 500 kilometers overOmaha, Nebraska will generate an EMP that covers thecontiguous land mass of the United States. The electric fieldstrength diminishes with increased distance from groundzero directly under the burst. The asymmetry in contours is

a result of the orientation of the Earths magnetic field withrespect to the detonation point.

For detonations near ground level, there is also anEMP generated by a different physical mechanism.49This phenomenon is termed source region EMP(SREMP) and may severely damage electronic

47. E3 is generated by expulsion of magnetic flux from the ionized,expanding nuclear fireball and by the additional displacement offlux due to the rise (heave) of a heated and ionized patch ofatmosphere directly under the detonation point.48. The E2 component of EMP immediately follows E1 and isdominant in the time domain from about 1 microsecond to 1second. It is of significantly lower intensity than the E1 componentand is generated by late arriving neutrons and scattered gamma rays.It has the electrical pulse characteristics of lightning, and becausestandard lightning protection also offers protection against E2,this component is often neglected in discussions of high-altitudeEMP. There are circumstances, however, when E2 may assumeimportance, such as in a scenario where an E1 pulse first damageselectronic circuit breakers and other lightning controls.49. SREMP is generated by an asymmetric current of Comptonelectrons.

components that fall within its footprint. However, itseffects tend to be localized, generally within the blast-damaged region already affected by the immediatedestructive effects of the bomb. Nevertheless, insome scenarios, the damaging electric currents maybe conveyed on long runs of conductors to regionsbeyond those immediately proximate to the burstlocation and contribute additional electronic damagebeyond the blast zone.

The Department of Defense has sponsored a numbeof attempts to achieve a robust predictive capabilityof EMP-induced damage against specific targets but,in the final analysis, relegated EMP damage to abonus effect. Nonetheless, our own critical militarysystems have generally been hardened against thesort of electronic damage that might be produced by

an adversary weapon.However, it is only very recently that any attention

has been paid to assessing the broader societaand infrastructural issues associated with EMPSpecifically, the EMP Commission has focusedattention on damage that might be incurred by thevulnerability of critical digital control systems andother electronic systems that pervade and sustainmodern technological societies. While progress hasbeen made, there remain wide uncertainty bands.

Airblast. A nuclear blast wave emerges from thefireball as a spherical shock front characterized by asharp increase in static overpressure (above ambientpressure). Behind the shock front, the overpressuredecays sharply and actually reaches negative values(below ambient pressure) in the tail of the blast waveThe blast wave also produces strong winds (dynamicpressure) as the air is displaced radially outwardand subsequently inward during the negative phaseOverpressure can crush or weaken a structure;dynamic pressure can displace or tear a structure

apart through drag forces. The range from ground zeroto a specific level of overpressure increases with theheight of the detonation up to an optimal height ofburst and then decreases sharply for greater heights.50

The dynamic pressure follows similar trends.

50. This trend is most prominent at overpressure levels belowabout 100 psi. The optimum height of burst is often referred to asthe knee in the overpressure curves, represented as iso-pressurecontours plotted in height-of-burst versus range space.


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Airblast is perhaps the most studied and bestunderstood of all the nuclear weapon effects becausethe propagation medium (air) is well characterized,and similitude considerations allow scaling of airblastfrom small-scale conventional explosions tolarge-yield nuclear explosions. However, real-worldenvironments can introduce significant perturbationsin so-called idealized airblast approximations.Terrain, whether natural or man-made, cansignificantly modify the local blast environment.Also, past nuclear tests have shown that fireballheating of certain surfaces can produce a blow-off ofhot particulates, which in turn heat a layer of airadjacent to the surface. The higher sound speed inthis heated layer causes the portion of the shock wavetraveling within it to speed up, creating a precursorwave that propagates ahead of the main shock. The

Figure 7. One Kiloton Iso-Pressure Contours. In the MachReflection region, the incident and reflected shock waveshave merged to form a single shock front called the Machstem. Extended knees in the Mach reflection region, moreprominent at overpressure levels below 100 psi, makeairbursts more effective for maximum overpressure damageto structures and other ground targets. 51

51. The Regular Reflection region starts at ground zero and ischaracterized by an incident shock wave followed by a reflectedshock wave, which intersect at the ground surface. At a rangeapproximately equal to the height of burst, the reflected shock wave,which is traversing shock-heated air, catches up and begins to mergewith the incident shock wave to form a single shock wave knownas the Mach stem. This is the start of the Mach Reflection region.In the Regular Reflection region, an above-ground structure willexperience two shock waves; in the Mach Reflection region, such astructure would see only one shock wave, provided the Mach stemhas grown to a height that is taller than the structure at that groundrange.

resulting near surface, dust-laden flowfield is highlyturbulent and characterized by significantly enhanceddynamic pressure. Finally, atmospheric conditionssuch as temperature inversions can significantly affecthe range for low overpressure effects, includingdamage to unhardened structures and windowbreakage. These non-ideal blast perturbations dependupon the vagaries of the local environment and arelargely ignored in present day predictive tools.

Most of our predictive airblast algorithms assumethe air-ground interface to be a flat and perfectlysmooth surface. For nuclear weapons detonatedwithin or above a city, such an assumption is not validHowever, with modern computational techniques, itis possible to create a computational grid for an entirecity and calculate the shock waves as they reverberate

and diffract in and around buildings. While suchcalculations may be computationally intensive,current knowledge will support an assessment ofairblast effects at painstaking levels of detail andfidelity.

Groundshock. Groundshock is created by the directcoupling of energy to the ground in the vicinity of thecrater, assuming a ground burst, and by the airblast-induced motions at the air-ground interface for bothground and air bursts. The subsequent propagationof the stress wave in the ground is governed by the

geologic stratification and the material propertiesof the various strata, which are rarely known tosufficient fidelity to allow a confident prediction ofstress, acceleration, velocity, and displacement atdepth. Most groundshock predictive codes assumecontinuum behavior of geologic material, when infact many geologic materials, such as jointed rock,behave in a much more discretized manner.

The effects of groundshock on structures areclosely related to those of an earthquake, although

considerably lower in displacement and duration. Foa surface burst, the groundshock domain of plasticdeformation extends out to about 2 to 3 crater radiiWithin this region, the combined direct- and airblast-induced groundshock can significantly damageunhardened infrastructure components such as utilitypipes and subway tunnels. Beyond the plastic region,airblast effects will dominate any groundshock effectswith respect to structural damage.


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For underground explosions, as in the case of aterrorist device detonated on the lower levels of anunderground parking garage, groundshock will bethe dominant damage mechanism for the surroundingbuildings. Assuming a rudimentary understanding ofthe local geology and constitutive properties, extantpredictive tools are sufficient to support order ofmagnitude assessments of the effects of groundshock.For surface or above-ground detonations, airblastwill dominate and groundshock will not have anysignificant play.

Cratering. Most of the nuclear cratering database comes from the large-yield (megaton) testingprogram, conducted on various islands of EnewetakAtoll, also known as the Pacific Proving Grounds(PPG). A small number of low-yield (kiloton) tests

were conducted at the Nevada Test Site (NTS). Themorphology of the craters from the NTS tests, withtheir characteristic bowl shape, was significantlydifferent from the pancake-shaped craters observedduring the PPG eventsan anomaly that was notresolved until the 1980s and ultimately attributed tothe gradual slumping of the weaker crater walls in thecoral geology of the PPG. A considerable number ofsub-surface cratering bursts were also conducted atNTS to evaluate the excavation potential of nuclearweapons for peaceful purposes, under the Plowshare

Program.In general, the size and shape of the crater are

strongly dependent on the burst height (or depth), theyield, and the geology. Assuming a weapon with afixed yield, as the burst height is lowered, the firstcrater manifestation is that of a compression crater,created by the reflection of the shock wave from theair-ground interface. As the burst height approachesthe surface, an excavation crater begins to form. Thecrater volume increases substantially for detonationsbelow the surface and reaches a maximum at the

optimal depth of burst.52Below this depth, the cratersize and volume decrease, largely because of fallbackand ultimately because the downward force of thegeologic overburden approaches the upward forceproduced by the explosion. At that point, there may

52. As an example, the Peaceful Nuclear Explosion (PNE) EventSedan conducted in desert alluvium at NTS in 1962 achieved anoptimal depth of burst at 635 feet for a 104-kiloton device, forminga crater that was 320 feet in depth and 1,280 feet in diameter.

still be a surface vestige of the explosion, manifestedin some geologies as a bulking or uplift near groundzero. This is sometimes referred to as a retarc(crater spelled backwards). At still deeper depthswhere the overburden is sufficient to fully containthe energy release, the underground cavity createdby the explosion will eventually collapse, causingthe column of soil above it to slump and form asubsidence crater at the surface.

Figure 8. The Sedan Crater. A physical relic of the daywhen the United States and the Soviet Union explored the

peaceful uses of nuclear weapons, the Sedan Crater stillooms large today at the Nevada National Security SiteCreated by a specially designed high-fusion output devicewith a yield of 104 kilotons detonated at the optimum depthof burst, it is one of the largest such excavations on Earthand served as a training venue for Apollo astronauts. Photocourtesy of the National Nuclear Security Administration/Nevada Field Office.

While the cratering phenomenon is reasonablywell understood, the variation in the geology anduncertainties in geophysical properties make itdifficult to confidently predict crater size for anarbitrary location and burst geometry. However, thecombined weapon effects environment in the vicinityof the crater virtually ensures total destructionAccordingly, the inherent uncertainties in thecratering phenomenon are important primarily as asource function for lofted radioactive particulates andtheir subsequent fallout.


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Underwater Explosions. One of the first nucleartests following the Trinity event was a 21-kilotonunderwater explosion, detonated 90 feet below thesurface (halfway to the ocean bottom), near the islandof Bikini. Dubbed Operation Crossroads, Event Baker,the explosion created a bubble that vented and formeda tall column of water, collapsing of its own weightseconds later. This in turn created a 900 feet tall basesurge, not unlike the mist created by a waterfall.Unfortunately, the mist was highly radioactive, andit coated virtually every ship involved in the test.Because this was totally unexpected, no provisionsfor the decontamination were made.

Figure 9. Operation Crossroads, Event Baker. The Bakeratomic test was conducted at Bikini Atoll on July 25, 1946using a Fat Man device. It was the second test conducted

after the Hiroshima and Nagasaki bombings in 1945 andthe first underwater test. Eight of 57 Navy test ships wereunintentionally sunk; all ships within 1,000 yards of thedetonation sustained serious structural damage, and allvessels were heavily contaminated by unexpected base surgefrom the collapsing water-laden cloud stem.

While we understand the physics of underwatershock formation and associated damage to ships, thebase surge effect is still poorly understood. Thedetonation of even a relatively low yield nuclearexplosion in the harbor of a large coastal city could

result in massive contamination of high populationcenters. The additional damage that might be createdby any associated water waves is also poorlyunderstood, and toolsets for doing so are lacking.

Fires. Nuclear explosion initiation of fires is amulti-faceted and temporally staged phenomenon.The thermal pulse emanating from the fireball andheated air surrounding it will initially ignite manyof the exposed flammable surfaces within its line

of sight, out to some distance where the intensityof the radiated pulse has weakened sufficientlyThere follows a complex interaction with the trailingnuclear blast wave, which may snuff out many of theinitial ignitions. Subsequently, secondary ignitionswill contribute to fire growth following blast damageto gas lines, stoves, and similar fire sources. Fires thusstarted may continue to grow and spread damagebeyond the initial blast damage zone.

In the two instances of nuclear weapon employmenduring World War II, the large number of simultaneousignitions produced firestormsextraordinarilyintense, large-area mass fires with most of theencompassed fuel burning all at once and radiallyinward directed hurricane-scale winds feedingfresh oxygen to the infernothat made escape by

survivors from the blast affected areas in Hiroshimaand Nagasaki almost impossible.53,54 Modern urbancenters with concrete and steel construction replacingwood may prove more resistant to such firestormformation, but many cities in the third world remainsusceptible to the outbreak of such a conflagration.

While the incidence of nuclear-weapon-ignitedfires is inevitable, predicting the scale of suchevents has proven difficult. The nuclear weaponscommunityincentivized to account for fire startsbecause incorporating such effects would mean

each weapon could be counted as more effective intargeting plans and by a desire to avoid unwantedcollateral effectshas invested in multi-year efforts to

53. The Allied strategic bombing campaigns during WWIattempted to achieve similar incendiary effects through patternedlaydowns but, according to the U.S. Strategic Bombing Surveyquoted in the 1983 National Academy of Sciences report The Effectson the Atmosphere of a Major Nuclear Exchange, succeeded onlyon four occasions, in Dresden, Hamburg, Kassel, and Darmstadtwhere the dense fuel loadings of wood-constructed buildings andthe closely spaced and near simultaneous ignitions over a largetarget area produced an extreme fire phenomenon. Loss of life wassimilarly horrificcumulative estimates vary widely, ranging from167,000 to 300,000 for the four eventswith similar reports ofinability to escape the burning zone.54. The conditions that define a firestorm and whether thoseconditions are met in individual instances remain matters of scientificcontroversy. Thus, for example, Nagasaki is not categorized as afirestorm by some assessments that point, inter alia, to hilly terrainthat may have impeded ignition and coalescence to the degreeexperienced in Hiroshima. Darmstadt and Kassel, which suffereddevastating fire damage and many thousands of casualties, arenevertheless left off some lists of WWII firestorms.


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some of whom are also continuing to investigatethe ozone depletion issue, continue to argue for itsimportance.

Fallout. Following a nuclear blast in theatmosphere, radioactivity from fission products

and neutron-activated particulates will serve asatmospheric contaminants threatening humanhealth when they fall back to Earth over the courseof hours to days, exposing population to the directharmful effects of radiation and contaminating theenvironment for extended periods. Exposure tointense levels of radiation will be lethal within arelatively short period, hours to perhaps days. Lessthan immediately lethal exposure may eventuallycause cancers and other life-shortening illnesses.

Figure 11. HPAC Fallout Prediction. Depicted are the bandsof varying fallout contamination as predicted by the HazardPrediction Assessment Code (HPAC). Each color contourrepresents the cumulative dose that would be seen by asensor situated at that location from the time of detonation.Because many fission products decay rapidly, a sensorintroduced at later times would accumulate a significantlylower total dose.

The morbidity and mortality curves for radiationexposure are well understood, as is the generation ofthe initial amount of radioactive material by thenuclear burst. Although excellent transport modelsnow exist, less predictable are the subsequentphysical dispersion and scavenging processes in theatmosphere and the longer term infiltration of theagricultural cycle. Multi-year contamination of the

environment may render regions effectivelyuninhabitable, absent heroic cleanup endeavors. The

Japanese fallout/rainout experience has been intenselyinvestigated along with U.S. atmospheric testexperience, and much progress has been mademodeling the process to include such atmosphericeffects as scavenging and rainout. Statistical tools areavailable to provide reasonable estimates ofpopulation exposure.

Human Response. Humans are susceptible tovirtually all nuclear weapons effects except EMPsave for those who are dependent on electricadevices for their viability. Prompt ionizing radiationcauses cellular damage; the thermal pulse causesflash blindness and burns; the shock wave can induceblunt-force trauma, eardrum rupture, contusions, and

bone fractures; and fallout creates a radiation hazardthat, depending on dose, can result in responsesranging from prompt death to late-stage cancers.

The experiences at Hiroshima and Nagasaki remainthankfully, the only direct source of information aboutthe human response to the thermal pulse of a nuclearweapon and have been extensively analyzed. Decadesof research, including extensive animal studies, andwartime use, as well as inadvertent human exposuresin military, medical, and the civilian power industryhave provided a firm basis for understanding and

predicting the response of humans to different levelsof radiation exposure. The response of unprotectedhuman bodies to the impulsive force of a nuclearairblast is also very well understood from extensivepast explosive effects testing and insights gained fromwartime experience.

High-Altitude Nuclear Effects (other than EMP)High-altitude nuclear explosions create significanregions of ionization above ambient conditions,caused by direct interaction of bomb gamma

rays, neutrons, and x-rays with air molecules, betadecay of bomb fission products, and positive ionsin the weapon debris. These ionization regions caninterfere with radio frequency (RF) (radar and radiopropagation by causing refraction and scattering,phase errors, and multipath interference. Criticasatellite communications can be disrupted, includingGlobal Positioning System (GPS) outages. Fortunatelymost of these effects are relatively short-lived, lastingfrom minutes to no more than hours.


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Public revelations56 by senior Russian officialsover the past 15 years suggest plans to field a newclass of tactical, low-yield weapons whose dominanenergy output is from fusion reactions. Others57havesuggested that it may be possible to fabricate purefusion weapons through the use of various alternativesto the classic fission trigger. If such a weapon couldbe fabricated, it would be inherently more usablebecause it produces no fallout, greatly reduces theradioactive contamination of the environment,and minimizes blast damage while delivering anenhanced lethal radiation footprint. Effects of suchweapons cannot be presumed to be the same aspredicted by current handbook and computationaalgorithms but are nonetheless calculable to withinreasonable accuracies despite a limited experimentadata base on their possible effects.

PREDICTIVETOOLS

In addition to acquiring this substantial body ofknowledge, over the years, the Department ofDefense has developed a large suite of handbooksand predictive tools to assess the consequences ofthe military application of nuclear weapons. Thereare a host of official handbooks that provide nucleareffects assessments and/or operational guidance. Themost authoritative of this genre is the venerable, and

classified, official bible of nuclear weapons effectsCapabilities of Nuclear Weapons, widely referred to byits original document designation, Effects Manual-1,or EM-1,58 which originated in the former DefenseNuclear Agency and is presently maintained andperiodically updated by its successor organization,DTRA. In the unclassified domain are MathematicaBackground and Programming Aids for the Physica

56. Such weapons are viewed as providing more credibledeterrents against U.S. conventional superiority and invasions byground troops. See for example, William Conrad, The Future ofTactical Nuclear Weapons,Air and Space Power Journal(2001).57. Andre Gsponer, Fourth Generation Nuclear Weapons: MilitaryEffectiveness and Collateral Effects (Geneva: Independent ScientificResearch Institute, 2006), 925.58. Defense Threat Reduction Agency, Capabilities of NucleaWeapons, Effects Manual Number 1(Ft. Belvoir, VA: Defense ThreaReduction Agency). An unclassified redacted version of the outlineof the 1972 edition is available at http://www.dtic.mil/cgi-binGetTRDoc?AD=ADA955403.

There is one notable exception: bomb-generatedelectrons trapped in the Van Allen belts. Low-Earth-orbiting satellites traversing these belts will demiseover a period of days to months as they accumulatea lethal dose of radiation. The 1.4-megaton StarfishPrime high-altitude burst, detonated over JohnstonIsland in the Pacific in 1962, resulted in the demise ofall publicly acknowledged satellites, and the pumpedbelts lasted into the early 1970s. Today, with thevast proliferation of space-based assets, the ensuingdisruption would be far more serious. Computationaltools that assess the accumulation of dose on orbitingspace assets from the trapped electron phenomenonare available, but predicting space environmentsproduced by modern weapon designs never testedbefore the end of the atmospheric test program in1962 comes with significant uncertainty.

WEAPONDESIGNCONSIDERATIONS

We note that there is a potential influence of weapondesign on the weapons effects discussed previously,which in some cases can be significant. However,to a first-order approximation, the nuclear analogof Saint-Venants principle55 holdsthe differencebetween the effects of different weapon designs thatproduce the same total energy yield is vanishinglysmall at sufficiently large ranges from ground zero,

regardless of the initial energy partitioning amongx-rays, gamma rays, neutrons, and bomb debris. Thisis not so for close-in effects, where the details of theoutput energy spectrum become more important. Forexample, highly energetic (hot) x-rays will couple moredeeply into geologic media, resulting in enhancedgroundshock. High-energy x-ray deposition nearground zero can also result in a dense, dusty blow-off layer, which can retard the shock wave travelingwithin it, leading to increased overpressure whencompared to calculations that ignore such surface

interactions. The magnitude of the EMP environmentresulting from a high-altitude burst may also varydepending on the device design.

55. A. Saint-Venant was a nineteenth-century elasticity theoristwho formulated the principle bearing his name that the differencebetween the effects of two different but statically equivalent loads onan extended solid body rapidly diminishes with increasing distancefrom the loaded segment.


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Vulnerability System for Nuclear Weapons,59 whichdescribes the mathematics of selected portions of thePhysical Vulnerability HandbookNuclear Weapons,and the classic and much quoted Effects of NuclearWeapons,60jointly published by the Departments ofDefense and Energy, which offers an authoritativeprimer on a wide range of nuclear weapon effects.

Figure 12. Nuclear Bomb Effects Computer. Previously

provided as a supplement to Glasstone and Nolans classicEffects of Nuclear Weapons, this shirt pocket slide rulecalculator was widely used in the 1950s1970s but has nowbeen replaced by digital computational resources that utilizefast-running predictive codes and algorithms.

Available as well is a large library of modeling andsimulation tools accessible through DTRAs IntegratedWeapons of Mass Destruction Toolset (IWMDT)enterprise services. These computational tools rangefrom simple predictive algorithms to first-principles,

finite-difference, and finite-element models and cutacross the full spectrum of conventional, nuclear,radiological, biological, and chemical weaponeffects.

59. Gilbert C. Binninger, Paul J. Castleberry, and Patsy M. McGrady,Mathematical Background and Programing Aids for the PhysicalVulnerability System for Nuclear Weapons(Washington, DC: DefenseIntelligence Agency, 1974), available at http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADB010375.60. Glasstone and Dolan, Effects of Nuclear Weapons.

While some tools carry more uncertainties thanothersin particular the high-altitude codes sufferfrom a lack of opportunity for validationthey wouldall seem adequate to provide input to a more generaconsequence assessment, but that is also their mainlimitation. Because they were developed by theDepartment of Defense to speak to issues focusedon specific defense applications, they were neverasked to assess the impact of all these effects on thebroader society. How will the various weapon effectsenumerated here affect our ability to generate electricpower to sustain a technologically advanced societyto maintain a robust telecommunications networkthat enables every financial transaction involving abank or the stock exchanges, or to protect the foodchain that feeds a population? These questions havenever been asked of our tools, and while they havemuch to contribute in response, there remains muchwork to be done.

OTHERSOURCESOFKNOWLEDGE

Often overlooked perspectives on the consequencesof nuclear use are those of the general public and thepolitical leadership of the country. For these groupstechnical descriptions of nuclear weapons effects arelargely irrelevant. Their views of consequences areshaped instead by their exposure to the history of

Hiroshima and Nagasaki, as well as by representationsof nuclear war and its aftermath in popular mediasuch as movies, television, photographs, drawings,books, and museums exhibits.

These media sources are far too vast to survey hereInstead, we merely describe a small sample to conveya sense of the emotional power of this material as awhole. Much of it falls into three broad categories(1) fictional depictions of nuclear war in books andmovies, (2) victims autobiographical accounts,personal reflections, and drawings, and (3) artifactsand photographs of the physical destruction andhuman casualties in Hiroshima and Nagasaki. Ouselection is heavily influenced by popularity and, byimplication, its influence on the public.

On the Beach61 describes the aftermath of anuclear war in which all that remains of humanity

61. Nevil Shute, On the Beach (London: William HeinemannLtd., 1957).


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is a small group in Australia facing certain death aslethal radioactive fallout approaches. This book,later released as a movie, was enormously influ-ential in shaping public perceptions about nuclearwar, even though its central premise that humanextinction wouldbe the inevitableoutcome was andremains vanish-ingly improbable.

Hadashi noGen62 (BarefootGen) is a semi-autobiographicalstory of a 6-year-old boy, Gen, and

his family, startingshortly before theatomic bombing of Hiroshima. It began as a formof manga serialized in the Japanese weekly comicShukan Shonen Jampu and was later made intoseveral film versions, a television drama series,and 10 books, which follow Gens experiencesthrough 1953. The central themes of heartbreak,loss, despair, and anger are tempered by subthemesof courage and endurance.

The Day After63 is a television movie first aired

in 1983 to an audience estimated at over 100million depicting the buildup and aftermath ofa nuclear war, the culmination of a crisis overBerlin. While NATO first uses nuclear weaponsto stop the advance of Warsaw Pact armies intoWestern Europe, which side escalates to massivestrikes against the other is unclear. What is clearare the devastating consequences to individualsand to society conveyed by following the survivorsin a small town in Kansas as they succumb to

62. Keiji Nakazawa, Barefoot Gen, Volume 1: A Cartoon Story ofHiroshima; Volume 2: The Day After; Volume 3: Life After the Bomb;Volume 4: Out of the Ashes; Volume 5: The Never-Ending War;Volume 6: Writing the Truth; Volume 7: Bones into Dust; Volume 8:Merchants of Death; Volume 9: Breaking Down Borders; Volume 10:Never Give Up.First serialized in the Japanese weekly comic ShukanShonen Jampu under the title Hadashi no Gen, 19723.63. ABC Television Network, The Day After, written by EdwardHume, produced by Robert Papazian, directed by Nicholas Meyer;first aired November 20, 1983, released on DVD by MGM on May18, 2004.

radiation poisoning, disease, and the collapseof civil infrastructures and norms of civilizedbehavior. This film, distributed internationally andshown on Soviet television, was widel

the uncertain consequences of nuclear weapons use

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