Bandelier National Monument

1 hour drive from Santa Fe;

30 minutes from Los Alamos.

Radiation

As A toxic exposureAn energy sourceAn air pollutant

Measuring Radiation

• Coming from a source– Curie (Ci) – Becquerel (Bq)

• Absorbed by a person– Rad– Gray (Gy)

• Biological risk– Rem– Sievert (Sv)*

• Definitions– Ci: 37 x 109 disintegrations/second– Bq*: 1 disintegration/second– Or: the amount of a radioactive material

released• Chernobyl released 81 x 106 Ci of cesium Cs134

Cs135 Cs137.

Rad (radiation absorbed dose):Gray* (Gy): 100 rad

Rem: rad x Q (quality factor)Sievert* (Sv): 1 SV = 100 rem

Rads or Grays depend on the type of radiation:(alpha, beta, gamma, X-ray)

*Systeme Internationale

Exposure to Radiation

• Average annual exposure:• naturally ~ 360 mrems• Occupational exposure• 5,000 mrem/year

• http://www.ans.org/pi/resources/dosechart/

• (Website of the American Nuclear Society, which considers itself the “recognized credible advocate for advancing and promoting nuclear science and technology”.)

• Common sources (in mrem)• Cosmic rays: 26• Construction: 0-7• Terrestrial: 30• Power plants: 0.04• From food & water - 40• From air - 200 (now 228)• Medical procedures• whole-body CT scan: 1000• chest X-ray: 10• chest CT scan: 700 • Dental X-ray: 4-15 (now 0.5)• barium enema: 405 (now 800)• Plutonium-powered pacemaker: 100

mrem

Sources of Exposure to Radiation in the United States Today

whyfiles.org/020radiation/ index.php?g=4.txt

Another Estimate: from WHO

http://www.who.int/ionizing_radiation/env/en/

Understanding the toxicity of radioactivity

• Early experimenters• Manhattan Project• Civilian uses

– Medical• Diagnostic

– X-rays• Therapeutic

– Baths– X-ray treatments

– Consumer goods• Watch dials• Fluoroscopes

• Nuclear power– Post WW II

Radon: the Indoor Air Pollutant

• U238 --> radium --> radon• Radon

– Inert gas– Short half-life– Radon daughters are not inert

• Source of radon:– Uranium in soil, rock strata

• Recognition of problem– 1985, Reading PA

• “Reading Prong”• Also

– Florida -- phosphate mining– Rockies --uranium tailings– Illinois - radium in bedrock

Levels likely in basements:

1: > 4 pCi/L2: 2-4 pCi/L3: < 2 pCi/L

Radon as an Indoor Air Pollutant

Bandelier National Park (image from Wikipedia)

Risk Perception

• People fear risks that are– Catastrophic– Mysterious– Not in their control

• People accept risks that are– Incremental– Well understood– Seemingly under their control

Arguments For Nuclear Power

• Intrinsically cheaper– Uranium is plentiful in the US

• Does not generate greenhouse gases• Safer than coal or oil

– Include costs of • Mining• Transport• Air pollution

• All forms of energy generate hazardous waste

• Technology to deal with small amounts of high-level waste exists– Reprocessing plutonium means

we will enver run out of nuclear fuel

• Low level waste is not a problemCoal-fired plant near Dussledorf, Germany

For a thorough defense, see: http://www.phyast.pitt.edu/~blc/book/chapter11.html

Arguments Against Nuclear Power

• Failures are catastrophic• The technology is not safe• Wastes are hazardous for millennia• Cost estimates must include waste

disposal• Mining is as hazardous as coal

mining if long-term effects are included

• Technology to deal with not-so-small amounts of high-level waste does not exist

• Reprocessing plutonium is an invotation to nuclear terrorism

• Low level waste is a problem

Three Mile Island: 1979

Arguments Against Nuclear Power: Chernobyl

• 25 April 1986• Graphite-moderated reactor

– Obsolete– Not used for power plants in US

• Melt-down• Explosion• 70% of nuclear material spewed out• 7,000-10,000 direct deaths• 300-400 millio exposed in 15 countries

– 150,000 at risk of thyroid cancer– 700,000 children at risk of

leukemia• 2 million acres farm land unuseable

– 20% of arable land in Ukraine• $400 billion costs (in USSR/Ukraine)• 200 years to repair the damage

And windmills have opponents also

Best and Worst Days: Great Smokies National Park, 1999

Air Pollution:Basics

Air Quality Varies With Season

Air Quality Varies by Region

Best days in east ~ worst days in mountain/west

East: 18-73 mile visibilityWest: 63-220 mile visibility

26 mi

137 mi

Air Quality is Actually Improving:

Emissions in tons x 106 - 1990-2003

1970

Air Pollution

N2 + O2 + CO2 +

NOx + = SmogSO2 +O3 + VOCs +Hydrocarbons +Industrial pollutants

http://mtsu.edu:11233/Smog-Atm1.htm

Great London Fog, 1952

4,000-12,000 dead

Smog over Mexico City: December 2010

http://en.wikipedia.org/wiki/Smog

Smog-Related Atmospheric Molecules

• Major:– Nitrogen: N2

– Oxygen: O2

– Carbon dioxide: CO2

• Minor:– Oxides of nitrogen: Nox

– Sulfur dioxide: SO2

– Ozone: O3

– Hydrocarbons– Industrial pollutants

• Reactions of Interest– S + O2 --> SO2

– SO3 + H2O --> H2SO4

– N2 + O2 --> NO2

– NO2 + H2O --> HNO3

Interactions1. Generation of atomic oxygen:

NO2 + hv --------> NO + O Where hv = light at < 440 nm.

2. Ozone formation:

O + O2 + M ----> O3 + M M = 3rd molecule, typically N2

or O2

.

3. Ozone destruction:

NO + O3 ----> NO2 + O2

4. Hydroxy radical formation:

4 O + H2O 2 OH

O3 + H2O ------> 2(OH) + O2 at wavelengths < 320 nm.

Formation of peroxyacetyl nitrates (PAN)

• RH + OH H2O + R where RH is any hydrocarbon

• R + O2 RO2 (very fast)

• RO2 + NO NO2 + RO where R’CHO is an aldehyde

• RO + O2 R’CHO + HO2 (very fast)

• R’CHO + OH R’CO + H2O where R’CO is an acyl radical, and

• R’CO + O2 R’C(O)O2 (very fast) R’C(O)O2 is an acylperoxyl radical

• R’C(O)O2 + NO2 R’C(O2)NO2 where R’C(O2)NO2is an acylperoxyl

nitrate

R’-C=O O-O-NO2

http://mtsu.edu:11233/Smog-Atm1.htm

40 km

390 km

Smog Over American Cities