Nuclear Data for Fission and Fusion

Arjan Koning

NRG Petten, The Netherlands

Post-FISA Workshop

Synergy between Fission and Fusion research

June 25 2009, Prague

koning@nrg.eu

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Contents

• Introduction • Fission: nuclear data and neutronics• Fusion: nuclear data, neutronics and activation• Quantifying Quality: Uncertainties• Conclusions

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Nuclear data for applications

All effects of an interaction of a particle (usually: neutron) with a nucleus in numerical form:

• Cross sections (total, elastic, inelastic, (n,2n), fission, etc.)

• Angular distributions (elastic, inelastic, etc.)

• Emission energy spectra

• Gamma-ray production

• Fission yields, number of prompt/delayed neutrons

• Radioactive decay data

• Etc.

Complete nuclear data libraries can be obtained through a combination of experimental and theoretical (computational) nuclear physics

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Introduction

Nuclear data is crucial for reactor and fuel cycle analysis:• Energy production, radiation damage, radioactivity, etc.• Currently large emphasis on uncertainties: nuclear data

uncertainites lead to uncertainties in key performance parameters

More complete and accurate nuclear data for advanced reactor systems does not prove the principle, but

• Accelerates development with minimum of safety-justifying steps

• improves the economy whilst maintaining safetyThe nuclear industry claims that improved nuclear data, and

associated uncertainty assessment, still has economical benefits of hundreds of million per year (S. Ion, ND-1997 proceedings, Trieste, Italy, p. 18)

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Nuclear data needs and tools

A well-balanced effort is required for:

• High accuracy differential measurements (Europe: JRC Geel + others)

• Nuclear model development and software (Europe: TALYS)

• Data evaluation, uncertainty assessment and library production and processing (Europe: JEFF)

• Validation with simple (criticality, shielding) and complex (entire reactors) integral experiments (Europe: e.g. CEA Cadarache (fission), ENEA Frascati (fusion))

All this is needed for both fission and fusion: the approach is similar, the energy range is different.

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Nuclear data cycle

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World Nuclear Data Libraries

ENDF/BJEFF

BROND

CENDL JENDL

Fusion: FENDL (IAEA)

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EU nuclear data measurement projects

• HINDAS (1999-2003): data above 20 MeV for ADS

• N-TOF (1999-2003): data for astrophysics and ADS

• EUROTRANS (2005-2010) – DM5: data for ADS

• NUDAME (2006-2008): neutron measurements at IRMM Geel

• EFNUDAT (2006-2008): Important network for nuclear data measurements – 11 European labs

• EUFRAT (2009-2011): neutron measurements at IRMM Geel

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Fast reactors: Target accuracies from industry and research (CEA + AREVA table)

Table 1. Fast Reactor and ADMAB Target Accuracies (1σ) Multiplication factor (BOL) 300 pcm Power peak (BOL) 2% Burnup reactivity swing 300 pcm Reactivity coefficients (Coolant void and Doppler - BOL) 7% Major nuclide density at end of irradiation cycle 2% Other nuclide density at end of irradiation cycle 10%

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SG-26 results (Salvatores et al)Table 1. Summary Target Accuracies for Fast Reactors

Energy Range Current

Accuracy (%) Target

Accuracy (%) σinel 6.07 ÷ 0.498 MeV 10 ÷ 20 2 ÷ 3 U238 σcapt 24.8 ÷ 2.04 keV 3 ÷ 9 1.5 ÷ 2

Pu241 σfiss 1.35MeV ÷ 454 eV 8 ÷ 20 2 ÷ 3 5 ÷ 8

(SFR,GFR,LFR) (ABTR,EFR)

Pu239 σcapt 498 ÷ 2.04 keV 7 ÷ 15 4 ÷ 7 σfiss 1.35 ÷ 0.498 MeV 6 1.5 ÷ 2

Pu240 ν 1.35 ÷ 0.498 MeV 4 1 ÷ 3

Pu242 σfiss 2.23 ÷ 0.498 MeV 19 ÷ 21 3 ÷ 5 Pu238 σfiss 1.35 ÷ 0.183 MeV 17 3 ÷ 5

Am242m σfiss 1.35MeV ÷ 67.4keV 17 3 ÷ 4 Am241 σfiss 6.07 ÷ 2.23 MeV 12 3 Cm244 σfiss 1.35 ÷ 0.498 MeV 50 5 Cm245 σfiss 183 ÷ 67.4 keV 47 7 Fe56 σinel 2.23 ÷ 0.498 MeV 16 ÷ 25 3 ÷ 6 Na23 σinel 1.35 ÷ 0.498 MeV 28 4 ÷ 10 Pb206 σinel 2.23 ÷ 1.35 MeV 14 3 Pb207 σinel 1.35 ÷ 0.498 MeV 11 3

σinel 6.07 ÷ 1.35 MeV 14 ÷ 50 3 ÷ 6 Si28

σcapt 19.6 ÷ 6.07 MeV 53 6

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ITER - design

Toroidal field coil Poloidal field coil

Cryostat

Vacuum Vessel

Divertor

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Fusion: Typical flux values

Plasma

First wall Blanket Shield Vacuum vessel

TF coil

9.45 x 1014

2.78 x 1014

3.30 x 1012

1.87 x 106

7.58 x 10-2 n cm-

2s-1

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Monte Carlo neutronics for ITER

Monte Carlo calculational procedure specifically suitable for ITER neutronics analyses

Many relevant parameters can be determined:

- Neutron flux distributions

- Gamma flux distributions

- Radiation dose in optical fibers + required shielding

- Dose rates in port cell

- Nuclear heating

- Other relevant response parameters

Complete and good quality nuclear data libraries are essential for a full simulation of all these effects.

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Upper port plug model with MCNP

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MCNP calculations (Hogenbirk, NRG)

neutron flux distribution

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MCNP calculations (NRG)

Gamma flux distribution

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MCNP calculations (NRG)

Distribution of radiation heat

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Relative importance of regions of ITER

upper port plug

Contributions of:

equatorial port plug divertor port plug

neutron flux distributions

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Activation

- Activation calculations are necessary for many areas of nuclear technology: fission, fusion and accelerator applications

- They provide answers on three time scales:- At short times the heat produced and the

inventory of short-lived nuclides are important to accident studies

- At medium times the -dose rate can determine operator dose and maintenance issues

- At long times the activity and radio-toxicity determine decommissioning and the disposal or recycling of materials

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Activation calculations for fusion- Fission always involves actinides and fission products

- Fusion reaction - NO production of actinides and fission products potential for very environmentally friendly energy production (tritium as an intermediate fuel)

- D-T fuel involves the production of high-energy (14 MeV) neutrons causing activation

- The amount and impact of this activated material depends on the choices made for the various components of the fusion power plant

- This crucial distinction between fission and fusion explains the large effort to understand activation of materials and to define various classes of Low Activation Materials (LAM)

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D-T neutrons- D + T 4He + n, En= 14.06 MeV, E = 3.52 MeV

- Neutrons interact with surroundings mean energy decreases due to elastic and inelastic collisions and reactions such as (n,2n)

- Reactions at all energies cause activation

- Ignoring the many reactions at low neutron energies gross under-prediction of the activation effects

First wall spectrum of a fusion power plant

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Neutron-induced reactionsReactions that are most important for fusion applications are:

- (n,2n)

- (n,p) - produces hydrogen

- (n,) - produces helium

- (n,)

- (n,n') - important if isomeric states

Isomers

- Excited nuclear state that lives sufficiently long that it is sensible to consider it as a separate species. Some isomers can have very long half-lives:

- 58mCo (8.94 h)

- 119mSn (293 d)

- 178nHf (31 y)

- 192nIr (240.8 y)

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Model calculations

Modern nuclear data libraries consist almost entirely of results from nuclear model calculations:

• Are tuned to existing experimental data

• Can produce very reasonable guessess for all particles, all energies, all nuclides, all cross sections etc. for both fusion and fission applications

• TALYS (NRG-CEA) is now the most used nuclear reaction model code in the Netherlands, France, Europe and probably the World, for fission, fusion and other nuclear applications from several keV up to 200 MeV.

• Why? Because we can not measure everything, especially above a few MeV when many reaction channels are possible.

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Loop over energies

and isotopes

PRE-EQUILIBRIUM

Exciton model

Partial densities

Kalbach systematic

Approx DSD

Angular distributionsCluster emissions

emission

Exciton model

Hauser-Feshbach

Fission cascade

Exclusive channels

Recoils

MULTIPLE EMISSIONSTRUCTURE

Abundances

Discrete levels

Deformations

Masses

Level densities

Resonances

Fission parameters

Radial matter dens.

OPTICAL MODEL

Phenomenologic

Local or global

Semi-Microscopic

Tabulated

(ECIS)

DIRECT REACTION

Spherical / DWBA

Deformed / Coupled channel

Giant Resonances

Pickup, stripping, exchange

RotationalVibrational

COMPOUND

Hauser-Feshbach

Fluctuations

Fission Emission

Level densitiesGC + IgnatyukTabulatedSuperfluid ModelINPUT

projectile n

element Fe

mass 56

energy 0.1.

TALYS code schemeTALYS code scheme

OUTPUT

Spectra

XS

ENDF

Fission yields

Res params.

FF decay

How ? 11/09/2007 - FINUSTAR 2 6/20

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Data for 27Al(n,p)27Mg

Smooth join of EAF-2003 with TALYS-5

Al-27(n,p)Mg-27

Final

Cro

ss s

ect

ion (

b)

Energy (eV)

0.0E+00

3.0E-02

6.0E-02

9.0E-02

1.2E-01

1.5E-01

0.0E+00 1.0E+07 2.0E+07 3.0E+07 4.0E+07 5.0E+07 6.0E+07

SystmTSU88ANL87KTO88KTO90AUW00RAS78MUA85TIL92BUC92TIL87TIL92USM85RI 72CHM86BIA78GEL00JAE88BIR76TSU88NPL78KOS82THS85KOS86RI 97JAE93BIA78BIR85BIR85KOS86LAS67BIA83KTY62SHI77HAR60NPL72ANL75ANL75NAP68LAS54ANL75

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Uncertainties

Since no stage in nuclear science is perfectly under control, all scientific results should come with uncertainties (or more generally, covariance data).

Providing uncertainties may be natural to experimentalists, theoretical and computational physicists are only now slowly introducing full uncertainty propagation in their methods.

This should finally lead to full uncertainty propagation in full core fission and fusion reactor design, with positive impact on safety and economical margins.

A nuclear data example: Use of the TALYS model code and computing power!

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ResonanceParameters

.TARES

Experimental data

(EXFOR)

Nucl. model parameters TALYS

TEFAL

Output

Output

ENDFGen. purpose

file

ENDF/EAFActiv. file

NJOY

PROC.CODE

MCNP

FIS-PACT

Nuclear data scheme + covariances

-K-eff

-Neutron flux

-Etc.

-activation

- transmutation

Determ.code

Othercodes

+Uncertainties

+Uncertainties

+Covariances

+Covariances +Covariances

+(Co)variances

+Covariances

+Covariances

TASMAN

Monte Carlo: 1000 TALYS runs

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Conclusions

Nuclear data development needed in 4 main categories“Front-end” of nuclear data:• High-precision differential measurements

- Address reactor sensitivity results as much as possible• Advanced nuclear models

- Main challenges: actinides and covariance data“Back-end” of nuclear data:• Nuclear data library evaluation for Sust. Nuclear Energy:

- Most important materials (actinides), including covariance data

• Validation, processing and industrial implementation:- GEN-IV, ADS, fusion sensitivity analyses, flexible use

in reactor codes, new integral measurements may be needed.

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Conclusions

With the existing

• Large experimental databases

• Modern nuclear reaction model software

• Computer power

completely new calculation methods, including uncertainty propagation, are within reach, and actually already under development.

This is especially important for reactors (GEN-IV, fusion) that require extrapolation from known cases rather than interpolation between known cases (current reactors)