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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
2
Contents
• Introduction • Fission: nuclear data and neutronics• Fusion: nuclear data, neutronics and activation• Quantifying Quality: Uncertainties• Conclusions
3
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
4
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)
5
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.
8
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
9
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%
10
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
13
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.
19
Relative importance of regions of ITER
upper port plug
Contributions of:
equatorial port plug divertor port plug
neutron flux distributions
20
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
21
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)
22
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
23
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)
24
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.
25
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
26
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
27
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!
28
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.
32
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)