Nuclear Data for Fission and Fusion Arjan Koning NRG Petten, The Netherlands Post-FISA Workshop Synergy between Fission and Fusion research June , 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 safety The 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.

6 Nuclear data cycle

7 World Nuclear Data Libraries ENDF/B JEFF BROND CENDL JENDL Fusion: FENDL (IAEA)

8 EU nuclear data measurement projects HINDAS ( ): data above 20 MeV for ADS N-TOF ( ): data for astrophysics and ADS EUROTRANS ( ) – DM5: data for ADS NUDAME ( ): neutron measurements at IRMM Geel EFNUDAT ( ): Important network for nuclear data measurements – 11 European labs EUFRAT ( ): neutron measurements at IRMM Geel

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

10 SG-26 results (Salvatores et al)

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12 ITER - design Toroidal field coil Poloidal field coil Cryostat Vacuum Vessel Divertor

13 Fusion: Typical flux values Plasma First wallBlanketShieldVacuum vesselTF coil 9.45 x x x x x n cm -2 s -1

14 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.

15 Upper port plug model with MCNP

16 MCNP calculations (Hogenbirk, NRG) neutron flux distribution

17 MCNP calculations (NRG) Gamma flux distribution

18 MCNP calculations (NRG) Distribution of radiation heat

19 Relative importance of regions of ITER upper port plug Contributions of: equatorial port plugdivertor 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  4 He + n, E n = 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 reactions Reactions 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: - 58m Co (8.94 h) - 119m Sn (293 d) - 178n Hf (31 y) - 192n Ir (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 distributions Cluster 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 Rotational Vibrational COMPOUND Hauser-Feshbach Fluctuations Fission  Emission Level densities GC + Ignatyuk Tabulated Superfluid Model INPUT projectile n element Fe mass 56 energy 0.1. TALYS code scheme OUTPUT Spectra XS ENDF Fission yields Res params. FF decay How ? 11/09/ FINUSTAR 2 6/20

26 Data for 27 Al(n,p) 27 Mg Smooth join of EAF-2003 with TALYS-5

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 Resonance Parameters. TARES Experimental data (EXFOR) Nucl. model parameters TALYS TEFAL Output ENDF Gen. purpose file ENDF/EAF Activ. file NJOY PROC. CODE MCNP FIS- PACT Nuclear data scheme + covariances -K-eff -Neutron flux -Etc. -activation - transmutation Determ. code Other codes +Uncertainties +Covariances +(Co)variances +Covariances TASMAN Monte Carlo: 1000 TALYS runs

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31 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)