Improved nuclear data for material damage applications in LWR spectra

Transcription

1 Improved nuclear data for material damage applications in LWR spectra Focus on uncertainties, 59 Ni, and stainless steel Petter Helgesson,2 Henrik Sjöstrand Arjan J. Koning 3, Dimitri Rochman 4 Stephan Pomp Klaes-Hȧkan Bejmer 5 Uppsala University, Uppsala, Sweden 2 Nuclear Research and Consultancy Group NRG, Petten, The Netherlands 3 IAEA Nuclear Data Section, Vienna, Austria 4 Paul Scherrer Institute PSI, Villigen, Switzerland 5 Vattenfall Nuclear Fuel, Solna, Sweden Petter Helgesson / 9 October 9, 25

2 Before the rest: New 59Ni cross section data produced within the MA BiL project Cross section [b] (n,α) (n,p) (n,γ) (n,el) (n,tot) -3-3 Neutron energy E [ev] 5 7 Random files for Monte Carlo uncertainty propagation Includes carefully evaluated thermal cross sections Coarse approach for the rest Petter Helgesson 2 / 9

3 Petter Helgesson 3 / 9 Using this data for stainless steel in an LWR #39 Normalized frequency # R (n,α), 59 Ni /R (n,α), Ni R (n,α), 59 Ni /R (n,α), Ni Distribution (w.r.t. 59 Ni data) for the helium production increase with nickel at 59 Ni-peak compared to natural nickel Expected increase of: 4.9±.3 Standard deviation due to 59 Ni data (7±3)% Asymmetric

4 TMC (Total Monte Carlo, []) Model parameters p (),p (2),... e.g. T6 (talys +...) d (),d (2),...,d (n) n nuclear data files e.g. mcnp. ND uncertainty propagation methodology based on random sampling of nuclear model parameters ( random ND files ) Allows for non-linearities and non-gaussian distributions No need to process covariance matrices Flexibility (extra useful for relatively non-standard applications) [] A. Koning and D. Rochman, Towards sustainable nuclear energy: Putting nuclear physics to work, Annals of Nuclear Energy 35, 224 (28) Petter Helgesson 4 / 9

5 TMC (Total Monte Carlo, []) Model parameters p (),p (2),... e.g. T6 d (),d (2),...,d (n) (talys +...) n nuclear data files What distributions to sample from? e.g. mcnp. ND uncertainty propagation methodology based on random sampling of nuclear model parameters ( random ND files ) Allows for non-linearities and non-gaussian distributions No need to process covariance matrices Flexibility (extra useful for relatively non-standard applications) [] A. Koning and D. Rochman, Towards sustainable nuclear energy: Putting nuclear physics to work, Annals of Nuclear Energy 35, 224 (28) Petter Helgesson 4 / 9

6 .4 Outline: two paths 5 y [cm] 5 5 eighted 5.6 x [cm] Belt-line weld Sensitive points 3 z [cm] y [cm] ND uncertainty of high E Flux [%] z [cm].8 2 Flux φ (E > MeV) [cm 2 s ] x [cm] barn] 59 Ni/58 Ni(initial) [%] Weighting nuclear data using experiments Example: 56 Core Reflector Full power years 35 4 (n,α) (n,p) (n,γ) (n,el) (n,tot) 9 (n,α) Fe and shielding fuel assemblies (n,p) 7 6 (n,γ) Simulating experimental errors 3 2 (n,tot) Ni for helium production in stainless steel in 4 Cross section [b] Used with LWR (n,el) 2 (n,α) (n,p) (n,γ) (n,el) (n,tot) Neutron energy E [ev] 7 z r = cm h = cm y x Normalized frequency #39 #43 Petter Helgesson 5 / R(n,α),59 Ni /R(n,α), Ni R(n,α),59 Ni /R(n,α), Ni 7

7 Petter Helgesson 6 / 9 Path starting with the example

8 Shielding fuel assemblies [2] [barn] Belt-line weld Sensitive points x 2.6 Damage to pressure vessels of Ringhals 3-4 may limit lifetime Parts of fuel replaced by steel We added uncertainty in flux due to 56 Fe data: 2.5±.2% (σ) z [cm] y [cm] x [cm] Flux φ (E > MeV) [cm 2 s ] [2] K.-H. Bejmer et al., Second Generation Shielding Assemblies Neutron Flux Impact on Reactor Pressure Vessel and Core Design, in Presented at PHYSOR 24 (24) Petter Helgesson 7 / 9

9 Shielding fuel assemblies [2] Damage to pressure vessels of Ringhals 3-4 may limit lifetime Parts of fuel replaced by steel We added uncertainty in flux due to 56 Fe data: 2.5±.2% (σ) [2] K.-H. Bejmer et al., Second Generation Shielding Assemblies Neutron Flux Impact on Reactor Pressure Vessel and Core Design, in Presented at PHYSOR 24 (24) Petter Helgesson 7 / 9

10 Shielding fuel assemblies [2] [barn] Belt-line weld Sensitive points x 2.6 Damage to pressure vessels of Ringhals 3-4 may limit lifetime Parts of fuel replaced by steel We added uncertainty in flux due to 56 Fe data: 2.5±.2% (σ) z [cm] y [cm] x [cm] Flux φ (E > MeV) [cm 2 s ] [2] K.-H. Bejmer et al., Second Generation Shielding Assemblies Neutron Flux Impact on Reactor Pressure Vessel and Core Design, in Presented at PHYSOR 24 (24) Petter Helgesson 7 / 9

11 Shielding fuel assemblies [2] [barn] Belt-line weld Sensitive points x 2.6 Damage to pressure vessels of Ringhals 3-4 may limit lifetime Parts of fuel replaced by steel We added uncertainty in flux due to 56 Fe data: 2.5±.2% (σ) z [cm] y [cm] x [cm] Flux φ (E > MeV) [cm 2 s ] [2] K.-H. Bejmer et al., Second Generation Shielding Assemblies Neutron Flux Impact on Reactor Pressure Vessel and Core Design, in Presented at PHYSOR 24 (24) Petter Helgesson 7 / 9

12 Shielding fuel assemblies [2] eighted Damage to pressure vessels of Ringhals 3-4 may limit lifetime Parts of fuel replaced by steel We added uncertainty in flux due to 56 Fe data: 2.5±.2% (σ) z [cm] y [cm] 5 5 Belt-line weld Sensitive points 5 x [cm] ND uncertainty of high E Flux [%] 3 2 [2] K.-H. Bejmer et al., Second Generation Shielding Assemblies Neutron Flux Impact on Reactor Pressure Vessel and Core Design, in Presented at PHYSOR 24 (24) Petter Helgesson 7 / 9

13 Path : Weighting random ND [3][4] Statistically rigorous inclusion of experimental data Automatized interpretation of experiments including correlations Applied to e.g. UO 2 /MOX pins, dose rate, SFA Future developments: Improved treatment of resonances Treat model defects. Experimental point # Exp. correlation matrix, 239 Pu(n,*), E MeV Experimental point # [3] P. Helgesson et al., Incorporating experimental information in the TMC methodology using file weights, Nuclear Data Sheets 23, 24 (25) [4] P. Helgesson et al., Sampling of systematic errors to estimate likelihood weights in nuclear data uncertainty propagation, Accepted for publication in Nuclear Instruments and Methods in Physics Research A, Oct. 8 (25) Petter Helgesson 8 / 9

14 Path : Weighting random ND [3][4] Statistically rigorous inclusion of experimental data Automatized interpretation of experiments including correlations Applied to e.g. UO 2 /MOX pins, dose rate, SFA Future developments: Improved treatment of resonances Treat model defects. Normalized frequency 6 x Fast flux at sensitive point with SFA 9 Unweighted Weighted Fit, unweighted Fit, weighted φ(e > MeV) [ 9 cm 2 s ] [3] P. Helgesson et al., Incorporating experimental information in the TMC methodology using file weights, Nuclear Data Sheets 23, 24 (25) [4] P. Helgesson et al., Sampling of systematic errors to estimate likelihood weights in nuclear data uncertainty propagation, Accepted for publication in Nuclear Instruments and Methods in Physics Research A, Oct. 8 (25) Petter Helgesson 8 / 9

15 Path : Weighting random ND [3][4] Statistically rigorous inclusion of experimental data Automatized interpretation of experiments including correlations Applied to e.g. UO 2 /MOX pins, dose rate, SFA Future developments: Improved treatment of resonances Treat model defects. Normalized frequency 6 3 UO2 pin cell at EOL varying 239 Pu data Unweighted Weighted Fit, unweighted Fit, weighted k [3] P. Helgesson et al., Incorporating experimental information in the TMC methodology using file weights, Nuclear Data Sheets 23, 24 (25) [4] P. Helgesson et al., Sampling of systematic errors to estimate likelihood weights in nuclear data uncertainty propagation, Accepted for publication in Nuclear Instruments and Methods in Physics Research A, Oct. 8 (25) Petter Helgesson 8 / 9

16 Petter Helgesson 9 / 9 Path 2 developed for 59 Ni within MȦBiL

17 Petter Helgesson / 9 Why 59 Ni? Many stainless steels (SS) contain % nickel But: 59 Ni does not occur in nature

18 barn] Why 59 Ni? 4 59 Ni/ 58 Ni (initial) [%] 3 2 Core Reflector Full power years Data from [5]. 58 Ni(n,γ) 59 Ni 59 Ni 59 Ni has unusually large thermal (n,α) and (n,p) cross sections! Gas production and energy release (Q α = 5.MeV) Evaluated data: No uncertainties ((n,α/p): not even in TENDL!) Gas production cross section uncertainties in action list of [6] [5] M. Griffiths, The Effect of Irradiation on Ni-containing Components in CANDU Reactor Cores: A Review, AECL Nuclear Review 2 (23) [6] R. Stoller et al., Primary Radiation Damage Cross Sections: Summary Report of the First Research Coordination Meeting, Tech. Rep. INDC(NDS)-648, IAEA-INDC (23) Petter Helgesson / 9

19 Petter Helgesson 2 / 9 Evaluating thermal cross sections Included uncertainties are identified, starting from σ = C ǫnφt or σ = CN T ǫ φ C NT ǫ φ σ, C = counts, ǫ = det. eff., N = # nuclides, φ = flux, T = time, Prime ( ) indicates reference measurement If not included: Background ǫ /ǫ ǫ N φ /φ Rel. std. dev. (%)

20 Petter Helgesson 3 / 9 Error components are simulated In each simulation: Same uncertainty contribution in several measurements same error Each cross section obtained as weighted average Bayes theorem used to include physical constraints Sample from full distribution obtained, including: Thermal (n,α) cross section [b] This work 2.87(2) ±.72(2) Mughabghab 2.3 ±.6 JEFF/ENDF 3.5 (n,α) (n,p) (n,γ) (n,el) (n,tot) (n,α) (n,p) (n,γ) (n,el) (n,tot) Correlations in %

21 Completing the n = 9 Total Monte Carlo random files Unsatisfactory source of resonance parameters % uncertainty Not trivial to use resonance parameters for (n,α), (n,p)... but possible! Low E resonances adjusted to simulated thermal cross sections Rest of ENDF files (higher E, etc.) obtained from default T6 [7] run Cross section [b] (n,α) (n,p) (n,γ) (n,el) (n,tot) -3-3 Neutron energy E [ev] 5 7 [7] A. Koning and D. Rochman, Modern Nuclear Data Evaluation With The TALYS Code System, Nuclear Data Sheets 3, 284 (22) Petter Helgesson 4 / 9

22 Helium production in SS MCNP6 model SS 34 pancake in LWR spectrum [8] Nickel content modified to 59 Ni peak (in [5]) (n,α) reaction rate compared to SS containing natural Ni x z r = cm y h = cm [8] M. Pescarini et al., ENEA-Bologna Multi-Group Cross Section Libraries for LWR Shielding and Pressure Vessel Dosimetry Applications, Tech. rep., ENEA (2) [5] M. Griffiths, The Effect of Irradiation on Ni-containing Components in CANDU Reactor Cores: A Review, AECL Nuclear Review 2 (23) Petter Helgesson 5 / 9

23 Petter Helgesson 6 / 9 Helium production in SS: the result again #39 Normalized frequency # R (n,α), 59 Ni /R (n,α), Ni R (n,α), 59 Ni /R (n,α), Ni Distribution (w.r.t. 59 Ni data) for the helium production compared to SS with natural nickel Increase of 4.9(3)±.83(6) ( 59 Ni data uncertainty of (7±3)%) Extreme observations due to coarse resonance treatment Refinement necessary More details in Licentiate thesis Defense on Tuesday!

24 Petter Helgesson 6 / 9 Helium production in SS: the result again #39 Normalized frequency # R (n,α), 59 Ni /R (n,α), Ni R (n,α), 59 Ni /R (n,α), Ni Distribution (w.r.t. 59 Ni data) for the helium production compared to SS with natural nickel Increase of 4.9(3)±.83(6) ( 59 Ni data uncertainty of (7±3)%) Extreme observations due to coarse resonance treatment Refinement necessary More details in Licentiate thesis Defense on Tuesday!

25 Petter Helgesson 6 / 9 Helium production in SS: the result again 4 (n,α) cross section [b] This work File # Neutron energy E [ev] Distribution (w.r.t. 59 Ni data) for the helium production compared to SS with natural nickel Increase of 4.9(3)±.83(6) ( 59 Ni data uncertainty of (7±3)%) Extreme observations due to coarse resonance treatment Refinement necessary More details in Licentiate thesis Defense on Tuesday!

26 Petter Helgesson 7 / 9 More to do on 59 Ni and SS Apply with transmutation, starting from natural Ni Include uncertainty of other nuclides Particularly 58 Ni(n,γ) More realistic application He-production benchmark? Proceed with damage energy, KERMA, PKA.

27 Petter Helgesson 8 / 9 To conclude TMC has advantages, but the distributions of the nuclear data must be more rigorously justified by experiments Two paths discussed here:. Weighting random ND files Some work to do Simulating experimental errors to get justified distributions from the start Path 2 applied to 59 Ni Important for He production in SS in thermal spectra 5-fold increase at 59 Ni peak expected Large uncertainty due to 59 Ni data Pessimistic? Revisit resonance parameters

28 Petter Helgesson 9 / 9 Thank you for listening!

29 Petter Helgesson / 2 Appendix

30 Petter Helgesson 2 / 2 4 (n,α) cross section [b] This work JEFF/ENDF Neutron energy E [ev]