Benchmark Testing of CENDL 3 232 Th Liu

Benchmark Testing of CENDL 3 232 Th Liu Ping China Nuclear Data Centre 12/05/2004

Content n Introduction n Benchmarks n Data Processing n Benchmark Testing n Discussion

1 Introduction The CENDL-3 preliminary evaluation of 232 Th was completed in 2002. A previous benchmark testing of the preliminary version was performed in 2002. Referring to the conclusion obtained in previous benchmark testing, the elastic scattering angular distributions and (n, 2 n) cross sections were adjusted. The latest evaluation is improved relative to the previous evaluation. The purpose of this paper is to report on testing of 232 Th data (CENDL-3, ENDF/B-VI. 2, JENDL-3. 3) for HEUMF and IEUCI benchmarks. In terms of neutron spectrum, there are fast, intermediate and thermal cases. The characteristics of each benchmark are discussed briefly. The NJOY code system was used for generating nuclear data libraries for benchmark calculations. The MCNP code was utilized for the benchmarks testing calculations. Some integral data were compared between CENDL-3, ENDF/B-VI. 2 and JENDL-3. 3. The results from ENDF/B-V and ENDF/B-VI. 2 here were taken from IHBECSBE.

. 2 Benchmarks 2. 1 High Enriched Uranium Metal Fast (HEUMF) Benchmarks The highly enriched uranium, thorium, and polyethylene assemblies considered in this work are HEU-MET-FAST-068(KBR-22, KBR-23 assemblies).

2. 2 Enriched Uranium Mixed ( IEUCI) Benchmarks The enriched uranium mixed with thorium and polyethylene assemblies selected in this work are IEUCOMP-INTER-001(KBR-18, KBR-19, KBR-20, KBR-21). Among these benchmarks, KBR-19, 20 had intermediate spectrum and are appropriately categorized as “INTER”. KBR-18 had a fast spectrum and is more appropriately categorized as “FAST”, and KBR-21 had a thermal spectrum and is better categorized as “THERM”. The neutron spectrum is given in Figure D. 1.

3 Data Processing The data of 232 Th from CENDL-3 and JENDL-3. 3 were processed with the NJOY nuclear data processing system in ACE format. In benchmark calculations for CENDL-3 and JENDL-3. 3, all materials, 232 Th excepted, were taken from ENDF 60.

4. Benchmarking Testing and Analysis The MCNP code was utilized for the benchmarks testing calculations. The calculated results for these benchmarks are shown in table 5 to table 6 and figure 1~6.

It can be seen that CENDL-3 gives excellent result for the KBR-22 calculation, and the results based on ENDF/BV, ENDF/B-VI. 2, JENDL-3. 3 are good for this assembly. In the KBR-23 calculation, overestimation with 3. 34% from CENDL-3 and 3. 59% from JENDL-3. 3 was presented respectively. This may due to the overestimated continuum inelastic scattering of 232 Th. In the KBR-21 calculation, underestimation with 4. 22% from ENDF/B-VI. 2 and 3. 83% from ENDF/B-V was presented respectively, and underestimation from CENDL-3 and JENDL 3. 3 was also given. The may indicate that there is problem with 232 Th capture cross sections.

5 Discussion In the keff or k∞calculations of fast systems, results based on ENDF/B-V, ENDF/B-VI. 2, CENDL-3 and JENDL-3. 3 are higher than the experimental results for KBR-18, KBR-23 calculations. This may indicate the (n, 2 n) cross sections of 232 Th in the Me. V range are underestimated for all evaluated libraries, and the continuum inelastic scattering of 232 Th is overestimated. In the keff or k∞calculations of intermediate spectrum systems, the results based on CENDL-3, JENDL-3. 3 for KBR-19, KBR-20 are higher than the experimental results, and the results based on ENDF/B-V, ENDF/B-VI are better. This may due to an over estimation of the 232 Th inelastic scattering angular distribution for CENDL-3 and JENDL-3. 3. In the keff or k∞calculations of thermal spectrum system, the results based on CENDL-3, ENDF/B-VI. 2, JENDL-3. 3 are higher than the experimental results for KBR-21, this may indicate a problem with 232 Th capture cross sections, and 232 Th capture cross sections of all evaluated libraries probably need to be improved.

Table 5 Calculated Results for k∞(KBR-18~KBR-21) and keff (KBR-22~KBR-23) Benchmark KBR-18 KBR-19 Measured k∞ or keff 0. 969± 0. 005 MCNP ENDF/B-V MCNP(1) CENDL-3 MCNP(2) JENDL-3. 3 0. 9871 0. 9893 ± 0. 0003 0. 9873 1. 0003 ± 0. 0004 KBR-21 KBR-22 KBR-23 1. 014± 0. 006 0. 964± 0. 012 1. 0001± 0. 004 1. 0008± 0. 004 0. 9824 ± 0. 0004 1. 0099 ± 0. 0005 1. 016 ± 0. 0005 0. 9233 0. 9271 ± 0. 0005 KBR-20 0. 980± 0. 003 MCNP ENDF/B-VI. 2 0. 9785 1. 0013 ± 0. 0005 1. 0211 ± 0. 0006 ± 0. 0003 0. 9978 ± 0. 0004 1. 0042 ± 0. 0004 1. 0439 1. 0355 ± 0. 0005 0. 9347 ± 0. 0005 0. 9450 ± 0. 0005 1. 0062 0. 9994 ± 0. 0005 1. 0100 ± 0. 0005 1. 0242 ± 0. 0006 1. 0367 ± 0. 0006 ± 0. 0005

Table 6 Calculated Results/Experimental Measurement Benchmark Measured k∞or keff MCNP ENDF/BVI. 2 MCNP ENDF/B-V MCNP(1) CENDL-3 MCNP(2) JENDL-3. 3 KBR-18 0. 969± 0. 005 1. 0187 1. 0209 1. 0189 1. 0323 KBR-19 0. 980± 0. 003 0. 9985 1. 0024 1. 0182 1. 0247 KBR-20 1. 014± 0. 006 0. 9960 1. 0020 1. 0295 1. 0212 KBR-21 0. 964± 0. 012 0. 9578 0. 9617 0. 9803 0. 9696 KBR-22 1. 0001± 0. 004 1. 0012 1. 0061 0. 9993 1. 0099 KBR-23 1. 0008± 0. 004 1. 019 1. 0234 1. 0359

Fig. 7 Inelastic cross sections compared with experimental data for 232 Th

Fig. 8 (n, 2 n) cross sections compared with experimental data for 232 Th

Fig. 9 (n, 2 n) DDX compared with experimental data for 232 Th of CENDL-3

Fig. 10 (n, 2 n) DDX compared with experimental data for 232 Th of CENDL-3

1 2 3 4 5 6 7 8 References R. E. Mac. Farlane, D. W. Muir, “The NJOY Nuclear Data Processing System”, LA 12740 -M, Los Alamos National Laboratory report, (1994). J. F. Briesmeister, Ed. , “MCNP - A General Monte Carlo N-Particle Transport Code”, LA-12625 -M, Los Alamos National Laboratory report (1993). “International Hand Book of Evaluated Criticality Safety Benchmark Experiments”, NEA/NSC/DOC (95)03, Nuclear Energy Agency, OECD, Paris (September 2003 Edition). V. I. Golubev, A. V. Zvonarev, V. G. Kozlovtsev et al. , “Calcualtional and Experimental Investigations on Elaboration of Neutron Cross Sections of Nuclides of Thorium Cycle in Fast Reactors, ” Atomnaya Energiya, Vol. 71, Issue 3, September 1992, p. 245. V. I. Golubev, A. V. Zvonarev, V. M. Lityaev et al. , “Studies at Fast Critical Assemblies for Justification of Thorium Utilization in Fuel Cycle, ” Conference on Problems in Reactor Physics VOLGA-93, Vol. 2, p. 55. S. M. Bednyakov, V. I. Golubev, A. V. Zvonarev et al. , “Experimental and Calculational Studies of Neutron Characteristics of Thorium Cycle in Fast Reactors, ” Proceedings of International Conference on Reactor Physics and Computations, January 23 – 26, 1994, Tel-Aviv, Israel, p. 780. V. I. Golubev, A. V. Zvonarev, V. G. Liforov et al. , “Experimental Investigations of Neutron Characteristics of Thorium Cycle, ” Proceedings of International Conference on the Reactor Physics PHYSOR-96, “Breakthrough of Nuclear Energy by Reactor Physics”, September 16 – 20, 1996, Mito, Japan, Vol. 2, p. E-276. “MCNPXS – Standard Neutron, Photon, and Electron Data Libraries for MCNP 4 B, ” Los Alamos National Laboratory, Los Alamos, New Mexico