Nuclear Science NEA/WPEC-26 www.oecd-nea.org I nternational Evaluation Co-operation Volume 26 Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations Nuclear Science ISBN 978-92-64-99053-1 NEA/WPEC-26 International Evaluation Co-operation VOLUME 26 UNCERTAINTY AND TARGET ACCURACY ASSESSMENT FOR INNOVATIVE SYSTEMS USING RECENT COVARIANCE DATA EVALUATIONS A report by the Working Party on International Evaluation Co-operation of the NEA Nuclear Science Committee CO-ORDINATOR M. Salvatores Argonne National Laboratory/Commissariat à l’Énergie Atomique USA/France MONITOR R. Jacqmin Commissariat à l’Énergie Atomique France ©OECD 2008 NEA No. 6410 NUCLEAR ENERGY AGENCY ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT The OECD is a unique forum where the governments of 30 democracies work together to address the economic, social and environmental challenges of globalisation. The OECD is also at the forefront of efforts to understand and to help governments respond to new developments and concerns, such as corporate governance, the information economy and the challenges of an ageing population. The Organisation provides a setting where governments can compare policy experiences, seek answers to common problems, identify good practice and work to co-ordinate domestic and international policies. The OECD member countries are: Australia, Austria, Belgium, Canada, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Japan, Korea, Luxembourg, Mexico, the Netherlands, New Zealand, Norway, Poland, Portugal, the Slovak Republic, Spain, Sweden, Switzerland, Turkey, the United Kingdom and the United States. The Commission of the European Communities takes part in the work of the OECD. OECD Publishing disseminates widely the results of the Organisation’s statistics gathering and research on economic, social and environmental issues, as well as the conventions, guidelines and standards agreed by its members. This work is published on the responsibility of the Secretary-General of the OECD. The opinions expressed and arguments employed herein do not necessarily reflect the official views of the Organisation or of the governments of its member countries. NUCLEAR ENERGY AGENCY The OECD Nuclear Energy Agency (NEA) was established on 1st February 1958 under the name of the OEEC European Nuclear Energy Agency. It received its present designation on 20th April 1972, when Japan became its first non-European full member. NEA membership today consists of 28 OECD member countries: Australia, Austria, Belgium, Canada, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Japan, Luxembourg, Mexico, the Netherlands, Norway, Portugal, the Republic of Korea, the Slovak Republic, Spain, Sweden, Switzerland, Turkey, the United Kingdom and the United States. The Commission of the European Communities also takes part in the work of the Agency. 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FOREWORD A Working Party on International Evaluation Co-operation has been established by the OECD/NEA Nuclear Science Committee (NSC) to promote the exchange of information on nuclear data evaluations, validation and related topics. Another specific aim is to provide a framework for co-operative activities between the members of the major nuclear data evaluation projects. This initiative includes the possible exchange of scientists in order to encourage co-operation. Requirements for experimental data resulting from this activity are also compiled. The working party determines common criteria for evaluated nuclear data files in order to assess and improve the quality and completeness of evaluated data. The parties to the project are: ENDF (United States of America), JEFF/EFF (member countries of the NEA Data Bank) and JENDL (Japan). Co-operation with evaluation projects of non-OECD countries, specifically the Russian BROND and Chinese CENDL projects, are organised through the Nuclear Data Section of the International Atomic Energy Agency (IAEA). This publication reports the conclusions from the work undertaken by Subgroup 26, which focussed on the development of a systematic approach to define data needs for advanced reactor systems and to make a comprehensive study of such needs for Generation-IV (Gen-IV) reactors. A comprehensive sensitivity and uncertainty study has been performed to evaluate the impact of neutron cross-section uncertainty on the most significant integral parameters related to the core and fuel cycle of a wide range of innovative systems, even beyond the Gen-IV range of systems. A compilation of preliminary “Design Target Accuracies” has been put together and a target accuracy assessment has been performed to provide an indicative quantitative evaluation of nuclear data improvement requirements by isotope, nuclear reaction and energy range, in order to meet the Design target accuracies, as compiled in the present study. First priorities were formulated on the basis of common needs for fast reactors and, separately, thermal systems. The opinions expressed in this report are those of the authors only, and do not necessarily represent the position of any member country or international organisation. This report is published under the auspices and responsibility of the Secretary-General of the OECD. 3 MEMBERS OF SUBGROUP 26 M. Salvatores Argonne National Laboratory, USA (Co-ordinator) Commissariat à l’Énergie Atomique, France G. Aliberti Argonne National Laboratory, USA M. Dunn Oak Ridge National Laboratory A. Hogenbirk NRG, The Netherlands A. Ignatyuk CJD-IPPE, Russian Federation M. Ishikawa Japan Atomic Energy Agency, Japan I. Kodeli OECD Nuclear Energy Agency, France A.J. Koning NRG, The Netherlands R. McKnight Argonne National Laboratory, USA R.W. Mills Nexia Solutions, Ltd., United Kingdom P. Oblozinsky Brookhaven National Laboratory, USA G. Palmiotti Idaho National Laboratory, USA A. Plompen Joint Research Centre, Belgium G. Rimpault Commissariat à l’Énergie Atomique, France Y. Rugama OECD Nuclear Energy Agency, France P. Talou Los Alamos National Laboratory, USA W.S. Yang Argonne National Laboratory, USA 4 TABLE OF CONTENTS Foreword .......................................................................................................... 3 Executive summary .......................................................................................... 11 1. Introduction ............................................................................................... 15 2. Approach and theoretical background ................................................... 17 2.1 Sensitivity coefficients ........................................................................ 17 2.1.1 Multiplication factor ................................................................ 19 2.1.2 Power peak ............................................................................... 19 2.1.3 Reactivity coefficients............................................................... 21 2.1.4 Nuclide transmutation .............................................................. 22 2.1.5 Reactivity loss during irradiation ............................................ 22 2.1.6 Neutron source (e.g. at fuel fabrication) .................................. 23 2.1.7 Decay heat ................................................................................ 23 2.2 Uncertainties and target accuracies ..................................................... 25 2.3 Sensitivity/uncertainty analysis using Monte Carlo methods .............. 25 3. Covariance data ......................................................................................... 27 3.1 ANL covariance matrix ....................................................................... 27 3.2 BOLNA covariance matrix ................................................................. 28 4. Calculation tools ........................................................................................ 35 5. Systems and integral parameters analysed ............................................. 35 6. Uncertainty analysis .................................................................................. 50 6.1 Uncertainty evaluation ........................................................................ 50 6.2 Summary of lessons drawn from the uncertainty analysis .................. 57 7. Target accuracy ......................................................................................... 60 7.1 Data target accuracies .......................................................................... 60 7.2 Computational strategy ........................................................................ 62 7.3 Target accuracy results ........................................................................ 64 7.3.1 Analysis for separated systems ................................................. 66 7.3.2 Analysis for groups of systems ................................................. 81 7.4 Summary of the target accuracy study ................................................ 85 7.5 Complementary use of differential and integral experiments ............. 86 8. General conclusions and recommendations ............................................ 87 References ........................................................................................................ 90 5 Appendix A Accuracy of measurements ....................................................... 93 Appendix B Evaluation of Doppler reactivity uncertainty ............................ 101 Appendix C Evaluation of fission spectra uncertainty and their propagation ....................................................................... 115 Appendix D Comments on response parameter uncertainty due to fission spectrum uncertainties ........................................ 127 Appendix E Nuclear data for the handling, reprocessing and disposal of spent nuclear fuel .................................................... 139 Appendix F Resonance region importance for advanced fuel cycle applications ...................................................................... 159 Appendix G BNL methodology for cross-section covariances ..................... 165 Appendix H Report to Subgroup 26 on the preliminary conclusions of the April 2007 meeting in Nice............................................. 173 Appendix I Importance of 23Na reaction cross-correlations in the uncertainty assessment of SFR characteristics .................... 185 Appendix J Subgroup 26 recommendations for future work ....................... 199 Appendices available on CD-ROM Appendix K Model description Appendix L Isotope contributions Appendix M Total isotope uncertainty breakdown Appendix N (cid:2)n, n, burn-up component due to (cid:2)n, decay, dose, f neutron source uncertainty (%) breakdown Appendix O Uncertainty (%) breakdown by isotope, energy group, cross-section Appendix P Complete lists of target accuracy results Appendix Q ANL diagonal matrix Appendix R BOLNA diagonal matrix 6 List of figures Figure 1. Energy correlations used in the ANL partial energy correlation (PEC) matrix ................................................................ 29 Figure 2. Covariance matrix in 15 groups for the 239Pu(n,f) reaction ............ 31 Figure 3. Covariance matrix in 187 (left) and 15 (right) groups for the 240Pu(n,(cid:3)) reaction ..................................................................... 32 Figure 4. Covariance matrix in 187 (left) and 15 (right) groups for the 241Pu(n,f) reaction ..................................................................... 33 Figure 5. Covariance matrix in 187 (left) and 15 (right) groups for the 241Am(n,f) reaction ................................................................... 34 Figure 6. ABTR direct flux distribution ........................................................ 37 Figure 7. ABTR adjoint flux distribution ...................................................... 37 Figure 8. SFR direct flux distribution ............................................................ 38 Figure 9. SFR adjoint flux distribution .......................................................... 38 Figure 10. EFR direct flux distribution ............................................................ 39 Figure 11. EFR adjoint flux distribution .......................................................... 39 Figure 12. GFR direct flux distribution ........................................................... 40 Figure 13. GFR adjoint flux distribution ......................................................... 40 Figure 14. LFR direct flux distribution ............................................................ 41 Figure 15. LFR adjoint flux distribution .......................................................... 41 Figure 16. ADMAB direct flux distribution .................................................... 42 Figure 17. ADMAB adjoint flux distribution .................................................. 42 Figure 18. VHTR direct flux distribution ........................................................ 43 Figure 19. VHTR adjoint flux distribution ...................................................... 43 Figure 20. PWR direct flux distribution .......................................................... 44 Figure 21. PWR adjoint flux distribution ........................................................ 44 7 List of tables Table 1. Features of investigated systems .................................................... 8 Table 2. ABTR, SFR, EFR nominal values ................................................. 45 Table 3. GFR nominal values ....................................................................... 46 Table 4. LFR nominal values ....................................................................... 46 Table 5. ADMAB nominal values ................................................................ 47 Table 6. VHTR nominal values .................................................................... 47 Table 7. PWR nominal values ...................................................................... 48 Table 8. (cid:2)n (units) and (cid:2)n/n nominal values ............................................... 49 f Table 9. Fast neutron systems: total uncertainties (%) ................................. 51 Table 10. High burn-up VHTR: uncertainties (%) ......................................... 52 Table 11. High burn-up PWR: uncertainties (%) ........................................... 52 Table 12. (cid:2)(cid:4) burn-up uncertainty breakdown into components (pcm) .......... 52 Table 13. Fast reactor systems: uncertainties (%) due to Pu isotope cross-sections (BOLNA) ................................................................ 54 Table 14. Fast reactor systems: uncertainties (%) due to selected MA cross-sections (BOLNA) ......................................................... 54 Table 15. Fast reactor systems: uncertainties (%) due to inelastic and capture (BOLNA) .................................................................... 55 Table 16. Uncertainty (%) on Pu isotope density at end of cycle (EFR) .................................................................................... 56 Table 17. Uncertainty (%) on selected MA density at end of cycle (EFR) .................................................................................... 56 Table 18. Thermal systems: uncertainties (%) due to selected isotopes and reactions (BOLNA) ................................................... 58 Table 19. SFR k uncertainties (%): energy breakdown (pcm) eff for selected isotopes/reactions ........................................................ 58 Table 20. Fast reactor and ADMAB target accuracies (1(cid:5)) ........................... 61 Table 21. Target accuracy (1(cid:5)) for UO - and PuO -fuelled HTRs ................ 61 2 2 Table 22. PWR target accuracies (1(cid:5)) ........................................................... 61 Table 23. Integral parameter uncertainties (%) using the BOLNA diagonal covariance matrix ............................................................ 63 8 Table 24. (cid:6) sets used for the analysis ............................................................ 63 i Table 25. ABTR: uncertainty reduction requirements needed to meet integral parameter target accuracies .................................. 69 Table 26. SFR: uncertainty reduction requirements needed to meet integral parameter target accuracies .................................. 70 Table 27. EFR: uncertainty reduction requirements needed to meet integral parameter target accuracies .................................. 71 Table 28. GFR: uncertainty reduction requirements needed to meet integral parameter target accuracies .................................. 72 Table 29. LFR: uncertainty reduction requirements needed to meet integral parameter target accuracies .................................. 73 Table 30. ADMAB: uncertainty reduction requirements needed to meet integral parameter target accuracies .................................. 74 Table 31. Summary target accuracy requirements occurring for at least two fast reactors ............................................................ 75 Table 32. Summary of Highest Priority Target Accuracies for Fast Reactors............................................................................. 76 Table 33. VHTR: uncertainty reduction requirements needed to meet integral parameter target accuracies .................................. 77 Table 34. PWR: uncertainty reduction requirements needed to meet integral parameter target accuracies .................................. 77 Table 35. Integral parameter uncertainties (%) with initial and required cross-section uncertainties ............................................... 78 Table 36. Transmutation uncertainties (%) with initial and required cross-section uncertainties .............................................................. 79 Table 37. Integral parameter uncertainties (%) with initial and required cross-section uncertainties ............................................... 81 Table 38. Transmutation uncertainties (%) with initial and required cross-section uncertainties .............................................................. 82 Table 39. Integral parameter uncertainties (%) with initial and required cross-section uncertainties ............................................... 83 Table 40. Transmutation uncertainties (%) with initial and required cross-section uncertainties .............................................................. 84 9