OECDDOCUMENTS Physicsof Phtoniwn Recycling VolumeI Issuesmd Perspectives A reportby the WorkingParty on Physicsof PlutoniumRecgcling of the NEA NuclearScience Committee NUCLEAR ENERGY AGENCY ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT Pursuant to Article 1 of the Convention signed in Paris on 14th December 1960, and which came into force on 30th September 1961, the Organisation for Economic Co-operation and Development (OECD) shall promote policies designed: - to achieve the highest sustainable economic growth and employment and a rising standard of living in Member countries, while maintaining financial stability, and thus to contribute to the development of the world economy; - to contribute to sound economic expansion in Member as well as non-member countries in the process of economic development; and - to contribute to the expansion of world trade on a multilateral, non-discriminatory basis in accordance with international obligations. The original Member countries of the OECD are Austria, Belgium, Canada, Denmark, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, Turkey, the United Kingdom and the United States. The following countries became Members subsequently through accession at the dates indicated hereafter: Japan (28th April 1964), Finland (28th January 1969), Australia (7th June 1971), New Zealand (29th May 1973) and Mexico (18th May 1994). The Commission of the European Communities takes part in the work of the OECD (Article 13 of the OECD Convention). NUCLEAR ENERGYAGENCY 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 consisrs of all European Member countries of OECD as well as Australia, Canada, Japan, Republic of Korea, Mexico and the United States. The Commission of the European Communities tokesparl in the work of fke Agency. The primary objective of NEA is 10 promote co-operarion among the governmenfs of its porficipating countries in furthering the development of nuclearpower ns a safe,environmentally acceptable and economic energy source. This is achieved by: - encouraging karmonization of narional regulatory policies and practices, with particular referenceto the safety of nuclear insfallations, protection of man against ionising radiodon and preservation of the environmen:, radioactive waste management, and nuclear third parry liability and insurance; - assessing the conbiburion of nuclear power to the overall energy supply by keeping under review the technical and economic aspects of nuclear power growth and forecasting demand and supply for rke diffeerenrpkases of rke nuclear fuel cycle; - developing exchanges of scientific and technical informalion particular/y through participation in common services; - setting up international research and development programmes and joint underta,kings. In these and related tasks, NE4 works in close collaboration with the Internotional Aromic Energy Agency in Vienna, with which if has concluded II Co-operation Agreement, as well as with other international organisations in the nuclear field. 0 OECD 1995 Applications for permission to reproduce or translate all or pan of this publication should be made to: Head of Publications Service, OECD 2, rue And&Pascal, 75775 PARIS CEDEX 16, France. FOREWORD The OECD/NEA Nuclear ScienceCommittee set up in June 1992 a Working Party on Physics of Plutonium Recycling. It deals with the status and trends of physics issuesrelated to plutonium recycling with respectto both the backend fuel cycle and the optimal utilisation of plutonium. For completeness, issuesrelated to the use.of the uranium coming from recycling are also addressed. The objectives set out are: l To provide the Member countrieswith up-to-dateinformation on: - The core and fuel cycle issues of multiple recycling of plutomum in partly-loaded LWRs with MOX fuel, and full MOX fuel recycling LWRs cores; - The flexibility of fast reactors to produce or burn plutonium within standard fuel cycles (ex.: using MOX fuel), or advancedfuel cycles (ex.: metal, nitride fuels); - The core and fuel cycle physics issuesrelated to the use of plutonium fuel without uranium (e.g.,plutonium in inert matrices)to enhanceplutonium burning capability; - The physics issuesrelated to the useof uranium from recycling, and; - The core and fuel cycle issuesof recycle of plutonium through advancedconverter; l To provide advice to the nuclear community on the developments needed to meet the requirements(data and methods,validation experiments,strategic studies) for implementing the different plutonium recycling approaches. A co-ordination with complementarystudies performed by other task forces/working parties of NSC and by other committeesis in place. The Working Party met three times: once in 1993 to better define the studies to be undertakenand twice in 1994 to discuss results and finalise the reports describing them. About seventyexperts from thirteen countrieshave contributedto this work. The resultsare summarisedin the presentvolume. This general volume addressesthe issues as seen from the physics point of view and puts into perpective the experiencegained. It summarisesthe results obtained from a series of “benchmark’ studiescovering physics problems arising from different recycling scenarios.These specific studies,of greatinterest to the scientific community, arethe object of four further volumes. Finally some further investigations that should answer the questions concerning the physics limitations to multirecycling of plutonium in LWRs are proposed. This report is publishedon the responsibility of the Secretary-Generalof the OECD. The opinions it expressesare those of their authors only and do not representthe position of any Member country or internationalorganisation. 3 CONTENTS Contributors to this study .......................................................................................................................... 11 Chapter 1. Introduction ........................................................................................................................... 15 Chapter 2. Physics and some engineering aspects of plutonium recycling in light water reactors ............. 21 2.1 I”trod”ctio” ................................................................................................................... 21 2.2 Plutonilun utilisation concepts in LWRs ........................................................................ 21 2.2.1 Plutonium generation in LWRs ........................................................................... 21 2.2.2 Plutonium utilisation strategies.. ......................................................................... 22 2.2.3 MOX fuel assembly concepts for PWRs and BWRs.. ........................................... 22 2.2.4 Improved fuel utilisation, multirecycling strategies ............................................. 23 2.3 Neutron physics ............................................................................................................. 24 2.3.1 General aspects.. ................................................................................................. 24 2.3.2 Calculational methods ........................................................................................ 25 The situation of nuclear data ............................................................................... 26 The determination of the space-energy distribution ............................................. 21 2.3.3 MOX design Issues ............................................................................................. 27 Plutonium-containing cells ................................................................................. 27 MOX fuel assemblies .......................................................................................... 27 MOX-containing LWR cores .............................................................................. 29 2.3.4 Veritication of plutonium recycle cases ............................................................... 30 Theoretical benchmarks ...................................................................................... 30 CriticaI experhnenrs ............................................................................................ 30 Experience with MOX-containing LWR cores .................................................... 34 2.4 Mechanical and chemical properties of MOX fuel and MOX fuel rods ........................... 35 2.4.1 General aspects. .................................................................................................. 35 2.4.2 MOX fabrication ................................................................................................. 36 2.4.3 In-core behaviour of MOX fuel ........................................................................... 38 2.4.4 Reprocessing aspects.. ......................................................................................... 39 2.5 Snnunary and conclusions ............................................................................................. 40 References ........................................................................................................................... 42 Chapter 3. Analysis of physics benchmarks for plutonium recycling in