EXPERIENCE WITH SOLUTIONS TO CONVERSION CHALLENGES. for U.S.-Supplied Research Reactors EXPERIENCE WITH SOLUTIONS

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1 NATIONALNUCLEARSECURITY ADMINISTRATION EXPERIENCE WITH SOLUTIONS TO CONVERSION GLOBAL THREAT CHALLENGES REDUCTION INITIATIVE for U.S.-Supplied Research Reactors EXPERIENCE WITH SOLUTIONS TO CONVERSION CHALLENGES for U.S.-SUPPLIED RESEARCH REACTORS J. E. Matos, Ph.D. GTRI Conversion Program HEU Minimization J.E. Matos, Methods PhD Section Argonne GTRI Conversion National Laboratory Program HEU Minimization Methods Section Russian-American Argonne National Symposium Laboratory on Conversion of Research Reactors to LEU Fuel Russian-American Moscow, Russia Symposium on Conversion of 8-10 Research June, 2011 Reactors to LEU Fuel Moscow, Russia 8-10 June

2 Brief Historical Background In the Atoms for Peace Programs from the 1950s: The U.S. initially supplied research reactors with <20% enriched uranium fuels. The Soviet Union initially supplied research reactors with 10% enriched uranium fuels. In the 1960s and 1970s, In many U.S. supplied research reactors, power upgrades required increased 235 U element loadings to reduce fuel consumption and contain fuel fabrication costs. HEU (93%) became the standard enrichment in U.S. supplied research reactors. In Soviet-supplied research reactors, power upgrades required changing from pin-type to tubular fuel assembly geometries, as well as increasing the 235 U element loading. HEU (36%, 80% & 90%) became the standard enrichment in Soviet-supplied research reactors. Russian-American Symposium on Conversion of Research Reactors to LEU Fuel, Moscow, 8-10 June

3 Brief Historical Background The U.S. DOE initiated the Reduced Enrichment for Research and Test Reactors (RERTR) Program in The US exported ~1200 kg HEU per year to fuel western research reactors for the eight years between 1970 and In the 1970s, a nuclear explosion in India, unsafeguarded nuclear activities in other countries, and growing terrorist activities renewed concerns about nuclear proliferation. Russia was also concerned about its exports of fuel assemblies containing 80-90% enriched uranium to research reactors that it had built abroad since the late 1950s. Russia s Ministry of Atomic Energy also initiated a program around 1978 to convert foreign research reactors from 80-90% enriched uranium to 36% enriched uranium. After 1989, Russia exported only fuels containing 36% enriched uranium to Russian-built research reactors. More recently, in collaboration with DOE/NNSA since ~2004, foreign research reactors built by Russia are being converted to LEU fuels. 3

4 Brief Historical Background During the 1980s, reactor operators in eastern Europe stated that the Soviet Union had initiated a reduced enrichment program similar to the U.S. program, but there was no contact or collaboration between the two programs. The first formal contact to discuss collaboration on research reactor conversions took place at NIKIET facilities in Moscow in March At the meeting, U.S. and Russian scientists discovered that they had much in common regarding research reactors. It was decided to initiate a contract between ANL and NIKIET on conversion studies and fuel development (lead by the Bochvar Institute). Russian-built research reactors have been converted in the Czech Republic, Hungary, Libya, Ukraine, Uzbekistan, and Vietnam. Conversion work is in progress in Belarus, Bulgaria, Kazakhstan, and Poland. In the United States, 20 research reactors (17 university, 2 DOE, 1 commercial) have been converted to LEU fuel. Outside the U.S., 34 research reactors originally supplied with HEU by the U.S. have been converted to LEU fuel in 25 countries. 4

5 RERTR Program Goals and Experience RERTR Program goals from the beginning have been to convert research and test reactors to LEU fuels without significant penalties in: Experiment Performance Operating Costs Component Modifications Safety Characteristics Generally, nearly all of the conversions that have taken place have largely achieved these goals. There are some complaints about the cost of new fuels assemblies, but the cost of both HEU and LEU fuels have increased substantially over the last 30 years. Thermal neutron fluxes in experiment positions are generally reduced by 5-15%, but depend on the specific reactor and on experiment locations in the reactor. For some ambitious organizations with lower power reactors, both fuel lifetime and flux performance were increased substantially by reducing the size of the core. This is not the case for the high performance reactors which already have small cores. However, there have been many challenges. 5

6 Challenges for Research Reactor Conversions Political Challenges Funding Challenges Schedule Challenges Technical Challenges Qualify LEU fuels Commercial fabrication Reactor performance Reactor safety analyses Regulatory Challenges Some Safety Analysis Reports out of date Need to redo Safety Analyses using modern methods Fresh and Spent HEU Fuel Removal Challenges Political, Technical, and Economic Issues These challenges are common to both U.S.- and Russian-supplied reactors. This talk addresses experience with U.S.-supplied research reactors. 6

7 Political, Funding, and Schedule Challenges Political Challenges are addressed by DOE/NNSA. Financial support by DOE/NNSA has been essential. LEU fuel development and testing Conversion safety analyses Removal of fresh and irradiated HEU fuel The U.S. NRC has provided financial support for regulatory reviews. Significant funding to support LEU fuel development, conversion analyses, regulatory reviews, and spent fuel removal have been provided by many countries, particularly: Argentina, Canada, France, Germany, Japan, Netherlands, S. Korea Funding for regulatory reviews have been provided by participating countries. The IAEA has supported many conversion-related activities. Schedule challenges: DOE/NNSA has set aggressive LEU conversion and HEU removal schedules under its Global Threat Reduction Initiative (GTRI). 7

8 In the Beginning: Significant Opposition and Significant Cooperation At the beginning of the RERTR Program in 1978, there was considerable skepticism and strong opposition to LEU conversions by research reactor operators Some thought that the additional U-238 in LEU fuel would severely reduce the neutron flux performance of research reactors They were mostly wrong! Others thought new LEU fuels would take many years to develop, qualify, and license They were right! But there was also considerable cooperation among Western international participants in the research reactor fuel cycle: Fuel Developers Fuel Vendors Fuel Testers Fuel Shippers Fuel Reprocessors International Organizations (IAEA) National Programs (Argentina, Canada, Germany, Japan) U.S. and Foreign Research Reactor Operators 8

9 Foreign Research Reactors Supplied with Enriched Uranium by the U.S. Restrictions on Exports of HEU Strict reviews by several U.S. government agencies are performed for each export case. If a qualified LEU fuel was commercially available, reactors were asked to make preparations for conversion. Restrictions on Acceptance of Spent Fuel A commitment to LEU conversion is required to return spent fuel to the U.S. Challenges were overcome by: Joint Work on Fuel Development and Testing There has been strong international participation in developing & testing LEU fuels. Independent Work on Conversion Analyses Joint Work on Conversion Analyses (many) Considerable assistance has been available for conversion safety analyses. IAEA Contributions have been very important (following slide) Sharing of Conversion Technology Annual RERTR and RRFM international meetings Extended visits to host laboratories 9

10 Foreign Research Reactors Supplied with Enriched Uranium by the U.S. Removal of fresh and irradiated HEU fuels is an important part of HEU Minimization Challenges have been overcome by: In the early 1980s, dissolution tests on irradiated miniplates confirmed that LEU silicide fuel could be reprocessed at the Savannah River Site. DOE updated its legal notices for acceptance of LEU fuels in This was important in allowing conversions to take place in countries that require a confirmed spent fuel disposition path before LEU fuel could be ordered. DOE completed an Environmental Impact Statement for acceptance of both HEU and LEU fuels in 1996 and initiated the Foreign Research Reactor Spent Nuclear Fuel Acceptance Program. 5 metric tons of U.S. origin HEU in spent fuel became eligible for return to the U.S. To date, ~3.4 tons have been shipped to the U.S. or France for disposition Work is in progress to disposition the remaining HEU The program is scheduled to end in Shipments to the U.S. can continue until

11 IAEA Contributions Have Been Very Important The Role of the IAEA has been very important since the beginning of the program. IAEA sponsored International participation in developing guidebooks on reactor conversions in the 1980s Guidebook on Research Reactor Core Conversions (IAEA-TECDOC-233, 1980) Guidebook Addendum on Heavy Water Reactors (IAEA-TECDOC-324, 1985) Guidebook on Safety and Licensing, Volumes 1-5 (IAEA-TECDOC-643, 1992) This joint international effort was important to define the penalties to be expected in neutron flux performance of the reactors and to identify the parts of safety analysis reports that need to be redone for conversions. Good agreement by all participants helped to overcome skepticism and reduce opposition to conversions. IAEA also sponsored: Courses/seminars on Preparations Needed to Ship Spent Fuel to Its Country of Origin for both U.S. and Russian origin fuels. Fellowships to participants from developing countries to work on conversion analyses. Numerous consultancies related to research reactor conversions Cooperative Research Projects on research reactors, accelerator driven sources, and Mo-99 production using LEU. 11

12 U.S. Research Reactor Conversions In the early 1980 s, there was significant opposition to LEU conversions at US universities with reactors that used HEU fuel. Major concerns were: Funding to do the conversion work Potential interventions by anti-nuclear groups that could shut the reactors down A hearing was held in the U.S. Congress How This Challenge Was Overcome In 1986, the U.S. NRC issued a Rule that required conversion of its licensed reactors provided that: A qualified and suitable LEU fuel was available DOE informed NRC that sufficient funds were available The SAR amendment for conversion was approved by the NRC All regulatory requirements have been satisifed An important provision of the NRC Rule is that the NRC orders the reactor to convert when everything is in place. In this way, the NRC is responsible to defend the order in court and for legal fees if there was a public intervention that required hearings and time in court. None to date. 12

13 U.S. Research Reactor Conversions Two activities that were important in helping to resolving technical and regulatory challenges for both U.S. and foreign research reactors conversions: Conversion Demonstrations by DOE University of Michigan ( ), 2 MW, UAl x -Al Fuel, 1.7 g U/cm 3, 19.75% Enr. This fuel was used with HEU (93%) in the 250 MW ATR reactor in Idaho since ~1965 The main purpose was to demonstrate the physics of reactor conversion. Oak Ridge Research Reactor ( ), 30 MW, U 3 Si 2 -Al Fuel, 4.8 g U/cm 3, 19.75% Enrichment. The purposes were to: Demonstrate gradual conversion of a high power research reactor Qualify three commercial fuel fabricators (B&W, CERCA, and NUKEM) Provide further information for qualification of U 3 Si 2 -Al fuel for licensing purposes. LEU Fuel Safety Evaluations by NRC Safety Evaluations were completed by the U.S. NRC for three LEU fuels: U 3 Si 2 -Al fuel with up to 4.8 g U/cm 3 ; Al cladding (NUREG-1313; July 1988) UZrH x (TRIGA) fuel with up to 3.7 g/cm 3 (45 wt-% U); SS cladding (NUREG-1282; August 1987) UO 2 (in SPERT fuel); 4.8% Enrichment; Stainless Steel cladding (NUREG-1281, August 1987) 13

14 U.S. Research Reactor Conversions Conversion Analyses were completed for the 20 U.S. research reactors that have been converted to date. The challenges were overcome by providing substantial assistance: SARs amendments for MTR-type reactors were performed by mostly by joint work between universities and Argonne. Some were done by universities alone, and some by Argonne alone. SARs amendments for TRIGA reactor conversions were performed by General Atomics alone in some cases and by universities (with assistance from Argonne). SAR chapters related to changing the reactor fuel were re-analyzed using up-to-date methods and codes. One result was to revitalize research reactor analyses at many universities. Upgraded analysis infrastructure 14

15 Closing Remarks There have been and still are many challenges to converting research reactors to LEU fuel and removing fresh and irradiated HEU fuels. However, over 60 research reactors worldwide have overcome these challenges. Operating reactors are performing their missions successfully using LEU fuels 15

16 THANK YOU FOR YOUR ATTENTION 16