[en] Beginning from 1996 US Department of Energy jointly with National Laboratories is working with Kazakhstan on non-proliferation problems and nuclear safety related to the BN-350 reactor. The first cooperative work has included the modernization of system for nuclear materials accounting and control on the reactor as well as creation of the Centre of Nuclear Technologies Safety for coordination of jobs related with the reactor and the others issues of safety. Hereupon fulfillment of two joint project were began. The first one includes safety provision for spent fuel in the dry safe depository. At present joint teams have completed the fuel package procedures. The second project is a irreversible withdrawal of the BN-350 reactor and it transfer into safe disposal condition for 50 years. This prevents a possibility of nuclear material production at the reactor those would be used for an unforeseen aims. The paper shows, that USA and Kazakhstan are working out the second project and it gives presentation about of status of conducting jobs. An especial attention was paid to cooperation between Kazakhstan and USA which is the part of works on the BN-350 reactor decommissioning

[en] A number of specific tasks arises during decommissioning of the reactor with liquid metal sodium as a coolant. The implementation of these tasks affects directly safety of the reactor unit and population near the installation. The high level of technology, development of technical decisions and trained personnel are needed to observe present requirements of normative documents. Peculiarity of liquid metal sodium as a coolant of the BN-350 reactor consists in its high chemical activity, fire risk, and high level of radioactivity. The strategy of management of such substance is drawn up on a stage-by-stage decreasing of tbe level of its danger for people and environment. The first stage consists of sodium cleaning from radionuclides that determine its radioactivity. Cesium-137 is the main isotope among others. The world wide practice came to the conclusion that the most effective method of cleaning from cesium isotopes is adsorption on carbon materials. The second stage includes the draining of cleaned sodium into tanks of storage. This stage demands development of special technological decisions and equipment to remove fully liquid metal coolant from the reactor vessel and circuits' loops. The third stage of sodium treatment consists of processing of drained sodium in chemically passive substance. There are different technologies in the world; their selection is made in the basis of detailed analysis taking into account many factors. For the BN-350 reactor at present is assumed sodium processing into sodium hydroxide with the following transfer into sodium from acceptable for disposal. During the fourth stage remains of sodium are removed from inner parts of the reactor unit. The location of sodium after the bulk draining depends on design particulars of the reactor and circuits. The given report contains the detailed description of each of four stages with indication of existing technologies as applied to the BN-350 reactor. The intended way of liquid sodium coolant transfer into safe form is pointed out. The work is implementing under technical and financial support of State Department and Department of Energy USA

[en] The BN-350 reactor was one of the most powerful fast neutron facilities in the world. The nominal designed reactor power was 1000 MW and electric power output was 350 MW. The desalination facility could produce up to 120,000 tons of fresh water a day. The reactor core was cooled by liquid sodium. The reactor core consisted of heat release assemblies with highly enriched fuel. Blanket assemblies containing natural uranium were located around the core were used for plutonium production resulting from nuclear reactions with fast neutrons. The plutonium produced could be used for nuclear weapon creation and as fuel for other rectors. The reactor finally was shutdown by decree of the Kazakhstan Government on April 22, 1999. The decision was taken to place it into SAFSTOR for 50 years with subsequent final dismantling. At the same time, the Kazakhstan Government appealed to the US Government to provided technical and financial assistance for BN-350 decommissioning activities. Many of programs are being conducted by joint efforts of Kazakhstan and the United States of America with the support of International Atomic Energy Agency. A particular note is the assistance provided under the US Cooperative Threat Reduction Program, which is commonly known as the Nunn-Lugar Act after its two primary sponsors in the US Senate. This project was the beginning one of the world's largest and he most successful nonproliferation project. The main areas of activity is: packaging, transportation and safe storage of BN-350 spent fuel. The contribution of an enhanced physical protection system, material monitoring systems and the packaging of the materials has virtually eliminated the proliferation risk. Right on schedule in June 2001, a joint Kazakhstan-US team closed 478-th canister and successfully completed the 2 and 1/2 year effort to package the BN-350 spent fuel, probably the largest such effort ever undertaken anywhere. At the present rime, the US Government is planning to support the placement of the packaged BN-350 fuel into long-term storage in 'Baikal' site in the Kurchatov city (National Nuclear Center). Kazakhstan, with the financial and technical support of the US, is developing a BN-350 Decommissioning Plan for international peer review. The main objective of the plan is identify areas of potential technical support by technologically developed countries. At the present time, the plans has already been drafted and in the end of 2002 it will be submitted for review to the IAEA. Once IAEA experts provide their comments on the plan, all necessary changes will be incorporated and it will be presented to potential donor countries to allow them to consider the possibility of funding different parts of the BN-350 decommissioning activities. The European Commission has supported this activity through TACIS projects. In particular, within framework of the BN-350 decommissioning activity a primary and secondary circuits sodium handling will be considered. The task of its draining and subsequent processing is a very expensive and complicated technical task. This US Government-funded project, may be split into three subprojects: Development, installation and operation of cesium traps to reduce the radioactive cesium level in the BN-350 primary sodium. The project also includes the improvement of reactor fire safety to support sodium trap operation; Sodium draining from reactor vessel and loops and elimination of sodium residuals; Sodium processing into a state appropriate for long-term storage or disposal. It is envisaged that during the implementation of the project the production capacities of Kazakhstan enterprises and specialists will be maximally exploited