ORGANIZATION AND IMPLEMENTATION OF NUCLEAR REACTOR DECOMISSIONING AT FSUE “RISI”

The implementation of various research projects involves using nuclear reactors. Many world scientific centers have nuclear reactors available for their experiments. Such installations were built at different periods of time and for different purposes. The optimization of scientific programs, on the one hand, and necessity to reduce the nuclear hazards at the facilities, on the other hand, demand analyzing the efficiency of using hardware, developing safety, protection and upgrades programs for the reactors or their removal from operation. As many reactors are unique and there is no experience of their decommissioning, each stage of decommissioning requires serious preparation and different types of research. The report presents principles of organization and some results of the Research Institute of Scientific Instruments’ reactors decommissioning that have allowed RISI to decrease the scale of the physical protection system, reduce the number of material balance areas, simplify nuclear material control and accountability and implement nuclear material consolidation. In the second half of the 20th century intensive work was done in the Soviet Union and more specifically at the Research Institute of Scientific Instruments (RISI) using research nuclear reactors [1]. As the research was being completed, the reactors were shut down, put on standby. In late 90s in order to increase the nuclear and radiation safety at the site, consolidate the nuclear materials and reduce the risks of their proliferation, reduce the scope and cost of the MC&A operations, a decision was made to decommission the out-of-use equipment. It was proposed that a number of reactors should be decommissioned, the nuclear fuel removed from the Institute, the site rehabilitated and the radioactive waste reprocessed or sent away for ultimate disposal. This proposal was approved by the management of the Ministry of Atomic Energy of Russia and, in 1998 the work began on decommissioning BARS-3M, a pulse solid fuel reactor. 2 Since there was no prior experience in this type of work, a decision was made to begin with a reactor with the least risk to radiation safety. The preparatory stage made it obvious that to make the endeavor successful, it was necessary to develop a long-term conceptual plan of experimental reactor decommissioning at the Institute. Such a plan was developed and approved by the Ministry of Atomic Energy of Russia in 2002. It included decommissioning of the research reactors listed in Table 1 and other facilities.