B. K. Bylkin

Induced Radioactivity and Waste Classification of Reactor Zone Components of the Chernobyl Nuclear Power Plant Unit 1 After Final Shutdown

Abstract The dismantlement of the reactor core materials and surrounding structural components is a major technical concern for those planning closure and decontamination and decommissioning of the Chernobyl Nuclear Power Plant (NPP). Specific issues include when and how dismantlement should be accomplished and what the radwaste classification of the dismantled system would be at the time it is disassembled. Whereas radiation levels and residual radiological characteristics of the majority of the plant systems are directly measured using standard radiation survey and radiochemical analysis techniques, actual measurements of reactor zone materials are not practical due to high radiation levels and inaccessibility. For these reasons, neutron transport analysis was used to estimate induced radioactivity and radiation levels in the Chernobyl NPP Unit 1 reactor core materials and structures. Analysis results suggest that the optimum period of safe storage is 90 to 100 yr for the Unit 1 reactor. For all of the reactor components except the fuel channel pipes (or pressure tubes), this will provide sufficient decay time to allow unlimited worker access during dismantlement, minimize the need for expensive remote dismantlement, and allow for the dismantled reactor components to be classified as low- or medium-level radioactive waste. The fuel channel pipes will remain classified as high-activity waste requiring remote dismantlement for hundreds of years due to the high concentration of induced 63Ni in the Zircaloy pipes.

Computational Estimates of the Radiation Characteristics of Irradiated Graphite after Final Shutdown of a Nuclear Power Plant with an RBMK Reactor

A method of calculating the radiation characteristics of irradiated graphite masonry of an RBMK reactor is described. The MCNP computer code is used to determine the spatial distribution of the neutron flux density in the interior volume of the graphite, the CHAIN code is used to determine the isotopic composition and the radition characteristics of the irradiated graphite on the basis of the MCNP fluxes.The results of the calculation of the radiation characteristics of graphite from the reactors in the Nos. 2 and 3 units of the Leningrad nuclear power plant and the No. 1 unit of the Chernobyl nuclear power plant are presented and the contribution made by the accident to the flow of fuel mass into the masonry is estimated.

Decommissioning of nuclear and radiation-hazardous objects of the russian science center “Kurchatov Institute”

Data are presented on research reactors which form the experimental base used for research in radiation materials science, neutron physics, solid-state physics, and other directions in science and technology. The characteristic features of the decommissioning of research reactors are analyzed. The results of work on the decommissioning of reactors and spent-fuel and radioactive-waste repositories are presented. 3 figures, 2 tables, 12 references.

Development in a nuclear power station project of matters concerning the dismantling of equipment at the stage of power unit decommissioning

We discuss problems that arise during the dismantling the equipment of nuclear power stations at the final stage of their life cycle and must be taken into account in developing the projects of new units for nuclear power stations.

Database for Decommissioning Power-Generating Units at the Leningrad Nuclear Power Plant

It is shown that the database plays a role and has a place in the decommissioning of a nuclear power plant. The technical requirements for the program structure and the functional possibilities of the database are formulated.

Problem-Oriented System for Designing a Technology for Disassembling Equipment for Decommissioning the Power-Generating Units of a Nuclear Power Plant

The principles for constructing a problem-oriented system for designing a technology for disassembling the equipment in the power-generating units of nuclear power plants which are being decommissioned, starting from the rules of organization and use of the design space on the basis of informational and expert methods and taking account of the influence factors of the environment where the technology functions, are presented. 2 figures, 10 references.

Decommissioning industrial uranium-graphite reactors

The basic problems in decommissioning industrial uranium-graphite reactors are analyzed, taking account of experience in decommissioning the I-1 and ÉI-2 reactors at the Siberian Chemical Combine. On the basis of the analysis, decommissioning with delayed dismantling of the reactor structures is recommended.

Technical and economic assessments of planned and premature removal of first-generation nuclear power plants from operation in Russia

Four power-generating units are now being removed from operation in the Russian Federation - the first-second units with water-graphite reactors AMB in the Beloyarsk and VVER in the Novovoronezh nuclear power plants; these units were shut down in 1983, 1989, 1984, and 1990. respectively. Work is now being performed on these units in preparation for removal from operation. In connection with the exhaustion of the service life, from 2001 to 2010 another 15 power-generating units with a total electric capacity of about 10 GW will be removed from operation in Russia.