Ensuring Irradiation Conditions for Metal Specimens within a Materials Science Assembly to Validate the BN-600 Operational Life Extension.

In order to extend the operational life of the BN-600 reactor, it is necessary to validate operability of the nonreplaceable reactor elements—including the neutron reflector—that operate under the conditions with high damaging doses and high temperatures. This can be done through irradiating metal of a simulating package inside a materials science assembly (MSA) inserted in the BN-600. The paper describes the main characteristics of the assembly, including the design features and irradiation parameters. Described are the basic principles of selecting the location for the materials science assembly in the reactor and for specimens inside the assembly in order to ensure the required irradiation conditions for the metal specimens. With comparison of the locations of the materials science assembly in the reactor core and in the radial blanket, the effect that the location of the materials science assembly has on the characteristics of the reactor standard fuel assemblies and on the neutron flux field is discussed. To calculate the irradiation parameters and the effect that the location has on the materials science assembly, the same methods and programs are used as for the reactor core design work. The effect of the materials science assembly on the reactor core neutronic characteristics has been shown to be minimal when the assembly is installed in the radial blanket. [ABSTRACT FROM AUTHOR]