The purpose of the test and evaluation of tamper indicating devices (TIDs) described in this report is to assure that the recommended TID technologies are acceptable for use at the Mayak FMSF. TID acceptance is based on TID performance with respect to mutually agreed functional, operational, and security requirements for the FMSF, taking into account both the United States and the Russian Federation views. Although some Russian views have been documented, very little information at the level required for formal test planning had been received prior to the start of the testing campaign. Consequently, this report currently represents US recommendations for an arms control and/or safeguards and security application. Acceptance of these test results and recommendations by those Russian Federation entities responsible for the Mayak FMSF will be required before implementing any TID regime at Mayak FMSF.

The remains of the nuclear fuel that was severely damaged in the 1986 Chernobyl unit 4 accident lie in large masses in the premises under the reactor. The fuel debris exists in the form of dusts, chunks, and lavas, and the quantities are substantial--some rooms contain several tons of fuel. Since there is a possibility of water entering these rooms, there is an obvious concern over criticality safety. Incidents of increased neutron count rates have been noted in the vicinity of nuclear fuel debris. Pacific Northwest National Laboratory (PNNL), under a program funded by the US Department of Energy, responded to this safety concern by assembling a new monitoring system to characterize the radiation environment in the vicinity of major fuel deposits. The new monitoring system will measure the gamma and neutron radiation fields in several locations. The measurement data can be tracked over time to determine the characteristics of the radiation fields and better understand the nuclear safety conditions in the vicinity of the fuel. The monitoring system was designed to provide information that will allow a better interpretation of any future events.