Blend Down Monitoring System Fissile Mass Flow MonitorImplementation at the Siberian Chemical Enterprise, Seversk, Russia

摘要

In this paper the implementation plans and preparations for installation of the Fissile Mass FlowrnMonitor (FMFM) equipment at the Siberian Chemical Enterprise (SChE), Seversk, Russia, will bernpresented. The FMFM, developed by Oak Ridge National Laboratory (ORNL), is part of the BlendrnDown Monitoring System (BDMS) for the U.S. Department of Energy (DOE) Highly EnrichedrnUranium (HEU) Transparency Implementation Program (TIP). The BDMS provides confidence tornthe United States that the Russian nuclear facilities supplying the lower assay (~4%) product lowrnenriched uranium (P-LEU) to the United States from down-blended weapon-grade HEU arernmeeting the nonproliferation goals of the 1993 HEU Purchase Agreement signed between thernRussian Federation and the United States.rnThe first BDMS has been operational at Ural Electrochemical Integrated Plant (UEIP), Novouralsk,rnsince February 1999. The second BDMS became operational at Electro Chemical Plant (ECP),rnZelenogorsk, in March 2003. These systems are successfully providing HEU transparency data tornthe United States. The third BDMS was successfully installed on the HEU down-blending tee in thernSChE Enrichment Plant in October 2004.rnThe FMFM makes use of a set of thermalized californium-252 (252Cf) spontaneous neutron sourcesrnfor modulated fission activation of the uranium hexafluoride (UF6) gas stream for measuring thern235U fissile mass flow rate. To do this, the FMFM measures the transport time of the fissionrnfragments created from the fission activation process under the modulated source to the downstreamrndetectors by detecting the delayed gamma rays from the fission fragments retained in the flow. ThernFMFM provides unattended nonintrusive measurements of the 235U mass flow of the UF6 gas in thernblending tee legs of HEU, the LEU blend stock, and the resulting P-LEU. The FMFM also confirmsrnthat HEUF6 gas identified in the HEU leg flows through the blending tee into the P-LEU leg. Thisrnpaper will discuss details of the SChE FMFM equipment characteristics as well as the technicalrninstallation requirements.