The Role of Blend Down Monitoring System Fissile Mass Flow Monitors for the HEU Transparency Program in Russia

The paper discusses the role of the Blend Down Monitoring System Fissile Mass Flow Monitor (FMFM) systems implemented at the Ural Electrochemical Integrated Enterprise at Novouralsk (February 1999), the Electrochemical Plant at Zelenogorsk (March 2003), and the Siberian Chemical Enterprise at Seversk (October 2004) highly enriched uranium (HEU) down blending facilities in Russia for the U.S. Department of Energy/National Nuclear Security Administration HEU Transparency Program (TP). The 1993 HEU Purchase Agreement between the United States and the Russian Federation (RF) requires the down blending of HEU from dismantled RF nuclear weapons for use as nuclear fuel. The FMFM is designed to measure 235U fissile mass flow in the UF6 process pipes in these RF facilities. The FMFM also traces the HEU flow through the HEU blending tee into the resulting down blended product flow, thus confirming down-blending of the HEU. The paper covers details of the FMFM’s operational characteristics and technical installation specifications, which are optimized for the facility process characteristics so that the measurement performance required for the TP objectives and goals is achieved. Typical FMFM measurement data reports and a summary assessment of the overall results are also discussed.