Open AccessThe Graphite Isotope Ratio Method (GIRM): A Plutonium Production Verification Tool
Author(s) -
J.P. McNeece,
BD Reid,
T. Wood
Publication year - 1999
Language(s) - English
Resource type - Reports
DOI - 10.2172/967298
Subject(s) - plutonium , nuclear engineering , graphite , criticality , nuclear reactor core , neutron flux , mox fuel , neutron , fission , radiochemistry , plutonium 240 , neutron moderator , environmental science , nuclear fission , rod , container (type theory) , nuclear physics , nuclear reactor , plutonium 239 , materials science , neutron temperature , neutron cross section , chemistry , physics , engineering , metallurgy , medicine , alternative medicine , pathology , composite material
Over the lifetime of a production reactor, neutrons from the fission process not only convert U-238 into plutonium but also bring about changes in the elements of the reactor's core components. Components such as shielding, pressure vessels, coolant piping, control rods, structural supports, and, in the case of graphite moderated reactors, the solid graphite moderator are all affected. Because a reactor's total plutonium production is directly related to total neutron fluence, and, likewise, changes in the elements and isotopes of a reactor's core components are directly related to fluence; it was argued that measuring these changes could provide an accurate estimate of a reactor's total plutonium production. The U.S. Department of Energy funds a project at Pacific Northwest National Laboratory (PNNL) to develop this concept into a practical plutonium production verification tool for graphite moderated reactors. The following sections describe the GIRM project development process. The purpose of this document is to provide a simple, concise description of the graphite isotope ratio method (GIRM) for use as a verification tool in estimating a graphite-moderated reactor's total plutonium production. The description covers the theory behind the technique and how the method is actually applied