The Use of Stable Noble Gases for Safeguard Applications

Ensuring that any spent reactor-fuel processing matches state declarations is becoming a major con- cern. Many countries are using nuclear power to solve their energy problems, and strengthened safeguards (INFCIRC/540) are being integrated into traditional safeguards (INFCIRC/153) to increase effectiveness and reduce costs. One method to help meet the demands of strengthened safeguards while ensuring that the fuel being processed is as declared is the use of stable fissiogenic isotopes of the noble gases xenon and krypton. This paper examines an advanced approach that uses these gases collected directly on-stack from a reprocessing facility as the fuel is dissolved. Precision analysis of these isotopic ratios can be used for determining burnup characteristics, fuel type, and the reactor type of the fuel from which the sample was obtained. Through the use of selected advanced reactor-physics codes, sensitive, high-precision mass spectrometers, and sophisticated mathematical backward and forward analysis, this methodology can provide a sound means of veri- fication of spent-fuel characteristics. The paper discusses this methodology and demonstrates its validity.