Criticality concerns in cleaning large uranium hexafluoride cylinders

摘要

Cleaning large cylinders used to transport low-enriched uranium hexafluoride (UF6) presents several challenges to nuclear criticality safety. This paper presents a brief overview of the cleaning process, the criticality controls typically employed, and their bases. Potential shortfalls in implementing these controls are highlighted, and a simple example to illustrate the difficulties in complying with the Double Contingency Principle is discussed. FInally, a summary of recomended criticality controls for large cylinder cleaning operations is presented.