Determination of fire resistance of plutonium storage containers

Abstract

Seismic upgrades to safety systems at the Plutonium Facility at Los Alamos, NM, USA, are needed based on the latest facility safety analysis. The design basis accident of concern is a large scale seismically induced fire on the processing floor. Such an accident could involve large quantities of plutonium in dispersible forms stored in containers that cannot be counted on to prevent material release. As part of the effort to improve the safety posture of the facility in the near term, we developed a test method to evaluate the capability of storage containers to prevent release of their contents in the event of a seismically induced fire. To provide a defensible basis for testing to the Department of Energy (DOE) and Congressional oversight, we adopted standard test methods from consensus codes and standards. These tests included a time–temperature exposure up to 870°C and a 20 L kerosene open pool fire test. After the thermal tests, containers were dropped from a height of 4 ft onto a steel plate. We measured the amount of a non-toxic plutonium surrogate released following the drop tests to establish a conservative value of expected material release (referred to as damage ratio) in the event of the facility accident. The DOE approved thermal and impact test protocols we developed are used to demonstrate a quantitative value for material release from containers where the assumption of total material release results in unacceptably high accident consequences.