Hot fuel examination facility-north fuel element puncturing and gas sampling system

A remotely operated laser fuel element gas-sampling system has been put into service at the Hot Fuel Examination Facility (HFEF) North. This system provides the ability to puncture the cladding of a capsule or fuel element in its plenum region to measure its free volume and pressure and to gather gas samples for composition and isotopic analyses. The element is punctured and pressure data are taken with which to calculate the element's prepuncture internal pressure. After a gas sample is taken, the plenum is evacuated and then back-filled from known calibrated volumes to determine its free volume. The element or capsule may then be repressurized with any specified gas and the cladding puncture rewelded. Although these welds are primarily for radioactive contamination control of the element and the hot cell and are not qualified for fuel element in-reactor service, the welds that have been made are well characterized and have been tested to 6.89 x 105 Pa (100 psia)