Example of a flanged tritium waste container. Courtesy photo
Building 1028 in Technical Area 54 at Los Alamos National Laboratory. Courtesy photo
BY MAIRE O’NEILL
Los Alamos National Laboratory has notified the Environmental Protection Agency of a new point source for radionuclide air emissions at Technical Area 54 from a venting operation set to begin April 7 for four flanged tritium waste containers (FTWC) currently stored in Building 1028, a 10-foot by 24-foot shipping container that was modified for long-term drum storage.
Headspace gases containing hydrogen, oxygen and radioactive tritium will be vented from the FTWCs, which are specialized high-pressure storage vessels. They are approximately 50 gallons in size and are stored in 85-gallon steel drums for ease of handling and disposal. It is speculated the tritium may be in the form of water vapor or elemental hydrogen gas.
A pre-construction document sent to the EPA in May 2019 indicates that the four FTWCs contain significant tritium inventory consisting of tritium contaminated metal parts and molecular sieve media, a pebble-like material used to absorb water from exhaust airstreams, contained in metal canisters along with some loose media material in bags.
Over time, the document states, tritiated water vapor absorbed onto the media can become liberated onto the FTWC headspace.
Radiolysis can cause separation of the water vapors possibly resulting in a hazardous hydrogen-oxygen mixture within the FTWCs. Continued tritium storage in these containers could pose an unsafe condition, so the plan is to vent them in place to remove hazardous gases, the document says.
The gas will be sent though a tritium capture system called a “getter bed” that will capture available tritium and direct it into an exhaust duct system that will be installed to provide controlled, continual exhaust flows and emission monitoring from the operation.
The four FTWCs are estimated to contain some 114,000 curies. LANL anticipates the off-site dose will range from .20 mrem to just over 8 mrem which is still within the 10 mrem standard.
“The benefit of removing this potentially hazardous source from LANL offsets the one year of elevated emissions,” the document states.
In addition to source emissions monitoring, there are a variety of ambient air samplers located around Technical Area 54 and at four public receptor locations in the White Rock community which is a little over a mile from Building 1028. These stations are part of the LANL Airnet program, and continuously measure the ambient air for airborne particulates and tritiated water vapor.
Triad and N3B personnel have been conducting emergency training drills in preparation for the venting operation. Although N3B is responsible for legacy waste cleanup, the FTWCs have been placed under Triad control until they have been vented and transported to the Weapons Engineering Tritium Facility for final disposition.