IDAHO FALLS, Idaho – A team working for the Idaho Site EM program recently built a shielded container to ship a unique waste to the Waste Isolation Pilot Plant (WIPP), an in-house project that saved time and money over procuring the product off-site.
Ken Krivanek and his team from EM cleanup contractor Fluor Idaho worked with fabricators in the Idaho Nuclear Technology and Engineering Center (INTEC) Maintenance Shop to develop the container to shield neutron-emitting transuranic sources fabricated at the Monsanto-Dayton Laboratory prior to its demolition in the late 1980s. Neutron-emitting sources are extremely rare at INTEC, a facility that has extensive experience handling gamma radiation sources most often shielded by lead.
A type of plastic called lexan was chosen as the preferred container material because neutrons are best shielded with materials containing lots of hydrogen, such as plastics, which are composed of carbon and hydrogen molecules.
The containers go inside 16-gallon drums that are placed in 55-gallon drums for characterization prior to disposal. Placing the contents in 55-gallon drums is necessary to use a chamber at INTEC built to determine the radiation dose rate and curie content inside standard 55-gallon drums.
“Usually a company would contract out the fabrication of these types of shielded containers,” Krivanek said. “But we have the talent in-house, which saved time and money.”
Once approved for shipment, the high-activity waste will be loaded into specialty casks and shipped to the New Mexico repository for permanent disposal.
“Using the Lexan containers to house this waste really serves two purposes,” Krivanek said. “They protect workers who have to handle the drums and they provide extra shielding that’s necessary for the material to go to WIPP.”