The Defense Nuclear Facilities Safety Board (DNFSB) said in a new report the Energy Department Office of Environmental Management has more work to do on safety issues connected with criticality and flammable gas at the Pretreatment Facility for the Waste Treatment Plant at the Hanford Site in Washington state.
The 100-page-plus technical report centers on four areas of concern: hydrogen in process vessels, criticality in process vessels, standard high-solids vessel design, and hydrogen in piping and ancillary vessels.
“If DOE chooses to treat waste containing heavy plutonium particulate in the Pretreatment Facility, the proposed criticality safety strategy does not provide an adequate basis” for safe operations, according to the DNFSB report. The board sent a copy of the document to acting DOE Assistant Secretary for Environmental Management Jim Owendoff on Oct. 12.
Among other things, the board said nuclear modeling calculations used at WTP don’t meet proper industry standards; certain key assumptions on criticality in process vessels don’t have necessary “technical rigor;” and there are many uncertainties surrounding “location, quantity and properties” of plutonium particulate in the Hanford Tank Farms.
There has already been a significant amount of back-and-forth between DOE and the DNFSB on the Pretreatment Facility when it comes to potentially explosive gases and criticality hazards. In January, DOE sent a letter to DNFSB outlining progress in addressing areas such as criticality in process vessels and hydrogen in piping and ancillary vessels (HPAV). While DOE considers the progress sufficient to allay safety concerns, DNFSB isn’t so sure.
The Pretreatment Facility is one of four primary sections of the WTP, which will convert up to 56 million gallons of chemical and radioactive waste at Hanford into a glass form for permanent storage. It will receive Hanford tank waste and divide it into separate streams for the Low-Activity Waste and High-Level Waste Facilities.
Under a federal court order, full operations of the WTP must begin by the end of 2036. The plant must legally begin treating Hanford’s less-radioactive low-level waste by 2023, though Bechtel would major fees if processing does not begin in 2022.
