At the urging of the Government Accountability Office (GAO), the Department of Energy will conduct a root cause analysis of the May 2017 partial collapse of Tunnel 1 of the Plutonium Uranium Extraction (PUREX) Plant at the Hanford Site in Washington.
The evaluation should be completed by the end of the year. The GAO called for a thorough investigation and examination of what contributed to the collapse, and generally wants DOE to do a better job of monitoring the status of old contaminated facilities at Hanford.
The Energy Department’s Office of Environmental Management is planning regular inspections of other contaminated excess facilities at the former plutonium manufacturing complex near the Columbia River, according to the GAO report made public Thursday.
At the request of Hanford cleanup contractor CH2M Hill Plateau Remediation, DOE’s Richland Operations Office initially waived performance of a root cause analysis in lieu of a less rigorous review of the physical causes of the accident, congressional auditors wrote. In the immediate aftermath of the accident the focus was on emergency repair and stabilization of the tunnel, while minimizing radiological risk to workers, according to the report.
Hanford workers found a partial collapse of roof timbers at one of the PUREX Plant’s two underground storage tunnels in May 2017. The tunnels are used to store contaminated equipment and railcars underground.
The accident did not injure anyone or result in the measurable release of radiation and toxic materials. It did, however, raise questions about the adequacy of the surveillance and maintenance program at the site, the GAO said. Such surveillance and upkeep efforts are meant to ensure the old facilities remain safe until cleanup.
PUREX Tunnel 1, built in the 1950s, was filled with grout for stabilization by November 2017. In April 2019, CH2M Hill Plateau Remediation finished shoring up the second of two storage tunnels with grout. The PUREX Plant itself is not expected to be taken down until at least 2032.
Concerns have been raised since the 1970s about the structural stability of Tunnel 1. A structural analysis was done in 1991, but a follow-up scheduled for 2001 still hadn’t been done as of May 2017, the GAO said in the report.
The government watchdog said some sites at the highly contaminated Hanford reservation are inspected “infrequently or never,” either physically or “by remote means.” For example, the Reduction-Oxidation (REDOX) Plant, which irradiated fuel rods for the U.S. nuclear weapons program, has not been entered in 50 years.
The PUREX facility was one of five huge plutonium plants or “canyons” that processed 110,000 tons of nuclear fuel from Hanford’s nine nuclear reactors for the U.S. military program. PUREX extracted plutonium from chemical processing of irradiated fuel rods.
There are roughly 800 contaminated excess facilities at Hanford. Fifteen were designated as “key” in the last update to the Tri-Party Agreement on Hanford cleanup milestones between DOE, the state Department of Ecology, and the U.S. Environmental Protection Agency. These include major facilities like PUREX, REDOX, a plutonium processing plant, and Hanford’s nuclear reactors.
Two of the 15 are either undergoing remediation or have already been cleaned up, the GAO said.
The GAO conducted its audit between March 2018 and January 2020 at the request of members of Congress including Sen. Ron Wyden (D-Ore.). On Thursday, Wyden wrote to Energy Secretary Dan Brouillette asking what “specific steps” DOE will take to prevent “any future unexpected failures of containment at legacy radioactive waste facilities at Hanford.”
Wyden attributes the unexpected partial collapse to a failure of DOE and its contractors to independently verify the tunnel’s physical condition. The senator called this the type of error “replicated over many years” across the Hanford Site. Advances in remote technology suggest better monitoring is possible in areas too contaminated for workers to safely enter, he added.
Wyden asked the energy secretary to reply to his information request by March 20.
The Energy Department agrees with the report’s recommendations and is working to improve inspection and oversight of contaminated facilities, DOE Senior Adviser for Environmental Management William (Ike) White said in a December letter to GAO Natural Resources and Environment Director David Trimble. The letter is included in the new report.
The Hanford Site is spread across 586 square miles around the Tri-Cities region of southeastern Washington near the cities of Richland, Pasco, and Kennewick. The Columbia River cuts through about 50 miles of the site.
