By George Lobsenz
A federal safety oversight board has warned Energy Secretary Steven Chu in unusually strong terms about significant unresolved issues with cooling systems for intensely radioactive plutonium-238 containers at Los Alamos National Laboratory, saying lab officials have failed to address the problems even though the systems are needed to prevent “one of the lab’s highest consequence accident scenarios.”
The Defense Nuclear Facilities Safety Board (DNFSB), which oversees safety at DoE nuclear facilities, told Chu in a letter last month that it was “deeply concerned” about the lab’s failure to act on safety deficiencies at the vault water baths for the plutonium-238 containers because overheating of just one container posed the risk of huge radiation releases.
The board expressed particular concern about plutonium-238 stored in some 200 “non-safety-class” containers, which are not as robust as safety-class containers. The containers are stored underwater in the vault water baths in Los Alamos’ Plutonium Facility, where the “heat source” plutonium is used to fabricate radioisotope power systems for NASA space missions.
The DNFSB said it first raised concerns about the vault water baths in an Oct. 16, 2007, letter to the National Nuclear Security Administration (NNSA), the semi-autonomous DoE agency that manages the department’s nuclear weapons facilities. Among other issues, the board’s letter said the heat exchanger needed to dissipate heat from the plutonium containers was probably undersized, and that Los Alamos officials failed to adequately assure the cooling system would operate as needed under normal and abnormal conditions.
In its April 7 letter to Chu, the board said Los Alamos officials had done little to resolve the safety issues raised by the DNFSB 18 months ago, even though failure of the cooling system could quickly lead to serious consequences.
“The board has determined that the safety function of the vault water baths has not been effectively defined, implemented, or protected,” it said. “As a result, inadequate controls exist to make certain that vital water level and cooling are maintained to ensure that all of the non-safety-class heat source plutonium containers will remain submerged and adequately cooled during all anticipated normal and abnormal conditions.
“In particular, a failure of the system cooling function for the vault water baths, which is not credited as a safety control, could allow the water in the baths to boil in as little as 18 hours, followed shortly by uncovering of the containers.”
The DNFSB said Los Alamos also lacked sufficient information to reliably predict how some of the containers would respond to such a loss of cooling. However, the board said it could cause containers to over-pressurize and fail–leading to a deadly release of radiation if offsite exposures were not mitigated by containment or emergency response procedures.
“The unmitigated offsite consequences of an overpressurization event involving even a single container of heat source plutonium amount to nearly 500 rem; the consequences of multiple failures are much higher,” the board said.
The DNFSB said Los Alamos officials and NNSA’s Los Alamos Site Office had “acknowledged the existence of these issues, however, it is not clear that proposed near-term actions will resolve the issues in an acceptable manner
“The existing [Los Alamos] system surveillance required only a monthly verification of water level and a spot check that the non-safety-class containers were submerged,” the board noted.
The DNFSB said its confidence in Los Alamos’ ability to maintain the vault water baths was also undermined by the fact that lab officials failed to identify any of the cooling system issues when they conducted an assessment of the vault water baths in 2008.
In sum, the board said: “This system is relied upon to protect the public by preventing one of the laboratory’s highest consequence accident scenarios. Despite this critically important safety function, significant unresolved issues with this safety-class system are unaddressed, leaving it in an indeterminate and degraded state with respect to operability, reliability, and effectiveness–a situation that is unacceptable to the board.”
The board, imvoking its statutory authority, asked for a report and briefing within 45 days of its letter on short-term actions taken by NNSA to improve the safety of the vault water baths and its strategy for correcting the deficiencies cited by the board.
Damien LaVera, director of public affairs for NNSA, declined to respond to the DNFSB letter other than to say NNSA would publicly release its formal response to the board when it was made.
Officials at Los Alamos, which is operated for NNSA by a consortium led by the University of California and Bechtel, declined to comment.
Beyond the DNFSB’s concerns about the vault water baths, Los Alamos’ overall management of the plutonium-238 program was harshly criticized earlier this year by an official in DoE’s Office of Nuclear Energy.
The Project on Government Oversight (POGO), a DoE watchdog group, last week released a Jan. 9, 2009, memo from Owen Lowe, acting director of the radioisotope power system program in the Office of Nuclear Energy, to NNSA’s Los Alamos Site Office castigating Los Alamos for “chronic poor performance on this program,” including a failure to provide a planning document for the program.
Lowe added that “the performance issues on this program are not new and extend far beyond the receipt of this single planning document. For at least the last several years, Los Alamos has been unable to prepare basic plans or routine reports.”
Lowe said DoE had provided Los Alamos with $13 million for the radioisotope power system program, but that “I cannot allow continued expenditures of taxpayer funds with no accountability.”
LaVera said POGO’s release of the memo was unfair because Lowe’s criticism was based on a misunderstanding between his office and Los Alamos on the terms of the program. LaVera said the miscommunication was quickly resolved after Lowe’s memo and Los Alamos provided the needed documents to the Office of Nuclear Energy.