Another criticality report at PF-4

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It’s closing in on a year that the Los Alamos National Laboratory paused full-time operations at its Plutonium Facility.
LANL director Charlie McMillan stopped operations to address nuclear criticality safety concerns back in June of last year.
The Defense Nuclear Facilities Safety Board remains concerned and it wants the lab to take more time to address the criticality issues.
DNFSB chair Peter Winokur wrote a letter to NNSA administrator Frank Klotz May 16, addressing the concerns.
“During this pause, NNSA briefed the Board on a strategy to develop criticality safety evaluations (CSE) for higher-risk operations prior to resumption. The Board is aware that this plan has evolved such that the LANL Director intends to resume many higher-risk operations without first developing compliant CSEs.
“Department of Energy directives and industry consensus standards require that CSEs unambiguously demonstrate how fissionable material operations will remain subcritical under both normal and credible abnormal conditions. These CSEs identify controls to ensure safe operation.
“Therefore,, the Board requests a briefing from NNSA within 14 days on how the NNSA will ensure that adequate controls will be identified as the laboratory resumes higher-risk operations in the Plutonium Facility.”
McMillan was in Washington in April to address the Senate Armed Services Strategic Forces Subcommittee.
At that time, McMillan did not offer a timetable for a resumption of activties.
Meanwhile, according to an April 25 DNFSB site representative report, there was another criticality scare at PF-4.
The site report read, “Facility personnel performing a confirmatory neutron measurement on a standard waste box (SWB) identified that the measured value exceeded the limits specified by the criticality safety evaluation by a factor of nearly two. The measured value also exceeded the combined, individual measured values of the items inside the SWB by a factor of nearly four.
“Workers took the correct immediate actions to secure the area, back off, and make notifications. During a critique, facility personnel questioned the adequacy of the calibration of the equipment and agreed to reconvene to determine a path forward for confirming the contents of the SWB. The Site Representatives note that critique personnel did not bring or review as part of the critique the calibration procedure, the procedure for assaying the waste, or the procedure for loading the SWB.”