A security inspection at Diablo Canyon nuclear power plant in March revealed problems that could result in a downgrade in the overall safety ranking of the plant.
The findings resulted from a “force-on-force” inspection which tests how well plant personnel defend against a simulated attack. Such inspections are conducted every three years.
In a letter dated July 23, the federal Nuclear Regulatory Commission informed plant managers that the inspection found problems “of greater than very low security significance.”
Neither the NRC nor Pacific Gas and Electric Co. would provide details of the problems or the findings, citing security concerns. However, the letter says the problems are associated with ongoing troubles at the plant that involve “failure to use conservative assumptions in decision making.”
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According to an NRC fact sheet, the frequency of “force-on-force” inspections was increased from every eight years to every three years after the Sept. 11, 2001, terrorist attacks.
Such an inspection “includes both tabletop drills and simulated combat between a mock commando-type adversary force and the nuclear plant security force,” the agency says.
“During the attack, the adversary force attempts to reach and damage key safety systems and components that protect the reactor’s core (containing radioactive fuel) or the spent nuclear fuel pool, potentially causing a radioactive release to the environment. The nuclear power plant’s security force, in turn, seeks to stop the adversaries from reaching the plant’s equipment and causing such a release.”
Findings of greater than very low security significance mean that some aspects of the plant’s overall security rating could go from green — which is the best ranking possible — to white, which indicates that additional inspections are needed.
Problems identified by the inspection were corrected while the inspectors were on site, said Victor Dricks, NRC spokesman. Additional inspections will be conducted to verify that the corrections have been made.
Such inspections are not “pass or fail” tests, Dricks said. They are intended to be opportunities for improvements to be made.
“The fact that deficiencies were identified doesn’t mean the plant is unsafe,” he said. “We believe the facility remains safe and secure.”
PG&E will hold a regulatory conference with the NRC to discuss the results of the inspection, said Paul Flake, PG&E spokesman. The conference will be held within a month and will not be open to the public. The results of the inspection will be finalized following the regulatory conference.
The inspection results will fuel concerns about the overall safety of the plant, said Jane Swanson, spokeswoman with the San Luis Obispo Mothers for Peace. The anti-nuclear group has focused in recent years on what members say are safety and security issues at Diablo Canyon.
“Since 2008 the NRC has repeatedly found that PG&E lacks the ability to identify and resolve problems at the Diablo Canyon nuclear plant,” Swanson said. “This recent security inspection report again documents this fundamental lack of competence to manage the two aging reactors.”