VERNON — Less than seven months after Vermont Yankee ceased producing power, the Nuclear Regulatory Commission's resident inspector office at the plant went dark.
But even after pulling its inspectors from the Vernon facility, the NRC pledged that “periodic and targeted” monitoring would continue.
Proof of that is in the NRC's newest inspection report, a product of visiting decommissioning specialists poring over details, including operations of Vermont Yankee's spent fuel pool, plans for a massive water-storage facility, and the proposed design of the plant's second spent fuel pad.
From an operational standpoint, the NRC's overall conclusion for Vermont Yankee was simple: “No findings of safety significance were identified.”
Plant owner Entergy shut Vermont Yankee at the end of 2014, ending 42 years of power production. Entergy defueled the plant's reactor in January and is readying the site for SAFSTOR, a decades-long period of extended dormancy before actual decommissioning work commences.
The NRC established its resident inspector program in 1978 and assigned two inspectors to Yankee. That inspection program ended at VY this past summer “commensurate with the reduced safety risk associated with a permanently shut-down reactor,” an NRC official said at the time.
The plan now is to “perform quarterly decommissioning inspections at Vermont Yankee until the plant formally enters the SAFSTOR phase,” NRC spokesman Neil Sheehan said. “The plant is currently in what we would describe as the post-operational transitional phase.”
The NRC's first quarterly inspection report since resident inspectors left the plant was issued Oct. 22, and it is based partly on site visits in late July and mid-September. The report covers a variety of topics, including:
• The visiting inspectors observed plant technicians “collect, prepare, and analyze spent-fuel pool water samples.” That is a key safety site at the plant prior to the transfer - expected by the end of 2020 - of all spent nuclear fuel into more-stable dry-cask storage.
Inspectors also checked groundwater-monitoring wells and effluent-monitoring points, and they watched technicians work with environmental air samples.
The NRC's report says that “waste-treatment systems were maintained and operated in accordance with site procedures” and that “effluent releases to the environment were being properly controlled, monitored and quantified as required by NRC regulations.”
• The report says Entergy is meeting its “occupational dose projections” - in other words, the company's projections for its workforce's exposure to radiation.
The goal, Sheehan said, is not only to stay within those estimated doses but also to pursue a standard dubbed ALARA (“as low as reasonably acceptable”).
“Whenever workers or contractors enter high radiation areas at a plant, work plans must be developed so that exposure is limited to the greatest extent possible,” Sheehan said. “Dosimeters worn by the employees, as well as radiation scans performed prior to and after entry to those areas, provide additional checks.”
• NRC inspectors reviewed plans to abandon Yankee's condensate storage tank - “a massive tank holding hundreds of thousands of gallons of water,” according to Sheehan - and switch to a reservoir called the “torus” at the base of the reactor containment building during SAFSTOR.
“Our inspectors found that the analysis and work behind this switch were properly and safely executed,” Sheehan said.
• Entergy still is seeking state permission to build a second spent-fuel storage pad at Yankee, and some have been critical of the company's planning and siting process for that pad.
But the NRC now has signed off on the project's design, with the inspection report noting that Entergy hopes to start construction in 2016.
Federal inspectors examined issues including Entergy's “conclusions about the acceptability of the storage pad's design with respect to the site's hydrology, geology, and seismology,” the report says.
“The NRC inspectors found that the company's engineering evaluations of the design were thorough and acceptable,” Sheehan said.
In addition to examination of decommissioning operations, radiological programs and the fuel-pad plans, Entergy spokesman Martin Cohn said the NRC inspection also included the plant's management oversight.
The report's finding of no issues of safety significance, Cohn said, “confirms Entergy's commitment and effectiveness to safely decommission Vermont Yankee.”
Sheehan said the NRC's routine inspections of Vermont Yankee will continue after the plant enters SAFSTOR, “but the inspection frequency will decrease.”