San Onofre operator eyes major dismantling start in Q1 2020
Southern California Edison (SCE) is implementing corrective fuel loading measures at San Onofre following an incident in August 2018 and major dismantling and decontamination (D&D) work could start in early 2020 pending regulatory approvals, John Dobken, SCE spokesman, told Nuclear Energy Insider.
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The ongoing impact of a fuel canister incident at the 2.2 GW San Onofre Nuclear Generating Station (SONGS) highlights the sensitivity of fuel loading on decommissioning schedules.
SONGS was shut down in 2013 and the transfer of spent fuel has been suspended since August 2018, when contractor Holtec did not sufficiently lower a fuel canister into the cavity enclosure container (CEC) on the dry cask storage pad. The canister came to rest on the top of the divider shield ring and against the inside surface of the transfer cask.
Safe and fast spent fuel transfer is critical to minimizing decommissioning schedules and costs. Completion of fuel transfer reduces plant monitoring and labor requirements and allows contractors to commence major dismantling and decontamination (D&D) work. SCE awarded the D&D and site restoration contract for SONGS to a joint venture held by EnergySolutions and AECOM.
SCE is yet to transfer 44 of the 73 fuel canisters at the site and has been working with the Nuclear Regulatory Commission (NRC) and regional stakeholders to resolve oversight concerns and restart the transfer process.
SCE is implementing corrective measures and is awaiting final approvals from the NRC and the California Coastal Commission (CCC), Dobken told Nuclear Energy Insider.
SCE hopes to restart the fuel transfer process in the coming months and complete it in the fourth quarter of this year, Dobken said.
This would allow "major" D&D work to commence in the first quarter of 2020, he said.
SCE aims to complete the major D&D work at the site by late 2028 and complete decommissioning and site restoration within 20 years of shutdown.
Corrective actions
The fuel loading incident at SONGS centred on insufficient handling and oversight of a crane operation, the SONGS Community Engagement Panel (CEP), a body of local authority representatives, said in an earlier statement.
“The crane operator could not see the MPC [multi-purpose canister] (because this is an operation commonly called a blind lift) and a spotter assigned to observe the MPC did not recognize the slack sling condition," the CEP said.
Key oversight personnel were located 150 feet away in a low radiation area and believed, “because the slings appeared to be taut, that the [canister] was being lowered to the bottom of the CEC," the panel said.
Elevated radiation measurements taken near the cask transporter indicated that the canister had not been fully lowered to the bottom of the CEC. The operation was appropriately corrected, but canister-loading was stopped and preliminary findings by the NRC in October cited training, procedures and oversight deficiencies.
SCE is now implementing corrective actions which focus on five key areas of fuel transfer operations, Dobken said.
• Better training programmes and re-training for crews.
• More detailed procedures.
• Improved equipment, including load monitoring, cameras and alarms.
• More intrusive and effective oversight of operations, including changes to ISFSI project management and increased oversight personnel with dry fuel canister loading experience.
• A corrective action program: to identify lessons to be learned and implementing a lower threshold for taking corrective actions.
SCE will conduct a series of internal and independent readiness reviews before any fuel transfer operations are restarted, Dobken said.
Environmental challenges
The SONGS plant was shut down at relatively short notice. Many other decommissioning projects, such as Pacific Gas and Electric’s Diablo Canyon plant, will benefit from years of planning in which they can optimize the transfer from shutdown to dismantling and minimize the high upfront costs.
Announced US nuclear plant closures in 2018-2025
Source: US Energy Information Administration (EIA), September 2018.
The SONGS project is also faced with the combined challenges of California's lengthy environmental permitting process and a large number of local government stakeholders.
The SONGS site spans 84 acres and is bounded by the Pacific Ocean and the major interstate highway. The land is owned by the Department of the Navy and the operator must coordinate with agencies such as the California State Lands Commission (CSLC), Army Corp of Engineers, the California Coastal Commission (CCC), the Department of Toxic Substances Control, the Department of Public Health and the Regional Water Quality Board.
The CSLC has approved certification of the environmental impact report (EIR) for the decommissioning project as well as a new lease for SCE’s offshore structures until 2035, Dobken said.
The approved lease includes the planned removal of the primary and auxiliary intake structures-- the largest structures that protrude up from the seafloor—and a number of other components, he said.
SCE still requires a Coastal Development Permit (CDP) from the CCC, which includes both onshore and offshore elements of project. The next scheduled meeting of the CCC is planned for June, Dobken said.
While the fuel canister incident has delayed fuel transfer, total decommissioning costs are expected to stay within current estimates, Dobken said.
In 2018, SCE estimated the total decommissioning cost of the project at $4.4 billion and the operator is due to submit its next decommissioning cost report in 2021.
By Neil Ford