Humboldt Bay officially decommissioned, site released for unrestricted use

November 23, 2021, 9:30AMRadwaste Solutions
The Humboldt Bay nuclear power plant as seen from Humboldt Hill in 2010. (Photo: Wikimedia Commons.)

The license for Pacific Gas & Electric Company’s Humboldt Bay Unit 3 nuclear power plant near Eureka, Calif., has been terminated by the Nuclear Regulatory Commission, and the site has been released for unrestricted use. A 65-MWe boiling water reactor plant, Humboldt Bay-3 operated commercially from 1963 to 1976.

After decommissioning the facility to meet the NRC’s radiation protection standards, PG&E in October submitted final status surveys of the Unit 3 site and requested license termination. The NRC said that its staff evaluated the surveys, conducted inspections, and reviewed confirmatory analyses before concluding that the site meets its criteria for license termination for unrestricted use.

The NRC issued a safety evaluation report on November 18 in response to PG&E’s request to terminate the Humboldt Bay-3 license.

Background: After being shut down in July 1976 for refueling and to conduct seismic modifications, Humboldt Bay-3 underwent an updated economic analysis, which indicated that restarting the reactor would not likely be cost-effective. In June 1983, PG&E announced its intention to decommission the unit, placing it in the NRC’s SAFSTOR decommissioning status, in which a nuclear facility is maintained in a safe condition for up to 60 years before decommissioning is completed.

In December 2003, PG&E formally submitted a license application to the NRC for a dry cask independent spent fuel storage installation (ISFSI) at the Humboldt Bay site, which the NRC approved in 2005. The transfer of spent fuel from the fuel storage pool to the ISFSI was completed in December 2008, and active decontamination and decommissioning work on Humboldt Bay-3 began in 2009.

Reactor caisson: Humboldt Bay was unique in that the reactor core was situated in a watertight, 60-foot diameter concrete caisson buried 80 feet below grade. The caisson was a first of its kind to house a nuclear containment structure, pressure suppression chamber, and nuclear steam supply system underground. While the caisson made decommissioning the site challenging, crews were able to remove the structure by 2018.

ISFSI: Humboldt Bay–3’s ISFSI will remain under a separate NRC license. PG&E is responsible for the security and protection of the ISFSI and is required to maintain $53.3 million in liability insurance coverage until the fuel has been removed from the site, the NRC said. PG&E is also responsible for the decommissioning of the ISFSI once the fuel has been removed.


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