Humboldt Bay Nuclear Power Plant

The Humboldt Bay Nuclear Power Plant is a 63 MWe boiling water reactor, owned by Pacific Gas and Electric Company that operated from August 1963 to July 1976 just south of Eureka, California. On Monday, January 23, 1961, Pacific Gas and Electric held a luncheon to invite the community to observe the start of the major construction of the nuclear unit. Concern about previously undiscovered seismic faults combined with more stringent requirements required after the Three Mile Island accident rendered the small plant unprofitable if restarted. It was shut down for refueling and seismic upgrades in July 1976, which dragged on due to changing requirements. PG&E announced plans to permanently shutter the plant in 1983, and it was then placed in SAFSTOR inactive status in 1988.

In 2004 Pacific Gas and Electric Company announced that three nuclear fuel rods were unaccounted for due to conflicting records of their location. The fuel rods were never accounted for, though PG&E investigators believe that they are still onsite in a storage pool. The investigation is believed to have cost one million dollars.

In December 2008, PG&E finished moving the spent nuclear fuel into dry cask storage on site. The next step is the decommissioning of the plant, planned to begin in 2010 along with the two original fossil-fuel-powered steam-turbine generators on site. The plant began being powered by an array of modern, multi-fuel Wärtsilä reciprocating engine-generators in late 2010. The work to dismantle the older turbine generators and continued dismantling of the nuclear side of the operations is scheduled to finish by April 2013.

In the 2012 Nuclear Decommissioning Cost Triennial Proceeding (NDCTP) of the California Public Utilities Commission (CPUC) PG&E requested approval of expending additional funds to remove more of the subterranean unit. As of 2009, PG&E planned to leave in place all HBPP3 structures three feet or more below grade (except for the Spent Nuclear Fuel (SNF) pool), including the concrete caisson surrounding the reactor vessel. In 2012, PG&E concluded that complete removal of the reactor caisson, and containment by a cement slurry wall, is the only appropriate alternative to meet NRC standards for remediating C-14 contamination. Currently, used fuel rods are being stored 44 feet above sea level in containers with 22,000 pound lids. These containers are filled with Helium, and will remain there for several decades. According to the NRC (Nuclear Regulatory Commission), the dry casks are safe for at least 60 years beyond their licensing agreement.

Based on PG&E’s schedule of planned decommissioning activities, which incorporates various assumptions, including approval of its proposed new scope, decommissioning of the Unit 3 site is expected to conclude in 2019.