By John Stang
Pacific Gas & Electric (PG&E) expects full cleanup of its Diablo Canyon nuclear power plant to cost at least $5.1 billion, according to paperwork filed Wednesday with the U.S. Nuclear Regulatory Commission.
That breaks down to $3.16 billion for decommissioning the complex, $1.26 billion for spent fuel management, and about $738,000 for site restoration, California’s largest utility said in its post-shutdown decommissioning activities report (PSDAR). The work would largely be complete by 2038, 13 years after the facility is fully retired.
In March, PG&E had $3.2 billion in its decommissioning trust fund for the two-reactor power plant. Sometime next year, the utility expects a decision from the California Public Utilities Commission on increasing rates to provide another $1.6 billion it says is needed to fully fund decommissioning.
In 2016, PG&E announced plans to retire Diablo Canyon’s two pressurized water reactors as their Nuclear Regulatory Commission licenses expire. The San Luis Obispo County facility is the last operating nuclear power plant in California.
Reactor Unit 1, which began operations in 1985, is scheduled to shut down in November 2024. Reactor Unit 2, online since 1986, would follow in August 2025. Pacific Gas & Electric aims to replace the reactors with other clean energy sources.
In September, the NRC gave permission for PG&E to use $187.8 million from its trust fund for decommissioning preparations between now and Diablo Canyon’s closure. This money would cover engineering work on decommissioning, contract procurements, and obtaining permits.
Pacific Gas & Electric will conduct decommissioning preparations from November 2024 to April 2027, according to the PSDAR. These will include setting up safe power sources for the decommissioning work, modifying the infrastructure to handle decommissioning and conducting studies on contamination.
Moving spent fuel from the reactors to wet storage for cooling is expected to be done by May 2027. Later movement of that fuel to dry storage is scheduled for completion by June 2032.
Removing some equipment and chemical wastes will occur simultaneously during decommissioning. Removing the reactor vessels and tearing down most of the buildings will occur from 2032 to 2035.
Site restoration would take place from 2035 to 2038, the PSDAR says. This will include demolition of nonradiological structures, final radiological surveys, and other work to terminate the site’s NRC operations licensing in 2038.
The PSDAR anticipates the spent fuel remaining in dry storage at Diablo Canyon until 2067.
Since 2009, PG&E has completed seven campaigns to transfer used fuel to a dry storage site at Diablo Canyon as of March 2019. The pad holds 1,856 used fuel assemblies in 58 casks. Another 1,596 assembles are in the plant’s wet storage pools.
Diablo Canyon’s Nuclear Regulatory Commission license allows it to store 138 loaded casks containing 32 assemblies in each cask — meaning a total of 4,416 assemblies.
In January, PG&E filed for Chapter 11 bankruptcy protection in U.S. Bankruptcy Court for the Northern District of California, due to expected liabilities of $30 billion or more connected to wildfires in the state in 2017 and 2018. PG&E’s transition lines and other equipment have been blamed for many of the fires. So far, the utility has publicly said the bankruptcy and reorganization will not affect its decommissioning plans.
