Diablo Canyon Independent Peer Review Panel (IPRP)

What is the Diablo Canyon Independent Peer Review Panel (IPRP)? 

In 2006, the California legislature enacted Assembly Bill (AB) 1632 which directed the California Energy Commission (CEC) to assess the potential vulnerability of the state’s nuclear plants to major disruptions, including seismic events. The CEC’s resulting AB 1632 report recommended that the utilities perform enhanced seismic studies with two- and three-dimensional seismic surveys in the areas onshore and offshore from DCPP and SONGS. In D.10-08-003, the CPUC approved funding for DCPP seismic studies and established the Independent Peer Review Panel (IPRP) to review them. The IPRP is tasked with providing expertise to the Commission while also assuring the public that the studies are being performed in an appropriate manner. Passage of AB 361 in October 2015 authorized funding for IPRP through 2025 which was subsequently extended through 2030 with the passage of SB 846 in September 2022.

The IPRP is comprised of technical experts from the CEC, California Geological Survey, California Coastal Commission, California Seismic Safety Commission, and the County of San Luis Obispo. PG&E submits its seismic studies to the IPRP for review, the most recent of which was its Central Coastal California Seismic Imaging Project (CCCSIP) report, submitted in September 2014. Following the submission of these studies, the IPRP convenes for public meetings to review and discuss the results, and ultimately submits an IPRP Report. Since the IPRP’s inception it has issued ten reports, each available by clicking the following links:

PG&E issues responses to these reports which are available below (NOTE: PG&E did not formally respond to Report Nos. 1 and 4):

The IPRP meets periodically. The date, time, and location of future meetings can be found by visiting the CPUC calendar.

PG&E’S 2024 DIABLO CANYON UPDATED SEISMIC ASSESSMENT

In February 2024, in accordance with Senate Bill 846 (2022, Dodd), PG&E published an Updated Seismic Assessment of the Diablo Canyon Nuclear Power Plant. As required under Public Utilities Code Section 712, the IPRP reviewed PG&E’s Seismic Assessment in IPRP Report No. 16, which it published in August 2024. PG&E responded to Report No. 16 in January 2025; the IPRP published its own response letter in February 2026. All of these documents are available below.

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