Case Studies

Generic Safety Issue 191 (GSI-191) Pilot

On Tuesday, July 11, the Nuclear Regulatory Commission (NRC) approved a License Amendment Request (LAR) for South Texas Project (STP) Nuclear Operating Company’s use of a risk-informed resolution to the long-standing industry issue – Generic Safety Issue 191 (GSI-191). For nearly 20 years, GSI-191 – the assessment of debris accumulation on PWR sump performance – has been an industry-wide safety issue. Despite significant efforts, closure of GSI-191 has eluded resolution for plants with large amounts of fibrous insulation. The NRC’s GSI-191 concern centers around the impact of fibrous debris following a loss of cooling accident (LOCA) on the ability of the containment sumps to maintain long-term cooling.

SoTeRiA-IAP Industry Liaison Ernie Kee served as technical project lead on the seven-year, industry-academic pilot project where he identified resources, defined the research scope, managed and coordinated ongoing technical work performed by the University of Illinois at Urbana-Champaign, the University of Texas at Austin, ABS Consulting Inc., Alion Science and Technology, the University of New Mexico, Texas A&M University, and Los Alamos National Laboratory.

SoTeRiA-IAP Director Zahra Mohaghegh contributed to the Integrated Probabilistic Risk Assessment (I-PRA) approach of GSI-191, and provided academic oversight on technical reporting to the NRC and the Advisory Committee on Reactor Safeguards (ACRS).

The approved LAR eliminated the need to replace fibrous insulation in both units at STP and avoided 176 REM of exposure. The cost savings are estimated at approximately $43 million.

The team won a Nuclear Energy Institute (NEI) 2018 Top Industry Practice (TIP) award for its risk-informed approach to addressing GSI-191.


South Texas Project receives U.S. nuclear energy industry top honor

STP awarded for Nuclear Industry Innovation