Public Interest Briefs

Center Opposes Licensing of Diablo Canyon Nuclear Power Plant

Cites Dangers Posed by Closeness to Major Earthquake Fault

The serious accident at the Three Mile Island Nuclear Power Plant in Pennsylvania underscores the seriousness of the Center’s challenge to the Diablo Canyon Nuclear Power Plant.

Diablo Canyon sits just three miles from the Hosgri fault, a major California earthquake fault. During recent hearings before the Nuclear Regulatory Licensing Board, Center attorneys backed by expert testimony of geologists and structural engineers demonstrated to the Board that the fault is capable of producing a tremor much larger than the plant’s systems are designed to withstand.

Dr. Clarence Hall, Professor of Geology and former Dean of the UCLA School of Earth and Space Sciences, testified that the Hosgri fault was more dangerous than had been assumed when Diablo Canyon was designed. The fault line is longer than originally thought, and larger faults are known to produce stronger earthquakes. The strength of the potential quake on the Hosgri fault could be greater than originally predicted, and his research showed a “contiguous zone of faulting” in the immediate area of the plant. Hall believes that there has been a great deal more movement along the fault than Pacific Gas and Electric, the utility company that built the plant, contends.

The Center’s other two expert witnesses, Drs. Mihailo Trifunac and Enrique Luco, professors at the University of Southern California and the University of California at San Diego respectively, sharply criticized the plant’s seismic design and the related engineering analysis. They criticized Pacific Gas and Electric for understanding the magnitude of the stress that an earthquake on the fault would create and also for failing to incorporate design features which would enable the plant to withstand that stress. Thus, the complex safety systems may not be able to withstand the pressure from an earthquake. The presence of these two scientists at the hearings represented an important procedural victory for the Center. Both had stated that, in order to maintain their scientific neutrality, they would testify only if subpoenaed to do so. Yet the Licensing Board, without explanation, refused to issue the subpoenas. The Center appealed this ruling to the Atomic Safety and Licensing Appeals Board, and that Board reversed the rulings and ordered those subpoenas issued immediately.

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