A Nuclear Horror

Of all the disasters that could be caused by a severe earthquake, perhaps none is so frightening as the destruction of a nuclear power plant. Ruptured by the heaving of the once solid ground, it would release radioactive particles into the air. There, they could form a colorless, odorless cloud that would contaminate everything in its path, poisoning the land, killing some people, causing cancer in others.

To guard against this horror, the now disbanded Atomic Energy Commission and its successor, the Nuclear Regulatory Commission, have enforced strict rules. All atomic power plants located in earthquake zones must be constructed to withstand the most severe shaking ever recorded in the area. But geologists keep finding new earthquake faults--sometimes after construction has started. The latest example is an almost completed $1 billion nuclear facility on the California coast.

The Diablo Canyon plant is being built about 12 miles from San Luis Obispo by Pacific Gas & Electric Co., the nation's second largest investor-owned electric utility (1975 revenues: $2.2 billion). It consists of two giant reactors that will produce 2.2 million kilowatts of electricity. One reactor is nearly ready to go into operation; the other will be finished in August 1977. When construction started in 1968, PG&E knew all about the San Andreas fault, 45 miles inland, and the Rinconada fault, some 20 miles away. So its engineers designed the plant to survive a quake registering 6.75 on the Richter scale.* The concrete foundations are 14 ft. thick, for example, and a cross section of the mammoth dome over each reactor would show 3 1/2 ft. of concrete, liberally laced with steel reinforcing rods.

In 1971, however, Shell Oil Co. geologists prospecting offshore found an underwater fault that runs only 2 1/2 miles west of Diablo Canyon. At first, this Hosgri fault was thought to be inactive. But studies sponsored by the U.S. Geological Survey revealed that it was probably responsible for a 1927 quake estimated at 7.25 on the Richter scale. PG&E experts dispute that conclusion, insisting that a more distant fault caused the quake. If they are right--a crucial if--the plant is designed with a sufficient margin of safety to survive any probable jolt in the area.

Higher Rates. The Nuclear Regulatory Commission must now decide whether to grant the plant an operating license. For safety's sake, it can delay the license until the building is strengthened further. That might help soothe widespread public fears about the safety of not only the Diablo Canyon plant itself--which critics are now attacking--but also about nuclear energy in general. This is an especially important consideration in California, where citizens will vote in June on a proposal that in effect would block more atomic power plants in the state. On the other hand, if PG&E is correct, buttressing the plant would cost millions of dollars, which would be passed on to consumers in higher electricity rates. The NRC says it will decide by March 1. If it gives a go-ahead, it must then live with the chance of being wrong.

*By this measure, a jolt with a magnitude of 2 at its epicenter is barely perceptible; one that registers 5 may cause minor damage. The worst recorded quake in the U.S. (1964 in Alaska) hit 8.4.

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