U.S. nuclear plants still dependable

By William D. Balgord, Ph.D.

This article originally appeared in the Opinion section of the Des Moines Register.


The headlines this week deal with the North Anna nuclear plant in Virginia and the earthquake that struck nearby. Earlier in the summer, it was the Fort Calhoun and Cooper nuclear plants in Nebraska and the encroaching Missouri River floodwaters. Before that it was Japan’s earthquake and tsunami and the Fukushima nuclear complex.

At North Anna on Tuesday, initial reports said auxiliary power units kept the cooling water circulating after the plant’s emergency safety systems shut the plant down — just as it was designed to.

At Fukushima, however, events unfolded in an eerie sequence:

A 9.0 magnitude earthquake strikes;

30- to 50-foot tsunami waves produced by the quake smash inland;

Reactors flood, and the nuclear crisis begins.

As the quake struck, control rods dropped into the reactor cores and stopped the nuclear fission process immediately. But in-rushing water disrupted diesel pumps that circulated cooling water through the shutdown reactors. Battery-operated pumps took over, but they too became exhausted.

Heat from decaying fission products boiled away water from the containment vessels. Later that day, exposed reactor rods began to melt in Reactor 1 (possibly others) producing hydrogen that exploded and blew the roofs off two reactor buildings.

Despite assurances, TV coverage of Fukushima fed hysteria among some U.S. citizens. Within days, stocks of potassium iodide disappeared from drug stores on the West Coast, purchased by consumers anticipating a radioactive cloud that never arrived.

How will the Japanese tragedy affect the U.S. industry?  Nuclear safety is again being questioned by critics and politicians. Older plants may be shut down irrespective that nuclear accounts for more than 20 percent of our electricity.

Obtuse policies have forestalled introduction of advanced technologies that operate water-free and preclude hydrogen explosions.

There are fundamental differences in safety standards between nuclear plants in Japan and the United States. Of 104 U.S. facilities only two along the Pacific are considered remotely vulnerable to tsunamis, contrasting with Japanese plants built on tectonically unstable land.

The Duane Arnold plant near Palo and the two in Nebraska are rated by the U.S. Nuclear Regulatory Commission to be at very low risk of an earthquake capable of causing core damage. The NRC expects to complete an exhaustive review and recommendations for upgrading all U.S. plants, where needed, this fall.

Fort Calhoun nuclear station near Omaha on the Missouri River posed concerns for residents in Nebraska and western Iowa primarily because of the flooding. Those concerns eased as water levels on the Missouri River receded.

Media identify “reactor melt-down” with a worst case that penetrates a reactor’s primary containment, as portrayed in the movie “China Syndrome.” Post-mortems following the Three Mile Island nuclear accident showed corrosion from meltdown proceeded barely into the 6-inch-thick steel containment vessel. Partially molten materials never breached the steel containment vessel, and no deaths of Three Mile Island workers could be attributed to the release of radiation, despite much adverse publicity.

Chernobyl contrasts starkly with Three Mile Island. The faulty design at the ill-fated Soviet nuclear facility (lacking containment buildings and abetted by operator error) led to out-of-control fires that contaminated wide areas of Ukraine. Engineers later described the plant as designed to fail “un-safely.”

Under societal pressures the utility industry is responding to demands for “renewable energy.” But wind and solar power are not immune from vagaries of weather and season. Both require back up with coal-, gas-fired or nuclear plants.

Over-dependence on wind energy that supplies the Texas grid turned out to be short-sighted last winter. Blackouts triggered by high peak demand during calm, frigid conditions caused hardship for residents there. Heat-related deaths soared this summer in Japan deprived of air conditioners without electricity supplied by idled nuclear plants.

Objections from anti-nuclear activists would prevent the replacement of aging plants with a generation of safer reactors.

If wind and solar are to ever contribute more than a nominal 1.5 percent to the U.S. power grids, dependable base-load nuclear power will be needed wherever — and whenever — the wind doesn’t blow and the sun doesn’t shine.

 

 


William D. Balgord, Ph.D., heads Environmental & Resources Technology Inc. in Waukon and has taught nuclear chemistry.

 

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