President Obama responded to Japan's nuclear reactor crisis yesterday by asking the Nuclear Regulatory Commission to make a comprehensive safety review of U.S. nuclear plants to assess their ability to withstand natural calamities.

Speaking at the White House, NRC Chairman Gregory Jaczko said yesterday the study would be made. He repeated his statements this week that the commission considered the 104 U.S. nuclear plants to be secure, but the evidence from Japan's devastating reactor damage would be the basis for a new review.

"We're going to take a look at what happened, we're going to do a systematic and a methodical review of the information, and if we need to make changes to our program, we'll make changes to our program," Jaczko said. "But I want to emphasize and stress that we have a very robust program where we look at the safety and the security of our nuclear facilities on a minute-by-minute basis. "

Today, Japan's Self-Defense Force units shot water from fire trucks at the Unit 3 reactor at the Fukushima Daiichi nuclear plant, hoping to raise water levels in the unit's spent fuel cooling pool and prevent more radiation leaks from overheated fuel rods. More dousing operations would occur today, authorities said.

The chief of staff of the Air Self-Defense Force, Shigeru Iwasaki, said the SDF crews were exposed to no more than several millisieverts of radiation during the operation, levels that he said would not prevent continued attempts to cool the reactor, NHK reported. However radiation levels were registered elsewhere in the complex, up to 20 millisieverts per hour at some points, the news service said. Japan's science ministry said today that relatively high radiation levels were detected about 30 kilometers northwest of the plant.

The Los Angeles Times reported that the spent fuel pool in Unit 4 appears to have been damaged, possibly by the force of the earthquake, which could have led to leaks of the protective water cover that keeps spent fuel from overheating. The newspaper quoted an unnamed U.S. utility official as saying that water sprayed into the pool was disappearing faster than could be explained by evaporation.

A critical step in the weeklong battle is scheduled tomorrow, when Tokyo Electric Power Co. said it hoped to restore outside electric power to two of the crippled reactor units to see whether normal cooling of reactor cores and spent fuel pools could be restored at Units 1 and 2.

U.S. experts have said the resumption of cooling operations offers the best hope for containing radioactive releases of steam and gas at the complex, but it is not yet known whether hydrogen explosions and damage to reactor cores will permit this to happen.

Tokyo Electric Power, owner of the Fukushima Daiichi plant, said today it had shelved plans to build a new nuclear reactor in Aomori Prefecture. At 1,380 megawatts, it would have been Japan's largest.

Separately, owners of the 104 U.S. commercial nuclear power plants announced yesterday they will inspect their units to verify each company's ability to maintain safe reactor operations if confronted with natural disasters, fires, aircraft impact and explosions that go beyond the threats that plants are designed to withstand.

"We can do the best planning and analysis, and we can never guarantee zero risk, and we need to be prepared," Anthony Pietrangelo, chief nuclear officer of the Nuclear Energy Institute, told reporters. He said lessons from the Japanese reactor crisis will be studied. "We will learn from them. We will get that operating experience. We will apply it and try to make our units even safer than they are today."

The question of the safety of U.S. nuclear plans was also the subject of a report issued yesterday by the Union of Concerned Scientists, authored by David Lochbaum, a nuclear engineer who heads UCS's nuclear safety program. The report reviewed 14 significant safety-related events that triggered special oversight by NRC in 2010.

Some demands for a temporary shutdown

Lochbaum's report highlighted three cases in which NRC inspectors pursued problems to secure fixes and three cases with problems NRC overlooked or dismissed, it said.

"The chances of a disaster at a nuclear plant are low," the UCS report said. But it added the severe accidents at Three Mile Island in 1979 and Chernobyl in 1986 "occurred when a handful of known problems—aggravated by a few worker miscues—transformed fairly routine events into catastrophes."

The new inspection program by the nuclear operators follows demands from some members of Congress for a temporary shutdown and inspection of older U.S. plants, particularly the 23 reactors with the same reactor models present in the crippled Fukushima Daiichi complex.

General Electric Co. has defended its Mark 1 reactor—the design at the crippled Japanese complex—as a reliable industry workhorse. Tom Cochran, a nuclear physicist and senior scientist with the Natural Resources Defense Council calls the design "demonstrably deficient." He says "the diesel generators are in the basement and spent fuel is in the attic. It should have been the other way around."

Pietrangelo said the inspections would go beyond the scope of regular safety checks at the plant. The companies will verify that plant operators could safely shut down reactors if there were a total loss of electric power; that crucial emergency equipment and systems could survive earthquakes, fires or floods, and that emergency personnel were properly qualified and trained, said Pietrangelo, speaking on behalf the industry's chief nuclear officers.

NRC requires nuclear plant operators to show that if hit with a single, or series of "worst case" scenarios, such as an earthquake and simultaneous rupture of the pipe delivering cooling water to the reactor, that the plant can be shut down safely without core damage. That is the standard, day-to-day requirement, he said. "We're going beyond that in this initial look," Pietrangelo said.

He said he did not think companies will report results of the inspections separately to NRC but, like all operational information, the findings will be available to NRC inspectors.

A power loss at a U.S. reactor

The UCS report focuses on the effectiveness of the resident NRC inspectors stationed at the U.S. plants. The cases included in the report show both diligent attention by NRC, and complacency that allowed operators to sweep problems under the rug.

One of the incidents covered in the UCS report was an electrical fire at Progress Energy's H.B. Robinson nuclear plant near Hartsville, S.C., on March 28 last year.

The incident began with a short-circuit on a major electrical cable, which caused a drop in power supplied to a large pump circulating water through the reactor. The reactor shut down automatically, but the incident damaged the main power transformer connecting the plant to the outside electrical grid, and other events left about half of the plant's equipment without power.

That power loss caused a sequence of problems with valves affecting the control of the reactor's temperature, but operators failed to notice the problems for nearly an hour, the report said.

After four hours, operators tried to restore power to the circuit where the short had occurred but did not check first to see that that problem had been solved. It had not been, and when the line was re-energized, another fire resulted. The failed cable, installed in 1986, did not meet design parameters, the report said.

Six months later, another series of equipment failures and operator errors caused another reactor shutdown at the plant. One of the equipment issues had been known to the operators since 2003 but had not been fixed, the report said. In this case, the operators relied on an auxiliary water supply system to provide cooling to the reactor by first disabling safety controls. The goal was to avoid a critical NRC review, the report said.

NRC issued a notice yesterday saying that while it concluded the plant had operated safely last year, commission staff will be stepping up inspections and oversight based on problems surrounding the reactor shutdowns.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC., 202-628-6500