As General Electric defends the reactors it designed for Japan's Fukushima Daiichi nuclear power plant, independent nuclear specialists are also coming to the company's defense amid the nuclear crisis.
Five of the six reactors at Fukushima I are GE's so-called Mark I boiling water reactor models, developed in the 1960s and installed in Japan in the 1970s.
"I think GE should really be saluted for their design of the reactors," says Najmedin Meshkati of the University of Southern California, Los Angeles, a nuclear safety expert who has studied power plants worldwide, including at Chernobyl and in Japan. "[The crisis] really hasn't been a problem with the reactor design."
The most pressing issue now at the plant is a possible crack in a spent fuel pool, which sits above the reactor containment vessel and was damaged during explosions earlier this week. The containment vessels that hold the actual nuclear reactors, meanwhile, appear to have largely withstood a 9.0-magnitude earthquake, a 30-foot tsunami, explosions, and fires.
"I think GE is a hero in this," says Dr. Meshkati.
Mark I design scrutinized
The Japan nuclear crisis has brought scrutiny on GE for its Mark I design, which was criticized in the 1970s as susceptible to explosion and rupture. Three GE employees quit in 1975 in protest over safety concerns around the Mark I and US regulators even considered discontinuing the system
The world's biggest nuclear-equipment supplier, however, has maintained that its containment vessel design is reliable in the face of reports this week of possible design weaknesses.
"We’d like to set the record straight," GE said in a statement Friday. "The Mark I meets all regulatory requirements and has performed well for over 40 years."
GE points to a statement in 1980 from the Nuclear Regulatory Commission (NRC), which advised that it had given careful consideration to concerns raised in a 1972 memorandum by Stephen Hanauer, an Atomic Energy Commission official, who said that the Mark I's smaller containment design was more susceptible to explosion. The NRC found that the commission's "staff, including Dr. Hanauer, has concluded that the pressure suppression concept for containment design is safe.”
A GE spokesman told Agence France-Presse the NRC ordered US operators to retrofit Mark I plants in the 1980s to strengthen the containment vessel, as was also done to the containment units at Fukushima Daiichi.
GE also rejected claims that modifications to the Mark I were driven by threats of lawsuits from utilities over alleged flaws in the system. "The Mark I containment designs were modified in the 1980s to address improvements in the technology and changing regulatory requirements," the Connecticut-based company said.
GE has had engineers in Japan helping to bring the tsunami-hit Fukushima reactors under control since the quake hit March 11, a GE spokesman told Reuters.
Plant's diesel generators failed
GE's statement is unlikely to quell critics of the Mark I design.
Dr. Meshkati of the University of Southern California, however, says a root-cause analysis traces the current crisis back to the failed diesel generators. The March 11 earthquake and tsunami knocked out electricity to the plant, which triggered the activation of diesel generators that stopped operating within hours. At that point, cooling water was no longer pumped into the reactors to prevent the fuel rods from overheating.
As to why the generators failed to withstand the earthquake and tsunami, Meshkati says that's a question for plant operator Tokyo Electric Power Co. (TEPCO) and the Japanese regulatory body. "Had the diesel generators worked, we wouldn’t be talking today," he says.