Fukushima No 4 reactor doused

Japan’s military sprayed water from fire engines to cool the Fukushima Dai-Ichi number four reactor, the site of two blazes last week, while pressure in number three stabilised as the fight to contain the crisis entered its second week.

Chief Cabinet Secretary Yukio Edano said in Tokyo today that while efforts to prevent the crisis from worsening have had some success, problems at the power station are unlikely to be resolved quickly. Tokyo Electric Power Co, owner of the crippled 40-year-old power plant at the centre of the worst nuclear catastrophe in a quarter century, is yet to provide an update on its plan to partially restore power at two reactors by 4 pm local time. Workers reconnected a 1.5-km power cable yesterday to unit number two seeking to revive cooling systems knocked out after the magnitude-9 temblor and tsunami.

“This is a necessary step because they’ve got to migrate from emergency-response mode, where they’re relying on unusual or improvised approaches, to a regular, engineered system,” Roger N Blomquist, principal nuclear engineer at the US Energy Department’s Argonne National Laboratory, near Chicago, said in a telephone interview. “The end state you want is to have the reactor and the spent-fuel pools cooled.”

Tokyo Electric, known as Tepco, said water pumps and controls may fail to function even with power restored due to damage from the disaster.

A successful hook-up would’ve advanced efforts to prevent a total meltdown of the reactors following the March 11 disaster. Tepco planned to partially restore power at the number one and number two reactors by 4 pm today, according to Teruaki Kobayashi, a nuclear maintenance official.

Japan’s military sprayed water from fire engines to cool the number four reactor, the site of two blazes last week. Storage pools used to cool spent fuel rods atop the number four reactor had little or no water, and large amounts of radiation could be released as the exposed rods overheat, Gregory Jaczko, the chairman of the US Nuclear Regulatory Commission, told Congress on March 16, citing reports he received from NRC officials in Japan.

Efforts to prevent a full-scale meltdown of the reactors have been hampered by radiation that made it hazardous for workers to spend prolonged periods in the immediate vicinity of damaged buildings. Soldiers from Japan’s Self Defence Force and firefighters from Tokyo have used long-range water cannons, specialised fire equipment and helicopters to douse damaged reactor number three for the past five days.

Pressure stabilised
Pressure levels at the number three reactor stabilised, eliminating the need to vent radioactive steam, which had been considered earlier today, Tokyo Electric spokesman Naoyuki Matsumoto said.

Radioactive steam will be released from the reactor today to reduce pressure and dousing operations will continue after that, said Hidehiko Nishiyama, a spokesman for the Nuclear and Industrial Safety Agency.

“There will be more ups and downs in the process to improve the situation,” Edano told reporters today. “This kind of situation will continue for a while.”

Temperatures of spent-fuel storage pools at the number five and number six reactors fell after workers restarted the cooling pump from backup generators, said Takashi Kurita, spokesman at Tokyo Electric, known as Tepco. Unit number five was undergoing maintenance at the time of the earthquake and was one of the least damaged.

Power hub
Engineers at Tepco hope to use a separate power cable attached to the number two reactor as a hub to restore electricity to the other five reactors, said Hikaru Kuroda, chief of the company’s nuclear facility management department. Reactors number five and number six may be connected tonight, he said.

“We are making progress one step at a time, but we will not let our guard down,” Japan’s Deputy Chief Cabinet Secretary Tetsuro Fukuyama said on public broadcaster NHK TV today.

The longer the company can prevent overheating of the reactor cores and water-filled pools used to store spent fuel, the smaller the supply becomes of the most dangerous, volatile elements.