Fukushima Reactor Begins to Release Gray Smoke

Mar 21, 2011, 07:34 by David Hope

Fukushima Reactor personnel and nuclear engineers worked Monday to restore power at two reactors in Japan's quake-ravaged Fukushima nuclear plant but smoke rising from another raised new concerns.

Tokyo Electric Power Co., operator of the crippled plant, temporarily evacuated some of its workers after reporting gray smoke rising from the No. 3 reactor shortly before 4 p.m., local time, although its cause was not immediately known.

The utility said the smoke later decreased, Kyodo News reported.

Ever since the disaster struck the six-reactor plant, No. 3 has been a source of major concern because of the danger of release of highly toxic plutonium. The reactor lost its cooling function and its core is believed to have partially melted while its roof and upper walls were blown away or knocked down by an explosion last week.

Groundwater spraying has continued to keep its spent nuclear fuel pool cool.

Kyodo reported no change in pressure inside the containment vessel of the No. 3 reactor following the smoke incident Monday.

The work involved laying power cables to restore electricity at the No. 2 and No. 5 reactors' control rooms so radiation can be monitored and also to cool down the storage pool at No. 2 to prevent further radiation releases.

The Nuclear and Industrial Safety Agency said the No. 2 containment vessel's pressure-suppression chamber has been damaged and the process might take some days as replacement parts are needed.

Although monumental efforts in the face of ever-present meltdown threat and radiation catastrophe from throughout the facility have shown some progress, there were reports of higher levels of radiation contamination in some food items.

Ground spraying of water continued to keep the fuel pools cool at the No. 4 reactor. While this reactor, along with Nos. 5 and 6, was not operating at the time of the May 11 disaster, some of No. 4's fuel was not in the reactor core but in a spent-fuel pool without a cooling function, Kyodo reported. The reactor's roof also was blown away in last week's explosion.

Reactors 5 and 6 were now reported to be in a stable, "cold shutdown" state.

The government Monday also planned to engage tanks of the country's Self-Defense Forces to clear quake-created building rubble near the reactors. Use of trucks for the job has not been possible because of the high-level of radiation at those locations.

The cooling functions in the first three of the six reactors failed apparently after being flooded by the tsunami that came on the heels of the 9-magnitude earthquake, Japan's worst. Their reactor cores are believed to have partially melted.

There were also reports that regardless of any progress the entire Fukushima plant may be shut down once the crisis ends because its structure and reactors reportedly have suffered serious damage.

The concern about contamination of food items arose following discovery of high radioactive levels in products like milk and spinach from the disaster-hit regions.

Chief Cabinet Secretary Yukio Edano said Monday the government ordered the Fukushima, Ibaraki, Tochigi and Gunma prefectures to suspend shipments of milk and two kinds of vegetables, Kyodo reported.

The report said trace amounts of radioactive substances were also detected in tap water samples collected Sunday and Monday in nine of the prefectures but they tested below intake limits set by the Nuclear Safety Commission.

Lawmakers from the Democratic Party of Japan-led ruling coalition warned trillions of yen would be needed in supplementary spending for reconstruction efforts, Kyodo reported. One trillion yen is about $12.3 billion.

The new fiscal year begins April 1 and the government is already under considerable pressure to bring about economic recovery and boost exports.

Source: UPI