The operator of the defunct Fukushima Daiichi nuclear plant has flown a balloon inside the No.1 reactor building to check the upper part of the structure.
Tokyo Electric Power Company on Wednesday launched a balloon from the first floor, to about 30 meters up inside the building.
The 2 meter wide balloon was equipped with 4 cameras and a device to monitor radiation.
Photos showed concrete debris from a hydrogen explosion scattered on the upper floors. But the crane for pulling out fuel rods, and a device for exchanging them, remained intact and had not fallen into the pool for spent fuel rods, as had been feared.
Radiation levels registered at 150 millisieverts an hour around the building’s second floor and 54 millisieverts an hour around the topmost fifth floor.
The cooling system for the No. 4 reactors hazardous spent-fuel pool came back to life Sunday at the crippled Fukushima No. 1 power plant after emergency repairs succeeded, Tokyo Electric Power Co. said.The cooling system automatically shut down on Saturday for unknown reasons, allowing the water in the pool to reach 42.9 degrees Sunday. The pool must stay filled to prevent the used rods from burning up.The cooling system resumed shortly after 3 p.m. The temperature in the pool, which is sitting perilously atop the reactor in a heavily damaged building, was 33.3 degrees when the cooling system failed Saturday morning.
A 35-ton piece of machinery has been found at the bottom of the spent nuclear fuel pool in the No. 3 reactor at the stricken Fukushima Daiichi plant, Tokyo Electric Power Co TEPCO said Friday.
TEPCO officials told a news conference that the device, which is used to exchange fuel, probably toppled over after the hydrogen explosion on March 12 last year, the day after the tsunami struck the plant, Fuji TV reported.
TEPCO said the device was spotted seven meters below the water a remote-controlled camera which it has been using to monitor the state of the reactor.
Officials detected a radioactive gas associated with nuclear fission at Japan’s tsunami-damaged atomic power plant Wednesday, indicating there could be a new problem at one of its reactors. They injected a substance that neutralizes nuclear reactions as a precaution.
Gas from inside the reactor indicated the presence of radioactive xenon, which could be the byproduct of unexpected nuclear fission. Boric acid was being injected through a cooling pipe as a countermeasure because it can counteract nuclear reactions.
The Tokyo Electric Power Co., or TEPCO, said there was no rise in the reactor’s temperature, pressure or radiation levels. The company said the radioactive materials inside the reactor had not reached criticality — the point when nuclear reactions are self-sustaining — and the detection of the xenon would have no major impact on their efforts to keep the reactor cool and stable.
FUKUSHIMA — Fukushima Prefecture vowed to shift away from nuclear power plants in its vision compiled Friday for reconstruction after the March 11 quake and tsunami.
The about-face came after Prime Minister Naoto Kan’s declaration Wednesday of pursuing a society free from dependence on nuclear energy and is expected to affect the policies of other prefectures that host atomic plants.
Fukushima may be the first prefecture with nuclear plants to vow to eliminate them, an official at the Natural Resources and Energy Agency said.
The operator of Japan’s Fukushima nuclear plant moved closer to ending its radiation crisis on Monday with the start of a system to cool damaged reactors that could also help avoid dumping highly contaminated water into the Pacific Ocean.
The move was hailed as "a giant step forward" by Goshi Hosono, an adviser to Prime Minister Naoto Kan.
"This is critical in two aspects," Hosono told a news conference. "First, the system will solve the problem of contaminated water, which gave all sorts of worries to the world. Second, it will enable stable cooling of reactors."
Experts have warned of a potentially dangerous radiation leak if Japan proceeds with plans to flood a damaged reactor containment vessel at the Fukushima Daiichi nuclear plant. The facility’s operator has admitted uranium fuel rods in the No 1 reactor partially melted after being fully exposed because of the 11 March tsunami.
Tokyo Electric Power (Tepco) said water levels had fallen to at least one metre below four-metre-long fuel rods inside the reactor core and melted fuel had slumped to the bottom of the reactor’s containment vessel.
The damage is more severe than Tepco had previously reported and is almost certain to frustrate its quest to bring the plant under control within six to nine months. Officials said the leaked fuel was being kept cool and there was no risk of an explosion of the kind that blew the roof off the reactor in March.
Japanese engineers on Tuesday started preparing to send workers inside the Fukushima nuclear power stations reactor one building for the first time since the plant was crippled by an earthquake and tsunami.Tokyo Electric Power Co TEPCO said it started work to install a ventilation system to clean the air inside the building at the Fukushima Daiichi plant.
Radiation has risen to high levels above the spent-fuel pool at reactor No. 4 and its temperature is rising, the nuclear safety agency said Wednesday, indicating the fuel rods have been further damaged and emitting radioactive substances. The radiation level 6 meters above the spent-fuel storage pool at the crippled Fukushima No. 1 nuclear plant was measured at 84 millisieverts per hour Tuesday. Normally, its 0.1 microsievert.The temperature of the pool was 90 degrees, compared with 84 before it caught fire on March 15 in a suspected hydrogen explosion, the agency said."Its quite an amount," figured Hidehiko Nishiyama, a spokesman for the Nuclear and Industrial Safety Agency.
In the country that gave the world the word tsunami, the Japanese nuclear establishment largely disregarded the potentially destructive force of the walls of water. The word did not even appear in government guidelines until 2006, decades after plants — including the Fukushima Daiichi facility that firefighters are still struggling to get under control — began dotting the Japanese coastline.
The lack of attention may help explain how, on an island nation surrounded by clashing tectonic plates that commonly produce tsunamis, the protections were so tragically minuscule compared with the nearly 46-foot tsunami that overwhelmed the Fukushima plant on March 11. Offshore breakwaters, designed to guard against typhoons but not tsunamis, succumbed quickly as a first line of defense. The wave grew three times as tall as the bluff on which the plant had been built.
Japanese government and utility officials have repeatedly said that engineers could never have anticipated the magnitude 9.0 earthquake — by far the largest in Japanese history — that caused the sea bottom to shudder and generated the huge tsunami. Even so, seismologists and tsunami experts say that according to readily available data, an earthquake with a magnitude as low as 7.5 — almost garden variety around the Pacific Rim — could have created a tsunami large enough to top the bluff at Fukushima.