Officials say overheated reactor crisis appears to be stabilizing
Problem still unresolved
TOKYO — Firefighters yesterday pumped tons of water directly from the ocean into one of the most troubled areas of the Fukushima Daiichi nuclear complex: the cooling pool for used fuel rods at the plant’s Unit 3.
The rods have been at risk of burning up and sending radioactive material into the environment.
Officials said the crisis at the plant appeared to be stabilizing, with near-constant dousing of dangerously overheated reactors and uranium fuel, but the situation was still far from resolved. Japan’s military planned to start dousing one troubled reactor — Unit 4 — for the first time shortly after daybreak this morning.
“We more or less do not expect to see anything worse than what we are seeing now,’’ said Hidehiko Nishiyama of the Nuclear and Industrial Safety Agency.
Utility crews said they were close to restoring electricity to the nuclear complex, which is needed to put the cooling systems back in operation.
Six workers trying to bring the Fukushima Daiichi plant back under control were exposed to more than 100 millisieverts of radiation — Japan’s normal limit for those involved in emergency operations, according to Tokyo Electric Power Co., which operates the complex. The government raised that limit to 250 millisieverts on Tuesday as the crisis escalated.
Japan has been grappling with a cascade of disasters unleashed by the 9.0-magnitude earthquake on March 11. The quake spawned a tsunami that ravaged Japan’s northeastern coast, killing more than 7,600 people and knocking out cooling systems at the Fukushima Daiichi nuclear plant, causing the complex to leak radiation.
More than 11,000 people are missing, and more than 452,000 are living in shelters.
At the Fukushima plant, emergency workers have been struggling to cool the reactors and the pools used to store used nuclear fuel, as well as to put the facility back on the electricity grid.
A replacement power line reached the complex Friday, but workers have to work methodically through badly damaged and deeply complex electrical systems to make the final linkups without setting off a spark and potentially an explosion. Company officials hope to be able to switch on the cooling systems today.
Once the power is reconnected, it is not clear whether the cooling systems will still work.
A firetruck with a high-pressure cannon pumped water into the cooling pool for used fuel rods at the plant’s Unit 3 — in a 13-hour operation that ended in the early morning hours today. Because of high radiation levels, firefighters only went to the truck every three hours to refuel it.
Holes were also punched in the roofs of Units 5 and 6 to vent buildups of hydrogen gas, and the temperature in Unit 5’s fuel storage pool dropped after new water was pumped in, according to officials with Tokyo Electric Power.
More workers were thrown into the effort — bringing the total at the complex to 500 — and the safety threshold for their radiation exposure was raised 2 1/2 times so they could keep working. Officials insisted that would cause no health damage.
The reactors and the storage pools both need constant sources of cooling water. Even when they are taken from reactors, uranium rods remain very hot and must be cooled for months, possibly longer, to prevent them from heating up again and emitting radioactivity.
Low levels of radiation have been detected well beyond Tokyo, which is 140 miles south of the plant, but hazardous levels have been limited to the plant.
People evacuated from around the plant, along with some emergency workers, have tested positive for radiation contamination. Three firefighters needed to be decontaminated with showers, while among the 18 plant workers who tested positive, one absorbed about one-tenth of the amount that could induce radiation poisoning.
Outside the bustling disaster response center in the city of Fukushima, 40 miles northwest of the plant, government nuclear specialist Kazuya Konno was able to take only a three-minute break for his first meeting since the quake with his wife, Junko, and their children.
“It’s very nerve-racking. We really don’t know what is going to become of our city,’’ said Junko Konno, 35. “Like most other people, we have been staying indoors unless we have to go out.’’
She brought her husband a small backpack with a change of clothes and snacks. The girls — aged 4 and 6 and wearing surgical masks — gave their father hugs.
The government conceded Friday that it was slow to respond to the crisis and welcomed ever-growing help from the United States in hopes of preventing a complete meltdown.
Nishiyama also said backup power systems at the plant had been improperly protected, leaving them vulnerable to the tsunami. The failure of Fukushima’s backup power systems, which were supposed to keep cooling systems going in the aftermath of the earthquake, let uranium fuel overheat and were a “main cause’’ of the crisis, Nishiyama said.