|An image released by TEPCO show the extent of the damage to the Daiichi nuclear power plant [Reuters]
A pair of thin robots on treads sent to explore buildings inside Japan's crippled nuclear reactor have returned with disheartening news: radiation levels are far too high for repair crews to go inside.
Nevertheless, Japanese officials remained hopeful on Monday they could stick to their freshly minted "road map" for cleaning up the radiation leak and stabilising the plant by year's end so they could begin returning tens of thousands of evacuees to their homes.
"Even I had expected high radioactivity in those areas. I'm sure [Tokyo Electric Power Co (TEPCO), operators of the Fukushima Daiichi power station] and other experts have factored in those figures when they compiled the 'road map'," Yukio Edano, Japan's chief cabinet secretary, said.
Officials said on Monday that radiation had jumped in a water tank in Unit 2 and contaminated water was discovered in other areas of the plant, underscoring the growing list of challenges facing TEPCO in cleaning up and containing the radiation. They also described in more detail the damage to fuel in three troubled reactors, saying pellets had melted.
Workers have not been able to enter the reactor buildings at the plant since the first days after the cooling systems were wrecked by the March 11 earthquake and tsunami that left more than 27,000 people dead or missing in Japan's northeastern coast.
In another development on Monday, Japanese legislators grilled the head of TEPCO, demanding he take responsibility for the disaster.
Appearing in parliament for the first time since a huge earthquake and tsunami crippled its Fukushima plant, the head of TEPCO faced a barrage of criticism from politicians.
"What do you plan to do to take ultimate responsibility [for the crisis]?" one opposition politician asked Masataka Shimizu, TEPCO's 66-year-old president, who has rarely been seen in public since the disaster struck.
"These documents contain very strict safety rules," Shuichi Kato of the opposition New Komeito party said, brandishing a copy of TEPCO's own safety regulations.
"This says the president regards nuclear safety as the top priority. With this in mind, let me ask how you feel now?"
Shimizu's appearance came a day after TEPCO said it would be nine months before the plant's six reactors could be put into "cold shutdown" - a stable condition in which temperatures drop and radiation leaks fall dramatically.
Legislators also attacked Naoto Kan, Japan's prime minister, for what they said was his slow response to the disaster.
"You should be bowing your head in apology. You clearly have no leadership at all," Masashi Waki, a legislator from the opposition Liberal Democratic Party, shouted at Kan.
"I am sincerely apologising for what has happened,'' Kan said, stressing the government was doing all it could to handle the unprecedented disasters.
Shimizu appeared ill at ease as legislators heckled and taunted him.