TOKYO, April 9, 2011 (AFP) - Japan's industry minister on Saturday met workers battling to cool overheating reactors and plug radioactive leaks in the first government visit to the country's tsunami-crippled nuclear plant.
The visit came as one of the country's top nuclear officials called for a sweeping review of safety standards in the industry and Tokyo warned the crisis at the plant was far from over.
Industry minister Banri Kaieda donned full protective gear for his brief trip to the damaged Fukushima Daiichi plant, his ministry said.
Kaieda, who has overall responsibility for all of Japan's 50-plus nuclear reactors, became the first government figure to step inside the compound since the giant tsunami of March 11 knocked out cooling systems.
A spokesman said the minister was driven into the plant mid-afternoon and stayed for around 45 minutes.
"He greeted crews working there and conveyed his appreciation for their hard work," he said.
Just 24 hours earlier, it emerged small amounts of radioactive water spilled from spent fuel cooling pools at another nuclear plant as a powerful aftershock rocked northeast Japan.
The cooling systems at three plants were forced onto back-up power when the 7.1 magnitude tremor late Thursday shut down electricity generation across a swathe of the country.
Hidehiko Nishiyama, deputy director general of Japan's nuclear watchdog, said the loss of power -- no matter how temporary -- was a serious issue.
"In the light of this experience, we need to review safety standards from all angles," he said.
The Nuclear and Industrial Safety Agency on Saturday ordered all power companies that run nuclear plants to secure at least two emergency diesel generators for each reactor, whether it is operating or not.
Under safety rules in force up till now, Japanese nuclear plant operators have been required to have just one back-up generator for each inactive reactor. A requirement for two generators for active reactors is unchanged.
On Friday, Tohoku-Electric Power, the operator of the Onagawa nuclear plant, said around four litres (a gallon) of mildly radioactive water had spilled from the spent fuel pool of one reactor.
The entire plant had been shut down since the March 11 disaster and the leak did not present any danger, the company said.
Kaieda's trip also included a stop at the "J-Village" sports complex, which is being used as a base for workers at the battered plant.
The complex lies inside a 20-kilometre (12-mile) exclusion zone around the plant, from which thousands of people were evacuated when levels of radiation in the area soared following the emergency.
Tokyo Electric Power Co (TEPCO) said Saturday it was planning to send an unmanned drone over the plant to help it assess the extent of damage.
The company will use a "T-Hawk" micro air vehicle developed by US conglomerate Honeywell as early as Sunday to record video images of crippled reactors 1 through 4, a TEPCO spokesman said.
The stricken plant has leaked radiation that has made its way into tap water and farm produce, sparking food export bans covering a large area.
Some highly radioactive water has leaked into the Pacific Ocean and this week TEPCO began dumping 11,500 tonnes of low-level radioactive water from the plant into the sea to free up urgently needed storage space.
Workers are injecting inert nitrogen gas into reactor No. 1 in a bid to head off a possible explosion from a build-up of hydrogen reacting with oxygen from the air.
The first of the 150,000 people still living in shelters began to move into temporary accommodation Saturday, with 36 families in the ravaged city of Rikuzentakata being given the keys to prefabricated units.
Local governments in hard-hit Miyagi and Iwate regions are aiming to build temporary housing for 62,000 households, but construction has only begun on 10 percent of them, Kyodo News said.
With so many still in shelters, ruling party lawmakers want an extra 500 billion yen ($5.9 billion) to construct a total of 70,000 units in tsunami-hit areas.
Nearly 13,000 people are known to have died in the disaster, with around 15,000 still officially listed as missing.
The government said it thinks at least 82 children were orphaned, more than the 68 who lost both their parents in the 1995 Kobe earthquake, Japan's last big natural disaster, which claimed 6,400 lives.
In one indication that life was gradually returning to normal, Tokyo Disneyland will reopen on April 15, a report said Saturday, after the largely-intact amusement park was forced to close because of rolling blackouts.