(CBS/AP) OKUMA, Japan - Japan's tsunami-hit Fukushima power plant remains fragile nearly a year after it suffered multiple meltdowns, its chief said Tuesday, with makeshift equipment -- some mended with tape -- keeping crucial systems running.
An independent report, meanwhile, revealed that the government downplayed the full danger in the days after the March 11 disaster and secretly considered evacuating Tokyo.
Journalists given a tour of the Fukushima Dai-ichi plant on Tuesday, including a reporter from The Associated Press, saw crumpled trucks and equipment still lying on the ground. A power pylon that collapsed in the tsunami, cutting electricity to the plant's vital cooling system and setting off the crisis, remained a mangled mess.
Officials said the worst is over but the plant remains vulnerable.
"I have to admit that it's still rather fragile," said plant chief Takeshi Takahashi, who took the job in December after his predecessor resigned due to health reasons. "Even though the plant has achieved what we call 'cold shutdown conditions,' it still causes problems that must be improved."
The government announced in December that three melted reactors at the plant had basically stabilized and that radiation releases had dropped. It still will take decades to fully decommission the plant, and it must be kept stable until then.
The operators have installed multiple backup power supplies, a cooling system, and equipment to process massive amounts of contaminated water that leaked from the damaged reactors.
But the equipment that serves as the lifeline of the cooling system is shockingly feeble-looking. Plastic hoses cracked by freezing temperatures have been mended with tape. A set of three pumps sits on the back of a pickup truck.
Along with the pumps, the plant now has 1,000 tanks to store more than 160,000 tons of contaminated water.
Radiation levels in the Unit 1 reactor have fallen, allowing workers to repair some damage to the reactor building. But the Unit 3 reactor, whose roof was blown off by a hydrogen explosion, resembles an ashtray filled with a heap of cigarette butts.
A dosimeter recorded the highest radiation reading outside Unit 3 during Tuesday's tour -- 1.5 millisievert per hour. That is a major improvement from last year, when up to 10 sieverts per hour were registered near Units 1 and 2.
Exposure to more than 1,000 millisievert, or 1 sievert, can cause radiation sickness including nausea and an elevated risk of cancer.
Officials say radiation hot spots remain inside the plant and minimizing exposure to them is a challenge. Employees usually work for about 2-3 hours at a time, but in some areas, including highly contaminated Unit 3, they can stay only a few minutes.
Since the March 11 crisis, no one has died from radiation exposure.