TOKYO - A new report says Japan's tsunami-ravaged nuclear plant was so unprepared for the disaster that workers had to bring protective gear and an emergency manual from distant buildings and borrow equipment from a contractor.

The report, released Saturday by plant operator Tokyo Electric Power Co., is based on interviews of workers and plant data. It portrays chaos amid the desperate and ultimately unsuccessful battle to protect the Fukushima Dai-ichi nuclear plant from meltdown, and shows that workers struggled with unfamiliar equipment and fear of radiation exposure.

The March 11 earthquake and tsunami destroyed the plant's power and crucial cooling systems, causing three reactor cores to melt and causing several explosions.

TEPCO has been criticized for dragging its feet on venting and sea water cooling the two crucial steps that experts say could have mitigated the damage. Company officials have said the tsunami created obstacles that were impossible to anticipate. An investigation by an independent panel is pending.

The report revealed insufficient preparations at the plant that TEPCO hadn't previously acknowledged.

When the Unit 1 reactor lost cooling functions two hours after the quake, workers tried to pump in fresh water through a fire pump, but it was broken.

A fire engine at the plant couldn't reach the unit because the tsunami left a huge tank blocking the driveway. Workers destroyed a power-operated gate to bring in the engine that arrived at the unit hours later. It was early morning when they finally started pumping water into the reactor - but the core had already melted by then.

They eventually ran out of fresh water and had to switch to sea water, which meant scrapping the reactor.

Other workers were tasked with releasing pressure from Unit 1's containment vessel to avoid an explosion. But first they had to get the manual, which was not in the control room but in a separate office building at the plant. Aftershocks struck as they retrieved it.

To activate an air-operated part of the vent, workers had to borrow a compressor from a contractor. And the workers who had to get close to the unit for the venting had to get protective gear from the offsite crisis management center, 5 kilometers (3 miles) away from the plant.

It took an hour just to put on air tanks, coveralls and face masks before the first two workers headed for the reactor building. The operation was a relay of three two-member teams to minimize exposures.

Rising radiation also disrupted the work, the report said. The second team had to abort their mission as radioactivity almost exceeded the limit at midway. Workers had to switch to a remote control, which was less effective than having humans do the work directly.

After repeated failures, workers managed to vent the containment vessel. But an hour later, the Unit 1 building exploded, damaging similar preparations at two other units, forcing workers to start all over and causing further delays.

Eight of the workers who fought the initial crisis were found to have been exposed to high levels of radiation and were removed from plant work.

The report also said workers borrowed batteries and cables from a subcontractor on the compound to set up a backup system to gauge water levels and other key readings.

Government reports released this month said the damage and leakage at the plant were worse than previously thought, with some of the nuclear fuel in three reactors likely having melted through the main cores and inner containment vessels. They said the radiation that leaked into the air amounted to about one-sixth of the Chernobyl nuclear disaster in 1986 _ double previous estimates.

TEPCO and the government have said they aim to bring the reactors to "a stable and cold shutdown" by January. But some experts say the plan is too optimistic because high radiation, contaminated water, debris and other obstacles have already caused delays.

On Sunday, TEPCO opened a door of Unit 2 to allow workers to install a cooling system and equipment to prevent an explosion. Workers have entered the reactor building before, but only for brief monitoring visits.

TEPCO said radiation to be released by the ventilation will be too small to threaten human health. Workers have taken similar steps at Unit 1, which is moving ahead of the other reactors.

Meanwhile, more radioactive water is pooling at the plant. Workers scrambled to restart a key cleanup system, which was shut down Saturday hours after beginning full operations because a component reached its radioactivity limit faster than expected.

More than 100,000 tons of contaminated water at the plant could overflow within two weeks if action is not taken.