Radioactive water build-ups at the plant also continue to devil workers, who are trying to prevent another major overflow into the Pacific Ocean.

TEPCO has meanwhile said that today it will for the first time open the doors at reactor No 2 to ventilate the thick, humid air in a procedure that will take eight hours to avoid stirring up radioactive dust and particles inside.

The company has been trying to filter radioactive particles out of the air inside the building for several days, and Japan’s Nuclear and Industrial Safety Agency approved Friday plans to open the airlock, TECPO announced.

The ongoing disaster had led to three European countries, Germany, Switzerland and Italy, abandoning nuclear power forever with Germany set to shut down its last reactor in 2022, and Switzerland in 2035. Italy’s popular referendum stopped plans to build reactors. Japan itself has said it will bulid no further nuclear power plants but remains unresolved about the further use of nuclear energy – while many government officials insist nuclear plants that were switched off after earthquake and tsunami on March 11, three quarters of the Japanese public are against continued use of nuclear power in their country.

Polls from several other nations that intend to keep pursuing their nuclear power programs reveal strong public opposition. And Russia has finally come forth and admitted that its own reactors could not withstand natural disasters, according to documents obtained by Bellona.

The 41-page TEPCO report, released over the weekend, offers a candid look at minute-by-minute errors during the first days of the disaster  of the the plant was struck by an earthquake and a tsunami on March 11, and is based on interviews with workers and plant data.

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.

A report by an independent panel appointed by Japan’s prime minister is still pending.

Lack of emergency planning led to chaos

The TEPCO report paints a picture of chaos amid the desperate and unsuccessful battle to protect the Fukushima Daiichi nuclear plant from meltdown in March in the wake of the natural disaster.

The report shows that workers struggled with unfamiliar equipment and fear of radiation exposure.

The tsunami and earthquake destroyed the plants cooling systems and cut off all power, causing the plants reactor Nos 1, 2, and 3 to melt down within hours.

Cooling power shut down in reactor No 1 two hours after the tsunami and workers tried to inject fresh water with a fire pump, but the fire pump was broken.

A fire engine at the plant couldn’t reach the reactor 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 reactor hours later. It was early morning when they finally started pumping water into the reactor — but the core had already melted by then.

The engine eventually ran out of water, meaning that seawater had to be used as a substitute, scrapping the reactors altogether. The dumping of hundreds and thousands of tons of seawater on the plant from water cannons and helicopters had created ongoing difficulties with leaks of highly contaminated water from reactor Nos 1 and 2.

Emergency manuals not on hand in control room

The TEPCO report revealed that as workers struggled to reveal building pressure in reactor No 1 no manual that told them how to operate the venting system was to be found in the control room. A group had to be dispatched to find it in a separate building.

Only after their return did workers learn that the valve, which had been impaired by the power loss, could be opened manually – and that there was a handle to do so. 

Delayed venting led to explosion

The failure to begin the venting procedure immediately after the plant black-out occurred has been cited by experts as being one of the most critical lapses leading to the eventual pressure explosion of reactor No 1’s containment building.

“Tepco should have prepared a manual on (manual) venting in advance, but it seems that wasn’t the case,” Keiji Miyazaki, professor emeritus at Osaka University and an expert on reactor accident management, told the Japan Times.

“Tepco also should have started the venting procedure right after the station blackout occurred,” he said.

The time line in the report showed that Japan’s nuclear industry minister Banri Kaieda ordered venting to begin at 6:50 am on March 12, nearly a day after the initial disaster.

Workers halted venting to avoid radioactive contamination to nearby population

But TEPCO did not send anyone to begin the manual venting procedure until 9:04 am because they were awaiting confirmation that residents of Okuma, one of the towns that hosts the power plant, had been evacuated from areas at risk of being contaminated by the radioactive steam and other materials that would be released in the process.

This shows the workers had run up against a very difficult choice between venting as soon as they received the order, and contaminating the surrounding population, or waiting to be sure they could reduce that risk.

Unfortunately, revelations about the subsequent massive spread of radiation from the rest of the plant that have been made since the tsunami by the Japanese government and independent groups revealed that awaiting the confirmation was a moot point.

To prevent a critical failure, the report said, the pressure should have been released from the reactor’s containment vessel, which would have allowed workers to inject more coolant water into the core.

Crucial equipment located kilometres away

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 centre, five kilometres away from the plant.

It took an hour for the workers 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.

After repeated failures, TEPCO finally managed to open the valves and release steam from reactor No 1 at 2:30 pm on March 12. But hydrogen generated from the already melting fuel rods exploded and blew up the building an hour later.

TEPCO highlights difficulties of preventing the explosion

In the report, TEPCO emphasized a number of difficulties that hindered its efforts.

All the lights in the central control rooms of reactors 1 through 3 eventually went dark after tsunami knocked out auxiliary power supplies at 3:42 pm on March 11.

At 9:51 pm that day, the main building of reactor 1 was declared off-limits because of rapidly rising radiation inside.

At 3:45 am March 12, workers opened a double-entry door to the reactor building to check radiation levels and prepare for venting. But after seeing a “white haze” inside, they immediately closed the door to avoid radiation exposure, the report said.

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 made no mention of their condition.

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

But darkness, debris, puddles and repeated tsunami warnings hindered their work by forcing them to repeatedly evacuate.

The hydrogen explosion at reactor 1 also damaged some of the cables they laid, prompting the workers to evacuate to the radiation-proof main operation center at the plant, Tepco said in the report.

Report follows government admission that it downplayed dangers early

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 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, the Associated Press reported. 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 at reactor No 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, said AP.

TEPCO said radiation released by the ventilation would be too small to threaten human health, and reported no abnormality. Workers have taken similar steps at Unit 1, which is moving ahead of the other reactors.

Radioactive water continues to be threatening

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.