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Originally posted by zworld
"At 15:03 reactor pressure at Unit 1 dropped so fast and the reactor coolant temperature decreased 55C per hour"
SL, SFA, TRN anyone. What does this mean and what could cause this 15 minutes before the tsunami and loss of power.
As for the steel megafloat, which is berthed at a quay near the plant, about 8,000 tons of low-level radioactive water will be transferred over the next three or four months. The government’s nuclear safety agency said TEPCO has not yet decided what to do with the water after it is transferred, but it will not be directly dumped into the sea.
During TEPCO’s press conference of May 30th, the CRIIRAD laboratory manager, Mr Chareyron, asked a TEPCO representative about the air contamination monitoring procedure in the vicinity of Fukushima Daiichi. TEPCO explained that there was only one monitoring station, located at the western gate, but stated that the device is used only about 20 minutes each day. This means that during the remaining 98,6 % of the time, the contamination of the air around the plant is not measured. The CRIIRAD wondered how it is be possible when a small NGO such as the CRIIRAD is able to run 5 air monitoring stations in France, that TEPCO could not afford one. TEPCO replied that it was not a money issue but a lack of personnel qualified to change the filters of the instruments.
FUKUSHIMA, Japan (AP) — When Unit 2 began to shake, Hiroyuki Kohno's first hunch was that something was wrong with the turbines. He paused for a moment, then went back to logging the day's radioactivity readings.
He expected it to pass. Until the shakes became jolts.
As sirens wailed, he ran to an open space, away from the walls, and raced down a long corridor with two colleagues. Parts of the ceiling fell around them. Outside, he found more pandemonium.
"People were shouting about a tsunami," he said. "At that point, I really thought I might die."
EDITOR'S NOTE: It was an ordinary Friday afternoon, and then the shaking began — harbinger of a nuclear nightmare that rages on, three months later. A moment-by-moment account of the crucial first 24 hours after an earthquake and tsunami devastated Japan's Fukushima Dai-ichi plant.
Breathless, Kohno climbed a small hill and turned to look back. Black plumes rose from the reactor units. The emergency generators, burning diesel, had kicked in.
He saw the wave. It crashed over the plant's seawall, stopping only when it reached the foot of the slope about 500 yards (460 meters) from where he stood.
Kohno watched, stunned.
On that day, Team A, a crew of 13, including a trainee, was overseeing Units 1 and 2 in one control room. In another, a crew of nine was responsible for Units 3 and 4. The latter, along with Units 5 and 6, was offline for maintenance.
The first news was good.
All three working reactors automatically came to an emergency shutdown when the shaking began. Within one minute, all control rods were inserted properly into the cores, stopping the nuclear reactions.
What came next changed everything.
The first wave hit the plant at 3:27 p.m. At 13 feet, it was easily blocked by the plant's breakwater, which stands 33 feet above sea level.
But the one that struck eight minutes later was off the scale.
It flowed up and over the barrier, washed over a 33-foot (10-meter) water tank and tossed passenger cars this way and that. Watermarks suggest the wave may have been as high as 50 feet (15 meters).
Team A watched, horrified, as the plant deteriorated by the minute. A detailed operator's log, along with a handwritten timeline on the control room whiteboard, showed how quickly the units failed.
"15"37' D/G 1B trip," said a scribbled notation indicating the Unit 1 diesel generator went out. It was 3:37 p.m., just two minutes after the second wave had struck.
Then: "SBO." Station Blackout. The power was out.
Four minutes later, at 3:41 p.m., Unit 2 lost power. Minutes after that, key instrument readings stopped.
In the dark, workers found a main power switchboard had been submerged and a main power line brought down by a mudslide. The basement of the Unit 1 turbine building was filled with water. Two workers would later be found drowned in the basement of another turbine room.
Exactly what was happening inside the reactors remained a mystery. At 3:50 p.m., Team A wrote: "Water levels unknown." If not replenished, the water in the core would boil away and the rods would melt.
Two minutes later, Team A added an even more dire note on Unit 2: "ECCS injection not possible." The emergency core cooling system, the last-ditch backup to keep the core from going dry, was down.
It was an hour after the tsunami, and Team A desperately requested emergency power vehicles. By the time they arrived and were hooked up, it would be too late.
Japan's nuclear nightmare had begun.
From 10:59 am to 12:14 pm on July 2, we conducted measurement of the radiation dose at the first floor Unit 3 Reactor Building using robot to check the cleaning effect the day before.
At 11:43 am on July 1, we started cleaning up the first floor of Unit 3 Reactor Building using a robot.
The No.3 reactor building has been filled with highly radioactive sand, dust and rubble since it was badly damaged in a hydrogen explosion in March.
The radiation level inside the facility is 170 millisieverts per hour at its peak. The high radiation is preventing workers from going inside and taking steps to prevent fresh explosions.
Tokyo Electric Power Company says the cooling system that began operating at the No.3 reactor on Thursday has brought the temperature of the nuclear fuel storage pool of the reactor to just below 40 degrees Celsius from the previous level of 62 degrees.