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The U.S. Department of State on Thursday lifted an advisory to families of U.S. embassy staff in Tokyo to leave Japan voluntarily on the grounds that efforts to control the troubled nuclear power plant in Fukushima Prefecture are going well.
''The situation at the plant is dramatically different today than it was on March 16 ... (because) planning has begun to control radioactive contamination and mitigate future dangers,'' it said.
Originally posted by JackBauer
The flooding water is believed to be an unintended side effect of TEPCO's stopgap measure of injecting water into the reactors and their spent nuclear fuel pools to prevent them from overheating.
Originally posted by Aeons
Why can't radiation be DIRECTED instead of contained?
Originally posted by Arluk
Haven’t we been told Reactor No. 4 was out of service, empty, being maintained, not working?
All the fuel was out of the reactor pressure vessel, right?
Therefore there should NOT be radioactive material potentially leaking from the vessel, but the report suggests there MIGHT be radioactive material somewhere in the vessel.
Is TEPCO unsure about the ‘real’ status of No.4 and what was, or is now, in the reactor vessel? Shards and powder from the explosions and disintegrating buildings to which water leaking from the damaged fuel storage pool oozed into the vessel and is now resulting in leakium
If radioactive material is potentially leaking from the vessel in quantities significant enough to result in a surge in radiation, something is not computing.
Am I reading the article correctly?
Maybe I have my reactors confused … and No.4 is not the empty one?
PS. Somebody did suggest that maybe No. 4 was in the process of being reloaded but this has not been substantiated.
Reactor 4 was undergoing routine maintenance at the time of the earthquake and tsunami, so there were no fuel rods in the reactor core. But the building was damaged by two fires on March 15 and 16, likely caused by a buildup of hydrogen from the rods in the spent fuel pool. Water has been regularly sprayed on the building and spent fuel pool using water cannons and concrete pumping trucks, and seawater has been added to the spent fuel pool. Lighting at part of the facility was restored on March 29.
At the time of the quake, Reactor 4 was offline and not generating power amid annual maintenance. As part of that, five months ago Tepco relocated all the fuel rods—the heavy tubes that contain radioactive fuel pellets—from inside the reactor to what's called a spent-fuel pool, a concrete holding tank that is less robustly protected than the reactor itself.
"We were carrying out checks on the inside of the reactor" and, thus, workers "had to remove the nuclear fuel from the reactor," said Takeshi Makigami, head of Tepco's nuclear-equipment-management section.
The active rods were in that pool when the March 11 quake struck. When the tsunami wiped out the plant's emergency generators, the water in the spent-fuel pool adjacent to the No. 4 reactor could no longer circulate, and fresh water could not be pumped in. Rods in the pools began to overheat, causing the water to evaporate as steam and exposing parts of the radioactive rods to the air—a critically dangerous situation. The heat spawned fires and the roof above the pool was partly destroyed, letting radiation out.
In the first days after the quake, officials weren't focused on the situation at Reactor No. 4, since it was one of the three reactors at the plant, along with Nos. 5 and 6, that were offline for maintenance.
According to a “background” telephone call with a senior U.S. nuclear executive, the spent fuel pool at reactor #4 had "normal water" as of Friday morning March 18 and, as a result, the fuel in it will not melt down releasing massive amounts of radiation into the atmosphere.
The executive said that on March 17, the concrete on one side of the pool fell away. That damage may have come from one of the hydrogen explosions. However, the one-and-half inch steel liner around the pool remains intact which means it is likely the pool is not leaking.
Due to maintenance in Unit 4 entire core stored in Fuel pool
Originally posted by PhysicsAlive
All of the still-fresh fuel from reactor 4 had been offloaded to the used fuel pool for maintenance of the reactor before the original earthquake and tsunami.
It is particularly "fresh", generating more heat and radiation and making it harder to keep the water in this pool cool and not boil away.
There are many pieces of evidence that the pool *did* boil away in the days after the accident. At this time, there may have been damage to the fuel rods and a large release of radioactive substances into the air. Normally, such hot fuel rods only exist in the containment vessels of the reactor - but sitting in the pool there is zero containment if the water boils away.
Radiation surges above 4's fuel pool
Tokyo Electric Power Co. was unsure whether the surge in radiation was being caused by the spent fuel rods or radioactive material leaking from the reactor's pressure vessel.
Nuclear fuel inside the crippled reactors at the Fukushima Daiichi power plant has partially melted and settled at the bottom of pressure vessels in the shape of grains, according to an analysis by the Atomic Energy Society of Japan made public by Friday.
The academic body's panel on nuclear energy safety has said the melted fuel at the No. 1 to 3 reactors has been kept at a relatively low temperature, discounting the possibility that a large amount of melted fuel has already built up at the bottom of their reactor vessels given the temperature readings there.
DAVID McNEILL in Tokyo
SCIENTISTS SAY the fight to bring Japan’s crippled nuclear power plant under control could take three months or more, even if not hampered by further earthquakes. The announcement comes after another day of aftershocks, including one with an epicentre about 25km from the Fukushima plant.
The head of the Atomic Energy Society of Japan, Takashi Sawada, said yesterday that fuel rods in reactors 1 and 3 have melted and settled at the bottom of their containment vessels, confirming fears that the plant suffered a partial meltdown after last month’s huge earthquake and tsunami.
Originally posted by mistafaz
reply to post by predator0187
Would you do the same if they were people?
Given the circumstances of this disaster...Yes even my own family if I had to. It doesn't make me happy or proud to feel this way but I'd do it if it meant less of a means for radiological particulates to spread. Saving those dogs is the weakness that embodies humanity in situations as these, compassion.
Originally posted by Wertwog
reply to post by Ektar
I would never leave my dog. She's my only child and as important to me as any family member. We'd pack up in the car together as soon as there was a hint of an incident and get on a plane outathere. People should have made arrangements for their animals. As humans it's our responsibility, part of the deal. Anyway.
A lot of talk about tarps and such. Not much going on eh? I doubt there's anything nefarious to these, probably just covering up generators, batteries, and other equipment to protect them from saltwater exposure on an open barge deck. Pretty common practice actually.
What did raise my eyebrows is if they are going to change the Capitol. Drip Drip Drip.... Que CBIRF team. Toyko, "you're on your own".
Unit-1, 2, 3 & 4, which were in full operation when the earthquake occurred, all shutdown automatically. External power supply was available after the quake. While injecting water into the reactor pressure vessel using make-up water system, TEPCO recovered the core cooling function and made the unit into cold shutdown state one by one. No parameter has shown abnormality after the earthquake occurred off an shore of Miyagi prefecture at 23:32, Apr. 7th
NO PLAN TO STOP JAPAN NUCLEAR REACTOR RADIATION LEAK FOR AT LEAST 3 MONTHS.
he manufacturer of the Fukushima nuclear reactor revealed the plan to end the nuclear reactor radiation leak which will be split into 3 phases over 10 years. The first stage will take about three months during which they plan to stabilize the nuclear reactor and spent fuel pools while preventing the radiation leak from increasing.
Complete new nifty plan explained in wiggle words here.www3.nhk.or.jp...
Reactor makers draft 10-year decommission plan Japanese manufacturer Toshiba, which helped build the Fukushima Daiichi plant’s now crippled nuclear reactors, says decommissioning them will take at least 10 years.
Toshiba has drafted a plan with 4 US companies in the nuclear power industry to decommission the plant, including the Number 2 and 3 reactors that it built.
The company’s President Norio Sasaki said on Thursday that it has submitted the proposal to Tokyo Electric Power and the Industry Ministry. Prime Minister Naoto Kan had earlier asked the utility to come up with a plan to end the nuclear crisis.
The proposal is divided into 3 phases. The short-term plan, likely to take several months, involves cooling and stabilizing reactors and spent fuel pools, while preventing radioactive water from increasing.
Toshiba will then move toward the medium-term plan, involving the safe removal of nuclear fuel rods from the pools and pressure vessels, using special cranes to be set up near the reactor buildings. Toshiba says this work will take 5 years.
The final phase, dismantling the reactors and clearing the land, will take another 5 years. Toshiba says that radioactive substances released in the process must be removed during this phase.