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Unit 3 of Fukushima Daiichi
CRYPTOME: Fukushima Daiichi Nuclear Power Plant Photos (first page) | Cryptome Nuclear Power Plants and WMD Series
the problems at Fukushima are complex and the situation is not yet under control - with three reactors at various stages of meltdown and another in jeopardy, there are also serious issues with the spent fuel pools which are full of "hot waste" - - volumes of radioactive pollutants are being discharged daily into the biosphere - the potential for additional explosions and the prolonged and significant uncontrolled dispersal of persistent deadly toxins will remain for some time to come
Tepco confirms extra partial fuel rod meltdown at plant
BBC News - 23 May 2011: Tokyo Electric Power (Tepco) has confirmed the meltdown of extra fuel rods in reactors at its damaged Fukushima nuclear power plant.
The company said that the rods were in its Number 2 and Number 3 reactors.
Earlier this month, Tepco had revealed that rods at its Number 1 reactor melted down. It was thought that a similar problem had occurred in the other reactors but it was difficult to confirm.
"Based on our analysis, we have reached the conclusion that a certain amount of nuclear fuel has melted down," Ken Matsuda, a Tepco spokesman told the BBC.
He said the analysis came from a report that Tepco was required to submit to Japan's Nuclear and Industrial Safety Agency (Nisa).
The spokesman added that most of the fuel from the Number 2 reactor had melted approximately 100 hours after the earthquake, which measured 9 on the Richter scale, struck Japan.
The meltdown in the Number 3 reactor took place about 60 hours after the quake.
Q & A: What's going on at Japan's damaged nuclear power plant?
Reuters | By Shinichi Saoshiro and Mayumi Negishi
TOKYO | Tue May 17, 2011 2:54am EDT
Japanese engineers are trying to gain control of the Fukushima Daiichi nuclear power plant, 240 km (150 miles) north of Tokyo, which was crippled by the huge March 11 earthquake and tsunami.
Radiation continues to seep into the sea and the air, although at far lower levels than at the peak of the crisis in mid-March.
Four of the six reactors at the plant, operated by Tokyo Electric Power Co (Tepco), are considered volatile.
Following are some questions and answers about efforts to end the world's worst nuclear crisis since Chernobyl:
WHAT IS HAPPENING?
Nuclear fuel rods at the plant's No. 1, No. 2, No.3 reactors melted in the immediate aftermath of the earthquake and tsunami and Tepco is trying to bring the reactors to a cold shutdown, where the water cooling them is below 100 degrees Celsius.
Efforts to cool the reactors by pouring water into them have brought down temperatures and the rods are no longer melting but the No. 1 reactor continues to leak radiated water and the No.2 and No.3 reactors are also believed to be leaking.
To achieve a cold shutdown, Tepco initially planned to use "water entombment," in which the containment vessels -- an outer shell of steel and concrete that houses the reactor vessel -- would be filled with water.
But this option is likely to be ruled out for the No. 1 reactor and possibly for the other two, after new data and inspections showed that the No. 1 reactor vessel had been punctured when the rods melted, allowing water being pumped as a coolant to pool in the basement of the reactor.
Tepco is readying a fallback plan that will involve decontaminating the water already accumulated and then pumping it back to cool the reactors.
Officials are also concerned about the slow pace of cooling at the No. 3 reactor and the No. 4 reactor was so badly damaged by a hydrogen explosion that workers will have to try to shore it up with steel beams and concrete to prevent a collapse.
In an effort to limit the spread of radioactive dust, the No. 1, No. 3 and No. 4 reactors will be covered with giant tent-like polyester covers supported by steel beams.
WHAT IS HAMPERING TEPCO?
Water is a huge headache for the operator. It has pumped in tens of thousands of tonnes of it to cool the reactors and much of it has ended up as contaminated runoff, accumulating as huge pools at the reactor buildings.
Preventing the massive pools of runoff from seeping out into the environment remains a challenge and Tepco is running out of space to store the radioactive water.
It is building tanks and towing in a massive barge to secure extra storage and is looking to build plants to treat some of the water. The operator caused in international outcry in April when it was forced to dump thousands of tonnes of contaminated water into the Pacific.
Weather conditions, such as the approaching rainy season and typhoons and lightning during the summer, could also pose problems.
Residents of Iitate village listen to Mayor Norio Sugano,right back to camera, explain a government plan to evacuate residents from the village that's about 40 kilometers (24 miles) from the radiation-spewing Fukushima Dai-ichi nuclear plant in northeastern Japan, on Wednesday April 13, 2011. (Kyodo News) JAPAN OUT, MANDATORY CREDIT, NO LICENSING IN CHINA, HONG KONG, JAPAN, SOUTH KOREA AND FRANCE - CRYPTOME: Fukushima Daiichi Nuclear Power Plant Photos 15
HOW LONG WILL THE CRISIS LAST?
In April, Tepco announced a timetable for its operations. Within the first three months it plans to cool the reactors and the spent fuel stored in some of them to a stable level and reduce the leakage of radiation.
The company then hopes to bring the reactors to a cold shutdown in another three to six months. That would take the initial phase of work to stabilize the plant to January.
But with the damage to the reactors being worse than initially thought some experts said the process could take longer. Tepco said constant aftershocks, power outages, high levels of radiation and the threat of hydrogen explosions were factors that could hamper its work.
Even after the plant is under control, recovery work at the site is expected to continue for years.
For reference, officials have cited the work to clean up Three Mile Island after that U.S. reactor suffered a partial meltdown in 1979.
The Three Mile Island cleanup involved over 1,000 workers and took 13 years. It took nearly six years before the fuel from the reactor could be safely removed.
TEPCO Says Core of Unit 1 Melted
All Things Nuclear
MAY 17, 2011
Last week, Tokyo Electric Power Company (TEPCO) officials announced that they now believe essentially all the fuel in reactor 1 at Fukushima melted early in the crisis, and is now lying in a mass at the bottom of the reactor vessel. But they believe that it did not melt through the bottom of the vessel—which would have been a full “meltdown”—and that it is mostly covered with water and has achieved “stable cooling.”
Figure 1: Results of a TEPCO analysis, adapted from, “Reactor Core Status of Fukushima Daiichi Nuclear Power Station Unit 1,” 15 May 2001.
TEPCO’s announcement about the extent of the fuel damage in Unit 1 came about last week when workers calibrated water-level sensors and found that the water level in the reactor vessel appears to be below the level where the bottom of the fuel rods should be in normal operation, and appears to have been that low since shortly after the earthquake and tsunami. This means that the fuel could no longer be in its usual location since without cooling it would have melted.
On May 15, TEPCO released details of its current guess about what happened in the core. This analysis says that most or all of the core had melted and relocated to the bottom of the reactor vessel within 16 hours of the time the reactor shut down. This analysis assumes the cooling system “lost its function after the tsunami arrived at around 15:30,” so relocation of the fuel happened within 15 hours of the end of cooling.
IAEA Update on Fukushima Nuclear Disaster
12 - 18 May 2011
Fukushima Daiichi Nuclear Power Plant Status
TEPCO has reported that information obtained after calibration of the reactor water level gauges of Unit 1 shows that the actual water level in the Unit 1 reactor pressure vessel was lower than was indicated, showing that the fuel was completely uncovered. The results of provisional analysis show that fuel pellets melted and fell to the bottom of reactor pressure vessel at a relatively early stage in the accident.
Nitrogen gas is still being injected into the containment vessel in Unit 1 to reduce the possibility of hydrogen combustion inside the containment vessel.
In Units 1, 2 and 3 fresh water is being continuously injected into the reactor pressure vessel; temperatures and pressures remain stable.
To protect against potential damage as a result of future earthquakes, TEPCO started work on 9 May to install a supporting structure for the floor of the spent fuel pool of Unit 4.
Fresh water is being injected as necessary into the spent fuel pools of Units 1 - 4.
Stagnant water with high levels of radioactivity in the basement of the turbine buildings of Units 1, 2 and 3 is being transferred to the condensers, the radioactive waste treatment facility, the high-temperature incinerator building and temporary storage tanks. Stagnant water in the basement of the turbine building of Unit 6 is being transferred to a temporary tank. Countermeasures against the outflow of water to the sea and to prevent and minimize the dispersion of radionuclides in water have been put in place.
Full-scale spraying of anti-scattering agent is continuing at the site with the use of both conventional and remote controlled equipment.
Deposition in 47 Prefectures
The daily monitoring of the deposition of caesium and iodine radionuclides for 47 prefectures is continuing. Since 12 May negligible deposition has occurred. I-131 was reported in only one prefecture and Cs-137 was reported in three prefectures, with a value of 4.8 Bq/m2 for I-131 and a range of from 4.7 to 10 Bq/m2 for Cs-137.
The activity concentrations of I-131, Cs-134 and Cs-137 in seawater close to the Fukushima Daiichi plant at the screen of Unit 2 have been measured every day since 2 April. Concentrations of Cs-134 and Cs-137 decreased from initial values of more than 100 MBq/L to less than 5 kBq/L on 7 May, but increased to levels of around 20 kBq/L on 16 May, and to about 10 kBq/L on 17 May. There was a significant increase in levels of I-131 from about 8 to 80 kBq/L from 10 to 11 May, in parallel with the increase for both radiocaesium isotopes. This indicates that there is still some production of fission products. The I-131 levels decreased to about 20 kBq/L on 17 May.
Fukushima - One Step Forward and Four Steps Back as Each Unit Challenged by New Problems
- Fairewinds Associates
May 13: Arnie Gundersen says Fukushima's gaseous and liquid releases continue unabated. With a meltdown at Unit 1, Unit 4 leaning and facing possible collapse, several units contaminating ground water, and area school children outside the exclusion zone receiving adult occupational radiation doses, the situation continues to worsen. TEPCO needs a cohesive plan and international support to protect against world-wide contamination.
In Japan Reactor Failings, Danger Signs for the U.S.
In Japan Reactor Failings, Danger Signs for the U.S.
By HIROKO TABUCHI, KEITH BRADSHER and MATTHEW L. WALD
- NYTimes.com - Published: May 17, 2011
TOKYO — Emergency vents that American officials have said would prevent devastating hydrogen explosions at nuclear plants in the United States were put to the test in Japan — and failed to work, according to experts and officials with the company that operates the crippled Fukushima Daiichi plant.
“You have the N.R.C. containment isolation guys who want containment closed, always, under every conceivable accident scenario, and then you’ve got the reactor safety guys who need containment to be vented under severe accident scenarios. It is a very controversial system.”
The failure of the vents calls into question the safety of similar nuclear power plants in the United States and Japan. After the venting failed at the Fukushima plant, the hydrogen gas fueled explosions that spewed radioactive materials into the atmosphere, reaching levels about 10 percent of estimated emissions at Chernobyl, according to Japan’s nuclear regulatory agency.
Venting was critical to relieving pressure that was building up inside several reactors after the March 11 tsunami knocked out the plant’s crucial cooling systems. Without flowing water to cool the reactors’ cores, they had begun to dangerously overheat.
American officials had said early on that reactors in the United States would be safe from such disasters because they were equipped with new, stronger venting systems. But Tokyo Electric Power Company, which runs the plant, now says that Fukushima Daiichi had installed the same vents years ago...
"Now that this experimental containment vent is demonstrated to have failed at Fukushima, we need to know who installed it at US plants, who didn’t and the justification for the continued operation of these deeply flawed and dangerous reactors"
Beyond Nuclear and co-petitioners demand NRC come clean on flawed "fixes" at Mark I reactors
In a press statement released on May 18, 2011, Beyond Nuclear demands that the NRC make public how many U.S. Mark I reactors have, or have not installed the venting system that demonstrably failed at Fukushima. Following on an exposé in the New York Times (see previous entry above) and the April 13, 2011 filing of its own emergency enforcement petition to the Nuclear Regulatory Commission (NRC), Beyond Nuclear is renewing its call on the NRC to suspend the operating licenses of 21 Mark I units in the United States. The US Mark I reactors are nearly identical to the Fukushima reactors that exploded into shambles and that are leaking radioactivity into the air and sea."
Beyond Nuclear charges that while some U.S. Mark I reactors possess the same now demonstrated failed venting systems, the NRC is aware that other Mark I reactor operators may not even have installed – and some may even have uninstalled – the now controversial venting systems. If the venting systems had worked as designed they would have prevented extensive damage to containment from the devastating hydrogen explosions witnessed at the Fukushima nuclear plant.
“The NRC left the retrofit of this experimental venting system to the voluntarily discretion of the US reactor operators,” said Paul Gunter, Director of Reactor Oversight at Beyond Nuclear. “Now that this experimental containment vent is demonstrated to have failed at Fukushima, we need to know who installed it at US plants, who didn’t and the justification for the continued operation of these deeply flawed and dangerous reactors,” he said.
Read the full Beyond Nuclear petition
The Implications of the Fukushima Accident on the World's Operating Reactors
May 22: Arnie Gundersen explains how containment vents were added to the GE Mark 1 BWR as a "band aid" 20 years after the plants built in order to prevent an explosion of the notoriously weak Mark 1 containment system. Obviously the containment vent band aid fix did not work since all three units have lost containment integrity and are leaking radioactivity. Gundersen also discusses seismic design flaws, inadequate evacuation planning, and the taxpayer supported nuclear industry liability fund.
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