|
Post by caucasoididiot on Mar 15, 2011 14:21:27 GMT -5
Glad to do my bit, Mr. A, such as it is.
Edit: Had to be away from news for hours today, which was sure trying. Developments since have involved the fire at unit 4 flaring up again, but it's apparently again been suppressed. There seem to be no reports of serious increases in radiation levels.
World Nuclear News' server seems OK, but I'll go ahead and post the text just in case.
Second fire reported at unit 4 16 March 2011
FIRST PUBLISHED 0.25am GMT UPDATE 1: 1:14am GMT Information from TEPCO spokesman and video feed
The Nuclear and Industrial Safety Agency said that a blaze was spotted in the reactor building of Fukushima Daiichi 4 at 5.45am local time this morning.
Attempts to extinguish it were reportedly delayed due to high levels of radiation in the area. A spokesperson for TEPCO said that by around 6:15am there were no flames to be seen. However, at around 10:05am there appeared to be white smoke emerging from the plant.
The incident is believed to be in the region of a used fuel pond in the upper portion of the reactor building.
Origins
Tokyo Electric Power Company issued a notice of an explosion at unit 4 at 6am on 15 March. This was followed by the company's confirmation of damage around the fifth floor rooftop area of the reactor building.
On that day, a fire was discovered but investigations concluded it had died down by around 11am.
At present it is not clear whether today's fire was a completely new blaze, or if the fire reported yesterday had flared up again. Researched and written by World Nuclear News
|
|
|
Post by caucasoididiot on Mar 15, 2011 23:06:59 GMT -5
Here's a good report on the radiation levels seen thus far, and a good description of the potential behaviour of further releases. online.wsj.com/article/SB10001424052748703566504576203051840211720.html?mod=googlenews_wsjEdit: Sort of hard to gauge the situation this morning. Neither IAEA nor WNN have anything very new. Workers are apparently heading back into the plant, and the fire at unit 4 and cooling of the spent fuel pools remain concerns. Just now I read that unit 3 was loaded with plutonium fuel. That's an extra concern in case of release, as its chemical toxicity is quite high and a significant extra risk. There are some charges that the Japanese are underplaying the seriousness of the situation. It's possible. Japanese corporate and official cultures both dislike acknowledging embarrassing facts. So, all in all, kind of a wait and see moment.
|
|
|
Post by caucasoididiot on Mar 16, 2011 13:32:24 GMT -5
Well, good news and bad news. Here's a fairly up to date exposure rate map I pulled from FNN. Note the 2 µSv per hour reading at the town of Kita-Ibaraki. That's fairly near the plant, located further up the coast (the grey dot labeled 福島第一原発). For evaluating those figures, typical total background rates in the US would be: Atlantic and Gulf coasts: 0.025 µSv / hr East, west and central US: 0.053 µSv / hr Colorado Plateau: 0.10 µSv / hr So, the good news is that as things stand, levels are elevated but not dangerous outside the plant. Even that 2 µSv / hr rate would take nearly four months to reach the ICRP annual limit for the general public, and a rad worker is considered safe taking ten times that dosage in a year. This is manageable. But . . . . . . the bad news is that as they move into spring weather patterns, northeasterly winds become common. In the event of a major release, that would blow it right down into Tokyo and the Kanto plain, where something like a quarter of all Japanese live. I could have done without that bit of information. Edit: FNN now reports the official toll at 4277 dead, 8531 missing.
|
|
|
Post by caucasoididiot on Mar 16, 2011 18:44:46 GMT -5
World Nuclear News' update on the fuel pool situation:
Problems for units 3 and 4 16 March 2011
FIRST PUBLISHED 0.25am GMT UPDATE 1:14am GMT Information from TEPCO spokesman and video feed
UPDATE 2: 4:10am GMT Change title from 'Second fire reported at unit 4' and information on Unit 3 and 4 from Yukiyo Edano UPDATE 3: 4.50pm GMT Status of fuel pond in unit 4, status of seawater pumping, radiological conditions UPDATE 4: 10.01pm GMT Unit 3's pond status and the current focus of work UPDATE 5: 22.47pm GMT Addition of pond temperatures
Chief cabinet secretary Yukio Edano has described problems that occurred on the morning of 16 March with Fukushima Daiichi 3 and 4, as well as plans to pump water into unit 4. Controlling the situation of the used fuel storage ponds is the urgent priority now.
At 8.34am white smoke was seen billowing out of Fukushima Daiichi 3. Efforts to determine the cause of this development were interrupted by the evacuation of workers after rising radiation readings. Readings from a sensor near the front gate had fluctuated for some time, although Edano said that on the whole there was no health hazard. Earlier in the morning readings had ranged between 0.6-0.8 millisieverts per hour, but at 10am readings rose to 1.0 millisieverts per hour before falling again just before 11am.
Edano said that one possibility being considered was that the unit 3 reactor had suffered a similar failure to that at unit 2 yesterday, where the torus pressure suppression structure is suspected of being damaged. However, there had been no reported blast or loud sound, which had been the case for unit 2. The immediate focus, said Edano, was on monitoring of water levels and checking pumping operations.
Fuel ponds
About 60% of the total used nuclear fuel from all six reactors is kept in a shared facility, while each of the units also has its own storage pool near the top of the reactor building. At unit 4, the reactor itself contains no fuel, this having been removed to the unit's own store over 100 days ago for maintenance work to take place.
Cooling pond temperatures
As reported by the International Atomic Energy Agency:
Unit 4
14 March, 10:08 UTC: 84 ˚C
15 March, 10:00 UTC: 84 ˚C
16 March, 05:00 UTC: no data
Unit 5
14 March, 10:08 UTC: 59.7 ˚C
15 March, 10:00 UTC: 60.4 ˚C
16 March, 05:00 UTC: 62.7 ˚C
Unit 6
14 March, 10:08 UTC: 58.0 ˚C
15 March, 10:00 UTC: 58.5 ˚C
16 March, 05:00 UTC: 60.0 ˚C There have now been two fires in the upper portion of unit 4's reactor building, thought to follow an explosion early on 15 March which left the building severely damaged and also damaged unit 3. The cause of the fires remains unknown due to radiation in the area, and they could in fact be one fire that died down before reigniting. The exact nature of the explosion is also unknown.
The Japan Atomic Industry Forum reports that the level of water in unit 4's fuel pond is low and damage to fuel stored there is suspected. Efforts are underway to refill the pool, including an abandoned attempt to douse the building with water from an army helicopter, hoping to get some to go through the damaged building. The temperature of the pond was last known to be 84ºC on 14 and 15 March, said the International Atomic Energy Agency. There was no data for today.
Unit 3's pond is also low and engineers are preparing to add water to both. This is the urgent focus of work for Tepco engineers. Without proper containment, the risk of serious radioactive release in the event of fuel damage or fire is very real. Tepco has not announced the original issue that allowed the water levels in the fuel ponds to drop so low.
Temperatures in the ponds of units 5 and 6 are also elevated. The IAEA gave figures showing a steady increase to around 60-63ºC.
Seawater pumping
Efforts to cool the partially exposed cores of units 1, 2 and 3 continue. So long as radiological conditions allow, a team of workers pumps seawater into the reactor vessels. This boils away, raising steam pressure which must later be vented. Fuel assemblies are exposed by between one and two metres at the top, but the high thermal conductivity of the zirconium alloy rod casings helps cooling with just the lower portion of the rods submerged. This process is set to continue until the heat produced by the core has reduced so that the entire core can be covered.
Radiation levels on site are fluctuating, which makes it difficult for engineers to work as well as to analyse the extent of possible damage to various functional systems in the reactor buildings. Venting steam from units 1, 2 and 3 contributes a certain amount which dissipates in a matter of hours. It is thought some emission is the result of damage to unit 2's torus. Any release due to damaged nuclear fuel is unknown.
The peak of radiation on site is near unit 3, where levels of 400 millisieverts per hour have been recorded. Dose limits to workers under emergency regulations have been raised to 250 millisieverts from 100 millisieverts after which they may not return. This compares to usual nuclear worker limits of 20 millisieverts per year.
Researched and written by World Nuclear News
|
|
Torgo
Moderator Emeritus
-segment with Crow?
Posts: 15,420
|
Post by Torgo on Mar 16, 2011 19:48:56 GMT -5
Jesus Christ that's a lot of people.
My thoughts are with the entire country. May it pull out of this mess as best it can.
|
|
|
Post by caucasoididiot on Mar 16, 2011 22:44:41 GMT -5
Yeah, the potential is still there for a real mess, though if I read FNN's site accurately they have water in pools 3 & 4 and expect offsite power back up for the plant tomorrow. That would be a great help. What they've already had has been bad enough. FNN's latest figures are 5178 confirmed dead, 8858 missing. The latest on the IAEA site is an update on injuries and contamination. The latter, so far, confined to people engaged in trying to gain control of the situation at the plant. They deserve a lot of credit. Japanese Earthquake Update (17 March 01:15 UTC) Injuries or Contamination at Fukushima Daiichi Nuclear Power Plant Based on a press release from the Japanese Chief Cabinet Secretary dated 16 March 2011, the IAEA can confirm the following information about human injuries or contamination at the Fukushima Daiichi nuclear power plant. Please note that this list provides a snapshot of the latest information made available to the IAEA by Japanese authorities. Given the fluid situation at the plant, this information is subject to change. Injuries * 2 TEPCO employees have minor injuries * 2 subcontractor employees are injured, one person suffered broken legs and one person whose condition is unknown was transported to the hospital * 2 people are missing * 2 people were 'suddenly taken ill' * 2 TEPCO employees were transported to hospital during the time of donning respiratory protection in the control centre * 4 people (2 TEPCO employees, 2 subcontractor employees) sustained minor injuries due to the explosion at unit 1 on 11 March and were transported to the hospital * 11 people (4 TEPCO employees, 3 subcontractor employees and 4 Japanese civil defense workers) were injured due to the explosion at unit 3 on 14 March Radiological Contamination * 17 people (9 TEPCO employees, 8 subcontractor employees) suffered from deposition of radioactive material to their faces, but were not taken to the hospital because of low levels of exposure * One worker suffered from significant exposure during 'vent work,' and was transported to an offsite center * 2 policemen who were exposed to radiation were decontaminated * Firemen who were exposed to radiation are under investigation The IAEA continues to seek information from Japanese authorities about all aspects of the Fukushima Daiichi nuclear plant.
|
|
|
Post by caucasoididiot on Mar 17, 2011 9:31:41 GMT -5
Latest from World Nuclear News:
Attempts to refill fuel ponds 17 March 2011
FIRST PUBLISHED: 4.25am GMT
UPDATE 1: 9.29am GMT Additional temperature, radiation data and context UPDATE 2: 10.00am GMT Further temperature data UPDATE 3: 1.41pm GMT Fire trucks in action
A major struggle is underway to maintain cooling of used nuclear fuel at Fukushima Daiichi 3 and 4. Helicopters have made water drops and large fire trucks are showering the buildings.
While unit 3 was in operation when the earthquake struck on 11 March, and has been in trouble since the tsunami took out emergency diesel generators, unit 4 was fully shut down at that time and had appeared to remain safe until 16 March when an explosion led to fires.
The explosion at unit 4 is thought to have been from a build-up of hydrogen in the area near the used nuclear fuel pond. It severely damaged the building, as well as that of adjacent unit 3, with which it shares a central control room.
Cooling pond temperatures
As reported by the International Atomic Energy Agency:
Unit 4
14 March, 10.08am GMT: 84 ˚C
15 March, 10.00am GMT: 84 ˚C
16 March, 05.00am GMT: no data
Unit 5
14 March, 10.08am GMT: 59.7 ˚C
15 March, 10.00am GMT: 60.4 ˚C
16 March, 05.00am GMT: 62.7 ˚C
Unit 6
14 March, 10.08am GMT: 58.0 ˚C
15 March, 10.00am GMT: 58.5 ˚C
16 March, 05.00am GMT: 60.0 ˚C Neither the IAEA nor the Japan Atomic Industry Forum have data for units 1, 2 and 3. Now the situation of the cooling ponds is the priority of authorities. Containing highly radioactive heat-generating nuclear fuel, they require an adequate level of water to be maintained as well as pumped circulation to control water temperature.
In the previous two days the temperature of unit 4's pond had been 84ºC but no more recent data is available. At these temperatures cooling by natural convection begins to be markedly less effective. Normal operating levels are about 25ºC. There is no information on the temperature of the pond at unit 3.
However, the high levels of radiation and presence of hydrogen at unit 4 strongly indicate that fuel is uncovered and suffering damage in the pond, although it is not clear that the pond is actually empty. At present, officials believe the pond contains some water, based on helicopter observations.
Radiation at ground level near units 3 and 4 is high: peaking at 400 millisieverts per hour on the inland side of unit 3, and 100 millisieverts per hour on the inland side of unit 4. At the highest exposure rate, a nuclear worker or soldier could remain in the area for less than 40 minutes before leaving the site, unable to return.
With such serious damage to the reactor buildings it is thought that radiation from further degradation of stored fuel at units 3 and 4 would be released to the environment unchecked.
Radiation at site border Despite high levels of radiation close to the units, levels detected at the edge of the power plant site have been steadily decreasing.
17 March, 4.00pm
0.64 millisieverts per hour
17 March, 9.00am
1.47 millisieverts per hour
16 March, 7.00pm 1.93 millisieverts per hour
16 March, 12.30pm
3.39 millisieverts per hour
With the seriousness of the situation and the radiation levels on the ground, it was decided to try to use a helicopter to douse the reactor building of unit 3. Around 100 metres above the facility radiation was around 87 millisieverts per hour.
Two army helicopters made four attempts to drop seawater on unit 3, but this did not appear accurate enough to be effective. Tepco said in a news conference that radiation readings had dropped from 3.78 millisieverts per hour to 3.75 millisieverts per hour, so the effect at present seems marginal at best. One attempt was made to douse unit 4 but pilots drew back after encountering high levels of radiation.
After clearing heavy explosion debris from tsunami and the various explosions across the site over the last six days, eleven high pressure fire trucks are now showering the reactors. It is thought they are targeting unit 3. Tackling that first may lower the high radiation levels on the ground near that unit, allowing more flexibility and speed when tackling unit 4 or any subsequent units whose fuel pools may get into trouble.
Researched and written by World Nuclear News
|
|
|
Post by caucasoididiot on Mar 17, 2011 11:42:53 GMT -5
Progress by on-site workers 17 March 2011
The high levels of radiation braved by workers at the scene in Fukushima Daiichi appear to have reduced after the expansion of the workforce and announcements of infrastructure improvements to come.
In recent days emergency managers were faced with an extremely complicated task to prioritise jobs across all four struggling reactor units in the main part of the site, while a skeleton operating crew maintained the status of units 5 and 6 about two hundred metres away.
There have been about 50 staff engaged in pumping seawater into the reactor cores and primary containment vessels of units 1, 2 and 3. From time to time these need to vent steam, which causes radiation to rise across the site and required the workers to move to a safer location.
Another 130 were also on site, according to reports, including soldiers from the Japan Self Defence Force.
Normally nuclear workers are allowed to receive a dose of 20 millisieverts per year, although in practice they often receive very much less. If that limit is exceeded in any year, the worker cannot undertake nuclear duties for the remainder.
In emergency circumstances safety regulators allow workers to receive up to 100 millisieverts with the same conditions applying, that they must leave the site should that limit be reached. The 100 millisievert level is roughly the point at which health effects from radiation become more likely. Below this it is statistically difficult to connect radiation dose to cancer rates, but above this the relationship starts to become apparent.
Under a special allowance from the Nuclear and Industrial Safety Agency, workers at Fukushima were permitted doses of up to 250 millisieverts. Managers must be careful to make the best use of those experienced workers with the most detailed knowledge and experience of the plant.
The small workforce battled to spray water into the damaged buildings of units 3 and 4, working when and where they could to avoid exceeding those radiation dose limits. World Nuclear News understands that the army fire engine was able to supply about 30 tonnes of water to unit 3's fuel pond, but this is not confirmed, nor is the expected drop in radiation levels expected to accompany. However, Tokyo Electric Power Company has been able to significantly expand the workforce and a range of other activities are now taking place.
External power, diesels coming
The Ministry of Economy Trade and Industry said at 8.38pm that a cable was being laid to bring external power from transmission lines owned by Tohoku Electric Power Company. This was to be connected when radiation levels had died down after a planned venting operation at unit 2.
In addition, one of the emergency diesel units can now be operated and will be used to supply unit 5 and 6 alternately to inject water to their used fuel pools. Later, the power will be used to top up water in the reactor vessels.
Casualties among power plant workers
* Two Tepco employees have minor injuries * Two contractors were injured when the quake struck and were taken to hospital, one suffering two broken legs. * A Tepco worker was taken to hospital after collapsing and experiencing chest pains. * A subcontract worker at an "important earthquake-proof building" was found unconscious and was taken to hospital. * Two Tepco workers felt ill whilst working in the control rooms of Fukushima Daiichi units 1 and 2 and were taken to the medical centre at Fukushima Daini. * Four workers were injured in the hydrogen explosion at Fukushima Daiichi 1. They were all taken to hospital. * Eleven workers (four Tepco workers, three subcontract workers and four members of Self Defence Force) were hurt following a similar explosion at Fukushima Daiichi 3. They were transferred to the Fukushima Daini plant. One of the Tepco employees, complaining of pain in his flank, was later transferred to hospital. * The whereabouts of two Tepco workers, who had been in the turbine building of Fukushima Daiichi unit 4, is unknown.
Contamination cases
* One Tepco worker working within the reactor building of Fukushima Daiichi unit 3 during “vent work” was taken to hospital after receiving radiation exposure exceeding 100 mSv, a level deemed acceptable in emergency situations by some national nuclear safety regulators.17 workers – nine Tepco employees and eight subcontract workers – suffered facial exposure to low levels of radiation. They did not require hospital treatment. * Two policemen were decontaminated after being exposed to radiation. * An unspecified number of firemen who were exposed to radiation are under investigation.
So far, only one casualty has been reported at the Fukushima Daini plant. A worker in the crane operating console of the exhaust stack was seriously injured when the earthquake struck. He subsequently died.
Researched and written by World Nuclear News
|
|
|
Post by caucasoididiot on Mar 17, 2011 15:43:22 GMT -5
|
|
|
Post by caucasoididiot on Mar 17, 2011 16:22:13 GMT -5
Here's a graphic that says a lot. You have to let it play awhile before the 9.0 hits, but after that the aftershocks are like flippin' popcorn. www.japanquakemap.com/
|
|
|
Post by BJ on Mar 17, 2011 22:17:40 GMT -5
^That graphic is insane. I had no idea there were that many aftershocks.
Thanks a lot for all these updates.
|
|
|
Post by caucasoididiot on Mar 17, 2011 22:28:23 GMT -5
Just wish I had better news to report. Today has felt a long, drawn out, pregnant pause, though a frenetic one for the workers onsite. Earlier in the day, IAEA had said that offsite power had been restored to unit 2, but now says that effort is still continuing. Reports are conflicting and difficult to make a coherent picture of. IEEE's site does have a very good "the story thus far" recap: spectrum.ieee.org/tech-talk/energy/nuclear/explainer-what-went-wrong-in-japans-nuclear-reactors
|
|
|
Post by caucasoididiot on Mar 18, 2011 10:01:15 GMT -5
|
|
|
Post by caucasoididiot on Mar 18, 2011 14:49:02 GMT -5
This is off of World Nuclear News:
UK advisor reassures on contamination fears 18 March 2011
The UK government's chief independent scientific advisor has told the British Embassy in Tokyo that radiation fears from the stricken Fukushima nuclear power plant are a "sideshow" compared with the general devastation caused by the massive earthquake and tsunami that struck on 11 March.
Speaking from London in a teleconference on 15 March to the embassy, chief scientific officer John Beddington said that the only people likely to receive doses of radiation that could damage their health are the on-site workers at the Fukushima Daiichi plant. He said that the general population outside of the 20 kilometre evacuation zone should not be concerned about contamination.
Beddington said that the current situation was that "the Japanese are trying to keep the reactors cool by pumping sea water that will keep the temperature down; that's their first line of defence." He added, "Up to now that's been working reasonably well." He noted that when the pressure within the containment vessel increases to a high level, workers release a mixture of steam and hydrogen into the atmosphere. This, he said, contains "really quite modest amounts of radioactive material."
"The first thing to say about that is do we have any concerns now in terms of human health? Well the answer is yes we do, but only in the immediate vicinity of the reactors
So the 20 kilometre exclusion zone the Japanese have actually imposed is sensible and proportionate. If they extended out a little bit more to 30 km, that is well within the sort of parameters that we would think are extremely safe."
John Beddington UK chief science advisor
Speaking of a worse-case scenario at the stricken plant, Beddington said that if workers were unable to keep the reactors sufficiently cooled, you can get "the dramatic word 'meltdown'." He noted, "What a meltdown involves is the basic reactor core melts, and as it melts, nuclear material will fall through to the floor of the container. There it will react with concrete and other materials ... that is likely ... remember this is the reasonable worst case, we don't think anything worse is going to happen."
"In this reasonable worst case you get an explosion. You get some radioactive material going up to about 500 metres up into the air," Beddington said. "Now, that's really serious, but it's serious again for the local area." He said that even if there was the worse weather situation, with strong winds pushing the release towards Tokyo, there would still be "absolutely no issue. The problems are within 30 kilometres of the reactor."
Not another Chernobyl
Beddington stressed that the events at the Fukushima Daiichi plant cannot be compared to those at the Chernobyl plant in Ukraine in 1986. "In Chernobyl, first of all the top blew off the reactor and then the core of the reactor, the graphite which surrounds the core, actually caught fire and burned for a very long time," he said. "Material was going up not just 500 metres but to 30,000 feet (9150 metres). It was lasting not for the odd hour or so, but lasted months, and that was putting nuclear radioactive material up into the upper atmosphere for a very long period of time. But even in the case of Chernobyl, the exclusion zone that they had was about 30 kilometres. And in that exclusion zone, outside that, there is no evidence whatsoever to indicate people had problems from the radiation."
"The problems with Chernobyl were people were continuing to drink the water, continuing to eat vegetables and so on and that was where the problems came from. That's not going to be the case here," according to Beddington.
He highlighted that it will be the workers at the Fukushima site attempting to keep the reactors stable who will receive the highest doses of radiation. However, he noted, "They will be completely screened by the Japanese authorities; they will be decontaminated in a whole series of mechanisms which are well understood by the nuclear industry."
Beddington noted that there had been concerns both in Japan and internationally about the information from Japanese authorities on radioactive releases from the Fukushima plant following the quake and tsunami. However, he said that releases of radiation cannot be concealed. "It's monitored throughout the world. We know we can actually monitor exactly what the radiation levels are around there externally so [concealment] is just not happening."
Researched and written
by World Nuclear News
|
|
|
Post by caucasoididiot on Mar 18, 2011 16:37:54 GMT -5
Current reports continue to suggest that the nuclear situation is at least stable. One piece of good news from the IAEA's most recent update is as follows:
2. Radiation Monitoring
As mentioned yesterday, regular dose rate information is now being received from 47 Japanese cities.
Dose rates in Tokyo and other cities remain far from levels which would require action - in other words they are not dangerous to human health.
First measurements in Tokyo by the Agency's newly arrived radiation monitoring team today showed no indication of Iodine-131 or Caesium-137. A second sampling will be carried out overnight.
|
|