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At the moment, I don't see a 'real' chance of a meltdown. It is a worst case scenario, which is what licensing space is all about.
Some of the worst case scenarios involve extraordinary, and not necessarily physical real situations. It's a bit like crash testing a car by dropping it out of an airplane at several thousand feet, knowing full well that such a car would never be able to achieve such a velocity on level ground since the engine could not achieve the speed or the tires would blow out well before the speed could be achieved.
Some in the media will sensationalize the situation in order to grab the audience in order to sell commercials for useless stuff. But I digress.
I'd like to keep the discussion here on the technical aspects - as soon as we learn from reliable sources.
We have the earthquake thread in P&WA.
No. And in fact, as far as I can tell - there will not be a molten puddle.
If the ceramic fuel melted, then the steel would melt sooner and it would dilute the fuel, displace the water, and there would be no moderation to make the system critical.
I believe in this context radiation leak means leak of a radioactive substance, not fact that radiation (be it alpha, beta, gamma) is detectable outside. Sure, when the radioactive substances leak there is a spike in the detected radiation, but it is an effect of the radioactive substances being present outside. As long as the radioactive material is present in the containment at least beta and alpha are almost completely stopped.
When they speak of radiation leaks, do they mean only neutrons, alpha, beta and gamma particles - or also other big atomic nuclei.
Look where the photo (I hope it was a remote robotic taking the picture) is centered. What do you think they were assessing? Does it look to you like there is a "slag-like" tongue of something hanging out of a relatively square hole in roughly the location that might correspond to the SFP, and that a sideways blast has taken out some of the structures external to the building as well as the roof of the building?
The damage from explosion at Unit 4 is fundamentally different than that at Unit 3, where all the structures seem to be blown out away from the primary containment.
Units 1 and 3 had significant explosions, whereas unit 4 may have had a smaller explosion or fire. Or, was it damaged by the explosion and fire of unit 3?
I expect they are trying to assess the damage to unit 4 and how they might get water to the spent fuel pool.
If memory serves me well unit 4 fire was explained as burning leaking oil - either lubricant or hydraulic. I can't locate source right now, besides, I read it in Polish.
I have heard the same - that the fire(s) at unit 4 came from a fuel source not related to the SFP. However, the situation seems to be evolving (rapidly deteriorating according to some).
BTW, just how much worse can it get considering the state of affairs in the other parts of Japan? Answer: Minuscule when compared to the destruction and carnage in the other quake and tsunami stricken areas of Japan.
Let put a nuclear accident in perspective:
As I have stated before, the nuclear events in Japan - if left to run to their conclusion without interdiction would not even closely rival the loss-of-life in one town hit by the tsunami (fear that 10,000 out of 164,000 people lost their lives). Many more Japanese towns face similar catastrophe losses. Not even for long term radiation exposure health risks.
The Japanese nuclear accidents will be a vey good study and design fodder for years to come. More than likey all BWR 1 thru 3's will be shut down due to biased fears.
No amount of Ad hominem circumstantial statements and uneducated guesstimates will change the out come.
So which is that statement? Ad hominem circumstantial or uneducated guesstimate?
Here is my guesstimate:
The designs were flawed. Multiple reactor facilities have been damaged and filled with salt water. Fires and explosions have occurred. Radiation has been released. Many thousands of stored fuel rods are not contained within quake/tsunami/fire/explosion-proof storage facilities.
Nuke workers will definitely be in demand in Japan for their reactor cleanup and decommissioning. Overall the Japanese nuclear program came out in relatively good shape considering they have over 50 nuke plants on the island.
The Institute of Nuclear Power Operations has compiled a detailed timeline of events at the Fukushima Daiichi nuclear power station after the March 11 earthquake and tsunami in Japan. The detailed report, prepared as part of the integrated response to the Japan events, was delivered on Nov. 11, 2011, to U.S. industry executives, the Nuclear Regulatory Commission and members of Congress.
Established by the nuclear power industry in December 1979, the Institute of Nuclear Power Operations is a not-for-profit organization headquartered in Atlanta.
NA-YGN provides opportunities for a young generation of nuclear enthusiasts to develop leadership and professional skills, create life-long connections, engage and inform the public, and inspire today's nuclear technology professionals to meet the challenges of the 21st century.
A large hydrogen explosion occurred in the Unit 3 reactor building at 1101 on March 14.
Hydrogen generated from the damaged fuel in the reactors accumulated in the reactor buildings - either during venting operations or from other leaks - and ignited, producing explosions in the Unit 1 and Unit 3 reactor buildings and significantly complicating the response. [color=Cyan]The hydrogen generated in Unit 3 may have migrated into the Unit 4 reactor building, resulting in a subsequent explosion and damage.
[color=Chartreuse]The loss of primary and secondary containment integrity resulted in ground-level releases of radioactive material.
Following the explosion in Unit 4 and the abnormal indications on Unit 2 on the fourth day of the event, the site superintendent directed that all nonessential personnel temporarily evacuate, leaving approximately 70 people on site to manage the event.
Unit 4 (shut down at 2:48pm on March 11th)
- Reactor is shut down and reactor water level is stable.
- Offsite power is available.
[color=Chartreuse]- At 0:43pm, Mar 13th, there was a signal indicating that one of the
control rods may have not properly inserted. However, we confirmed that
it was inserted completely by another signal. We will inspect the reason
- Status of main steam isolation valve: closed
- We do not believe there is leakage of reactor coolant in the
On March 15, however, a hydrogen explosion occurred in the Unit 4 reactor building.
This was unexpected, as workers did not believe there was enough decay heat in the pool to result in overheating and the subsequent high-temperature interaction of zirconium and water to produce hydrogen gas. After the explosion, however, some people suspected that the spent fuel was overheating, and they became concerned about subsequent hydrogen explosions caused by the fuel in the spent fuel pools on other units.
Some resources may have been diverted from attempts to stabilize the reactors, as extensive actions such as helicopter water drops and the use of water cannons were taken in an attempt to refill the pools.
Subsequent analysis and inspections performed by TEPCO personnel determined that the [color=FDD017]spent fuel pool water levels did not drop below the top of fuel in any spent fuel pool and that no significant fuel damage had occurred.
Current investigation results indicate that [color=FDD017]any potential fuel damage was likely caused by debris from the reactor building explosions.
Unit 4 was shut down and had been in an outage since November 30, 2010. [color=Cyan]All the fuel was in the spent fuel pool to facilitate reactor pressure vessel shroud work. The cavity gate was installed, isolating the spent fuel pool from the upper pools...
Federal regulators said Friday that an inspection at Progress Energy's Brunswick Nuclear Plant found fuel oil tank rooms serving emergency diesel generators weren't protected from possible flooding during hurricanes.
The violation – of "low to moderate safety significance" – has been corrected by the utility, the Nuclear Regulatory Commission said, and Progress did not contest the finding.
Along with correcting the issues noted by the NRC, Brunswick spokesman Ryan Mosier said Progress is continuing to work to make the nuclear plant more robust in relation to protection against potential flooding events. That includes looking at the plant's design, equipment, training and emergency procedures in the case of severe flooding.
RADIATION WATCH 2011
Inspection work has revealed tiny cracks on a penetration at the bottom of Gravelines 1's reactor pressure vessel. The power unit remains shut down until a repair has been made...
The tiny cracks were discovered within the pressure vessel in the area of welded alloy around the tube at Gravelines 1. The Nuclear Safety Authority (ASN) said it was the first time such a defect has been found in France, although [color=FDD017]similar faults were dealt with in 2003 at the South Texas Project site in the USA. EDF owns and operates Gravelines 1 along with France's 57 other power reactors...
EDF has been requested by the ASN to check all its 900 MWe and 1300 MWe reactors for similar cracks - a total of 54 units.
On April 12, 2003 with one of the two units at South Texas Project nuclear power station near Bay City, Texas shut down for routine refueling, an inspection of the bottom of a major safety component, the reactor pressure vessel, found cracking in two bottom-mounted instrumentation penetration nozzles.
The unanticipated cracking was discovered after small crystalline deposits of leaking reactor coolant were visually discovered around the penetration nozzles.
[color=Chartreuse]The “first-of-a-kind” cracking at South Texas is another in a series of mounting surprises that plague an aging nuclear power industry and its federal regulator.
In fact, the cracking in a relatively young South Texas reactor may indicate that the industry and its regulator are falling behind an event-driven curve of unanticipated and significant safety problems that are emerging faster than can be recognized and effectively managed.
Circumferential cracking around top-mounted control rod penetration nozzles was discovered just two years earlier at the Oconee-2 and -3 nuclear power stations in South Carolina.
Just last year, operators at Ohio’s Davis-Besse nuclear power station found extensive corrosion through the top of the reactor pressure vessel. [color=Cyan]Highly corrosive borated coolant leaking through cracked control rod drive penetration nozzles had eaten a football-size cavity through 6.75 inches of carbon steel in a previously un-inspected area of the vessel head, leaving only the thin corrosive-resistant stainless steel inner liner, a mere 3/16th of an inch thick.
The stressed liner had bulged out into the cavity due to the tremendous internal pressure. [color=Cyan]Analysis concluded that the vessel would likely have ruptured within 12 months of continued reactor operation.
Extremely tight and even microscopic through-wall cracks are of significant concern where a component can break before any telltale leakage is noticed, throwing the reactor into a cascade of failures and a catastrophic accident.
... The cracked nozzle segments were cut out and replaced with what is thought to be a more crack resistant Alloy 690.
[color=FDD017]The actual cause and rate of growth of the cracking and leakage largely remains a mystery to the industry and the NRC.
Unit 4 was shut down and had been in an outage since November 30, 2010. All the fuel was in the spent fuel pool to facilitate reactor pressure vessel shroud work. The cavity gate was installed, isolating the spent fuel pool from the upper pools...
What say you?
Originally posted by Aircooled
Almost a third of commissioners and examiners at Japan's nuclear safety commission received donations from the country's nuclear power industry, the Asahi Shimbun reported Sunday.
The influential daily said the governmental commission's neutrality could be brought into question at a time when the safety of nuclear reactors in Japan was in doubt after a March 11 earthquake and tsunami disaster.
The quake-tsunami disaster has left more than 19,000 people dead or missing and a nuclear power plant in meltdown, which has been since leaking radiation into the environment.
Two of the organisation's five permanent commissioners and 22 of its 84 outside examiners received donations from companies and industrial organisations related to nuclear power, in five years to March 2011, Asahi said.
The donations totaled about 85 million yen (1.1 million dollars), the daily said.
Of them, 11 received donations from nuclear reactor manufacturers and, or, power utilities and nuclear fuel companies which are examined by the commission, Asahi said.
The commission is authorised to guide the state and power utilities from a neutral position.
Haruki Madarame, chairman of the commissioners, received four million yen from Mitsubishi Heavy Industries between 2006 and 2009 when he was a professor at the University of Tokyo before assuming the commission's post last April, Asahi said.
Madarame denied he had given any favours to the company at all in return for the donations.
TOKYO -(Dow Jones)- Some members of the Japanese government's neutral panel on nuclear safety issues received a total of about Y85 million in donations from nuclear power-related companies, the Asahi Shimbun reported Sunday.
Of the 89 who were full-time and part-time members of the Nuclear Safety Commission at the time of the Fukushima Daiichi nuclear accident in March, 24 received the donations over a five-year period through March 2011, the report said.
The donations the members received were from nuclear reactor manufacturers as well as companies that the panel monitors, such as utility firms and nuclear fuel firms, the report said.
Separately, the Mainichi Shimbun reported Sunday that a deputy director at Japan's industry ministry, when he was the head of the section in charge of nuclear power policy in 2004, ordered his subordinates to hide some data showing estimated costs of spent nuclear fuel disposal.
If the data, which indicated that reprocessing spent fuel was more expensive than simply disposing of such fuel, had become public at the time, it could have affected the debate at the time over the country's plans to operate a nuclear fuel reprocessing plant in northern Japan, the Mainichi report said.
-By Juro Osawa, Dow Jones Newswires
(END) Dow Jones Newswires
Originally posted by Aircooled
Good morning gang. The New year is here. Hopefully this will bring on the year where we wipe out the nuke gang