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Regulations are loosened, and reactors are back in compliance."That's what they say for everything ...," said Demetrios Basdekas, a retired NRC engineer. "Every time you turn around, they say, 'We have all this built-in conservatism.' "The crisis at the decades-old Fukushima Dai-ichi nuclear facility in Japan has focused attention on nuclear safety and prompted the NRC to look at U.S. reactors. A report is due in July.But the factor of aging goes far beyond issues posed by Fukushima.

Commercial nuclear reactors in the United States were designed and licensed for 40 years. When the first were built in the 1960s and 1970s, it was expected that they would be replaced with improved models long before their licenses expired.That never happened. The 1979 accident at Three Mile Island, massive cost overruns, crushing debt and high interest rates halted new construction in the 1980s.Instead, 66 of the 104 operating units have been relicensed for 20 more years. Renewal applications are under review for 16 other reactors.As of today, 82 reactors are more than 25 years old.The AP found proof that aging reactors have been allowed to run less safely to prolong operations.

Last year, the NRC weakened the safety margin for acceptable radiation damage to reactor vessels -- for a second time. The standard is based on a reactor vessel's "reference temperature," which predicts when it will become dangerously brittle and vulnerable to failure. Through the years, many plants have violated or come close to violating the standard.As a result, the minimum standard was relaxed first by raising the reference temperature 50 percent, and then 78 percent above the original -- even though a broken vessel could spill radioactive contents."We've seen the pattern," said nuclear safety scientist Dana Powers, who works for Sandia National Laboratories and also sits on an NRC advisory committee. "They're ... trying to get more and more out of these plants."

Sharpening the pencilThe AP study collected and analyzed government and industry documents -- some never-before released -- of both reactor types: pressurized water units that keep radioactivity confined to the reactor building and the less common boiling water types like those at Fukushima, which send radioactive water away from the reactor to drive electricity-generating turbines.The Energy Northwest Columbia Generating Station north of Richland is a boiling water design that's a newer generation than the Fukushima plants.Tens of thousands of pages of studies, test results, inspection reports and policy statements filed during four decades were reviewed. Interviews were conducted with scores of managers, regulators, engineers, scientists, whistleblowers, activists and residents living near the reactors at 65 sites, mostly in the East and Midwest.

AP reporters toured some of the oldest reactors -- Oyster Creek, N.J., near the Atlantic coast 50 miles east of Philadelphia and two at Indian Point, 25 miles north of New York City on the Hudson River.Called "Oyster Creak" by some critics, this boiling water reactor began running in 1969 and is the country's oldest operating commercial nuclear power plant. Its license was extended in 2009 until 2029, though utility officials announced in December they will shut the reactor 10 years earlier rather than build state-ordered cooling towers. Applications to extend the lives of pressurized water units 2 and 3 at Indian Point, each more than 36 years old, are under NRC review.Unprompted, several nuclear engineers and former regulators used nearly identical terminology to describe how industry and government research has frequently justified loosening safety standards. They call it "sharpening the pencil" or "pencil engineering" -- fudging calculations and assumptions to keep aging plants in compliance.

Cracked tubing: The industry has long known of cracking in steel alloy tubing used in the steam generators of pressurized water reactors. Ruptures have been common in these tubes containing radioactive coolant; in 1993 alone, there were seven. As many as 18 reactors still run on old generators.Problems can arise even in a newer metal alloy, according to a report of a 2008 industry-government workshop.

Neil Wilmshurst, director of plant technology for the industry's Electric Power Research Institute, acknowledged the industry and NRC often collaborate on research that supports rule changes. But he maintained there's "no kind of misplaced alliance ... to get the right answer."Yet agency staff, plant operators and consultants paint a different picture:* The AP reviewed 226 preliminary notifications -- alerts on emerging safety problems -- NRC has issued since 2005. Wear and tear in the form of clogged lines, cracked parts, leaky seals, rust and other deterioration contributed to at least 26 of the alerts. Other notifications lack detail, but aging was a probable factor in 113 more, or 62 percent in all. For example, the 39-year-old Palisades reactor in Michigan shut Jan. 22 when an electrical cable failed, a fuse blew and a valve stuck shut, expelling steam with low levels of radioactive tritium into the outside air. And a 1-inch crack in a valve weld aborted a restart in February at the LaSalle site west of Chicago.

* A 2008 NRC report blamed 70 percent of potentially serious safety problems on "degraded conditions" such as cracked nozzles, loose paint, electrical problems or offline cooling components.* Confronted with worn parts, the industry has repeatedly requested -- and regulators often have allowed -- inspections and repairs to be delayed for months until scheduled refueling outages. Again and again, problems worsened before being fixed. Postponed inspections inside a steam generator at Indian Point allowed tubing to burst, leading to a radioactive release in 2000. Two years later, cracking grew so bad in nozzles on the reactor vessel at the Davis-Besse plant near Toledo, Ohio, that it came within two months of a possible breach, an NRC report said, which could release radiation. Yet inspections failed to catch the same problem on the replacement vessel head until more nozzles were found to be cracked last year.

Time crumbles thingsNuclear plants are fundamentally no more immune to aging than our cars or homes: Metals grow weak and rusty, concrete crumbles, paint peels, crud accumulates. Big components like 17-story-tall concrete containment buildings or 800-ton reactor vessels are all but impossible to replace. Smaller parts and systems can be swapped but still pose risks as a result of weak maintenance and lax regulation or hard-to-predict failures.Even mundane deterioration can carry harsh consequences.For example, peeling paint and debris can be swept toward pumps that circulate cooling water in a reactor accident. A properly functioning containment building is needed to create air pressure that helps clear those pumps. But a containment building could fail in a severe accident. Yet the NRC has allowed safety calculations that assume the buildings will hold.

In a 2009 letter, Mario V. Bonaca, then-chairman of the NRC's Advisory Committee on Reactor Safeguards, warned that this approach represents "a decrease in the safety margin" and makes a fuel-melting accident more likely.Many photos in NRC archives -- some released in response to AP requests under the federal Freedom of Information Act -- show rust accumulated in a thick crust or paint peeling in long sheets on untended equipment.Four areas stand out:

Brittle vessels: For years, operators have rearranged fuel rods to limit gradual radiation damage to the steel vessels protecting the core and keep them strong enough to meet safety standards.But even with last year's weakening of the safety margins, engineers and metal scientists say some plants may be forced to close over these concerns before their licenses run out -- unless, of course, new regulatory compromises are made.

Leaky valves: Operators have repeatedly violated leakage standards for valves designed to bottle up radioactive steam in an earthquake or other accident at boiling water reactors.Many plants have found they could not adhere to the general standard allowing main steam isolation valves to leak at a rate of no more than 11.5 cubic feet per hour. In 1999, the NRC decided to allow individual plants to seek amendments of up to 200 cubic feet per hour for all four steam valves combined.But plants have violated even those higher limits. For example, in 2007, Hatch Unit 2, in Baxley, Ga., reported combined leakage of 574 cubic feet per hour.

"Many utilities are doing that sort of thing," said engineer Richard T. Lahey Jr., who used to design nuclear safety systems for General Electric Co., which makes boiling water reactors. "I think we need nuclear power, but we can't compromise on safety. I think the vulnerability is on these older plants."Added Paul Blanch, an engineer who left the industry over safety issues, but later returned to work on solving them: "It's a philosophical position that (federal regulators) take that's driven by the industry and by the economics: What do we need to do to let those plants continue to operate?"Publicly, industry and government say that aging is well under control. "I see an effort on the part of this agency to always make sure that we're doing the right things for safety. I'm not sure that I see a pattern of staff simply doing things because there's an interest to reduce requirements -- that's certainly not the case," NRC chairman Gregory Jaczko said in an interview.

Corroded piping: Nuclear operators have failed to stop an epidemic of leaks in pipes and other underground equipment in damp settings. Nuclear sites have suffered more than 400 accidental radioactive leaks, the activist Union of Concerned Scientists reported in September.Plant operators have been drilling monitoring wells and patching buried piping and other equipment for several years to control an escalating outbreak.But there have been failures. Between 2000 and 2009, the annual number of leaks from underground piping shot up fivefold, according to an internal industry document.

I think that is true. But those are the locations that have been measured. I think there are many more.Mr. Kinoshita's blog has this bit of "rumor" from his worker at the plant:

As I have said before, I have never seen, or heard about, such steam.It's possible that he doesn't know but someone else may know. 2. About locations that exceed 10 sieverts/hr: In Mr. Kinoshita's blog:

The same worker] also told [his contact] that there are 6 locations that exceed 10,000 millisievert/hr [10 sieverts/hr], unlike what TEPCO has announced. Fukushima worker's tweet:

There are several cracks on the ground near the Containment Vessel, and the steam is coming out from them, not on a regular basis but sporadically. Wait, does that mean the floor of the reactor building is cracked? He doesn't say which reactor. And Fukushima worker has another tweet that says:

In the reactor buildings of Reactors 1, 2 and 3, there are many spots that measure even higher [than 10 sieverts/hr] and we can't go near them.So much for the plant being stable. But so far, the information is unsubstantiated (i.e. not admitted, or denied, by officials at TEPCO or the government). Speaking of the government, it will allow the residents in Okuma-machi and Futaba-machi, where the plant is located, to temporarily return to their homes later this month now that the plant is stable.

Now it is known that radioactive material, the melted core, is moving under the ground away from where it the measuring was being done according to Dr. Jacobs. He said that the reactors were not safe for earthquakes and there is evidence that Reactor #1 was melting down when the tsunami hit, putting reliability in question. 

There are continual aftershocks at the level of a 6.0, so when you have a fragile structure and what we have now, the radioactive core has melted down into the basement, into the bottom of the containment vessel. 

Russia Today reporting that new evidence suggests Fukushima's nuclear reactors were doomed to cripple even before the massive wave reached them adds weight to the unreliability of nuclear energy according to Dr. Jacobs. Canadians receiving extreme radiation in Tuesday rainout

The metal covers are in the Spent Fuel Pool, and the cracks were found at the welded parts.

The [cracks and discoloration] are all minor, and there is no effect on the environment, according to the operator.

I think what Yomiuri is talking about ("metal covers") is a channel box that houses fuel assemblies. For Onagawa Nuke Plant's channel boxes, apparently damaged by the March 11, 2011 earthquake, read my post from July this year.

"There are about 110,00 tons of contaminated water (in the plant) and the situation is still not completely under control because coolant water is leaking from the containment vessels. There is no guarantee that the irradiated water won't leak from the plant (and contaminate the environment)" if another natural disaster strikes, said Hisashi Ninokata, a professor of reactor engineering at the Tokyo Institute of Technology.

After achieving cold shutdowns of reactors 1, 2 and 3, the government may declare parts of the 20-km no-go zone around the plant safe. It may even let the evacuees return, as long as the area is decontaminated and crucial infrastructure restored.

But the longer the tainted water leaks, the more the radioactive waste will grow, leaving the Fukushima plant vulnerable to further disasters, Ninokata said. Before the Fukushima crisis can be said contained, the holes and cracks from which the water and fuel are escaping must be located and sealed. But this extremely difficult task could take years because the radiation near the reactors is simply too high to let workers get near them.

"It'll be too early to say that the situation has reached a stable phase even after Step 2 is completed," said Chihiro Kamisawa, a researcher at Citizens' Nuclear Information Center, a nonprofit group of scientists and activists opposed to nuclear power. When a reactor is in cold shutdown, the water cooling its fuel is still hot but no longer boiling, which significantly reduces the amount of radioactive emissions.

In late July, the temperature in reactor No. 1's pressure vessel fell below 100 degrees. On Monday, the same thing was achieved in reactor 3 after Tepco activated a system that pumps water deep into the containment vessel. But on Friday, reactor No. 2 was still boiling away with a reading of 112.6. "Efforts seem to be making smooth progress, and I think Step 2 is likely to be achieved by mid-January," said Shinichi Morooka, a Waseda University professor and reactor expert.

Another reason for optimism is the progress being made with the water decontamination system. The cleaning rate has greatly improved in the past few weeks and exceeded 90 percent of capacity last week. If the decontamination system ever reaches its full potential, it will allow Tepco to inject coolant at a higher rate and bring the melted cores to lower and stabler temperatures.

The government also plans to start decontaminating soil in various hot spots so the evacuees can return once the second step is completed. But some experts are questioning whether residents should be allowed to return so soon. The cracks and holes in the leaking reactors haven't even been pinpointed yet, let alone fixed, they say.

"As an engineer, I am worried (about the plan to let residents return) when it is still unclear what is really going on inside the reactors," said Morooka. For the time being, Tepco can only guess where the water is leaking from and which parts need repair, because radiation has prevented workers from fully exploring the buildings.

Spokesman Junichi Matsumoto said that since no extensive damage to the reactors was found during inspections of the first and second floors of the buildings, any holes or cracks are probably at the basement level. But with the basement floors flooded, Tepco's top priority is just to get the water out. Plans to fix the reactors aren't even being discussed yet, Matsumoto said.

Asked if the containment vessels can take another quake, the Tokyo Institute of Technology's Ninokata said he believes the impact would likely be distributed evenly through the structure without widening existing cracks or holes. But if the impact somehow focuses on parts damaged by the March 11 disasters, there could be further damage, he said. "The containment vessel is what really ensures the safety of a nuclear reactor," Ninokata said, warning that if radioactive materials are still leaking out, allowing residents to return would risk harming their health.

The first day we heard about the possibility of open criticality at Fukushima, a week or so after the Earthquake in March- I was shocked. It didn’t even register that this was possible. Now, it’s a regular occurrence to see it openly on these videos. (again – look for the gamma artifacts on the video – little white flashes that appear randomly on the screen) Five months ago everyone in the nuclear industry would have said what this video depicts is impossible and should be avoided at all human costs – and yet here we see it. 

Most of them are still unwilling to admit that it’s happening, yet it has. The jig is up, the noose is out….

f you need a definition of ‘criticality’ here it is (from BBC) This means the fuel rods are exposed to the air. Without water, they will get much hotter, allowing radioactive material to escape.

More remarkably, the Tokyo Electric Power Company (Tepco), which owns the power station, has warned: “The possibility of re-criticality is not zero“. If you are in any doubt as to what this means, it is that in the company’s view, it is possible that enough fissile uranium is present in the cooling pond in enough density to form a critical mass – meaning that a nuclear fission chain reaction could start.

The pool lies outside the containment chamber.  So if it happened, it would lead to the enhanced and sustained release of radioactive materials – though not to a nuclear explosion – with nothing to stop the radioactive particles escaping.  http://www.bbc.co.uk/news/science-environment-12762608

Looks like they have that now – F.C.

With the cancellation of the Yucca Mountain nuclear waste repository in Nevada, many nuclear operators are loading older fuel into sealed metal casks filled with inert gas. The Massachusetts Institute of Technology will get a grant to study how such “dry casks” perform in salt environments.

The money will go to a variety of projects at 31 universities in 20 states. Several focus on nuclear waste.

Another important concern in the nuclear power field is the aging of reactors. Researchers at Pennsylvania State University will get $456,000 to plan a system that will use ultrasonic waves to look for cracks and other defects in hot metal parts. The idea is to find “microscale” defects that lead to big cracks.

Some of the work is aimed at helping to improve new reactors. For example, a researcher at the University of Houston, with collaborators at two other universities, will study a “base isolation system” that would protect reactors against earthquakes.

In an earthquake, the ground moves back and forth at a certain frequency, similar to the way a gong struck by a mallet vibrates at a given frequency. But plants could be built atop materials with “frequency band gaps,” that do not vibrate at the frequency that is characteristic of earthquakes, the Energy Department suggests.