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Critical Nuclear Reactor Bolts Fail at Indian Point 2

A special inspection of the Indian Point 2 nuclear reactor found that more than a quarter of the stainless steel bolts needed to channel cooling water through active nuclear fuel rods were broken, distorted or “missing”, a finding that calls into question the effectiveness of the long term management of this and other aging power plants.

The inspection, which began March 7, concerned the 832 “baffle-former assembly bolts” which hold special metal plates around the 100-tons of uranium fuel within the reactor and channel cooling water to the bottom of the reactor and then up through center of the bundled 12-foot fuel rods to keep them from overheating. Entergy, which owns the twin Indian Point plants, stated in a March 29 report to the three judge panel of the Atomic Safety and Licensing Board (http://1.usa.gov/1Y1oqVO ) that 227 of the baffle-former bolts were degraded, broken, or “missing.” That is an extraordinarily high failure rate of 27.2%.

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In its public statement, Entergy sought to minimize the problem by stating they inspected some 2000 bolts and 11% of these were degraded. But their legal filing was more specific. It was only the 832 bolts holding the baffles that had the greatest exposure and suffered the most damage. All 227 of the deteriorated bolts were in this category. Entergy spokesmen at Indian Point and at their corporate office declined to discuss the issue.

The fact that entire bolts or parts of them could not be initially located is considered a serious safety threat. That was the cause of the partial meltdown of the Fermi power reactor outside Detroit in August, 1966. In that case, bits of metal blocked the flow of coolant through two bundles of active fuel rods, and they overheated and melted.

Because of that risk Entergy, after discussions with officials at the Nuclear Regulatory Commission, is considering whether or not to shut Indian Point 3 and conduct a similar inspection now, rather than wait until a scheduled refueling outage in 2017. That would be a difficult fiscal pill for Entergy to swallow. The twin plants currently provide only 5% of the electricity used in New York City and neighboring Westchester County, primarily through its 560 megawatt contract with ConEd, the regional transm爱上海同城论坛

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ission company. The New York Power Authority, which provides power to the subways, airports, and municipal buildings, dropped Indian Point two years ago because there are cheaper alternatives.

NRC spokesman Neil Sheehan said “Entergy will have to assess the implications for Indian Point Unit 3. There is no ETA at this point.”

For its part, the NRC is weighing whether or not other plants should be required to conduct similar special inspections of their reactor linings and, if so, how soon. It is not clear at this point how many other plants might have the same type of condition. But, said Sheehan, “we always look for possible generic implications and will do so in this case.”

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David Lochbaum, nuclear safety specialist with the Union of Concerned Scientists, said “the NRC is struggling with the question ‘Do we shut down Indian Point 3 and see if there is a problem, or龙凤

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do we look further?’ If it were just those two reactors it would be an easier decision.

“But if they shut down Unit 3 based on probable cause, then why not shut down the other plants that may have this issue? This problem has surfaced before at D. C Cook in Michigan and R.E. Ginna in upstate New York. Why assume those are the only ones?”

Critics of Indian Point urged the NRC to force Entergy to inspect both reactors. “Since IP3 is virtually identical in design as IP2,” said Gary Shaw of the Indian Point Safe Energy Coalition, “IP3 should be shut down immediately to examine the integrity of the reactor core liner. Aging management is a predicate of relicensing and the last year of problems and near misses has already shown that the plant should not be relicensed and decommissioning should be initiated as soon as possible.”

Forced by NY Attorney General

The special inspection that discovered the disintegration of the bolts was undertaken by Entergy to put an end to a series of challenges by the Environmental Unit of New York Attorney General Eric Schneiderman’s office dating to November, 2007. The Environmental Unit has filed more than 35 “contentions,” or legal challenges before the three-judge Atomic Safety and Licensing Board, the judicial arm of the NRC. Their decisions can be appealed to the full NRC board, whose commissioners can uphold, modify, or reverse their conclusions.

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Three of the New York challenges involve “embrittlement” of key components within the reactor, including the bolts holding the baffles. These serve a critical function in a pressurized system where temperatures approach 900 degrees Fahrenheit and it is difficult to even out the temperature fluctuations within the huge reactor core. Each of the fuel bundles has a temperature gauge at the end called a thermocouple, so the reactor operators can track the temperature o variations within the reactor. The danger of a breakdown of the zirconium cladding around the uranium fuel does not begin until the temperatures hit around 1,800 degrees Fahrenheit, so there is a lot of room for variation before temperatures hit a dangerous level.

At Fermi, operators saw the temperatures climb inside two of the fuel bundles, but assumed they were getting readings from faulty thermocouples since the other bundles were fine. But a metal plate which had fallen to the bottom of the reactor because of degraded bolts was blocking the flow of coolant through the inside of the two fuel bundles, and these heated up past the melting point.

The Environmental Unit asserted that Entergy’s ageing management program was inadequate and did not take into account the embrittlement of metal as a result of years of intense bombardment by high levels of radiation within the reactor.

In fact, the State’s attorneys found six cases – including Fermi, Cook, and plants in France that were younger than Indian Point – where metal pieces had become brittle, broken off, and blocked critical valves, control rods, or cooling water flow within the reactor. Despite those experiences, inspection of the baffle-former bolts is not required by the NRC and was not originally part of Entergy’s long-term maintenance plan, according to their court filings.

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“Entergy voluntarily agreed to have this inspection,” said Lochbaum. “Without the State of New York, that would not have happened. When you look at the reasons that the State wanted them to do the inspections, it is not a surprise that when Entergy did the inspection they found the problem that the State was warning about.

“It had happened many, many times before. Since our reactors are older than the French reactors where this problem showed up, it seemed just a matter of time before it happened here.”
Attorney General Schneiderman said in a statement yesterday that “For years, my office has raised serious concerns about the aging of components of the Indian Point nuclear plants, including “baffle-former assembly” bolts…Our concerns have been repeatedly dismissed by Entergy and the NRC.

“After finally conducting inspections that my office had long called for, Entergy revealed that at Indian Point Unit 2, over one-quarter of these bolts were found either missing or degraded to a point they must be replaced. This significant finding – coupled with the spate of other recent problems revealed at Indian Point – underscores real and present safety issues related to continuing to operate this aging nuclear facility in close proximity to more than 17 million people.”

Continue reading at Energy Matters.

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