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DB liner thinner than first thought - and cracking







"Dr. Bill Corcoran at NSRC" wrote:



> __________________________________________________________________________________________________________________ Nuclear

> plant's liner thinner than first thought

>

> The Associated Press

> 9/11/02 3:17 AM

>

> OAK HARBOR, Ohio (AP) -- The stainless-steel liner under the lid of

> the now-closed Davis-Besse nuclear reactor was thinner than officials

> originally believed and had begun to crack in several places, a

> laboratory analysis shows.

>

> The strength of the liner was critical because when corrosion created

> a large hole in the reactor's lid, the liner became the only barrier

> between the reactor's high-pressure coolant and the building that

> houses the reactor, The (Cleveland) Plain Dealer reported Wednesday.

>

> The liner was supposedly three-eighths of an inch thick. But testing

> determined that the liner was significantly thinner in places -- in

> one location nearly 50 percent thinner -- than plant owner FirstEnergy

> Corp. believed.

>

> Officials of Davis-Besse and the Nuclear Regulatory Commission don't

> know how or when the cracks formed, or even how deep they go, and said

> Tuesday that they are still reviewing the findings.

>

> But the presence of cracks raise questions about whether the barrier

> was as strong as FirstEnergy Corp. has said and how much longer it

> would have been able to withstand the reactor's operating pressures.

>

> The answers to those questions will affect the outcome of NRC and

> Davis-Besse studies to determine how close the Toledo-area plant came

> to a major nuclear accident. That finding, in turn, will dictate what

> penalties and continuing scrutiny FirstEnergy faces from the NRC.

>

> "We want to know more, obviously," said William Beecher, an NRC

> spokesman.

>

> "It's important to know what happened . . . every detail," agreed

> FirstEnergy spokesman Todd Schneider.

>

> Davis-Besse officials learned of the cracks Monday night, Schneider

> said.

>

> The reactor has been idle since February, when the plant shut down so

> workers could inspect for cracks in the 69 nozzles that penetrate its

> massive steel lid. Nozzle cracking has been a recognized issue

> industrywide for years in older reactors. The cracks were thought to

> be relatively benign, but the NRC became alarmed when more extensive,

> possibly dangerous cracks were found at a South Carolina reactor in

> 2001.

>

> At Davis-Besse, workers found not only serious cracking, but also the

> 6-by-8-inch hole formed by the reactor's corrosive coolant leaking

> from the cracks and pooling undetected on the lid for years.

>

> FirstEnergy has used the liner's strength as part of its argument to

> the NRC that Davis-Besse wasn't close to an accident, and thus it

> doesn't deserve a harsh punishment. Although the company will have to

> revise its safety calculations based on the new crack findings, its

> argument still holds, Schneider said.

>

> "We have to remember that the liner held normal operating pressure and

> that the plant shut down safely," he said.

>

>           Copyright 2002 cleveland.com. All Rights Reserved.

>

>

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>

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"Dr. Bill Corcoran at NSRC" wrote:



> Colleague, Please be so kind as to scroll down for today's update. I

> have been getting off-line messages from some of you and will be

> getting to them AWLP. Thanks for your patience. Best Regards, Bill

> Corcoran W. R. Corcoran, Ph.D., P.E.

> Nuclear Safety Review Concepts

> 21 Broadleaf Circle

> Windsor, CT 06095-1634

> 860-285-8779 Fax: 702-993-2408

> Mission: Saving lives, pain, assets, and careers through thoughtful

> inquiry. Check out our e-groups  at

> http://groups.yahoo.com/group/Root_Cause_State_of_the_Practice/

> where you will find all back issues of "The Firebird Forum" and at

> http://groups.yahoo.com/group/DBRVH_LTBL/

> where you will find a dialogue on the Davis-Besse near miss LOCA.,

> including photos, polls, files, tables, and links. For a complimentary

> subscription to our e-newsletter on root cause, organizational

> learning, and safety send a message to firebird.one@alum.MIT.edu

> Visit our web site at

> http://pages.prodigy.net/corcoran.nsrc/index.html

> ___________________________________________________________________________________________________________________

> Nuclear plant's liner thinner than first thought

>

> The Associated Press

> 9/11/02 3:17 AM

>

> OAK HARBOR, Ohio (AP) -- The stainless-steel liner under the lid of

> the now-closed Davis-Besse nuclear reactor was thinner than officials

> originally believed and had begun to crack in several places, a

> laboratory analysis shows.

>

> The strength of the liner was critical because when corrosion created

> a large hole in the reactor's lid, the liner became the only barrier

> between the reactor's high-pressure coolant and the building that

> houses the reactor, The (Cleveland) Plain Dealer reported Wednesday.

>

> The liner was supposedly three-eighths of an inch thick. But testing

> determined that the liner was significantly thinner in places -- in

> one location nearly 50 percent thinner -- than plant owner FirstEnergy

> Corp. believed.

>

> Officials of Davis-Besse and the Nuclear Regulatory Commission don't

> know how or when the cracks formed, or even how deep they go, and said

> Tuesday that they are still reviewing the findings.

>

> But the presence of cracks raise questions about whether the barrier

> was as strong as FirstEnergy Corp. has said and how much longer it

> would have been able to withstand the reactor's operating pressures.

>

> The answers to those questions will affect the outcome of NRC and

> Davis-Besse studies to determine how close the Toledo-area plant came

> to a major nuclear accident. That finding, in turn, will dictate what

> penalties and continuing scrutiny FirstEnergy faces from the NRC.

>

> "We want to know more, obviously," said William Beecher, an NRC

> spokesman.

>

> "It's important to know what happened . . . every detail," agreed

> FirstEnergy spokesman Todd Schneider.

>

> Davis-Besse officials learned of the cracks Monday night, Schneider

> said.

>

> The reactor has been idle since February, when the plant shut down so

> workers could inspect for cracks in the 69 nozzles that penetrate its

> massive steel lid. Nozzle cracking has been a recognized issue

> industrywide for years in older reactors. The cracks were thought to

> be relatively benign, but the NRC became alarmed when more extensive,

> possibly dangerous cracks were found at a South Carolina reactor in

> 2001.

>

> At Davis-Besse, workers found not only serious cracking, but also the

> 6-by-8-inch hole formed by the reactor's corrosive coolant leaking

> from the cracks and pooling undetected on the lid for years.

>

> FirstEnergy has used the liner's strength as part of its argument to

> the NRC that Davis-Besse wasn't close to an accident, and thus it

> doesn't deserve a harsh punishment. Although the company will have to

> revise its safety calculations based on the new crack findings, its

> argument still holds, Schneider said.

>

> "We have to remember that the liner held normal operating pressure and

> that the plant shut down safely," he said.

>

>           Copyright 2002 cleveland.com. All Rights Reserved.

>

>

>                    Yahoo! Groups Sponsor

                        ADVERTISEMENT





>

> To unsubscribe from this group, send an email to:

> DBRVH_LTBL-unsubscribe@yahoogroups.com

>

>

>

> Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.



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