ML102940102

E-Mail from Tsao to Manoly, Fea of Degraded Salem Unit 1 AFW Piping

ML102940102
Person / Time
Site:	Salem
Issue date:	04/26/2010
From:	John Tsao Office of Nuclear Reactor Regulation
To:	Kamal Manoly Office of Nuclear Reactor Regulation
References
FOIA/PA-2010-0334
Download: ML102940102 (4)

Text

Caponiti, Kathleen From: TsaoJohn Sent: Monday, Apnl 26, 2010 4:15 PM To: Manoly, Kamal Cc: Lupold, Timothy; OHara, Timothy

Subject:

- FW: FEA of Degraded .Salem Unit IAFW Piping 7 v Attachments: 1000494_301_RC-doc, Salem tiurned pipe flaw analysis RI 4-23-10 Doc;*docx; Salem buried pipe SIA, pdf; Salem unit,1F~ure p Evaluation draft.pdf~

Importance: High

Kamal, Tim O'Hara of Region I forwarded me the FEA. report.for the Salem buried AFW piping. Tim Lupold asked me to forward the FEA:report to you (see the firstattached file). Attachment No. 2 is my assessment of the FEA report.that I sent to Tim O'Hara this morning. Attachments No. 3 and 4 are the.preliminary information for the FEA. report.

Thanks.

John

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Original Message----, 7 \

From: OHara, Timothy ! )

Sent:. Friday, April 23, 20!0 2:23 PM To: Tsao, John Cc: Lupold, Timothy; Conte, Richard; Gray, Harold; Burritt, Arthur; Schroeder, Daniel; Balian, Harry; Cline, Leonard; Sande'rCarleen; Ennis, Rick.

Subject- FEA of.Degraded Salem Unit 1 AFW Piping Importance: High Hello John, Here is the FEA we've been discussing. Note that PSEG is still reviewing but they have provided this copy which will most likely not change. Please review this and let us know what you-think. Thanks.

Tim OHara

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Original Message----

From: Beriick,' Howard G. [mailto: Howard. Berrick@psegcom]

Sent: Friday, April 23, 2010 2:11 PM To: Schroeder, Daniel L.; OHara, Timothy

Subject:

Evaluation of Degraded Underground Auxiliary Feedwater Piping (SIA Report 1000494_301_RC)

Importance: High Attached ids the SIA ReportRE: Evaluation ofDegraded Underground Auxiliary Feedwater Piping Please note: This report has not been through.the, PSEG Owners Acceptance or Third Party Review process.

Howard-Berrick.. Inffmnatbo inthis record wevs deleted in PSEG Nuclear LLC aocordancewM tho Frm of Wr mAO 6 __ 1

Salem Regulatory Assurance PSEG Nuclear - Salem Generating Stations (W) 856-339-1862 (B) pb)( )-56-339-1448 (Fax)

(B~pr)Cj§_ý

<<1000494_301_RC.doc>>

The information contained in this e-mail, includiang,,any attachment(s), is intended solely for use by the named addressee(s). If you are not the intended recipient, or a person designated as responsible for delivering such messages to the 'intended recipient; you are not authorized to disclose, copy, distribute or retain this message, in whole:.ot in part, without written authorization from, PSEG. This e-mail may contain proprietary, confidential or privileged information. If you have received this message in error, please notify the sender immediately. This notice is included in all e-mail messages leaving PSEG. Thank you for your cooperation.

.2

An Assessment of '"ASME Code, Section I11,Design by Analysis Evaluation of a 4-inch Auxiliary Feedwater Piping" for SalemGenerating Station, Unit 1.

Background

The licensee identified localized wall thinning in severa! regions of the buried auxiliary feedwater (AFW) piping at Salem Generating Station, Unit 1, based on the guided wave technology. The licensee excavated the affected piping regions and.*found significant external corrosion. Subsequently the licensee'inspected the affected:piping segments using straight beam ultrasonic testingto determine the pipe Wall thickness. Several measurementlocations showed pipe wall thicknesses less than the design minimum wall thickness. The licensee performed stress calculations to demonstrate that the degraded AFW piping still meets allowable stresses of the ASME B31.1 Code of Construction and that the piping was operable during past operation..

Discussion Under ASME Section XI, a planar or laminar flaw.is dispositioned by the acceptance standards of IWB-3515. If:thelflaw is within the acceptancestandards of IWB-3515, the flaw can be left in service. If the flaw exceeds IWB-3514, theflawmay beaccepted by analysis of IWB13600 followed by 3 successive examinations. A pipe that contains a flaw that exceeds IWB-3600 will need to be repaired or replaced.

The ASME Code,Section XI, is stringent in that it minimizes flaws from growing uncontrollably to rupture. A pin hole leak that is caused by wall thinning, in general, does not lead to pipe rupture [I believe that a pipelrupture is defined as when the leak rate from a crack is so large that the pump cannot provide sufficient makeup to achieve the intended function of the pipe]. Salem's AFE pipe degradation mechanism, is wall thinning.

The ASME Code, Section Xl, does not have requirements for analyzing wall thinning. condition ex.cept in Code Case N-513-2. However, N-513-2 is not applicable to high energy line such as AFW line.

Code Case N-561-2, Alterhative Requirements for Wall Thickness Restoration of Class 2 and High Energy Class 3 Carbon Steel Piping, provides guidance for high energy Class 3 piping. However, the NRC has not approved N-561 in Regulatory Guide 1.147, Revision 15.

Therefore, the licensee used the rules of-the ASME Section III to satisfy 10 CFR 50,55a. Under the ASME Code,,Section Ill, the same pipe would not need to be repaired as long as the pipe satisfies the allowable stresses of NB-3200 or NB-3600. The.AFWipiping is ASME Class 3 pipe and should follow the rule of ND-3000 for piping design. However, the licensee selected the rules of Class' piping, (i.e., NB-3200 and/or SNB-3600) because rules in NB-3000 provide more detailed analysis procedures and allowables.

The licensee analyzed: five pipe segments, 12AF, 14AF, 14AK, AF13T, AF4T/AFST. The resultant stresses are shown on Pages 11 to 13 and page. 16 of the report. As shown on those pages, each of the pipe segments has certain locations that exceed the allowable stresses. However, when the licensee linearized the stresses in all the nodes in the model and calculatedza single stress, the linearized stress for each of the pipes is within the allowable as.shown in Table 1 (page 8). In other words, even though localized stress:at certain node in each of the pipes exceeds the allowable stress,. the overall (global):

stress of each of the pipe*are within the allowable.

The licensee did not use the as-found pipe wall thickness (the thinnest wall thickness) for the entire pipe in. calculating thestresses* .For example, the licensee did not use 0.077 inch to calculate the stress for

the'entire:pipe segment. Instead, the licensee used the as-found wall thickness (0U077 inch) to calculate the local stresses atthe node (location) where.the wall thinningwas found. For other nodal points of the pipe,0the licensee used the nominal'thickhess oor as-found pipe thickness-at those nodes which may notb6e degradedl. IAlthoughsorne pipe locations have severe wall thinning degradation, thelicensee was able to demonstrate that the structural integrity:ofthe pipe as a whole is acceptable.

Conclusion The staff finds that the degraded AFW piping satisfies the requirements of ASME Code,Section III, N8-321331i0,. N-322112, and NB-3228.1. However, the,staff concludes that the subject AFW piping is operable but degraded.

Recommendations

1. Page 4, last paragraph. The licensee stated that the worst wall thickness is 0.077 inch. Confirm that the minimum allowable pipe wall thickness is 0.190 inch as shown on page 5, second paragraph.

2. The stress analysis needs:to include detailed pipe wall tthickness measurements in all 5 subject AFW pipesso that thereviewer can understand the extent of the wall thinning..