RC-97-0041, Submits Request for Relief to Provide Alternative to Current Commitments W/Regard to Leaks to Bolted Connections Re Section XI of ASME Code

Submits Request for Relief to Provide Alternative to Current Commitments W/Regard to Leaks to Bolted Connections Re Section XI of ASME Code

ML20135C792
Person / Time
Site:	Summer
Issue date:	02/25/1997
From:	Gabe Taylor SOUTH CAROLINA ELECTRIC & GAS CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
RC-97-0041, RC-97-41, NUDOCS 9703040297
Download: ML20135C792 (7)

Text

South Carolina Electri: & Gas Company Gary J. Taylor

. P.O. Box 88 Vca President

. Jenkinsville. SC 29065 Nuclear operations ]

(803) 345-4344 SCE&G l escamian m l

February 25,1997 I RC-97-0041 Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555 l Gentlemen:

Subject:

VIRGIL C. SUMMER NUCLEAR STATION (VCSNS)

DOCKET NO.50/395 OPERATING LICENSE NO. NPF-12 BOLTED CONNECTIONS CORRECTIVE ACTIONS RELIEF REQUEST {

(NRR 970001) l South Carolina Electric and Gas Company (SCE&G) hereby submits the attached request for relief (Attachment I) to provide an alternative to our current commitments associated with Section XI of the ASME Code. The relief request pertains to the corrective actions prescribed by paragraph IWA-5250. These actions direct the disposition ofleaks found during the performance  ;

of a System Pressure Test and gives specific instructions with regard to leaks at bolted connections. However, the ASME Code has now recognized the impracticability of the requirements for bolted connections and has approved Code Case N-566 as an alternative. This alternative provides a more practical approach for leaks at bolted connections while maintaining the assurrance of structuralintegrity provided by the Code. Also, the code case is very sinular to relief requests that twe been previously approved by the NRC for applicatic2 at individual utilities, such as the Zion Station. Therefore, SCE&G is requesting approval of Code Case N-566 as an option for its Section XI programs.

SCE&G is currently committed to comply with the 1989 Edition of ASME Code, Section XI except where deviatior.s are either prescribed or allo.ved in accordance with 10CFR50.55a. IWA-5250(a)(2) of Section XI requires that any leakage detected at a bolted connection shall have the bolting removed and VT-3 visually exanuned for corrosion in accordance with IWA-3100. Some of the problems associated wiih this requirement are summarized as follows:

1. IWA-3100 does not provide an acceptance standard for a VT-3 bolt inspection.

2. The requirement calls for bolt removal without regard to the size of the leakage.

, 3. The requirement increases the radiological dose to workers for leaks that are often not a challenge to operational or structural limits.

4. Bolts sometimes cannot be removed without damaging the bolt or cannot be removed due to component configuration.

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5. It is not a requirement of the Code that the Owner must stop the leakage and l

inspection of the bolting is not necessarily going to stop leakage.

6. Removing one bolt at a time, if allowed by system conditions, may actually increase theleakage.

7. In many cases, implementation of the requirement would cause an unnecessary plant transient or delay startup.

I .

In addition to the problems associated with the requirements ofIWA-5250(a)(2), a Special Task

- Group of the 'ASME Committee has concluded that the Code does allow the acceptance of

[ leakage by the analytical evaluation methods of IWB-3142.4, and that the actions required by.

IWA-5250 should not preclude this acceptance. Also, the Working Group - Pressure Testing

. concluded that the system integrity of a bolted connection is not necessarily compromised by I leakage and recommended the approval of Code Case N-566.

Code Case N-566 resolves the implementation problems associated with IWA-5250(a)(2) and ,

maintains the conclusions of the ASME Committee by allowing two alternatives as corrective actions for leaks at bolted connections. Either of these two actions is sufficient to assure l structural integrity is maintained, which is the safety function of the Code, and eliminates the operational and radiological hardships of the current requirements. This conclusion is further supported by the background paper used in the ASME approval process (Attachment II).

h Due to the fact that Code Case N-566 has not yet been incorporated into Regulatory Guide l 1.147, " Inservice Inspection Code Case Acceptability, ASME Section XI,- Division -1", the attached relief request will be used in VCSNS program procedures to document the approval and use of the code case. The relief request provides component identification, current code

-requirements, alternate requirements and basis for the relief request. -

Based on the discussion above, the details included with the attached relief request, and the fact that the ASME has approved Code Case N-566 for use, it is SCE&G's pos%n that we have shown adequate evidence that Code Case N 566 provides en acceptable level of quality and safety l as required in 10CFR50.55a (a)(3)(i). Therefore, SCE&G has met all the requirements of

- 10CPR50.55a necessary to allow the approval of Code Case N-566 as an alternate means of  :

compliance with Section XI of the ASME Code. j Due to the date of our up coming outage, October 4,1997, and the desire to incorporate this I l relief request into the associated programs in time to provide site training, SCE&G requests the l review and approval of this relief request be completed by July 1,1997.

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Document Control Desk RC-97-0041 NRR 970001 Page 3 of 3 Should you have any questions, please call Mr. David Haile at (803) 345-4322.

Very Truly Yours, G Ji r DCH/JT/GJT/nkk Attachments (2) c: J.L. Skolds NRC ResidentInspector W.F. Conway J.B. Knotts, Jr.

R.R. Mahan (w/o attachments) NSRC R.J. White RTS (NRR 970001)

L.A. Reyes File (810.19-2)

A.R. Johnson DMS (RC-97-0041)

GeneralManagem

4 Attachment I to Document Control Dok Letter RC-97-0041 NRR 970001 Page 1 of 2 Request for Relief from IWA-5250(a)(2) Corrective Actions for Bolted Connections '

Subject:

This relief request provides alternate corrective actions that may be used in lieu of the corrective actions associated with leakage at bolted connections as prescribed by IWA-5250.

Components:

Any Class 1,2, or 3 bolted connection that has leakage identified in the course of an IWA-5000 pressure test.

Current Code Requirement:

Subparagraph IWA-5250 (a)(2) requires that the source of leakages detected during the conduct l of a system pressure test shall be located and evaluated by the Owner for corrective measures. If leakage occurs at a bolted connection, the bolting shall be removed, VT-3 visually examined for corrosion, and evaluated in accordance with IWA-3100.

Alternative Requirements j

Implement the requirements of Code Case N-566.  !

Basis for Relief:

Some of the problems associated with the current requirements of IWA-5250 (a)(2) are  !

summarized as follows:  ;

1. IWA-3100 does not provide an acceptance standard for a VT-3 bolt inspection.

2. The requirement calls for bolt removal without regard to the size of the leakage.

3. The requirement increases the radiological dose to workers for leaks that are often not a challenge to operational nor structural limits.

4. Bolts sometimes cannot be removed without damaging the bolt or cannot be removed due to the component configuration.

o .

l Attachment I to Document Control Desk Letter RC-97-0041

! NRR 970001 l Page 2 of 2

5. It is not a requirement of the Code that the Owner must stop the leakage and inspection of the bolting is not necessarily going to stop the leak. l

6. Removing one bolt at a time, if allowed by system conditions, may actually increase the leakage.

7. In many cases, implementation of the requirement would cause the plant an unnecessary transient or delay startup.

In addition to the problems associated with the requirements ofIWA-5250 (a)(2), a Special Task Group of the ASME Committee has concluded that the Code does allow the acceptance of leakage by the analytical evaluatica methods ofIWB3142.4, and that the actions required by IWA-5250 should not preclude this acceptance. Also, the Working Group-Pressure Testing l concluded that the system integrity of a bolted connection is not necessarily compromised by  !

j leakage and recommended the approval of Code Case N-566.

1 Code Case N-566 resolves the implementation problems associated with IWA-5250 (a)(2) and

~

l maintains the above conclusions of the ASME Committee by allowing two alternatives as corrective actions for leaks at bolted. connections. One option is to stop the leak and review the joint for integrity This review will consist of cleaning the joint after the leakage is stopped and

! documenting an inspection of the joint for corrosion or other signs of degradation. The second l option is that, if the leakage is not stopped, the joint must be evaluated in accordance with IWB-3142.4 of Section XI. This is an engineering evaluation that must consider the number and condition of bolts, the leaking medium, the bolt and component material, the system function, and the ability to monitorleakage.

l Summary:

! l

! Either of these actions are sufficient to assure structuralintegrity is mamtained, which is the safety function of the Code, and clinunates the operational, maintenance, and radiological hardships of the current requirements. This conclusion is further supported by the fact that the ASME has approved Code Case N-566.

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J Attaclun:nt II to Document Control Desk Letter 4

RC-97-XXXX CASE i NRR 970001 Page 1 of 2 N-566 '

l Approval Date: Augwt S.1996  ;

See NumericalIndex for supiration l

"' d and any rest!irman*cn dates.

l Case N 566 l

, Correcdve Action for W Identi5ed at Bohad Connecbons Secdon XI, Division 1 j l

5 l laguiry: What alternative to the requuc:nents of 'l

IWQ 5250(a)(2) may be usai when leakage is dere-~f I

i at bolted connecdons?

a Reply: It is the opinion of the Commier* that, as an alt.. native to the ig=wts of IWA-5250(a)(2),

' one of the following requiwets shall be met for l leakage at bolted ennndons

(a)'Ibe leakage shall be stopped, and the bolting and co:nponent matenal sha!I be reviewed for joint integ:ity.

(b) If the leakage is not stopped, the joint shall be evaluated in accordan e with IWB-3142.4 for joint integrity.This evaluation shallin:1ude connderation of the nurnber and condition of bolts, leaking medium, bolt and component marMal, system fun:non, and 1

leakage monitoring.

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~ Attachm nt H to Document Central Desk letter i

' RC-97-XXXX l

NiiR 970001 SGWCS 92-08 Page 2 of 2 l MAY 5,1995 l l

BACKGROUND FOR CODE CASE l

CORRECTIVE MEASURES FOR LEAKAGE IDENTIFIED AT BOLTED J

. CONNECTIONS I

\

The purpose of this code case is to give Owners an alternative to retcuving bolts from bolted connections for a VT-3 visual examination when leakage is identified. There  !

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'have been many inquiries and relief requests submitted for this code requirement. This i

code requirement has caused many hardships to the utilities without a return of safety. )

r The following are current problems with this code requirement:

IWA-5250(a) (2) directs the Owner to perform a VT-3 of the removed bolt and to evaluate in accordance with IWA-3100. IWA-3100 does not contain acceptance '

standards for VT-3 of bolting.

l The Code does not require the Owner to stop the leakage. Therefore, after pulling and examining the bolt, the leakage may continue.

i Removing one bolt at a time, the leakage may be even worse than originally found, i The Code does not address the integrity of the joint.  !

Bolts are damaged while being removed. 1 The Owner is required to remove the botting even if the leakage is minor, can be monitored, or if there is no corrosion concern. This often impacts startup and thus causes hardship and increases radiation exposure without a retum of safety.

The Special Task Group on Leakage has addressed thru-wall and mechanical joint leakage to recent code meetings. They have concluded that structuralintegrity does not imply _ leak tightness. This task group has concluded that the Code does allow acceptance of thru-wall leakage by analytical evaluation of IWB-3142.4. It is the opinion of Working Group Pressure Testing that the same opportunity to use engineering judgment and evaluation should also apply to leakage from mechanical connections.

The purpose of pres:ure testing is to verify piping, component, and system integrity. It is the opinion of the committee that leakage. does not necessarily compromise the integrity of the bolted connection. It is the consensus of Working Group Pressure Testing that the code requirement of IL .-5250 (a) (2) to remove bolting is not always necessary and therefore, propose the following code case.

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