ML20248M007

Forwards Request to Use Alternative to ASME Boiler & Pressure Vessel Code Section XI at Plant Re Actions to Be Taken in Event That Leakage Is Detected at Bolted Connection by Visual VT-2 Leakage Exam

ML20248M007
Person / Time
Site:	Crane
Issue date:	06/03/1998
From:	Langenbach J GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
1920-98-20293, NUDOCS 9806120224
Download: ML20248M007 (4)

Text

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GPU Nuclear,Inc.

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Route 441 South NUCLEAR P* *' D c ' B** ***

Middletown, PA 17057 0480 1920-98-20293 m m.s44 7e21 June 3, 1998 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

Subject:

Three Mile Island Nuclear Station, Unit 1 (TMI-1)

Operating License No. DPR-50 Docket No. 50-289 Insenice Inspection - Request for Alternative to ASME Boiler & Pressure Vessel Code Section XI Requirements Regarding Corrective Actions for Leakage at Bolted Connections Attached is the GPU Nuclear request to use an alternative to the ASME Boiler & Pressure Vessel Code Section XI (Attachment 1) at TMI-l related to actions to be taken in the event that leakage is detected at a bolted connection by visur.1 VT-2 leakage examination. This request is identical to the Duke Energy Corporation request, Serial Number 97-GO-001, Rev. I for Oconee, McGuire, and Catawba Nuclear Stations dated August 7,1997. That request was approved by the NRC in a Safety Evaluation dated October 15,1997.

TMI-l is currently scheduled to begin the Cycle 13 Refueling (13R) Outage in September 1999.

. Although certain VT-2 leakage examinations must be performed during a refneling outage, approximately half can be performed throughout the operating cycle. Therefo e GPU Nuclear requests that NRC approval be granted by September 1998 or as soon as practical. Use of this alternative could potentially help avoid an unnecessary plant shutdown or delay in plant restart following a shutdown.

Sincerely, h-w L

e 9806120224 980603 PDR ADOCK 05000289 James W. Lang( ba

[DR, a Vice President and Director, TMI

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Attachment r

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cc: Administrator, NRC Region I TM1 Senior NRC Resident Inspector TMI Senior NRC Project Manager File 98095 w__

's 1920-98-20293 i

j Page1of3 GPU Nuclear Request For Alternative From ASME Boiler And Pressure Vessel Code Section XI Requirements

Background

' Pursuant to 10 CFR 50.55a(a)(3)(i), GPU Nuclear requests the use of an alternative to the 1989 Edition with 1990 Addenda of Section XI of the ASME Boiler and Pressure Vessel Code (Code)

. for TMI-I related to actions to be taken in the event that leakage is detected at a bolted connection by visual VT-2 leakage examination. This request is identical to the Duke Energy Corporation request, Serial Number 97-GO-001, Rev. I for Oconee, McGuire, and Catawba Nuclear Stations dated August 7,1997. That request was approved by the NRC in a Safety Evaluation dated October 15,1997 TMI-l is committed to the 1986 Edition of the Section XI Code to satisfy the Inservice Inspection requirements of 10CFR50.55a(g). The 1986 Edition of Section XI, (no addenda),

paragraph IWA-5250(a)(2) states "ifleakage occurs at a bolted connection, the bolting shall be i

removed, VT-3 visually examined for corrosion, and evaluated in accordance with IWA-3100."

GPU Nuclear previously requested and was granted NRC approval to use the 1989 Code with 1990' Addenda as an alternative in a Safety Evaluation Report (SER) dated October 8,1992. The 1990 Addenda allows that only the one bolt closest to the leak be removed and visually examined

- for corrosion by a VT-3 inspector.

I.

System / Components for which Alternative is Required:

All Class 1,2, and 3 systems / components subject to IWA-5000 pressure testing.

11.

_C_otde Requirements:

Section XI of the ASME Code,1989 Edition with 1990 Addenda, Subsection IWA-5250(a)(2) states: "Ifleakage occurs at a bolted connection, one of the bolts shall be removed, VT-3 examined, and evaluated in accordance with IWA-3100. The bolt selected shall be the one closest to the source ofleakage. When the removed bolt has evidence of degradation, all remaining bolting in the connection shall be removed, VT-3 examined, and evaluated in accordance with IWA-3100."

Ill.

Requirement for Which Altemative Is Reauested:

Reliefis requested from the mandatory requirement to remove the bolt closest to the source ofleakage when leakage is detected at a mechanical connection.

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,1920-98-20293 Page 2 of 3 IV.

Basis for Requesting Alternative:

Removal of pressure retaining bolting at mechanical connections for visual (VT-3) examination and subsequent evaluation, in locations where leakage has been identified, is not always the most discerning course of action to determine the acceptability of the bolting. The Code requirement to remove, examine, and evaluate bolting in this situation does not allow the owner to consider other factors which may indicate the acceptability of mechanicaljoint bolting.

3 Other factors which should be considered when evaluating bolting acceptability when leakage has been identified at a mechanicaljoint include, but are not limited to: joint bolting material, service age ofjoint bolting materials, location of the leakage, history of leakage at thejoint, evidence of corrosion with thejoint assembled, and corrosiveness of the process fluid.

Performance of the pressure test while the system is in service may identify leakage at a bolted connection that, upon evaluation, may conclude the integrity and pressure retaining ability of thejoint is not challenged. It would not be prudent to negatively impact the availability of a safety system by removing the system from service to address a leak that does not challenge the system's ability to perform its safety function.

A situation frequently encountered at GPU Nuclear is the complete replacement of bolting materials (studs, bolts, nuts, washers, etc.) at mechanicaljoints during plant outages.

When the associated system piping is pressurized during plant startup, leakage may be identified at thosejoints. The root cause of this leakage is most often due to thermal expansion of the piping and bolting materials at thejoint and subsequent fluid seepage at thejoint gasket. Proper re-torquing of the joint bolting, in most cases, stops the leakage.

Removal of thejoint bolting to evaluate for corrosion would be unwarranted in this situation due to the new condition of the bolting materials.

V.

Alternative Examination:

When leakage is identified at bolted connections by visual VT-2 examination during system pressure testing, an evaluation will be performed to determine the susceptibility of the bolting to corrosion and assess the potential for failure. The evaluation will at a minimum, consider the following factors:

1. Bolting materials

2. Corrosiveness of process fluid leaking

3. Leakagelocation

4. Leakage history at connection or other system components

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5. Visual evidence of cstrosion at connection (while connection is assembled)

6. Service age of bolting materials

" When the pressure test is performed on a system that is in service or that Technical I

' Specifications require to be operable, and the bolting is susceptible to corrosion, the evaluation shall address the connection's structural integrity until the next component / system outage of sufficient duration. If the evaluation concludes the system J

parl perform its safety related function, removal of the bolt closest to the source of the leakage and a Visual, VT-3' examination of the bolt will be performed when the system or -

. component is taken out of service for a sufficient duration (to accomplish other system maintenance activities).

For bolting that is susceptible to corrosion, and when the initial evaluation indicates that the connection cannot conclusively perform its safety function until the next component / system outage of sufficient duration, the bolt closest to the source of the leakage will be removed, and a Visual, VT-3 examination will be evaluated in accordance

.with IWA-3100(a).

. VI.

Justification for Granting Ahernative:

The purpose of the Code required corrective action to remove bolts and visually examine

. them for degradation, as stated in IWA-5250(a)(2), is to ensurejoint integrity, in addition i

to removing bolts and performing a Visual VT-3 examination,Section V above states alternative methods to ensurejoint integrity of bolted connections. These alternative.

i methods have been determined to provide an acceptable level of quality and safety.

' VII.

Implementation Schedult TM1-1 is currently scheduled to begin the 13R Outage in September 1999. Although certain VT-2 leakage examinations must be performed during a refueling outage, approximately half can be performed throughout the operating cycle. Therefore GPU l:

Nuclear requests that NRC approval be granted by September 1998 or as soon as practical. Use of this alternative could potentially help avoid an unnecessary plant shutdown or delay in plant restart following a shutdown.

e l The acceptance criteria for Visual, VT-1 will be used to assess the acceptability of the bolting.