ML20115G677
| ML20115G677 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 10/23/1992 |
| From: | Skolds J SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9210260295 | |
| Download: ML20115G677 (3) | |
Text
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October 23, 1992 Document Control Desk U. S. NJclear Regulatory Commission Washington, DC 20555 Gentlemen:
Subject:
VIRGIL C. SUMMER NUCLEAR STATION DOCKET NO. 50/395 OPERATING LICENSE NO. NPF-12 CLASS 3 PIPE REPAIR REllEF REQUEST (NRR 920003)
South Carolina Electric & Gas Company (SCE&G) hereby submits the attached request for relief from performing an ASME Code Class 3 pipe repair. Virgil C. Summer Nuclear Station (VCSNS) intends to leave the flaw as is and will perform a code replacement of thE piping at the next scheduled outage exceeding 30 days, or the next scheduled refueling outage (Refuel 7).
This request is based on an evaluation of the code repair which resulted in a determination that the required time to complete the repair would be in excess of the time allowance of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> under the action statement for the Limiting Condition for Operation (LCO-3.5.2). The pipe is a 3/4 inch pressure test connection on a 20 inch Service Water line. To replace this section of pipe re:;uires a large portion of the "A" train of the Service Water System be drained. The repair would require shutdown of the "A" train Service Water System, resulting in inoperability of "A" train ECCS equipment.
VCSNS considers shutdown of the plant unwarranted due to the insignificance of the leak.
lhe defect it believed to be caused by microbiologically induced corrosion (MIC). The defect is located in the heat affected Zone of the weld connecting the 3/4 inch pipe to a fitting that is connected to the 20 inch Service Water line.
It is presently leaking approximately one drop every five minutes. An assessment of the flaw cannot be made using nondestructive methods due to the location of the defect. An evaluation was performed based on a catastrophic failure of the pipe.
It was determined that the Service Water System has available flow margin, no components or equipment would be affected by spraying water, the pipe is not an anti-falldown concern, and flooding is not a concern.
VCSNS will evaluate the leak at least once per week until the plant reaches Mode 5 or the leak is fixed. This evaluation will be documented and placed into the plant records.
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Document Control Desk NRR 920003 Page 2 of 2 This code relief was discussed with Geoffrey P. Hornseth of the NRC on October 15, 1992. SCE&G is submitting the attached relief request in accordance with 10CFR50.55a(a)(3)(i) and Generic Letter 90-05.
Should you have any questlons. please call at your convenience.
Very truly yours, han, 'T T! 'n fo r T /..C,k'c M s John L. Skolds UKW: led Attachment c:
- 0. W. Dixon R. R. Mahon R. J. White S. D. Ebneter G. F. Wunder General Managers NRC Resident inspector J. B. Knotts Jr.
File (810.19-2)
NUCLEAR EXCELLENCE - A SUMMER TRADITION!
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- Attachment to Document Control Desk tetter l
HRR 920003 Page,1 of 1 1
ASME Code Class 3 Pipe Repair Relief Request Components: 3/4" Service Water Pipe Class:
3 Iunction:
This is a 3/4" pressure test connection pipe (DF-SW-05-01) on 20' Service Water (SW) Supply line to the "A" Component Cooling Heat Exchanger. The ambient conditions of the pipe are 65 psig and 70T (95"F, Design Max.).
Code Requirement:
ASME Boller and Pressure Vessel Code,Section XI, 1977 edition, Summer 1978 Addenda, IWD-4000 requires the following:
" Defects shall be removed in accordance with IWD-4200.
If the cavity created by removal of this defect excaeds the acceptatte standards of IWA-3000 and repair by welding is necessary, tFe repair welds shall be made in accordante with IWA-4000 and this Article.
If repair welding is impractical, the defect may be removed cr reduced in size without welding, provided the requirements of IWA-3000 are met."
Alternate Requirement:
VCSNS intends to leave the flaw as is and will perform a code replacement of the piping at the next scheduled outage exceeding 30 days, or the next scheduled refuel 4ng outage (refuel 7). Until that time, VCSNS-will evaluate the leak at least once per week until the plant reaches Mode 5.
This ew19ation will be documented and placed into the plant records.
Basis for Relief:
1)
An evaluation of the code repair resulted in a determination that the-
- cquired time to complete the repair would be in excess of the time allowance of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> under the action statement for the Limiting Condition for Operation (LCO-3.5.2).
This section of pipe requires a large portion of the "A" train Service Water System to be drained for replacement which results in the inoperability of "A" train ECCS.
equipment.
2)
The following is an evaluation based on catastrophic failure of tne pipe:
a)
The minimum design SW flow during post accident conditions is 14,074 gpm. The design capacity of the SW pumps is 16,800 gpm leaving a margin of 2,726 gpm. A catastrophic failure of the pipe will produce approximately 185 gpm which is within'the available l
system margin.
b)
There are no essential to safe shutdown components or equipment t
I within the immediate area which would be affected by spraying f
- water, c)
The pipe is not an anti-falldown concern because it is approximately 4 feet above the floor and would fall to the floor without impacting any essential to. safe shutdown equipment.
d)
The Intermediate Building can flood to a level of 12 inches which provides an allowable voiume of 270,000 gallons. A leak of approximately 180 gpm would-take.24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to reach 12 inches, which would. provide. sufficient time to take compensatory action.
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