ML20058N796
| ML20058N796 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 08/09/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20058N793 | List: |
| References | |
| NUDOCS 9008150104 | |
| Download: ML20058N796 (4) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION i
RELIEF REQUEST NO. 89 0j l
i ASME CODE TEST REQUIREMENT FOR THE NUCLEAR SERVICE WATER SYSTEM DUKE POWER COMPANY l
MCGUIRE NUCLEAR STATION UNIT 1 i
DOCKET NO. 50-369
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1.
INTRODUCTION 10CFR50.55a(g)requiresexaminationsandtestsofnuclearpowerfacility piping and components to be performed in accordance with the requirements of the applicable ASME Section XI Code edition and addenda.
If it is impractical to meet the requirements; the licensee of the facility is required to notify the Commission and submit information in support of the determination that a requirement is impractical to perform.
By letter dated February 13, 1989, Duke Power Cosipany (the licensee),
submitted Relief Request 89-01 which requested relief from Section XI of the ASME Boiler and Pressure Vessel Code requirement for hydrostatic.
testing of welds RN1FW24-1, RN1FW57-1 and flange connections associated withNuclearStationModification(NSM)MG-12130Rev0,intheNuclear Service Water System (Rh) at the McGuire Nuclear Station Unit 1.
NSM MG-12130 involved the installation of new flanges and expansion joints on the suction piping to RN pumus IA and 18. The old expansion' joints were welded into place and were stowing signs of corrosion. To correct the problems associated with the expansion joints and to facilitate future removal and repair, stainless steel expansion joints and flanges were installed.
The replacement of the expansion joints was also due to a recent failure of the Unit 1 Train B expansion joint that failed due to corrosion and fatigue.
The function of the expansion joints is to reduce loacing on the RN pump suction casing.
II.
REQUESTS, REQUIREMENTS, SUPPORTING INFORMATION, EVALUATION, AND CONCLUSIONS RELIEF REQUEST (RR) NUMBER 89 RELIEF FROM ASME CODE SECTION XI l
REQUIREMENTS 1.
COMPONENT IDENTIFICATION System:
NuclearServiceWater(RN) i Component Descriptior.;
Class 3 Piping and Flanges y$SI 104 900809 lOCK05000369 p
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ASME CODE SECTION XI FIRST INTERVAL INSPECTION REQUIREMENTS i
ASME Boiler and Pressure Vessel Section XI, 1980 Edition through Winter 1980 Addenda, Article IWA-4400 and Article IWD-5000. The i
Code, Article IWA-4400, requires after r9 pairs on the pressure retaining. boundary, a system hydrostatic test to be performed in accordance with IWA-5000. Article IWA.5000 refers to Table IWA-2510-1 i
which refers to Article IWA-5212. Article IWA-5212 requires that system leakage tests and system hytYostatic tests be conducted at the test conditions of pressure and temperature specified in IWB-5000, IWC-5000, and IWD-5000. Article IWD-5000, " System Pressure Tests,"
requires that the system hydrostatic test pressure be (1) at least 1.10 times Psv for systems with design temperature of 200 degrees F or less or (2) at least 1.25 times Psv for systems with design temperature above 200 degrees F.
As used in Article IWD-5000, Psv is the system pressure corresponding to the' lowest pressure setting among the number of safety or relief valves provided for overpressure protection within the boundary of the system to be tested.
3.
RELIEF REQUESTED Relief is requested from hydrostatic testing after repairs by welding on the pressure retaining boundary in accordance with IWA-4000 and IWD-5000.
4.
BASIS FOR RELIEF The RN system is a low pressure, low temperature raw water system.
The piping at the suction side of the RN pumps which includes the new expansion joints has a design pressure of'35 PSIG and a design l
temperature of 95 degrees F.
The required hydrostatic test pressure for an ASME Class C system is 110% of the design pressure or 38.5 PSIG in this case.
Also, the hydrostatic test boundary isolation valves include a 36 inch butterfly valve and an 18 inch butterfly valve on each train. These valves do not offer adequate isolation to accomplish a hydrostatic l
test using conventional hydro equipment.
Another concern and possibly the most important is the potential for overpressurizing and damaging the bellows assembly on the expansion joints while conducting a hydrostatic test. The expansion joints have a design pressure of 35 PSIG.
For this low pressure section of piping,thealternatenondestructiveexamination(NDE)specifiedin Section 5, below, is an adequate method of detecting weld and flange defects with no risk of overpressurizing the bellows assembly.
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5.
LICENSEE'S PROPOSED ALTERhATIVE EXAMINATION i
All welding was-subjected to a magnetic particle examination on the.
I root pass and the final weld pass. An inservice leak test at system pressure and temperature was performed on all welds and flanges, j
6.
PLANT QUALITY & SAFETY magnetic particle examination-(ye penetrant examination'(PT) or The ASME Code requires only a d MT) on the finished weld surface for l
pipes with nominal sizes greater than 4 inches. The alternate NDE specified an additional MT on the root pass weld which did not i
detect any defects in the root weld. The inservice leak test as i
described above was performed and did not reveal any weld defects
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or defects in the flange connections.
7.
RADIATION CONSIDERATIONS i
i None 8.
STAFF EVALUATION AND CONCLUSIONS The Code requirement to hydrostatically test the repaired section of piping in the raw water system is impractical because of the system design. The valves that could be used to isolate the repaired section of piping are of the butterfly design, a design that is an inherently poor performer as an isolation valve.
In addition, i
pressurizing the system to the required Code' pressure could be counterproductive due to the possibility of causing damage to the bellows _ assembly. The staff has determined that the alternative tests proposed by the licensee provide adequate assurance of the structural integrity of the reptred section of piping, and corp 11ance with the specific ASME requirement would result in hardship.
Pursuant to 10 CFR 50.55a(g)(6)(1), we conclude that relief from the ASME Boiler and Pressure Vessel Code requirement may be granted as requested by the licensee.
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l Mr. H. B. Tucker August 9, 1990 I
Accordingly, relief from the hydrostatic test requirements is granted for McGuire Unit 1 as requested, pursuant to 10 CFR
- 50. 55a (g) (6) (i).
This relief is authorized by law and will not endanger life or property or the common defense and security and is otherwise in the public interest given due consideration to the burden upon the licensee that could result if the require-ments were imposed on the facility.
Sincerely, David B. Matthews, Director Project Directorate II-3 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
Enclosure:
As stated i
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See next page DISTRIBUTION sDocketfilecUl D. Hood NRC/ Local PDRs OGC POII-3 Reading File E. Jordan MNBB 3701 T. Murley/F. Miraglia 12/G/18 G. Hill P1 37 J. Partlow 12/G/18 ACRS (10)
C. Rossi 11/E/4 GPA/PA S. Yarga 14/E/4 0C/LFMB G. Lainas 14/H/3 McGuire Plant File R. Ingram l
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