ML20059B919
| ML20059B919 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 08/21/1990 |
| From: | Cross J PORTLAND GENERAL ELECTRIC CO. |
| To: | Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| REF-PT21-90 NUDOCS 9008300173 | |
| Download: ML20059B919 (4) | |
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'M NGenerd BedricW James E. Cross Vice President, Nuclear August 21, 1990 Trojan Nuclear P.lant Docket 50-344 License NPF-1 Mr. John B. Martin Regional Administrator, Region V U.S. Nuclear Regulatory Consission 1450 Maria 1.ane, Suite 210 Walnut Creek CA 94596-5368 l
Dear Sir:
l:
TROJAN NUCt. EAR PLANT Title 10 of the Code of Federal Regulations, i
Part 21 (10 CFR 21). SA-194 Grade 6 Check Valve Bonnet Nuts The attached report is submitted in accordance with 10 CFR 21.
Defects were found in the bonnet nuts for two Residual Heat Removal check valves.
The valves were supplied to Westinghouse by Copes-Vulcan and the nuts were manufactured by Sandusky Nut and Machine Company. The valves were supplied I
to Portland General Electric Company by Westinghouse as part of the Nuclear l
Steam Supply System contract.
Sincerely,
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U.S. Nuclear Regulatory Commission Atkn:- Document Control Desk Washington DC 20555 Mr. David Stewart-Smith State of Oregon Department of Energy Mr. R. C. Bare NRC Resident Inspector Trojan Nuclear Plant 9008300173 900821 PDR
/> DOCK 05 00344 S
PDC 121 SW Salmon St. Portland, OR 97204 503/4G4 8897 7
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, Trojan Buclear Plant Mr. John B. Martin Docket 50-344 August 21, 1990-License NPF-1 Attachment Page 1 of 3 TITLE 10 0F THE CODE OF FEDERAL REGULATIONS. PART 21 (10 CFR 21) DEFECT REPORT Portland Genera?. Electric Company (PGE)
Report No.:
90-01, Final Report 121 S.W. Salmon Street Report Date: August 21, 1990 Portland, OR 97204 Responsible Officer Mr. J. E. Cross, Vice President, Nuclear Date Responsible Officer Received Information August 21, 1990-Basic Comooyent or Activity Item: Check Valve Bonnet Nuts Type: One inch, Type 410 Stainless Steel, S UNC American Society of Mechanical Engineers (ASME) SA-194, Grade 6.*
Identification: Sandusky Lot E**
Purchase Order: 546-CCP-157431-BN
- NOTE: The code data reports for thesa nuts indicated that the material was'SA-193, Grado B6.
However, PGE's review of codes prior to the time of manufacture leads us do believe that these nuts should have been characterized as ASME SA-194, Craie 6.
- NOTE:
The nuts were identified with an
'S' inside a hexagon.. This symbol is used by Sandusky and also by Seaway Bolt and Specials Corporation.
Based on procurement documentation, the nuts appear to be from Sandusky.
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Trojan Nuclear Plant Mr. John B. Martin Docket 50-344 August 21, 1990 License NPF-1 Attachment Page 2 of 3 Fire Supolvina Basic Component Nut Sandusky Nut and Hachine Company 615 West Market Street Sandusky, OH 44871 Valve:
Copes-Vulcan Incorporated Martin and Rice Avenue Lake City, PA 16423 Nuclear Steam Sepply System (NSSS):
Westir.shouse Electric Corporation Nucle AP Energy System Pittr, burg, PA 15236 Descristion of Defect and Substantial Safety Hazard That Could Be Caused on March 16, 1990 during a routine maintenance inspection one nut on the A-train Residsal. Heat Removal (RHR) pump discharge _ check valve bonnet was found cracked. A visual examination revealed no defects-in the other 15 bonnet nuts. Hieroscopic examination of the defective nut revealed that the failure was caused by intergranular stress corresion cracking. Testing determined that the hardness value was excessive (40 HRC compared to an allowable of 28 HRC) which is a primary cause for stress corrosion cracking.
It is believed that this excessive hardness was due to improper heat treatment-during the manufacturing process.
In a follow up evaluation, it was determined that one other valve (the B-train RHR pump discharge.' heck valve) contained nuts from the identical vendor and lot number as the original defective nut. A visual examination of this valve revealed one broken and three cracked bonnet nuts. A random sampling of other nuts from the same vendor, but different lot numbers, revealed no additional defective nuts.
The RHR system forms a part of the Engineered Safety Features (ESP)
System by providing low-head, high-flow injection following a Loss-of-Coolant Accident (LOCA). The bonnets of the pump discharge check valves form a part of the pressure boundary of this system. A failure of the bonnet nuts would cause Reactor Coolant System (RCS) leakage through the RHR System and possible inability of both trains
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j Trojan Nuclear Plant Mr. John B. Martin Docket 50-344 August 21, 1990 License NPF-1 Attachment-Page 3 of 3 of the RHR system to deliver their required flow. Deficient RHR pump discharge check valve bonnet nuts, therefore, could have created a substantial safety hazard.
P=her and Location of Such C=onents In Use at the Troian Nuclear Plant A search of procurement documents indicated that nuts from Sandusky.
i Lot I were utilized in the A and B RHR pump discharge check valves.
1 Corrective Action l
All bonnet nuts for the two subject RHR check valves were temporarily replaced with ABME Carbon Steel Grade 2H nuts which are capable of withstanding greater stress than the original nuts.
l A sample of components with Sandusky Nuts of different lot numbers was inspected and no defective nuts were found.
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