ML20005E084
| ML20005E084 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 12/26/1989 |
| From: | Papanic G YANKEE ATOMIC ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-PT21-90-007-000 PT21-90-007-000, PT21-90-7, NUDOCS 9001030229 | |
| Download: ML20005E084 (3) | |
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- w iYANKEEATOMICELECTRIC COMPANY
'Q"%'ll%,"l" 7W5 580 Main Street, Bolton, Massachusetts 01740-1398
,YANKEIE o
December 26, 1989 y
United States Nuclear Regulatory Commission L
-Document' Control Desk.
Washington, DC 20555 Attention:
Dr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation
Reference:
(a) License No. DPR-3 (Docket No. 50-29)
Subject:
-10CFR21 Report on Safety Class-2, U-Tube Heat Exchanger Purchased-From Southwestern Engineering Company
Dear Dr. Murley:
Yankee has completed an evaluation under 100FR21 which concluded that a vendor's deviation from the technical requirements set forth in Section-VIII
-of the ASME code-for allowable stress values for bolting materials does-not represent a substantial safety hazard to the present operation of Yankee Nuclear-Power Station..However, we also concluded that this should be reported to ensure that-other plants are made aware of this situation, j
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' Enclosure 1 to this letter provides the necessary details of this situation. Should you have any questions regarding this matter, please contact us.
Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY Georg apanic, J.
Senior Project Engineer Licensing GP/gjt/0687v Enclosure cc: _USNRC Region I USNRC Resident Inspector, YNPS l
f(9 9001030229 891226 ADOCK 05000029
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ENCLOSURE 1 l
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,i Company Informing the Commission.
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' Yankee Atomic Electric Company l
J 580 Main Street Bolton, Massachusetts 01740
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Facility an
-Yankee Nuclear Power Station Star Route.
"!Rowe, Massachusetts 01367
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-Component, p
i LHeat Exchanger E-36 for the Water-Cleanup System
' Fire Supplying Component
' Southwestern Engineering Company
'242 Pearl Street
-Berlin, Wisconsin 54923 o
N,ature of Defect In support of the= Water Cleanup System (WCS) installation effort at the Yankee 3
-Nuclear Power Station, a Safety Class 2 U-tube heat exchanger was purchased from the Southwestern Engineering Company, 242 Pearl Street, Berlin,. Wisconsin
.i 54923. The WCS E-36 heat exchanger was purchased under Purchase
. Order QA40665. The design specifications for the heat exchanger were
. delineated within Yankee Specification YRS-028,. Revision 1.
Subsequent to the initial plant receipt inspection of the heat exchanger, a-l 7
plant preservice inspection evaluation (NDE) of the heat exchanger required the removal of the' studs on the channel cover.
During the removal process,
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- the breakaway torque of these studs was found to be, on the average, between
-800 ft/lbs.to 900 ft/lbs. These studs are A193 B7 3/4 inch 10 UNC.
After discussing the torquing requirements with the heat exchanger vendor, it l
became apparent that the vendor performed no procedure for tightening the l
studs and had no record of what torque value the studs were actually tightened L-
- to, prior to shipment. Further, it has been-noted by the Cognizant Engineer and the Quality Assurance Engineer who witnessed the hydrostatic testing of the heat exchanger, that the studs may have been overtightened in order to successfully complete the hydrotest.
The E-36 heat exchanger specification delineated the vessel to be designed, l
fabricated, inspected, and tested in accordance with the ASME Boiler and
-Pressure Vessel Code,Section VIII Division I.
Section UG-12 l-0687v l
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ENCLOSURE 1 (Continued) of the.ASME code sets'the maximum allowable stress values for acceptable
! bolting materials within Table UCS-23.
From this table, the following data
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and limits are imposed for SA-193 B7 bolting less than or equal to i
2-1/2-inches in length:
~ Minimum Yield = 105'ksi
' Minimum Tensile = 125 ksi Maximum Allowable Stress = 25 kai (approximately 110 ft/lbs)
It is apparent from the above data that the channel cover' bolting was tightened to a torque value well over the maximum allowable as set.forth within ASME VIII. The "as-found" bolt torque values are also approximately four times the EPRI;" Good Bolting Practices" guideline criteria.
Date of Incident The Yankee Nonconformance Report identifying the as-found condition was dated August 10, 1989.
Number of Components Yankee has only one heat exchanger in its Water Cleanup System.
Corrective Actions Taken Yankee replaced all the effected heat exchanger studs and approximately 75% of-the nuts due to galling.
I Related Advice Yankee's evaluation concluded that no substantial safety hazard currently exists at YNPS;since the equipment was undergoing preservice inspection at the time the deviation was discovered and the system was not operational.
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