ML19257C293
| ML19257C293 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 01/21/1980 |
| From: | Counsil W, Willie Lee NORTHEAST NUCLEAR ENERGY CO. |
| To: | Ziemann D Office of Nuclear Reactor Regulation |
| References | |
| TASK-03-11, TASK-3-11, TASK-RR NUDOCS 8001250529 | |
| Download: ML19257C293 (6) | |
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J ::?::".' T ;,"J l" C l January 21, 1980 Docket No. 50-245 Director of Nuclear Reactor Regulation Attn:
Mr. D. L. Ziemann, Chief Operating Reactors Branch #2 U. S. Nuclear Regulatory Commission Washington, D. C.
20555
References:
(1)
W. G. Counsil letter to D. L. Ziemann dated January 9,1980.
(2)
D. L. Ziemann letter to W. G. Counsil dated January 17, 1980.
(3)
B. H. Grier letter to W. G. Counsil dated January 14, 1980.
Gentlemen:
Millstone Nuclear Power Station, Unit No.1 Isolation Condenser System, Anchor X-lG\\
This letter is Northeast Nuclear Energy Company's (dNECO) response to a verbal request from Staff members in the Office of Nuclear Reactor Regulation, concerning the load combinations used for the Isolation Condenser steam-line anchor.
The Isolation Condenser at Millstone Unit No.1 has been declared administratively inoperable ever since January 4,1980, resulting in a self-imposed derate to 40% of full power. Plant Technical Specifications limited operation to 15 days of full power whenever the Isolation Condenser was made or found inoperable.
However, NNECO has applied for, and received, a Technical Specification change allowing continuous operation at 40% power whenever the Isolation condenser is inoperable, in lieu of the 15-day limitation at 100% power (Ref erences (1) and (2)). Thus, the plant is continuing operation at 40% power.
The inoperability of the Isolation Condenser derives from the presumed degrada-tion of the Isolation Condenser steam-line anchor at containment penetration X-10A.
The question of anchor degradation was raised following a water-hammer incident in December,1979.
For the last several weeks, NNECO has been evaluating the presumed degradation, the original anchor design bases, the safety factors for the supports anchor bolts, and anchor improvements that would meet the required safety f actors.
During this time, we have been in continuous communication with the NRC Office of Inspection and Enforcement (ISE). A telephone conference call, January 16, 1980, among NNECO, NUSCO, Teledyne, I&E, and NRR personnel concluded that the conditions stipulated by I&E in Reference (3) would be met before declaring the Isolation Condenser operable.
1809 Mi s onu so Sa9 g
8 During the conf erence call, NRR personnel requested that NNECO submit the reanalyzed load combinations used to demonstrate the anchor's design adequacy stipulated in Reference (3). The attached letter from Teledyne Engineering Services to Mr. Eric DeBarba of NUSCO provides the load combinations and design loads that are being used to modify the anchor. The complete response to Reference (3) will be forwarded to I&E as required on or before February 1, 1980.
Should you have any questions, please call us.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY W. G.flounsil Vice President By:
W. F. Fee Vice President Attachment 1809 352
W TELEDYNE ENGINEERING SERVICES 303 BE AR MtLL ROAD e
W ALTHAV. MASSACHilSETTS C2t 54 (517) 890-3350 Twx (710) 324-7508 January 18, 1980 3815A-1 Mr. Eric DeBarba Northeast Utilities Service Company P.O. Box 270 Hartford, CT 06101
Subject:
Isolation Condenser System - Anchor X-10
Dear Eric,
Teledyne Engineering Services has completed analysis of the subject anchor for the following loading conditions.
1.
Normal Operation + DBE 2.
Normal Operation + HEPB The loads for the above conditions were taken from the original Ebasco analysis for the anchor and are given in Attachment No. 1.
For Condition
- 1. above the existing design has a factor of safety greater than 2.
For condition 2.
above the existing design has a factor of safety of less than 2.
In performing the analysis for condition 2., TES applied all HEPB loads simultaneously assuming they could be + or - except for F which could only be applied in the - X direction. This is an extremely conservative assump-tion for the following reasons:
Each load is approximately equal to elastically calculated f ailure load of the piping system in the direction of the load.
It would therefore be impossible for the pipe to transmit all 3 forces and 3 moments to the anchor simultaneously.
A detailed pipe rupture analysis of the piping system for selected break locations would result in fewer individual loads applied to the anchor simultaneously.
For example a circunferential break in the vertical rise penetrating floor elevation 82.75 would result in 1 force and 2 moments of significant magnitude on the anchor.
There would be wave forces in the piping system which would produce all 6 components of load but the wave force is approximately equal to 10 percent of the thrust force and is a very short duration load.
However, since it was not possible to determine the appropriate com-binations for the Ebasco HEPB loads TES had to assume simultaneous applica-tion. Since this assumption resulted in a f actor of safety of less than 2, TES has recommended a modification of the anchor be implemented. A sketch of this modification is shown in Attachment 2.
Although the water. hammer loads have not yet been developed it is our feeling that the modified design will result in appropriate factors of safety for that condition.
1809 353 ENGINEERS AND METALLURGISTS
"#PTELEDYNE ENGINEERING SERVICES If you have any questions concerning this, please do not hesitate to contact me.
Very truly yours, TELEDYNE ENGINEERING SERVICES N
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Donald F. Landers Senior Vice President DFL:dem cc: RDC PMB l809 354
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SeTELEDYNE ENGINEERING SERVICES ATTACHMENT 1 Loads Used in TES Analysis Anchor X-10A Load Condition 1
2 F, LBS 129,000
-129,700 y
1 29,200 F, LBS 11400 1
y F, LSS 133,300 1132,100 Z
M, FT-LB5 163,600 1663,000 X
M, FT-LBS 1168,800 1478,800 y
f'Z, FT-LBS 171,500 1493,700 y (vtRT.)
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