ML20072G041
| ML20072G041 | |
| Person / Time | |
|---|---|
| Site: | Shoreham File:Long Island Lighting Company icon.png |
| Issue date: | 06/23/1983 |
| From: | James Smith LONG ISLAND LIGHTING CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| SNRC-907, NUDOCS 8306280265 | |
| Download: ML20072G041 (8) | |
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artep SHOREHAM NUCLEAR POWER STATION m.a.morem:- _--
P.O. BOX 618, NORTH COUNTRY ROAD + WADING RIVER, N.Y.11792 Dkut Dbl Number June 23, 1983 SNRC-907 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Jet Pump Hold-Down Beams Shoreham Nuclear Power Station - Unit 1 Docket No. 50-322
Dear Mr. Denton:
The purpose of this letter is to clarify LILCO's understanding relative to inspection requirements for the jet pump hold-down beams.
These requirements evolved from the failure of a jet pump hold-down beam at Dresden Unit-3 (BWR-3 plant) which was reported on February 2, 1980 and documented by the NRC via IE Bulletin No. 80-07 dated 4/4/80.
The cause of the failure was determined to be a crack in the beam.
Subsequent examination of this and other cracked beams, as documented in General Electric Co.
(GE) Service Information Letter (SIL) No. 330, led to the l
conclusion that the cracks are caused by Intergranular Stress Corrnsion Cracking (IGSCC).
It was also concluded that crack l
propragation from initiation to complete beam failure takes l
several years.
I Shoreham is a GE BWR 4 plant and utilizes beams similar to those at Dresden Unit-3.
In order to preclude the occurrence i
of beam failure due to cracking, certain actions were committed to by LILCO as documented in attachments to letters SNRC-545 dated 3/17/81 and SNRC-566 dated 5/15/81 (see attachments A and B).
Basically, these actions consisted of the following:
1) reduction of the hold-down beam preload from 30,000 to 25,000 pounds as recommended by GE 2) performance of in-service inspections 8306280265 830623 C3 PDR ADOCK 05000322 G
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- June 23, 1983 SNRC-907 Page 2 Attachment B provides a description of the in-service inspections planned for Shoreham.
This included a statement that NDT would be performed following detensioning of the beam and prior to retensioning. Since the' cracks in other plants initiated at the top surface of the beam near the bolt hole (see attachment C for_ beam configuration), it was originally thought that detension-ing the bolt and removing the bolt keeper and lockplate'would facilitate UT-inspection and provide more meaningful inspection results.
It is not LILCO's intent to' perform any NDT inspections prior to plant operation.
This is-not necessary due to the following:
1)
The crack initiator, IGSCC, requires certain conditions involving corrosive environment and stress.
These conditions will not be present until the plant operates.
2)
Beam. life and time from crack initiation to failure for the BWR-3 beam design have been. determined statistically utilizing crack initiation and failure data from operating plants.
Time to crack initiation, for a 2.5% probability of cracking, is 30,000 critical hours.
The corresponding time to failure is 47,000 critical hours.
3)
The BWR-4 beam used for Shoreham operates at peak stresses lower than the BWR-3 beams.
The reduction of the 30 kip preload represents an additional improvement.
Shoreham's beams are predicted to have a beam time to crack initiation level of from 19 to 40 years.
This issue was addressed in the Safety Evaluation Report (SER) and finally resolved in Supplement No. 1 to the SER based cn1 LILCO's commitment to periodic visual inspection and UT inspection of the beams as recommended by General Electric and as specified for other similar plants.
LILCO maintains, based on the background information cited previously in this letter, that this " periodic inspection" is analogous to in-service inspection.
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f June 23',
1983 SNRC-907
'Page 3 The reactor vessel at Shoreham is presently being maintained with the steam separator, steam dryer, and vessel head installed.
Removal of these components is not anticipated prior to pre-paration for fuel load.
Removal of these components and ultrasonically testing the jet pump hold-down beams at this time would represent a considerable cost with no apparent commen-surate benefit.
In conclusion, LILCO has retensioned the jet pump hold-down beams in accordance with vendor recommendations, and will include inspections of these beams in the Shoreham ISI program.
These commitments provide assurance that failure of the jet pump hold-down beams will not occur at Shoreham, and obviate the need for any additional pre-service inspections.
Should you have any questions, please contact this office.
Very truly yours, J.
L. Smith Manager, Special Projects Shoreham Nuclear Power Station RWG:bc Attachment cc:
J.
Higgins All Parties Listed in Attachment 1 U
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ATTACHMENT 1 I
I Lawrence Brenner, Esq.
Herbert H. Brown, Esq.
Administrative Judge Lawrence Coe Lanpher, Esq.
Atomic Safety and Licensing Karla J.
Letsche, Esq.
Board Panel Kirkpatrick, Lockhart, Hill U.S. Nuclear Regulatory Commission Christoper & Phillips Washington, D.C.
20555 8th Floor 1900 M Street, N.W.
Washington, D.C.
20036 Dr. Peter A. Morris Administrative Judge Atomic Safety and Licensing Mr. Marc W. Goldsmith Board Panel Energy Research Group U.S. Nuclear Regulatory Commission 4001 Totten Pond Road Washington, D.C.
20555 Waltham, Massachusetts 02154 Dr. James H. Carpenter MHB Technical Associates Administrative Judge 1723 Hamilton Avenue Atomic Safety and Licensing Suite K Board Panel San Jose, California 95125 U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Stephen B. Latham, Esq.
Twomey, Latham & Shea Daniel F. Brown, Esq.
33 West Second Street Attorney P.O.
Box 398 Atomic Safety and Licensing Riverhead, New York 11901 Board Panel U.S. Nuclear Regulatory Commission 37ashington, D.C.
20355 Ralph Shapiro, Esq.
Cammer and Shapiro, P.C.
9 East 40th Street Bernard M.
Bordenick, Esq.
New York, New York 10016 David A. Repka, Esq.
U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Matthew J. Kelly, Esq.
State of New York Department of Public Service James Dougherty Three Empire State Plaza 3045 Porter Street Albany, New York 12223 Washington, D.C.
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ATTACHMENT A MTEB-7 -- JET PUMP HOLD 0011tl..BEAtt CRACKIQG m _. 1_..
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1 General Electric has recommended to Lilco a reduction in the preload force o f ' jet -pump. hold down c. beams to 25,000 pounds at Shoreham.
An instruction to make this modification is scheduled to be issued in April 1981.
The Sh'oreham Project has committed to reduce hold dcun beam preload as recommended by GE.
It is estimated that l'
this work will be completed at the si te by October 1981.
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Shoreham Outstanding SER Issue #14 Jet Pump Hold-Down Beams Shoreham will conduct periodic inspections of the Jet Pump Hold-down Beams as part of the overall in-service inspection program.
Non-destructive tests-of the Jet Pump Hold-down Beams will be performed following detensioning of the installed beams (presently preloaded at 30,000 pounds force), and prior to retensioning the beams (to be preloaded at 25,000 pounds force).
The in-service inspections to be performed will consist of:
1.
Visual inspections via T.V.
cameras to authenticate Jet Pump structural integrity, and -
2.
Ultrasonic inspection of the Jet Pump Hold-down Beams Inspection frequencies are being developed by General Electric for these beams.
Shoreham will conduct in-service inspections in accordance with the G.E. recommendations for the beams installed.
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