ML17058B067

Requests That NRC re-review 910514 Submittal of Analysis Proposing Reduction in Condensation Oscillation (Co) Load Applied to Torus During Loco & Encl Rept Dtd 921119 Which Provides Addl Clarification of Analysis,Re SE Dtd 920825

ML17058B067
Person / Time
Site:	Nine Mile Point
Issue date:	11/23/1992
From:	Terry C NIAGARA MOHAWK POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML17058B068	List: ML17058B067 ML18038A726
References
MMP1L-0716, MMP1L-716, TAC-M80214, NUDOCS 9211300161
Download: ML17058B067 (6)

Text

wcczcza<rzD D~Sraram>OW DzmOx ~a~nox Svsrarvr REGULAT INFORMATION DISTRIBUTIO ZSTEM (RIDE)

ACCESSIM'BR:9211300161 DOC.DATE: 92/11/23 NOTARIZED: NO DOCKET FACIL:50-220 Nine Mile Point Nuclear Station, Unit 1, Niagara Powe 05000220 AUTH. NAME AUTHOR AFFILIATION TERRY,C.D. Niagara Mohawk Power Corp.

RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Requests that NRC re-review 910514 submittal of analysis proposing reduction in condensation oscillation (CO) load applied to torus during LOCO & encl rept dtd 921119 which provides addi clarification of analysis,re SE dtd 920825.

0 DISTRIBUTION CODE: AOOID OR COPIES RECEIVED:LTR Submittal: General Distribution I ENCL g SIZE: ++ R'ITLE:

NOTES:$ ~ h~~++

RECIPIENT COPIES RECIPIENT .COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD1-1 LA 1 1 PD1-1 PD 1 1 BRINKMANFD. 2 2 INTERNAL: ACRS 6 6 NRR/DET/ESGB 1 1 NRR/DOEA/OTSB11 1 1 NRR/DST/SELB 7E 1 1 NRR/DST/SICB8H7 1 1 N R~T/SRXB 8E 1 1 NUDOCS-ABSTRACT 1 1 OC/LFMB 1 0 OGC/HDS1 1 0 REG FILE 01 1 1 RES/DSIR/EIB 1 EXTERNAL: NRC PDR 1 1 NSIC 1 1 NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE NASTE! CONTACT THE DOCUMENT CONTROL DESK.

-ROOM PI-37 (EXT. 504-'2065) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 22 ENCL 20

I I I

'1!

NIAGARAMOHAWKPOWER CORPORATION/301 PLAINFIELDROAD, SYRACUSE, N.Y. 13212/TELEPHONE (315) 474-1511 November 23, 1992 NMP1L 0716 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Re: Nine Mile Point Unit 1 Docket No. 50-220 DPR-63 TA No, M80214 Gentlemen:

Subject:

NRC Safety Evaluation dated August 25, 1992 By letter dated May 14, 1991 (NMP1L 0583), Niagara Mohawk Power Corporation submitted an analysis which proposed a reduction in the Condensation Oscillation (CO) loads applied to the Nine Mile Point Unit 1 torus during a loss-of-coolant accident. On August 25, 1992, the NRC Staff provided a safety evaluation which concluded that the proposed reduction in CO loads on the torus is acceptable.

In reviewing. the NRC safety evaluation, -we have determined that the NRC evaluation of Niagara Mohawk's CO load reduction request was inconsistent with our method of analysis.

The NRC's analysis approach involved the absolute summing of the individual stress harmonics for the CO load case. Niagara Mohawk's approach combined the stress harmonics by absolute summing the 4 peaks and added this to the square root of the sum of the squares of the remaining 27 stress harmonics. This approach was the result of extensive structural analysis done for the Mark I Torus Program and is still valid. Both methods of analyses were accepted during the Mark I Torus Program. The method in our submittal of May 14, 1991 is consistent with the method we previously applied in the Mark I analysis.

Therefore, our CO load reduction request does not require a revision to the method of summation.

Niagara Mohawk's May 14, 1991 submittal provided a reduction in the CO load resulting from the geometry of the full scale test facility and the resulting effects, which is independent of the method of summation, as described above. As such, we request the NRC to re-review the May 14, 1991 submittal and the enclosed Teledyne Engineering Services Report dated November 19, 1992, which provides additional clarification of our analysis.

In the interim, we are continuing to defer implementation of torus modifications based on our measurements of torus thickness. This provides adequate margin for at least one more cycle based on the present corrosion rate on the torus as determined from the latest six-month Ultrasonic Test measurements. Furthermore, acceptance of the CO load reduction will provide for additional margin., 9211300 f 6j 92'23 mr nn~ PDR P

ADOCK 05000220 PDR

(P ~

t 4

We look forward to meeting with your technical reviewers to assure that our approach. is clearly understood. If you have any questions regarding this submittal, please contact Mr.

Nick Spagnoletti at (315) 428-7452.

Very truly yours, C. D. Terry Vice President Nuclear Engineering NAS/mls 003344GG Enclosure xc: Regional Administrator, Region I Mr. W. L. Schmidt, Senior Resident Inspector Mr. R. A. Capra, Director, Project Directorate I-l, NRR Mr. D. S. Brinkman, Senior Project Manager, NRR Records Management

0 0 I VE x>