ML17059A943
| ML17059A943 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 09/22/1995 |
| From: | Terry C NIAGARA MOHAWK POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NMP2L-1572, NUDOCS 9509280076 | |
| Download: ML17059A943 (8) | |
Text
PRIORITY 1 (ACCELERATED RZDS PROCESSZNG)
REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9509280076 DOC.DATE: 95/09/22 NOTARIZED: NO FACIL:50-410 Nine Mile Point Nuclear Station, Unit 2, Niagara Moha AUTH.NAME AUTHOR AFFILIATION TERRY,C.D.
Niagara Mohawk Power Corp.
RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
DOCKET 05000410 P
SUBJECT:
Forwards results of insps performed since mechanical stress improvement process applied in first refueling outage at facility for indication in weld joining HPCS nozzle safe end to safe-end extension (KC-32).
DISTRIBUTION CODE: A001D COPIES RECEIVED:LTR ENCL SIZE:
TITLE: OR Submittal:
General Distribution NOTES:
0 RECIPIENT ID CODE/NAME PD1-1 LA EDISON,G INTERNAL: ACRS NRR/DE/EMCB NRR/DSSA/SPLB NUDOCS-ABSTRACT EXTERNAL: NOAC COPIES LTTR ENCL 1
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1 RECIPIENT ID CODE/NAME PD1-1 PD ILE CENTER 01 NRR DRC CB NRR/DSSA/SRXB OGC/HDS3 NRC PDR COPIES LTTR ENCL 1
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NOTE,TO ALL "RZDS" RECZPZENTS:
PLEASE HELP US TO REDUCE WASTE!
CONTACT THE DOCUMENT CONTROL
- DESK, ROOM OWFN 5D8 (415-2083)
TO ELZMZNATE YOUR NAME FROM DZSTRZBUTZON LZSTS FOR DOCUMENTS YOU DON'T NEED!
TOTAL NUMBER OF COPIES REQUIRED:
LTTR 18 ENCL 17
(
g ~QOglgugg NIAGARAMOHAWKPOWER CORPORATION/NINE MILEPOINT NUCLEAR STATION, P.O. BOX 63, LYCOMING,N.Y.13093/TEL (315) 349-7263 FAX(31 5) 3494753 CARL 0. TERRY Vice President Nuciear Engineering September 22, 1995 NMP2L 1572 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 RE'ine Mile Point Unit 2 Docket No. 50-410 NPF-6
Subject:
High Pressure Core Spray (HPCS) Nozzle Safe-End Extension (KC-32) Weld Inspection Frequency Gentlemen:
During the first refueling outage at Nine Mile Point Unit 2 (NMP2), Niagara Mohawk Power Corporation (NMPC) identified an indication in the weld joining the High Pressure Core Spray (HPCS) nozzle safe end to the safe-end extension (KC-32) utilizing UT inspection techniques.
After evaluating the indication, NMPC applied Mechanical Stress Improvement Process (MSIP) to improve the residual stress distribution in the region of the flaw to eliminate the potential for flaw growth.
Subsequent to the application of MSIP, UT inspections were again performed during the first refueling outage, at a mid-cycle outage during the second fuel cycle and at the second, third, and fourth refueling outages.
No growth in the flaw has been identified by these inspections as compared with the first post-MSIP UT inspection.
NMPC has determined that the stabilization of the flaw is due to the application of MSIP which has maintained the flaw in compression.
By letter dated July 8, 1993, Niagara Mohawk committed to conduct a UT reinspection of the flaw at each subsequent refueling outage.
NMP2 Technical Specification 4.0.5.f states that an inservice inspection program for piping identified in Generic Letter (GL) 88-01 shall be performed in accordance with Staff positions.
In accordance with Generic Letter 88-01, "NRC Position on IGSCC in BWR Austenitic Stainless Steel Piping," KC-32 was categorized as an IGSCC Category "F" weld which, consistent with our commitment, requires that all indications be inspected every refueling outage.
Welds that have been treated by stress improvement that are classified as IGSCC Category "F" because they do not meet the applicable Staff positions may be upgraded to Category "E" ifno adverse change in crack condition is found after four successive examinations.
Category "E" welds are examined once every other outage.
Normally, the four successive exams would be conducted on a refueling outage cycle frequency.
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Page 2.
As indicated above, Niagara Mohawk has performed four successive examinations which indicate no adverse change in the cracking condition.
One of the exams was performed at a mid-cycle frequency (as mandated by the Staff) and, consequently, only three of four exams were conducted during a refuel outage.
However, Niagara Mohawk contends that the four exams indicate that MSIP has been effective in mitigating any crack growth and the intent of GL 88-01 has been met.
Further exams willresult in unnecessary radiation exposure while inspecting KC-32 at each outage.
Accordingly, Niagara Mohawk requests Staff approval to recategorize KC-32 as a category "E" weld.
Assuming Staff approval, the next scheduled exam willbe refueling outage six.
Attachment A provides the results of inspections performed since MSIP was applied in the first refueling outage.
Very truly yours, C. D. Terry Vice President - Nuclear Engineering CD T/JMT/kap Attachment XC:
Regional Administrator, Region I Mr. L. B. Marsh, Director, Project Directorate I-1, NRR Mr. G. E. Edison, Senior Project Manager, NRR Mr. B. S. Norris, Senior Resident Inspector Records Management
ie P
ATTACHIVIENTA EC-32 Inspection Results Inspection
- Post-MSIP (RF01) (December 1990)
Midcycle (August 1991)
RFO-2 (April 1992)
Length/% of Internal Circumference 3.40" (11.3%)
3.3" (10.9%)
2.6" Automated 3.3" Manual (8.6%)
(10.9%)
Depth/%
of Wall Thickness 0.35" (41%)
0.32" (38%)
0.25" (29%)
RFO-3 (October 1993)
RFO-4 (May 1995) 2.5" Automated (8.3%)
2.5" Automated (8.3%)
3.0" Manual (9.9%)
3.0" Manual (9.9%)
0.25" (29%)
0.30" (35%)
Cannot be counted toward four successive examinations (i.e., the weld experienced no service).
4 A
4