ML20058K903
| ML20058K903 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 12/28/1972 |
| From: | Mayer L NORTHERN STATES POWER CO. |
| To: | Anthony Giambusso US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 9104260266 | |
| Download: ML20058K903 (4) | |
Text
P Wgulatory File Cy;-
NSW NORTHERN STATES POWER COMPANY M IN N E A PO LI S, MIN N E S OT A 55401 A
December 28, 1972 g
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g Mr. A Giambusso Ibputy Director for Reactor Projects
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Directorate of Licensing 4
United States Atomic Energy Commission Washington, D C 205A5
Dear Mr. Giamburso:
MONTICELLO NUCLEAR GENF3ATING PIANT Docket No. 50-263 License No. DPR-22 Report of Main Steam Isolation Valre Performance
'Ihis report is submitted in accordance with paragraph 6.6.E.3.e of Appendix A, Technical Specifications of the Provisional Operating License for the Monticello Nuclear Generating Plant, which requires that a report on main steam line isolation valve (MSIV) leakage be submitted within 18 months of initial commercial service.
This Technical Specification paragraph was established to evaluate MSIV perfomance at Monticello and to review im-provements which other facilities may have found necessary to assure PSIV leak tightness.
She comprehensive MSIV surveillance testing program outlined in the Monti-cello Technical Specifications has been fully complied with. All esting discrepancies have been subjected tc thorough investigation by the plant technical sta_ f and review by the Operations and Safety Audit Co=mittees.
All significant discrepancies have been reported to AEC-DL.
Table I lists the MSIV surveillance tests conducted at Monticello, their frequency, number of times conducted since date of initial commercial service, and the number of times that testing discrepancies arose. Table II is a summary of the unsatisfactory M3IV surveillance tests listing date, nature of discrepancy, date.of report to AEC-DL, and the final resolution of each problem.
Regarding MSIV performance, the following general ob-servations can be made:
An MSIV has never failed to close during testing a.
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RN OTATE3 POWER COM sNY Mr. A Giambusso Decembe r 28, 1972 b.
Of the three instances of L= proper closing time, the only one of consequence was caused by external oil piping leakage All significant MSIV problems discovered to date were found c.
during the first six months of commercial operation I
We believe that the corrective action outlined briefly in Table II, and reported in detail in individual occurrence reports, has solved all sig-nificant ICIV problems experienced.
It has been our stated intent to repeat individual MSIV leakage tests at the first scheduled outage of sufficient length (7 days or more) to accommodate them.
This additional testing will confirm the effectiveness of repairs made earlier this year and will be perfomed no later than the refueling outage scheduled for March, 1973 We believe that the MSIV leakage report submittal date of 18 months from the start of commercial service was intended to include testing normally done during the first refueling outage. For this reason and to provide additional opportunity to obtain information on MSIV leakage experience from other plants, we intend to submit a supplemental report 60 days fol-lowing the end of the sprin6 outage.
Yours very truly, 69 L 0 Mayer, P..
Director of Nuclear Support Services LOM/T_fC4/br cc: B H Grier Attachments f
TABLE I Main Steam Isolation Valve Surveillance Testing Requirements and Summary of Besults (7/1/71 - 12/28/72)
No. of Valve Tests No. of Test Surveillance Test Frequency Perromed Discrepancies Test of simulated automatic Ehch operating Scheduled for closure cycle thrch,1973 outage (TS 4.7.D.1.a)
Trip test and measurement Quarterly 72 3
of closure times (TS 4.7.D.l.c (2))
Partial closure and Weekly 480 0
reopening FEIV exercise
( Ts 4.7. D. 2 )
FEIV Incal Leak Bate Test Ee.ch operating 8
4 (TS h.7.A.2.e) cycle To be repeated during first scheduled outage exceeding 7 days
TABLE II s
Summary of Main Steam Isolation Valve Problems Date of Feport Pesolution of Date Discrepancy to AEC-DL Discrepancy 8/26/71 FEIV 2-86C closure time found to be too short 9/9/71 Adjustment of oil during routine quarterly surveillance test dashpot flow control (2.0 see measured, 3 0 see min allowed) valve 11/13/71 MSIV 2-86C closure time found to be too short 11/26/71 Bepaired leak in !GIV (1.2 see measured, 3 0 see min allowed) and 2-86C oil dashpot MSIV 2-80B closure time found excessive (20.0 cylinder external see measured, 5 0 see max allowed) piping.
Feplaced spool piece in MSIV 2-80B main air valve 11/17/71 During ope 2 stional primary hydrostatic test 11/26/71 Poppet guide wear area MSIV 2-86A leakage found in excess of 11 5 overlayed with stellite.
SCFH limit (measured leaka6e in excess of Main mat and poppet 70 gpm of water) lapped and truing cut made on guide land.
Inakage reduced to 9 4 SCFH 11/26/71 Subsequent to 11/17/71 event all ICIV's leak 2/18/72 MSIV 2-80D main seat tested. MSIV 2-80D, 2-86B, and 2-86D also lapled to remove chip.
found to exhibit excessive leakage.
Test Pilot valve and seat of M3IV 2-86B and results were:
2-86D lapped to remove Valve Leak Bate (SCFH @ 25 psig) scratches.
Icakage 2-60D 15h following repair vas:
2-86B 150 2-86D 83 Valve Leak Pate (SCFH @ 25 pc'd 2-80D
< 0. 2 2-86B 39 2-86D
< 0. 2
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