ML19319D797
| ML19319D797 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 05/17/1978 |
| From: | Mattimor J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| Shared Package | |
| ML19319D798 | List: |
| References | |
| NUDOCS 8003250793 | |
| Download: ML19319D797 (2) | |
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! SACRAMEf.TO MUNICIPAL UTTUTY DISTRICT C 6201 $ Street. 2:x 15330. Sacran ento. California 95313; (915) 452 3211 v
May 17, I 78 ll Di rector of Regulaotory Operations
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ATTN:
Mr. R. H. Engelkan HDC Operations Office Region V 1903 North Cali fornia Boulevard Valnut Creek Plaza, Suite 202 Walnut Creek, California 945o6 A
RE: Ope.ating License DPR-54 Docket No. 50-312 J
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Reportable Occurance 78-5
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Dear Mr. Engelken:
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In accordance with Technical Specifications for Rancho Seco Nuclear Gener '
ating Station, Section 6.9.4.lF, the Sacramento Muniqipal Utility District is hereby submi tting a fourteen day follow-up report to Reportable Occurence 78-5.
which was.ini tially reported to your. office May 10, 1978.
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Cn May 9,1978, while investigating the possibility of reducing the ilowdown setting of the mai, steam safety valves, it was discovered that the hydroset purve utilized for adjusting tet points varied according to the type of orifice in the valve. The orifice refers to the minimum diameter of the inlet no::le of a Con-solidated tiaxi flow Safety Valve.
Subsecuent investigation of nameplate data re-vealed that four (4) of the eighteen (18) main steam safety valves were of a dif-ferent orifice si:e. The maintenance procedure !!T-004, " Main S team P.elief Set Pressure Verification", by which the safety valves are set at designated intervals, only included: the hydroset curve for a "R" size orifice.
tiaintenance records in-dicated that the four (h) valves in question, having a "Q" size ori fice, were -
infact set according to the hydroset curve for a "R" type ori fice. A comoarison of the hydroset curves for "Q" and "R" type orifices veri fied that utilizing the "R" ori fice curve on a valve wi th a "Q" ori fice resul ts in an error in the non-conservative di rectica. The four (4) valves were then declared inoperable.
Per Technical Soccifications, Section 3.4.2.1, the P.eactor, ooerating at 70% full power. was taken to the Hat Shutdown condition.
The Main Generator was taken of f the line. Maintenance crews, utilizing an accreved. revised procedure incorcor-ating tne acditional hydroset curva, reset the four (k) valves in question. ' hen utilizing tre orecer hydroset curve, :ne valves were declared ocerable.
- Oreset, THIS DOCUMENT CONTAINS P00R QUAUTY PAGES 8003250 7 73 f
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.s Mr. R. H. Engelken May 17, 1978
.i A Reactor Start-up was commenced approximately three (3) hours after the shutdown and the generator was put on-line approximately four (4) hours af ter seperation f,
from the line.
l Ths four (4) valves in question were SitVD 1.0. No,'s PSV-20554, 20555, 20556 1
and 20557 They are Consolidated Maxiflow Relief Valves manufactured by Dresser 1
Industrial Valve and inst. Div., Code No. 6-2777Q - RT 23-XLP.
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"i; Respectfully submitted, i
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.s lJ.J.Mattimoe t
l Assistant General Manager I
l Attachment and Chief Engineer i
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cs: Director, MIPC (3) i j
. Director, IE (30)
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