ML20093M343
| ML20093M343 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 10/12/1984 |
| From: | Kemper J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| CON-#484-587 OL, NUDOCS 8410220075 | |
| Download: ML20093M343 (4) | |
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j PHILADELPHIA ELECTRIC COMPANY 23O1 M ARKET STREET P.O. BOX 8699 PHILADELPHIA. PA.19101 OM 1 2 s 84 JOHN S. KEMPER vm..
m ENGlhER Reh6 AND R ESE A%M Mr. A. Schwencer,. Chief Docket Nos.:
50-352 Licensing branch No. 2 50-353 Division of Licensing U. S. Nuclear Regularcry Cmmission
-Washington, D.C.
20555 l
1
Subject:
Limerick Generating Station, Units 1&2 Muitional Information for Power Systens Branch (PSB) Regarding Turbine Overspeed Protection Systen
Reference:
Talecon between B. Siegel/E. '1bulinson i
(NPC) and R. J. Stipcevich (PECO), 10/12/84.
File:
GOVT l-1 (NRC)
Dear Mr. Schwencer:
I Limerick Tecnnical Specification sactJon 4.3.8.2.b specifies cycling of high pressure turbine control valves at least once per 31 days. Attached per the reference telecon is General Electric Technical Information Letter No. 969 which is applicable to Limerick and which provides technical justification for the 31 day test interval.
Sincerely,
- o. s. e-,-
JHA/mlb/10128410 cc: See Attached Service List 8410220075 841012 PDR ADOCK 05000352 A
PDR 8cdI
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s:
cc: Judge Helen F. Hoyt (w/ enclosure)
- Judge derry Harbour (w/ enclosure)
Judge Richard F. Cole (w/ enclosure)
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T1 GENERAL C ELECTRIC
( dENERAL ELECTRIC COMPANYLARGE STEAM TURBINE-GE
/
SCHENECTADY, NEW YORK Technical information Letter No.
969 MAY 22, 1984 Periodic Turbine Steam Valve Test - Nuclear Units CE recommendations for periodic nuclear turbine steam valve tests as contained in the Turbine Instruction Book call for daily test of the main stop, inter-mediate stop, and intercept valves and weekly test of the control valves.
]
These recommendatioris are similar to the test frequencies that have been in practice since the late 40's and early 50's on fossil-fueled turbines.
The operating experience accumulated on in-service nuclear units during the past 24 years has shown considerably lower valve failure rates than those values upon which the recommendations were based..These reduced failure rates are due to many design inprovements to the nuclear turbine valves and controls that have been incorporated through Technical Information Letters (TIL's) and Engineering Change Notices (ECN's).
)
In the " Memo Report - Hypothetical Turbine Missiles - Probability of Occur-rence," dated March 14, 1973, the probability of runaway failure and wheel burst of a CE nuclear turbine was given, based on the nuclear experience up to that time.
Included in the probability calculations were the recommended valve test intervals; i.e., daily for main stop and intermediate stop & inter-cept valves, weekly for control valves.
The Nuclear Wheel Information Letter No. 2, dated November 8, 1982, gave comparative values for the increased over-speed probabilities due to increasing test intervals.
Based on past in-service experience with nuclear turbine steam valves, turbine steam inlet valve reliability and testing intervals are no longer the major contributing factors in determining hypothetical turbine missiles.
The over-all probability of a hypothetical missile is therefore increased only a
/~h negligible amount by increasing the test interval of the valves.
Increasing d
test intervals will correspondingly decrease the probability of a system upset during such testing and should therefore increase the nuclear plant avail-ability.
Of course any problems detected during any testing should be brought to the attention of your local A&ES service engineer.
The service engineer i
may call on the LST-C Dept. if further assistance is necessary.
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1 COPYRIGHT CENERAL ELECTRIC COMPANY, 1984 Th g
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Electate le stateuy tashie, la breech of eestreet, breach of.arranty, negligest, or le is other respecte respemelble fee any alleged injury or damage owstaJned by your erg = ='-ad== me a result et applytag this laferusettes
- 9
o 969 I
Effective with this Technical Information Letter, the recommended valve test intervals for nuclear turbines are:
Main stop Valves Weekly Intermediste Stop Valves Weekly Intercept Valves Weekly Control Valves Monthly l'
Recommended test intervals for other control components remain unchanged.
Utilities should revise their Instruction Books to the new test intervals based on this TIL.
Revised Instruction Book Articles will not be sent from General Electric Co.
Because of the higher temperature and resulting increased oxidation build-up on the stems and bushings of fossil-fueled turbines, the valve test interval recommendations remain unchanged; i.e., daily test sf the main stop, combined intercept and reheat stop valves, and weekly test of the control valves.
If your Technical specification or other documentation upon which your NRC operating license is based contains any obligation or comunitment to test on a specific schedule, it is suggested that you take appropriate steps to modify that document if you wish to change your test intervals to these new recommendations.
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