05000237/LER-1979-027-03, /03L-0 on 790502:during Startup,Main Turbine Tripped on High Water Level.Caused by Packing Leak on Isolation Valve for PS-263-60B.Packing Adjusted,Tested & Sys Lineup Returned to Normal

/03L-0 on 790502:during Startup,Main Turbine Tripped on High Water Level.Caused by Packing Leak on Isolation Valve for PS-263-60B.Packing Adjusted,Tested & Sys Lineup Returned to Normal

ML19269D604
Person / Time
Site:	Dresden
Issue date:	05/30/1979
From:	Holland P COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML17173A895	List: 05000237/LER-1979-027, Forwards LER 79-027/03L-0 05000237/LER-1979-027-03, /03L-0 on 790502:during Startup,Main Turbine Tripped on High Water Level.Caused by Packing Leak on Isolation Valve for PS-263-60B.Packing Adjusted,Tested & Sys Lineup Returned to Normal
References
LER-79-027-03L-01, LER-79-27-3L-1, NUDOCS 7906050269
Download: ML19269D604 (2)

LER-1979-027, /03L-0 on 790502:during Startup,Main Turbine Tripped on High Water Level.Caused by Packing Leak on Isolation Valve for PS-263-60B.Packing Adjusted,Tested & Sys Lineup Returned to Normal

Event date:
Report date:
2371979027R03 - NRC Website

text

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63 EV ENT OATE 74 7S REPCRTQATE 80 EVENT OESCRIPTION AND PROBA8LE CONSEQUENCES h a : 1 During startup main turbine tripped on high water level.

"B" yarway reference lee hadl g

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g, g pressure switches PS-263-55C and D were isolated to isolate leak.

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3.1.1 requires 2 instrument channels per trip system, an orderly Rx shutdown was be-l g,3 2f6 l gun imm diately. Minimal safety significance since both trip systems were still oper-l able.

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o l A packing leak was found on the isolation valve for PS-263-608.

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263-59B, 58A, 583, 72B, and 72D. The packing was adjusted, tested, and the system g,

line up was returned to normal.' All instruments returned to the proper range as the reference leg filled.

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ATTACH'IENT TO LICENSEE EVENT REPORT 79-027/03L-0 COMMONWEALTH EDISON COMPA'IY (CUE)

DRESDEN UNIT (ILDRS2)

DOCKET # 050-237 During startup on Unit 2 at 1918 on May 2, 1979, the main turbine tripped on high water level.

It was discovered that a packing leak existed on the isolation valve for the local pressure indication, PS-263-60B.

The "B" reference leg drained to an abnormally low level through the packing leak.

This resulted in an upscale reading on all the yarways on instrument rack 2206. The "B" reference leg root valve was shut to isolate the leak which isolated the following components:

PS-263-55C, 550, LIS-263-58A, 58B, 72B, 72D, and LITS-263-59B. A control systems technician locally isolated PI-263-60B (local pressure indication) and PS-263-55D (reactor high pressure scram) via their common sensing line root valve.

The "B" reference leg root valve was then opened and the reference leg filled. Since Tech. Spec. Table 3.1.1 requires two in-strument channels per trip system, an orderly reactor shutdown was begun immediately.

The packing was tightened-and subjected to a hydro of 1000 psi.

No leaks were discovered. The isolation valves for PS-263-55D and PI-263-60B were opened and the common sensing line root valve was opened, returning the system to normal.

This event was of minimal safety significance, since one instrument channel per trip system was still capable of performing its intended function as designed. This was the first occurrence of this type on Unit 2.

There was no effect on public health or safety.

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