ML20086Q209
| ML20086Q209 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 10/15/1973 |
| From: | Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Anthony Giambusso US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8402270472 | |
| Download: ML20086Q209 (3) | |
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g PHILADELPHIA ELECTRIC COMPANY
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7 OCT181973> 42 h
U.S. ATC" C FGEL~.f 2301 MARKET STREET CCl,"CS:03 7
I PHILADELPHI A. PA.19101 Oj F:;Mny t.!::t utzn 121s1841 4000 k
g October 15, 1973 Mr. A. Giambusso Deputy Director of Reactor Projects United States Atomic Energy Commission Directorate of Licensing Washington, D. C.
20545
Reference:
Peach Bot tom Atomic Power Station - Unit 2 Facility Operating License DPR-44 Docket No. 50-277
Subject:
Abnormal Occurrences
Dear Mr. Giambusso:
Ouring the week of October 1, 1973, internal inspection of the RHR system valve M0-154-8 disclosed defective tack welds between the valve disc and stem nut.
Additionally, surveillance testing of the High Pressure Service Water sys'.em disclosed pump capaci ties below Technical Specification requirements.
These items were reported to Mr. Richard A. Feil, A.E.C. Region I Regulatory Office on October 5,1973. s.In accordance with Section 6 7 2.A of the Technical Specification Appendix A of DPR-44 for Unit 2 Peach Bottom Atomic Power Station, these deficiencies are being reported to the Directorate of Licensing as Abnormal Occurrences.
i High Pressure Service Water Pump Capacizies Routine surveillance testing of the High Pressure Service Water system during the week of 10/1/73 disclosed toat the 2A and 2C pumps were not meeting their pressure and flow as stated by Technical Specification 4.5.B.I.b.
At specified flow, the pump discharge pressure of the 2A and 2C pumps was 261 psig and 280 psig, respectively. The specified discharge pressure is 295 psig.
Investigation Investigation of tne low pump capacity disclosed that the impeller shaft pump casing clearance was improper on all four High Pressure Service Water pumps. The "as found" clearances varied from 0.250" to 0 500".
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Corrective Action The impeller shaft pump casing cicarance was adjusted to 0.030" per manufacturer 's directions. Retesting of three pumps following this adjustment indicated proper pump performance. A frozen sleeve on the shaf t of the 2A High Pressure Service Water pump prevented making the
, proper impeller casing clearance adjustment. These adjustments will be made and the pump retested following repair operations.
Safety Implications At the present time, with no irradiated fuel in the reactor vessel, the High Pressure Service Water system is not required per Technical Specification #3 5.B.1. The low discharge pressure exhibited by these pumps at rated flow would not have reduced the ability to effect proper torus cooling or decay heat removal during postulated accident conditions, therefore, there is no safety implication associated with the minor reduction in pump capaci ty.
MO-154-8 Valve Disc An internal inspection of the RHR system low pressure coolant injection
' line throt.tling valve M0-154-B was made following the observation of unusual noises emitting from the valve during shutdown cooling operation of the RHR system. This internal inspection disclosed cracked tack welds between the valve disc and the stem nut.which permitted the disc to come loose on the valve stem.
Investigation An internal inspection of this valve and its companion valve M0-154-A indicated that the tack welds made between the disc and nut were of poor quality having minimal penetration and insufficient strength. This determination was made by the valve manuf acturer's representative. The defective tack welds were made ~in the valve manufacturer's facility.
Corrective Action Following the direction of the valve manufacturer's representative, the defective tack welds on both valves were ground off,'the valve internals were cleaned and inspected, and the valve reassembled. The internal inspection disclosed no damage to the seating surfaces within the valve.
During the re-assembly, welds between the not and disc were made using approved welding procedure. The weld consisted of a 3/8" fillet 6" long on each side of the nut.
This weld was dye penetrant inspected and. found to be acceptable.
The quality of the new tack welds is sufficient that future failures i
are not expected to _ occur. Following assembly, the valves were stroke tested.
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s Safety Implications The two vc1ves in question are normally open valves during reactor.
power operation. The valves are used primarily to control reactor level following a loss of coolant accident which automatically initiates the RHR system. These valves are also used to control RHR pump flow during shutdown cooling operations. Since the valves are' no rmally open during power operation, RHR system performance during a loss of coolant accident would not have been affected unless the valve disc and stem had become completely separated. Even if this occurred, it is postulated that the flow rate through the valve would push the loose disc out of the flow path with only a minor effect on total flow capability to the reactor vessel. Since there is no irradiated fuel in the vessel at the present time, this defect has no safety implications.
4 Very truly yours, j
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Asst. General Superintendent Generation Division MJC:kan cc:
Mr. J. P. O'Reilly Director, Region 1 United States Atomic Energy Commission 631 Park Avenue' King of Prussia, Penna.
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