ML20090D386

Ro:On 730630,during Routine Surveillance Testing,Core Spray Differential Pressure Instruments Read 8.3 Psid or 3.3 Psid Above Instrument Check List.Caused by Instrument Drift. Calibr Cycle Will Be Increased to Every 2 Wks

ML20090D386
Person / Time
Site:	Nine Mile Point
Issue date:	07/06/1973
From:	Schneider R NIAGARA MOHAWK POWER CORP.
To:	Skovholt D US ATOMIC ENERGY COMMISSION (AEC)
References
5366, NUDOCS 8302280051
Download: ML20090D386 (2)

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NI AGARA MOH AWK POWER CORPORATIO N NIAGARA MOHAWK 300 ERIE BOULEVARD WEST Q g SYR ACUSE,N Y e3202 4

July 6, 1973 f

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JUL 1 1 1973> 1

' L- U.S. Aicmc matGy Mr. Donald J. Skovholt N'iSj8 ,

Assistant Director for Reactor Operations c3  % Sectes Division of Reactor Licensing d United States Atomic Energy Commission D A Washington, D. C. 20545

Dear Mr. Skovholt:

Re: Provisional Operating License: DPR-17 Docket No.: 50-220 This letter is to report a condition relating to the operation of Nine Mile Point Nuclear Station, Unit #1, in which, during routine surveillance testing the core spray differential pressure instrumentation (Barton 288-4802S3) was found to read higher value than that as set forth in the instrumentation surveillance check list. Technical Specification 4.1.4. (d) states:

" Core spray header AP Instrumentation" Check once/ day Calibrate once/3 months Test once/3 months On June 30, 1973 at 0100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> during routine surveillance testing both of the core spray differential pressure instruments were found to be reading 8.3 psid or 3.3 psi above the value as stated in the instrument surveillance check list, (5 psid) . This is the first deviation from the procedural accepted value of 5 psid. Notification was made to Mr. Brickly, Region I, Division of Regulatory Operations on June 30, 1973. These switches are designed and intended to provide an alarm only and de not have a protective circuitry function.

As a portion of the daily activities for the plant operators, they are required to read the dial indicator of the core spray differential pressure in the north inst rument room (E l . 237 ') . If these dial indicators had reached 5 psid or above (the alarm limit) it would have been recorded and thus awareness of an abnormal condition in the core spray header would be made known to Station Supervision that same day. g The primary function of the core spray differential pressurf. indicators is to monitor the condition of the core spray piping between the reactor vessel wall and the shroud inside the reactor vessel. As a consequence if ever the core spray piping between the reactor vessel wall and the shroud should suffer a loss of integrity the differential pressure instrument would read essentially recirculation pump differential pressure. Under normal power operating conditions the recirculation pump differential pressure would be in the range of 20-25 ps'd.

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, ,Mr. Donmid J. Skoi ,1t 's- July 6, 1973 U.3. Atomic Enargy Commission Therefore even had the integrity of the piping suffered a loss an alarm would have been sounded in the control room.

To prevent reoccurrence of this problem the cycle of calibration will be increased to every two weeks for a month. If no instrument drift problems occur during this increased surveillance the technical specification surveillance schedule will be reinstated.

It is therefore concluded that no undue hazard was present to the general public as a result of this procedural deviation from set point.

Very truly yours, Original signed by - R.R. Schneider Rudolph R. Schneider Vice President - Electric Operations RRS:cm a

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