ML20137Z772

Submits Methods Used to Determine That MSIV Air Pilot Valve Temp Limit of 170 F Not Exceeded & That Valve Operable.Data Trend Sheets Encl.Data Will Be Recorded Until Air Pilot Thermocouple Repaired

ML20137Z772
Person / Time
Site:	Dresden
Issue date:	03/07/1986
From:	Scott D COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
86-164, NUDOCS 8603130118
Download: ML20137Z772 (7)

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n1 March 7, 1986 g , i DJS LTR: 86-164 James G. Keppler . Region III, Regulatory Operations U.S. NRC i 799 Roosevelt Road Glen Ellyn, Illinois 60137 4

Subject:

Alternative Methods of Verifying that the 2-203-1B Main Steam 3 Line Isolation Valve (MSIV) Air Pilot Valve Temperature is Less j Than 170*F ,

Dear Mr. Keppler:

On March 3, 1986 the 2-203-1B Main Steam Isolation Valve (MSIV) air pilot valve temperature thermocouple failed upscale. On March 5, 1986 , I a conversation to determine what alternative methods would be used in ' verifying that the 2-203-1B MSIV air pilot valve temperature is below  ; i Technical Specification 3.7.D.4 limit of 170*F and that the 2-203-1B MSIV is operable was conducted with Lelnard G. McGregor, NRC Senior Resident Inspector, Dresden Station, John Achterberg, Technical Staff Supervisor, John Almer, Unit 2 Operating Engineer, and per conference i call, Dwayne C. Boyd, Section Chief. Section 2D of the NRC. 1 The following methods were agreed upon as being sufficient in deter-mining that the temperature limit of 170*F has not been exceeded, and that the 2-203-1B MSIV is operable: ,

1) Once per shift obtain and record:

I 4 a) The 2-203-1A, IC and ID MSIV air pilot valve temperatures ! in order to determine the ambient temperature adjacent to ! the 2-203-1B MSIV air pilot valve. ' I b) The 2-203-1B MSIV surrounding air temperature in order no determine if the valve stem packing is leaking and conse-quently increasing the MSIV air pilot valve temperature. < 2) Continue to perform Dresden Operating Surveillance (DOS) 250-1, "10% Closure Test of Main Steam Isolation Valves" twice per week in order to verify that the 2-203-1B MSIV air pilot valve is operable by actually cycling the valve to a partially closed position. 860313011g g4,0307 . PDR ADOCM 0300001o S PDR -{ f ( i MAR 101986

James G. Keppler March 7, 1986 Page 2

3) Once every two weeks the Instrument Maintenance Department will obtain:

a) The 2-203-1B MSIV pilot temperature by applying a 60 volt DC source of power to the thermocouple. In doing this, the oxide that might have accumulated on the sensing tip of the thermocouple will be burned of f long enough to give an accurate temperature reading. In addition, the thermo-couple resistance will be etasured. This shocking technique was performed on 3-3-86 and 3-5-86. On 3-5-86 the'as found resistance reading of the 2-203-1B themocouple was 330K ohms (indicating either an open cir-cuit or oxide build-up on the thermocouple sensing tip), after shocking the resistance fell to 156.6 ohms and the resulting temperature reading was 129'F. b) The 2-203-1A MS1V pilot temperature and resistance use this as a reference for item 3a. On 3-5-86 the measured resistance of the 2-203-1A thermo-couple was found to be 157.2 ohms, with a corresponding temperature reading of 125.5'F. These measurements match very closely with those taken in item 3a, therefore assuring the accuracy of this method.

4) The Technical Staff Systems Group will record and trend the above data along with the following:

a) The daily drywell_ air sample activity. This will be done in order to detect any steam leaks or reactor water leakage that may increase the MS1V temperature. b) The drywell unidentified leakage rate. This will also be done to detect any reactor water leakage that may increase the MS1V temperatures. Dresden Station believes that trending the data as seen in the attached tables provides sufficient indication that the temperature is below the Technical Specification 3.7.D.4 limit of 170*F for the 2-203-1B MSIV. Steps 3.A and 3.B for shocking the degraded thermocouple will continue 8-as stated, however, if the reading becomes unreliable, as compared to the referenced thermocouple, then trending data vill assure the 2-203-1B MSIV pilot valve operability.

James G. Keppler March 7, 1986 Page 3 A copy of the data trend sheets is being submitted for your review. Data will be recorded and trended daily until the 2-203-1B MSIV air pilot temperature thermocouple can be repaired during the upcoming Unit 2 snubber inspection short outage. Sincerely,

                                                          . :at D. . Scott Station Manager Dresden Nuclear Power Station DJS:JL:hjb Enclosures cc: J. Lizalek                                                                                                                                        I J. Achterberg J. Williams J. Almer L. McGregor D. Boyd D. Booth File /NRC l                                                             File / Numerical I

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MSIV PILOT TEW S (*F) DATg. 2-24-86 2-25-86 2-26-86 2-27-86 2-28-86 3-1-86 3-2-86 3-3-86 3-4-86 la MSIV 121. 123 125 122 122 123 123 121 132-15 MSIV 125 123 125 125 124 122 124 -- -- IC MSIV 118 118 119 117 119 118 118 118 116 ID MSIV 143 145 145 146 145 140 140 141 140 MSIV TEMPS (*F) DATE: 2-24-86 2-25-86 2-26-86 2-27-86 2-28-86 3-1-86 3-2-86 3-3-86 3-4-86 la MSIV 13 MSIV 140 139 138 139 140 IC MSIV ID MSIV CORGEENTS: 120lb

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