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Forwards Addl Info Re Methodology Used in Differential Pressure Switch Setpoint Characterization Test Program,Per 860718 Meeting.Test Results Concluded That 24 H Sufficient to Observe Full Static Pressure Error Effect for Switches
	ML20207G963
Person / Time
Site:	LaSalle
Issue date:	07/21/1986
From:	Turbak M; COMMONWEALTH EDISON CO.
To:	Harold Denton; Office of Nuclear Reactor Regulation
References
	1883K, NUDOCS 8607230264
	Download: ML20207G963 (9)
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_ Edison 72 West Adtms Street, Chic?go, Illinois

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'# Address Riply to: Post Offica Box 767 3'

Chicago, Illinois 60690- 0767 July 21, 1986 Mr. Harold R. Denton U.S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington, DC. 20555

Subject:

LaSalle County Station Unit 2 Additional Information Regarding Anomalous Behavior of Differential Pressure Switches NRC Docket No. 50-374

Dear Mr. Denton:

At a meeting with your staff on July 18, 1986, Commonwealth Edison was asked to supply additional information concerning the methodology used in the Differential Pressure Switch Setpoint Characterization Test Program. Specifically, your staff requested information used in ascertaining the time interval necessary to achieve the full effect of the apparent shift in the trip point of the SOR differential pressure switches. To obtain this data, a series of tests were conducted to measure the static pressure shift over various time intervals. Four switches were tested over periods of time longer than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months by holding them at elevated static pressures, and then cycling them every 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

From these tests, it was concluded that 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months was sufficient to observe the full static pressure error effect for the SOR differential pressure switches. Copies of the test results for periods of time greater than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months are attached to this letter.

Based on these results, all further time effect testing in the Setpoint Characterization Test Program was performed using a 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months time interval.

Very truly yours,

'y 3 C es .

S. Turbak A.

Operating Plant Licensing Director

/klj cc: R. Bernero T. Bournia Resident Inspector-LaSalle 1883K 8607230264 860721 j PDR ADOCK 05000374 p PDR- g )

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LASALLE S.O.R. DIFFERENTIAL PRESSURE SWITCH SETPOINT CHARACTERIZATION TEST PROGRAM METHODOLOGY USED TO DETERMINE THAT 24 HOURS IS SUFFICIENT TIME NECESSARY TO ACHIEVE FULL STATIC PRESSURE EFFECT In the LaSalle Setpoint Characterization Tests for acertaining the time interval necessary to achieve the full effect of the apparent shift in trip point of the S.O.R. differential pressure switches, a series of tests was conducted to measure the static pressure shift over various time intervals.

As described in Section V of the report, " Report of Investigation of Static "O" Ring Differential Pressure Switches," the switches labeled as

" Spare B203 Serial number 86-1-3269," "2B21-N024B," "2B21-N024D," and "2B21-N038A" were tested over various periods of time longer than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months by holding them at elevated static pressures, and then cycling every 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

This approach was taken because the type of phenomenon observed was likely related to the deformation of an elastomeric O-Ring after being exposed to high pressures over periods of time. Therefore cycling the switch at increments of 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months intervals without reducing the static pressure would not result in a reformation of the O-Ring toward its original shape.

As a confirmation to this hypothesis, one switch was allowed to go through multiple pressurizations at time intervals of 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , 48 hours5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months , and 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months while sitting undisturbed at elevated static pressure. In this test, the switch was held at elevated pressure for 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , and readings were taken.

Then the switch was allowed to relax and later was pressurized for a period of 48 hours5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months . Finally, the switch was allowed to relax for another interval, and was then pressurized for a period of 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months . In the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months period test, the switch showed a 2.95" W.C. static shift error. After the 48 hour5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months time interval, the switch exhibited a 3.25" W.C. shift (within the ILmits of measurement error of .7" W.C.) and finally after the 36 hour4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months test, the switch exhibited only a 2.63" W.C. shift. Prior to the first 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months test, the switch had been calibrated and set at 63.3" W.C. It was not adjusted again until after all time tests were completed.

From the above, it was concluded that 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months was sufficient to observe the full static pressure error effect for the SOR differential pressure switches. Copies of test results for periods of time greater than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months are attached. Based on these results all further testing was performed a 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months time interval.

Document 40471

4 STATIC-0-RING DIFFERENTIAL PRESSURE SWITCH DPERABILITY TEST DATA TIME TESTS - 24 HRS, 36 HRS, 48 HCS LASALLE COUNTY STAT 10N SWITCH TAG NO: LS-2B21-N036A TEST IATE: SEE TEST RESULTS BELOW SERIAL NUMBER: 85-1-2376 FUNCTION: FEACTOR VESSEL LEVEL 3 ADS MOLEL NO: 103AS-B212-NI-CIA-JJTTI6 PERMISSIVE

- ADJ FANGE: 7-100' W.C.

DESIRED SET PT.: 63.15

W.C. CORRESPUNDING TO: +13.4' REACTOR WATER LEVEL l

TECH SFEC NCM. S.P.: 63.78'W.C. CCRRESPONDIN6 T0: +12.5' REACTOR WATER LEVEL TECH S?EC LCO: 64.64' W.C. CORRESPONDING T0: +11.0' REACTOR WATER LEVEL AS-LEFT SETTING: 63.3* W.C.

AS-LEFT RESET: 54.5' W.C.

! EXISTING INSTRUMENT ALLCWAELE TOLERANCE BAND UFFER LIMIT: 63.78' W.C.

) EIISTING INSTRUMENT ALLOWABLE TULERANCE EAND LDhER LIMIT: 62.51' W.P.

i TIP.E TESTS - 24 HRS, 48 HRS, 36 HRS 07-01-86 ISET FOINT l RESET l l 'W.C. 'W.C. !

CYCLE 1 66.25 56.49 1000 PSIS ! 66.31 56.55 :

1ST 24 HRS i 64.92 1 56.49 l 07-03-66 ISET POINT l RESET :

'W.C. : 'W.C. :

j CYCLE 1 l 66.56 : 58.25 l j 1000 PSIS : 66.25 : 50.06 :

! IST 48 HRS 66.12 57.81 :

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l CYCLE 1 l 65.93 1 57.62 :

' 1000 PStB 65.93 58.00 1 4 IST 36 HRS : 65.93 1 57.87 :

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l STATIC-0-RING DIFFERENTIAL PRESSURE SWITCH OPERABILITY TEST DATA TIME TESTS LASALLE COUNTY STATION SWITCH TAG NO: LS-2B21-N024B TEST DATE: SEE TEST RESULTS BELOW SERIAL NUMBER: 85-1-2370 FUNCTION: REACTOR VESSEL LEVEL 3 ALARM MODEL NO: 103AS-B212-NI-CIA-JJTTI6 ADJ RANGE: 7-100' W.C.

DESIRED SET PT.: 63.15

W.C. CORRESPONDING TO: +13.4' REACTOR WATER LEVEL TECH SPEC NOM. S.P.: 63.78' W.C. CORRESPONDINGTO: +12.5' REACTOR WATER LEVEL TECH SPEC LCO: 64.84' W.C. CORRESPONDING TO: <!!.0" REACTOR WATER LEVEL AS-LEFT SETTINB: 63.2' W.C.-TEST 1 / 63.0" W.C.-TEST 2 AS-LEFT RESET: 56.0" W.C.-TEST 1 / 55.7' N.C.-TEST 2 EIISTING [NSTRUMENT ALLOWABLE TOLERANCE BAND UPPER LIMIT: 63.78' N.C.

EIISTINS INSTRUMENT ALLOWABLE TOLERANCE BAND LOWER LIMIT: 62.51' W.P.

TIME TESTS - 24 HRS TEST 11 l SET POINT i RESET l 06-23-86 i 'W.C. i 'W.C. I l_ ..l. .. ... I 69.21 i 54.25 i 1000 PS!6 1 69.13 ! 54.17 !

IST 24 HRS l 68.90 $4.17 l TEST 82 ISET PulNT l RESET I 06-26-86 i 'W.C. i 'W.C. I

! l... .I l 69.45 ! 53.07 i

, 1000 PS!6 I 67.48 I 52.91 1 AT 24 HRS I 67.32 53.07 i 1 TEST 82 ISET POINT I RESET I 06-27-86 i 'W.C. I 'W.C. I I ! .... I I 69.53 i 60.39 !

1000 PS16 I 68.11 1 62.52 :

AT 48 HRS : 65.43 1 61.81 I

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STATIC-0-RING DIFFERENTIAL PRESSURE SWITCH OPERABILITY TEST DATA TIME TESTS - 24 HRS, 36 HRS LASALLE COUNTY STATION SWITCH TA6 NO: LS-2821-N024D TEST DATE: SEE TEST RESULTS BELOW SERIAL NUMBER: 85-1-2374 FUNCTION: REACTOR VESSEL LEVEL 3 ALARM MODEL NO: 103AS-8212-NI-C1A-JJTT16 ADJ RANGE: 7-100' W.C.

DESIRED SET PT.: 63.15 ' N.C. CORRESPONDIN6 70: +13.4' REACTOR WATER LEVEL TECH SPEC NOM. S.P.: 63.78' W.C. CORRESPONDING TO: +12.5' REACTOR WATER LEVEL TECH SPEC LCO: 64.84' W.C. CORRESPONDIN6 TO: +11.0' REACTOR WATER LEVEL AS-LEFT SETTIN6: 63.5' W.C.

AS-LEFT RESET: 58.7' W.C.

EIISTING INSTRUMENT ALLOWABLE TOLERANCE BAND UPPER LIMIT: 63.78' W.C.

EXISTING lhSTRUMENT ALLOWABLE TOLERANCE BAND LOWER LIMIT: 62.51' W.P.

TIME TESTS - 24 HAS, 36 HRS 06-30-86 l SET POINT l RESET I 'W.C. ! 'W.C. l I..-- _.I.......... !

CYCLE 1 65.49 59.51 1000 PSIG 65.18 59.07 l AT 24 HRS : 65.05 l 58.94 l 07-01-86 ISET POINT l RESET I 'W.C. ! 'W.C. l l l .I CYCLE 2 1 65.87 l 59.76 l 1000 PS!6 1 65.49 I 59.51 :

AT 36 HRS I 65.37 ! 59.57!

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STATIC-0-RIN6 DIFFERENTIAL PRESSURE SWITCH OPERABILITY TEST DATA BENCH TEST-TIME 3269 f

LASALLE COUNTY STATION SWITCH TA6 NO: SPARE B203 TESTDATE: SEE INDIVIDUAL TESTS BELOW SERIAL NUMBER: 86-1-3269 FUNCTION: REACTOR VESSEL LEVEL 3 ALARM MODEL h0: 103AS-8203-NI-CIA-JJTTI6 (POSSIBLE)

ADJ RAN6E 20-200' W.C.

DESIRED SET PT.: 63.15

W.C. CaliRESPONDIN6 TO: +13.4' REACTOR WATER LEVEL ,

TECH SPEC NOM. S.P.: 63.78' N.C. CORRESPONDING TO: +12.5" REACTOR WATER LEVEL TECH SPEC LCO: 64.84' W.C. CORRESPONDIN6 TO: +11.0' REACTOR WATER LEVEL AS-LEFT SETTIN6: 63.1" W.C.

AS-LEFT RESET: 57.6' W.C.

EXISTING INSTRUMENT ALLOWABLE TOLERANCE BAND UPPER LIMIT: 63.78' W.C.

EIISTING INSTRUMENT ALLOWABLE TOLERANCE BAND LOWER LIMIT: 62.51' W.C.

TIME TESTS - 24 HR, 49 HR, 72 HR 06-25-86 l SET POINT l RESET !

! 'W.C. I 'W.C. !

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CYCLE 1 ! 68.50 l 59.53 l 1000 PSIS l 68.11 l 59.53 AT 24 HRS : 68.03 : 59.37 i 06-26-86 ISET POINT RESET '

l 'W.C. I *;;. i.. !

CYCLE 2 1 68.90 1 59.84 i 1000 PSIS I 68.50 1 59.69 :

AT 48 HRS I 68.43 i 59.53 I 06-27-86 ISET POINT I RESET i

! 'W.C. ! 'W.C. I l .... .. l . .I CYCLE 3 1 68.74 1 59.69 1 1000 PS!6 1 68.50 1 59.61 1 AT 72 HR$ ! 68.43 1 59.37 !

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70 0 24 48 72 Hours Note: B Hours tested at B psig Note: Vertical l ine r epresent s adjustment All others tested at 1602 psig for test rig di fferences

ML20207G963

Text

Subject:

Dear Mr. Denton:

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