ML20207J849

Part 21 Rept Re Potential Change in Allowable Operating Repeatability Ranges for 1E Qualified Series 9,8 & 1 Pressure Switches.Licensee Calibr Procedures Should Be Amended to Allow for Cycling (Hysteresis) Effects

ML20207J849
Person / Time
Site:	LaSalle
Issue date:	07/25/1986
From:	Engel R SOR, INC. (STATIC O-RING)
To:	Taylor J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
References
REF-PT21-86-335-000 PT21-86-335, PT21-86-335-000, NUDOCS 8607290272
Download: ML20207J849 (7)

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July 25, 1986 9

h(O Mr. J. Taylor Director of Inspection and Enforcement NUCLEAR REGULATORY COMMISSION Washington, D.C.

20555

SUBJECT:

10CFR21 NOTIFICATION, WIDER RANGE REPEATABILITY FIGURES FOR SOR 1E QUALIFIED SERIES 9,

8 AND 1 PRESSURE SWITCHES

Dear Mr. Taylor:

SCOPE This notification is to inform the NRC and the Licensees of a potential change in allowable operating repeatability ranges of SOR, Inc. gauge pressure switches with designators beginning with #9, 8 or 1 (i.e. :

9N6-B45-NX-C1 A-JJTTX6, 8N6..., etc. ).

The potential problem is isolated to 1E qualified pressure switches sold after January,1983.

The commercial grade switches will not exhibit this potential problem.

The phenomena yields a repeatability of 5% full scale.

The original design criteria and performance expectations were 1% full scale repeatability.

DISCUSSION LaSalle County Nuclear Power Station experienced an operating anomaly in February, 1986.

During this event, several gauge pressure switches did not actuate when other indications suggested they should have.

From this

event, LaSalle Station and the SOR factory performed an extensive investigation and testing prog ram.

As a result of this prog ram, it was i

demonstrated that the worst case set point repeatability of the existing i

switches can be five percent (5%) full scale.

This repeatability falls outside the expected values of the quoted figures.

The SOR Model 9N6-B45-NX-CI A-JJTTX6 is the specific switch in question.

Attached is a complete list of plants and models of the switches that are l

affected by this notification.

t The switches have shown no indications of failure and will continue to operate normally.

The switches at LaSalle had an adjustable range of 200 to l

1350 psig.

The set point exhibited a maximum change of less than 50 psig.

Analysis has shown that a 5% repeatability value exceeds the maximum expected shift.

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Page 2 July 25,1986 t

i Licensees should evaluate the application of the switches listed, if 5%

repeatability is acceptable, the installed switches will perform properly in the application.

The existing calibration data of the licensee should also be reviewed. Most switches in the field will have 1% repeatability and this data will give an indication of the -expected performance of the switch.

Once the switch exhibits a repeatability value, that individual switch will not change.

if the calibration data indicates 1% repeatability, its future performance will e

l remain within this parameter.

If calibration data indicates 5% repeatability, j

and the application requires better performance, SOR will replace the switch i

with a new switch capable of better than 11% repeatability.

)

The solution leading to improved performance consists of using a greater

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restriction in the tolerance control of two parts used in the switch in association with 100% inspection techniques.

SOR found the interplay l

between two parts manufactured on numerically controlled screw machines created greater operating forces when a material change was made to meet d

environmental qualification requirements.

The finish tolerance on the two parts allowed a tolerance buildup adverse to the repeatability.

By reducing j

the tolerance buildup, the operating characteristics are improved, i

The calibration procedures at the licensee should be amended to allow for

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cycling (hysteresis) effects.

Attached is a suggested calibration sequence l

for optimum set point accuracy of pressure switches.

Two procedures are i

required depending on the need for increasing or decreasing set points.

Many licensees have shown that they do not acknowledge the presence of this effect in their calibration procedures.

If additional questions need to be addressed, the factory contact may be either Jim Johnson or Russ Engel.

Should neither person be available, a j

message may be left with Sherry Dunlap and the request will be answered promptly.

SOR will be available to work with each licensee to determine the most appropriate method for solution to this possible problem.

Regards, l

st i

Russell

. Engel I

RCE:ms 072486-04/ms4 j

Attachments i

l cc: George Lanik - NRC/l f, E j

Roger Woodruff - NRC/l f, E j

J.T. Beard - NRC/NRR 4

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ATTACHMENT A Page 1 of 3 CAllBRATION PROCEDURE Purpose This procedure is a suggested sequence of steps to best achieve the proper set point on gauge pressure switches.

It is only one method, and it must be realized that each application is different thus often requiring a different series or sequence of steps and procedures.

For optimum switch performance, the calibration should closely approximate the "as used" pressure cycles.

Procedure j

1.

Determine the required set point.

If the switch actuation is required 1

on increasing pressure, perform Steps 2 through 9 and reference Sketch A.

If the switch actuation is required on decreasing pressure, perform Steps 10 through 18 and reference Sketch B.

l Increasing Set Points l

2.

Increase pressure to switch actuation.

Record pressure.

3.

Determine whether set point meets tolerance specifications.

4.

If required, recalibrate.

4A. Increase set point, or 48 Decrease set point.

t j

5.

Reduce pressure to zero.

l 6.

Repeat Steps 2 through 5 until set point meets tolerance.

7.

Increase pressure from zero to actuate switch.

Record pressure as "as left" set point.

8.

Decrease pressure to reset switch.

Record pressure as "as left" reset point.

9.

Reduce pressure to zero and return switch to service.

Decreasing Set Points 10.

Increase pressure to normal system operating pressure.

11.

Decrease pressure to switch actuation.

1 ATTACHMENT A Page 2 of 3 12.

Determine whether set point meets tolerance specifications.

13.

If required, recalibrate.

13A. Increase set point, or 138. Decrease set point.

14.

Increase pressure to normal system operating pressure.

15.

Repeat Steps 11 through 14 until set point meets tolerance.

16.

Decrease pressure to switch actuation.

Record pressure as "as left" set point.

l 17.

Increase pressure to reset switch.

Record pressure as "as left" reset point.

18.

Reduce pressure to zero and return switch to service.

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ATTACHMENT A Page 3 of 3 SKETCH A: CAllBRATION ON INCREASING PRESSURE SET PolNT h

PRESSURE p

p b

SET POINT RESET PolNT p

O PSIG CYCLE 1

. CYCLE 2 CYCLE N TIME

=-

)

CALIBRATION PolNTS p

FINAL 'AS LEFT~ SET P0lNT p

FINAL ~AS LEFT" RESET PolNT SKETCH B: CALIBRATION ON DECREASING PRESSURE SET PolNT n

PRESSURE NORMAL SYS.._

OPERATING PRESSURE RESET PolNT SET PolNT 0 PSIG CYCLE 1 CYCLE 2 CYCLE N CALIBRATION P0lNTS FINAL "AS LEFT' SET PolNT TIME

=

FINAL ~ AS LEFT" RESET P0lNT

~

ATTACHMENT _ B Paga 1 of 2 y

I i

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9. 8 & 1 l

SOR Order l

Customer / Plant Model Number Qty Purchase Order #

Number 1

i Bechtel/ Southern Cal. Ed. - San Onofre 9TA-BB45-NX-C1 A-JJTTX6 2

V4105083 54147A j

9TA-BB45-N X-C1 A-JJTTX6 4

V4105083 54147 Bechtel/ Houston Lighting & Power 1 N6-B B45-N X-CI A-JJTTX6 3

14926-4375 52041

{

1 N6-B B45-N X-C1 A-JJTTX6 3

14926-8375 52041 A

)

Carolina Power & Light - Brunswick 9TA-BB45-NX-C1 A-JJTTX6 3

220505AP 62993 Colt 9N6-B45-NX-CI A-JJTTX6 8

464549-0 47147 j

Colt 9N6-845-N X-C1 A-JJTTX6 2

468241-0 51416 I

Commonwealth Edison - La Salle 9N6-B45-NX-CI A-JJTTX8 4

287842 51098 9N6-845-NX-C1 A-JJTTX7 60 l

9N6-B45-NX-C1 A-JJTTX8 4

287842 51098 A i

9N6-B45-NX-CI A-JJTTX7 60

}

9 N6-B45-N X-CI A-JJTTX7 2

287842C 51098B

]

9N6-B45-NX-CI A-JJTTX6 6

297623 62741 3

9N6-B45-NX-C1 A-JJTTX8 1

302930 71788 l

9N6-B45-NX-C1 A-JJTTX7 1

9TA-B45-NX-C1 A-JJTTX7 18 295443 59042 Florida Power & Light Co.

I N6-B45-NX-CI A-JJTTX6 6

CO2635-70965C 76035 GPU - Oyster Creek 9N6-B45-NX-C1 A-JJTTX6 6

PP-033611 72405 9TA-BB45-NX-CI A-JJTTX6 5

9TA-B45-NX-C1 A-JJTTX6 10 9TA-B3-NX-CI A-JJTTX6 3

GPU - TMl 9TA-B45-NX-C1 A-JJTTX6 10 T P-006353 45008 l

l Niagara Mohawk 9TA-B B5-N X-C1 A-JJTTX7 4

NMP2-FPO-24065 67825 Northeast Utilities - Millstone 8N6-B45-NX-C1 A-JJTTX6 2

661864 48659 Southern Cal. Ed. - San Onofre 9TA-B B45-N X-CI A-JJTTX6 2

8 CON 5028 71550

ATTACHMENT B (Cont.)

Paga 2 of 2 Tai Power 9N6-645-N X-CI A-JJTTX4 10 2550 57539 Tennessee Valley Authority - Watts Bar 9N6-B B45-NX-C1 A-JJTTX6 4

85KLB-838106 66180 Toledo Edison - Davis-Besse 9TA-B4-N X-CI A-JJTT X6 3

064-0-82008 A-RH 51419 9TA-BBS-NX-CI A-JJTTX6 5

115-Q-92263B-RH 70651 9N6-B45-NX-CI A-JJTTX6 1

085-Q-90040 A-M B 67602 Vermont Yankee 9TA-B45-NX-C1 A-JJTTX6 5

22264 47462A

/

j;157 071686-01