ML20196K969

Forwards Relief Request PR-11 from Inservice Testing Program Requirements for Fuel Pool Coolant Pumps

ML20196K969
Person / Time
Site:	Wolf Creek
Issue date:	06/29/1988
From:	Withers B WOLF CREEK NUCLEAR OPERATING CORP.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
WM-88-0169, WM-88-169, NUDOCS 8807070183
Download: ML20196K969 (4)

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W$LF CREEK

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NUCLEAR OPERATING CORPORATION Bart D. Wahors President and June 29,1988 WM 88-0169 U. S. Nuclear Regulatory Commission ATTH:

Document Control D Mail Station PI-137 Washington, D. C. 20555

Reference:

VM 88-0100 dated April 14, 1988, from B. D. Withers, WCNOC to NRC

Subject:

Docket No. 50-4 82 :

Pump and Valve Inservice Testing Program Relief Request Gentlemen:

The referenced letter submitted relief request PR-ll in response to the Staff's SER for the Ins e rv ic e Testing ( IST)

Program for Wolf Creek Cenerating Station.

The attachment to this letter provides additional in fo rma t ion for relief requcer PR-ll as requested in a telephone conversation with the NRC.

Revision bars in the margin denote the areas of change.

A copy of this response is also being provided to dr. H. C. Rockhold of EC&C

Idaho, Inc.

If you have any ouestions concerning this submittal, please contact me or Mr. O. L. Maynsta of my staff.

Very truly yours, Bart D. Withers President and Chief Executive Officer Bt W/j ad Attachment c c t.

B. L. Bartlett (NRC), w/a D. D. Chamberlain (NRC), w/a R. D. Hartin (NRC), w/a T. K. McLellan (NRC), w/a f0I P. W. O'Connor (NRC), w/a (2)

11. C. Rockhold (EC&G), w/a "O. Box 411/ Burlington, KS 66839 / Phone: (316) 364-8831 8807070183 880629 PDR ADOCK 05000482 M EW Opwwy EW M DCVET P

PNU

Attachment to WM 88-0169 Page 1 of 3 RELIEF REQUEST NO. PR-ll PUMPS:

PEC01A and B, Fuel Pool Coolant Pumps.

CLASS:

ISI Class 3 TEST REQUIREMENT:

The allowable ranges of inservice test quantities in relation to the reference values are tabulated in Table IWP-3100-2.

This table limits the accer'.able performance of each pump dependent variable (flowrate or dif ferential pressure) to a maximum of 103 percent of the respective reference value.

If the Test Parameter should exceed this

limit, it shall be declared inoperative and removed from service.

(IWP-3200)

BASIS FOR RELIEF:

The requirement to de: Late a pump inoperative when a Test Parameter exceeds the reference value by 3 percent in nor tachnically justified, sound engineering judgement, nor acceptatle plant operating practice for the following reasons:

- Indiscriminate 1y dec larir g Safety System Pumps inoperative results in excessive and unneeded testing of other plant Sa f e guard Systems and Components.

Such testing could altimat.ly detract from the overall reliability of the Pi tnt Sa fety Systems.

In additios, unwarranted testin, unnecessarily adds to the burden of the i'peraticns Force and dilutes efforts focused on the oerformance of their primary duties. Also, Operator. are stbjected to additional, and unnecessary radiatici expos 2re.

- The case where a Test Parsmeter exceeds the re f e re nce value is not necess rily indicative of pump degradation.

It may aerely signify that the r e f e re r.c e value is probably at the lower side of the statistical scatter of the test data and the specific test in question is on the uppe r side. Note that the reference values are subj!c to the same elements of statistical error assoc ated with any other individual test.

Attachment to WM 88-0169 Page 2 of 3 RELIEF REQUEST NO. PR-11 (continued)

- The 3 percent limitation is overly restrictive when com pa red to the accuracy of the instrumentation used to gather the test data. Analysis has shown that, in order to consistantly remain below the 3 percent limit, Instrument Loop accuracies in the range 0.5 to 0.75 percent would be required.

This presents a significantly more restrictive requirement than that established by Paragraph IWP-4110 (+2 percent).

Pnwa r Plant Aparetir.; Oystems are not configured in a manner that provides the laboratory-type conditions demanded to meet the repeatability implied by the 3-percent restriction.

Several of the tests require throttling with large Gate or Butterfly Valves using remote manual control.

'thus, non-quantifiable System Flow conditions are created that are certain to affect measured test quantities.

- To ensure the re f e rence values do not reflect operations at the lower end of the performance l

spectrum and,

thus, ultimately be reflected in i

frequently exceeding the upper performance limits as a

result of instrument d ri f t,

all related l

instrumentation is calibrated on a frequent basis.

- This requirement provides no additional measure of reliability to the equipment.

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- When the upper limits are exceeded, the nnly l

reasonable way of correcting the inoperative l

condition is to conduct an analysis to ensure that the pump is iideed operable and capable of meeting its intended function.

When this is done, in l

accordance with Subarticle IWP-3230(c),

a new I

referenco value must be c-' ablished.

Due to the test cer.ditions and methods of t sting at WCCS, any change in the reference point eliminates the correlation of future test results with past pump pe r f o rmanc e.

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Because, the usefulness of any past data in l

determining a

trend for pump performance is essentially eliminated a primary goal and basis for l

the Inservice Testing Program could be jeopardized.

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d Attachment to WM 88-0169 Page 3 of 3 RELIEF REQUEST NO. PR-11 (Continued)

- The design minimum flow for worst case condition in the spent fuel pool is 32,500 gpm.

This flow rate correlates to the actual test flow.

The system design feature used to compensate for pump degradation is the pump discharge valve.

This valve is presently throttled approximately 2/5 open.

As pump flow and differential pressure degrade with

wear, the valve will be adjusted to maintain the minimum flow.

- The pump vendor (Could) stated that only the following two plausible situations would result in a dramatic drop in pump head:

1)

A loss in suction pressure causing the pump to go into "full cavitation".

2)

Improper setting of the impeller clearance after pump maintenance.

On this model of pump, the suction clesrance is crucial to pump performance.

Both of these situations are unaffected by "time in service" or pump wear.

The vendor has no information, either experience based or from test

data, to indicate that catastrophic failure in pump performance is likely after d eg rad at ion of approximately ten percent.

ALTERNATE TESTING:

Pumps will be tested in accordance with Subsection IWP with the following exceptions a)

The required act ion range (HIOH) will be above a value equal to 108 percent of the reference value for test quantities flowrate and differential pressure; and b)

The Alert-range (HIGH) will be above a value equal to 105 percent of the reference value for test quantitles of Flow Rate and differential pressure.