ML17055D724
| ML17055D724 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 03/29/1988 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17055D725 | List: |
| References | |
| NUDOCS 8804050207 | |
| Download: ML17055D724 (4) | |
Text
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UNITEDSTATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ItISERVICE TESTING PUMP TEST RELIEF NINE MILF. POINT NUCLFAR POWER STATION, UNIT NO.
1 DOCKET N0..50-220 V
INTRODUCTION
~
By letter dated July 8,'987, Niagara Mohawk Power Corporation submitted a
pump test relief request for the Inservice Testing Program for its Nine Mile Point Nuclear Station Unit 1 (NMP-1).
The requested relief will permit NMP-1 to measure the reactor liquid poison pump vibration instead of bearing temperature.once per year.
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~ ~ 4 DISCUSSION There are two high-pressure positive displacement liquid poison pumps in the NMP-1 plant.
Their function is to inje'ct a pre-determined amount "of concentrated boron solution into the reactor core within the required time in the event of
. massive control rods failure.
Each of the two'umps has the capacity to achieve
~ the. design objective by itself.
NMP-1 conducts monthly flow testing on these pumps at present.
Each pump is used to circulate demineralized water through a test tank.
The discharge pressure
':is controlled to 1275 psig by manually throttling a gate valve.
Bearing temp-eratures are measured during the annual flow test as required by IWP-3500(b) of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code Section XI.
Since the volume of the test tank is relatively small, the heat up rate of the pump fluid exceeds the rate allowed for bearing temperatures to stabilize.
The bearing temperatures thus increase with the fluid temperature and cause the pumps to run for the maximum test time of 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
The high fluid temperature also jeopardizes the integrity of pump.packings.
NMP-1 is proposing an alternative testing method by measuring bearing vibration instead of bearing temperatures.
Vibration measurements will.be taken in the outboard horizontal', vertical and axial directions as well as the inboard horizontal and vertical directions on a monthly basis.
The inboard axial direction is inaccessible for measurement.
The purpose of measuring bearing temperature is'o determine the degree
'o' bearing deterioration and degradation caused by.service.
They usually are more detectable toward the end of the service life.
By measuring vibration, however, more information can be revealed about the bearing condition.
The American Society of Mechanical Engineers Operation Im Maintenance Working Group 6
(OEM 6)
Standard established a set of rules for the vibration measurement and its acceptance criteria.
This set of rules should be used as guidance for the proposed alternative method.
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The alternative testing method proposed by NMP-1 would provide, under ideal conditions, comparable information about bearing deterioration and degradation caused by s~ervice.
In this case, the alternative testing method will provide better results for pump testing and also protect pump packings for better service.
The staff deems it acceptable when the OEM 6 acceptance criteria is used and recommends the requested relief be granted on that basis.-
CONCLUSION
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Based'n the review summarized
- herein, we conclude'h)t.'the..rely'ef'ma'y. b'e -,
qranted and pursuant to 50.55a(3)(i),
the propo'sed.'alternative, wil'1 provide an acceptable level of quality and safety.
PRINCIPAL CONTRIBUTOR'.
Shaw
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