ML20236C750

SER Supporting Util 880801 Request for Relief from ASME Code Pump & Valve Inservice Testing Program Requirements for Bearing Temp for Safety Injection Pumps

ML20236C750
Person / Time
Site:	Wolf Creek
Issue date:	03/09/1989
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20236C738	List: ML20236C737 ML20236C750
References
NUDOCS 8903220300
Download: ML20236C750 (2)

Text

a=

q' j ,w . -- -

gl w m: l pm'o g ' UNITED STATES 1

[_

G o NUCLEAR REGULATORY COMMISSION WASHINGTON D. C. 20055 i k ..... p SAFETY EVALUATION BY THE 10FFICE OF NUCLEAR REACTOR. REGULATION ly RELATED T0 RELIEF REQUEST NO. PR-14 FROM INSERVICE TESTING. PROGRAM WOLF CREEK. NUCLEAR OPERATING CORPORATION-WOLF. CREEK GENERATING STATION DOCKET N0. 50-482 ,

Background

In a letter dated August 1,.1988,.the licensee. submitted relief request PR-14 for the Wolf Creek Generating Station Inservice' Testing Program in accordance 1 with 10 CFR 50.55a(g)(5)(iii). The ASME Code requirement states that the safety injection pumps (PEM01A and B) bearing temperatures shall be measured

~

or observed and recorded (I W -3100). --The temperature of all centrifugal pumpi l bearings'outside the main flowpath shall be measured at points selected to be ,

responsive to changes in the temperature of.the bearing (IWP-4310). i l gcensee'sBasisforRelief l .a) Under normal operating conditions the only run' time for the Safety injec-tion (SI) Pumps is during the quarterly surveillance test. This. test runs' j the pump near its shutoff head with only 45 gpm miniflow. The~ test . )

duration is approximately 15 minutes. Paragraph IWP-3500 requires the pump be run until the bearing temperatures stabilize. Bearing temperatures are considered stabilized when three successive' readings taken at 10  !

minutes intervals do not vary by more than 3 percent. .This process' of l

measuring bearing temperatures would take approximately one hour. As:part ,

of the actions required by NRC Bulletin 88-04, " Potential Safety-Related.

Pump Loss", the pump vendor was contacte'd.to verify that current miniflow rates are sufficient to ensure that there will be no pump damage from low  ;

flow operation. The vendor indicated that the pump may be.run on the present minimum flow of 45 gpm for a period of time not to exceed'30 minutes with no noticeable degradation of. pump performance, b) The beering temperature cannot be measured directly. Measuring the temperature of the oil leaving the bearing is the only practical way to  ;

determine bearing temperature. The oil is cooled by component cooling water (CCW) which is cooled by service water. The temperature of CCW varies ~from 70' F to 100* F from winter to summer. Therefore, the oil temperature entering the bearing varies with the season.

4 c) Bearing temperature taken at ons-year intervals in accordance with-IWP-3300 provide little data toward determining the incremental degradation.of a bearing or providing any meaningful trend information.

d) The SI pumps are tested for vibration on a quarterly basis in accordance with IWP-4500. Vibration measurements are a significantly more reliable indication of pump bearing degradation than bearing temperature measurements.

8903220300 0 82)

PDR ADOCK pgug [g l P \

- - - - ~

h

)

1 In summary, other measurable parameters are more indicative of pump l performance and running the pump at low flows may actually be detrimental to pump performance. l Evaluation As stated by the licensee there is no direct means of measuring the pump bearing temperatures. An indirect means available to the licensee would be to infer bearing temperature by measuring the outlet lubricating oil system temperature. This measurement would be highly influenced by seasonal variations in temperature of the ultimate heat sink and would be an unreliable indication of bearing failure.

The staff believes that an unreasonable burden.would be placed on the licensee i if bearing temperatures were required to be measured. As stated by the licensee, i the ASME Code requires temperature stabilization over successive time intervals ,

before measurements can be taken. This process would require operating the l safety injection pumps for nearly one hour at miniflow conditions. Such actions would violate the pump vendor's recommendation that operation at miniflow conditions be limited to no more than 30 minutes and could, therefore, result in pump damage. This is significant because potential pump damage could degrade reliability of the safety injection pumps which, in turn, forms part of the emergency core cooling system.

Although alternative testing has not been proposed by the licensee, the ASME Code requires quarterly vibration testing. The staff believes that mcaitoring of vibration is a more reliable indication of pump degradation than temperature measurements.

l In conclusion, we have determined that the testing requirements are impractical for the safet 50.5Sa(g)(6)(y injection i), the pumps granting (PEM01A of relief and B) and, pursuant to 10 CFR is acceptable. '

principal Contributor- D. Pickett Dated: March 9, 1985' l

O I

l l

_ . - . ._ -