ML20040G888

Requests Exemption from 10CFR50,App R,Section III.0,oil Collection Sys for Reactor Coolant Pump

ML20040G888
Person / Time
Site:	Big Rock Point File:Consumers Energy icon.png
Issue date:	02/09/1982
From:	Bordine T CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	Crutchfield D Office of Nuclear Reactor Regulation
References
OC0282-00090142, OC282-90142, NUDOCS 8202160582
Download: ML20040G888 (9)

Text

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Consumers Power Company oeneral offices: 212 West Michleen Avenue, Jackson, MI 49201 *(517) 788 o650 February 9, 1982

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RECE4VED FEB121987.> Q Dennis M Crutchfield, Chief

' 88 %""T Operating Reactors Branch No 5 6

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Nuclear Reactor Regulation US Nuclear Regulatory Commission 4

d' Washington, DC 20555 DOCKET 50-155 - LICENSE DPR BIG ROCK P0' TNT PLANT - REQUEST FOR AN EXEMPTION FROM 10 CFR 50 APPENDIX R, SECTION III.0 NRC letter dated November 24, 1980 transmitted a revised Section 50.48 and a new Appendix R to 10 CFR 50 regarding fire protection features of nuclear power plants. The new 10 CFR 50.48 defines specific actions to be taken by all licensees and invokes a number of specific design requirements as detailed in Appendix R.

For the Big Rock Point Plant, the portions of Appendix R which thereby became applicable are Sections III.G, Fire Protection of Safe Shutdown Capability; III.J, Emergency Lighting; and III.0, Oil Collection System for Reactor Coolant Pump. Consumers Power Company submittal dated March 19, 1981 provided brief descriptions and schedules for completion of those modifica-tions noted above.

A meeting held on July 28, 1981 at Big Rock Point with representatives of the NRC and the Brookhaven National Laboratory provided a first hand description of the location and functional operation of the safe shutdown capabilities proposed for the plant, specifically the requirements of 10 CFR 50 Appendix R, l

Section III.G.

During the July 28, 1981 meeting, discussions included Consumers Power Company's position that the installation of an oil collection system for the reactor coolant pumps is unnecessary. This letter expounds our position and formally requests an exemption from the provisions of 10 CFR 50 l

Appendix R,Section III.0, Oil Collection System for Reactor Coolant Pump.

l.

As noted in Consumers Power Company's letter dated March 19, 1981, Consumers Power Company made a commitment to install an oil collection system on the reactor coolant pumps. Upon further evaluation, however, we have concluded that the installation of a reactor coolant pump oil collection system is unnecessary for the reasons outlined below.

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D M Crutchfield, Chief 2

Big Rock Point Plant 10CFRSO App R, Sec III.0 p

February 9, 1982 The publication of Appendix R in the Federal Register dated November 19, 1980 included the Technical Basis for the requirement of an oil collection system.

This Basis derived from a review of all plants, does not reflect the actual situation at Big Rock Point. The following comparisons point out the differ-ences between the Technical Basis and Big Rock Point.

1.

The Basis states that a typical pump motor contains 140 to 220 gallons of lube oil. The BRP Motor contains only 31.75 gallons of oil, less than one quarter of that in a " typical" motor. This presents a relatively small fire hazard when compared to other plants.

The lubricating oil of the Reactor Recirculating Pump and its Motor is associated with the motor only as the bearings of the pump are water lubricated.

The motor is vertical with a lower steady bearing and an upper steady and thrust bearing. Each bearing has its own oil supply with the lower reservoir containing 7 quarts and the upper reservoir containing 120 quarts. The oil reservoirs of both bearings are part of the motor end bell housings which are cast iron and do not consist of bolted assemblies (as shown in Drawing A).

Oil cooling is associated with the thrust bearing oil only and is accomplished by a water cooling coil in the oil.

No oil is brought outside the motor housing for conditioning or cooling.

The only locations where the possibility of oil leakage could occur are at the drain plugs and oil level sight glasses for each oil area and the packing glands for the cooling water inlet and outlet to the oil cooler.

There is no oil pumping and except for fractures, there is no way oil can leak internally.

There is a low oil level switch for the lower reservoir and both a low and high oil level switch for the upper reservoir. These switches are independently annunciated in the Control Room. The low oil alarms will alert the operators of possible oil leakage whether or not there is an accompanying fire.

In addition, high temperature in the three bearings are annunicated in the control room. To a certain extent the high temperature alarms back up the low oil alarms; however, there will be a time delay.

2.

The Basis, in discussing why a sprinkler system was deleted as an alternative, states that the fire water supply system is not designed to withstand seismic events. At Big Rock Point, the fire system serves as the Emergency Core Cooling System, with the sprinkler supply coming directly off the core spray piping. The seismic competency of the fire system is being reviewed as part of the on-going Systematic Evaluation Program in conjunction with the Probabilistic Risk Assessment analysis.

Any seismic deficiencies associated with the core spray system will be resolved under these programs.

oc0282-0009a142

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D M Crutchfield, Chief 3

Big Rock Point Plant 10CFR50 App R, Sec III.0 February 9,1982 Consumers Power Company letter dated August 31, 1979 provided information on the location of recirculation pump area sprinkler heads, method of actuation and system design density. The sprinkler system provides complete coverage for a potential fire between the coolant pumps and sumps.

In addition, because the floor of the coolant pump room slopes toward the sumps (as shown by the reactor building drawing enclosed), the oil could only traverse from the coolant pumps to the sump areas.

Therefore, the potential fire path resulting from an oil leak is covered by the sprinkler system.

The primary basis for installing the Oil Collection System is to prevent an oil fire from affecting operability of safety-related equipment inside con-tainment. An analysis submitted June 15, 1979 to the NRC showed that a recirculation pump oil fire will not affect the operation of safe shutdown equipment located in this area. The anlysis assumed that the fire consumed all of the oil in one pump, with the only means of heat removal being the ventilation system. This is very conservative, as the pump room itself is a vast heat sink, the entire volume of oil cannot possibly leak out, and no credit at all is taken for sprinkler system operation.

Indeed, the only damage to be expected from a fire like this would be to the recirculation pumps themselves. Attachment 1 provides the calculations of the June 15, 1979 subm'_ttal which were performed to analyze the possible heat damage to the cabling and operators for the emergency condenser outlet valves and the main steam isolation valve caused by a fire at the recirculation pumps.

Furthermore, the installation of a seismically qualified Oil Collection System involves working in a high radiation area. A man-rem estimate for the instal-lation of the oil collection system was made with the best available data.

This estimate suggest that the installation would result in an exposure of 40 to 70 man-rem.

Maintenance on the reactor coolant pumps has on the average been 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> of labor every three years per pump. The resulting exposure rate is estimated to be.26 man-rem per year. The exposure rate most likely would double if an oil collection system would have to be disassembled and then reassembled each time work is performed on the reactor coolant pump motors.

If the oil collection system would have to be removed to replace the pump seals, an additional 40 man-rem per year is estimated.

The exposure rates above, however, are in addition to the.230 man-rem per year estimate received during the annual maintenance activities for the sprinkler system and heat detectors. The benefits to be gained by installing such a system do not justify the personnel radiation exposure that would occur during installation, do not fall under the policy of keeping personnel exposure as low as reasonably achievable, and appear to have no beneficial effect with respect to mitigation of the consequences of a seismic event.

As stated above, Consumers Power Company has made a commitment to install an oil collection system for the reactor coolant pump. Adhering to 10 CFR 50.48, installation _for the oil collection system is required for the 1982 refueling oc0282-0009a142

D 11 Crutchfield, Chief 4

Big Rock Point Plant 10CFR50 App R, See III.0 February 9, 1982 outage, scheduled to begin February, 1982. Although this exemption request is beyond that allowed by 10 CFR 50.48(c)(6) Consumers Power Company believes that the additional information developed during the design and evaluation of the oil collection system warrents an exemption. Therefore, Consumers Power Company concludes that an exemption to the requirements of 10 CFR 50, Appendix R, Section III.0 is both reasonable and appropriate.

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Thomas C Bordine Staff Licensing Engineer CC Administrator, Region III, USNRC NRC Resident Inspector-Big Rock Point Attachments oc0282-0009a142

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ATTACEME6'T 1 1

TEMPERATURE RISE DUE TO AN UNCONTROLLED FIRE Knovns and assumptions:

31.75 gallons of lube oil per pump 10h00 BTU /lb assumed, typical lube oil value 0.8 specific gravity of oil, _3sumed, typical lube oil value 3 volume of room, approximate f}/minventilationthroughroom 100,000 30,000 ft

.2h BTU /lboF specific heat of air 3/32 in/ min burning rate, assumed, value for kerosene 0.08018 lb/ft3 density of air 153 F average ambient temperature Three different fire situations result in the same rate of burning. They are:

2 1.

50 ft spill on fire burr 30.67 minutes 2.

A 3 gpm spray on fire burns 10.58 minutes, this results in a slightly greater rate of heat release than the spill.

3.

A 3 gpm leak falling on the hot pump cast g and igniting, burns for 10.58 minutes.

Find pounds of oil 8.33 lb/ gal for water X

.8 specific gravity 6.66 lb/ gal X 31.75 gal 211.h6 lbo of oil Find BTU content 211.L6 lb X 20h00 BTU /lb h,313,78h BTU 2

Find burn time for 50 ft spill 31.75 gal 3

7.h8 gal /ft h.24 ft3 of oil 3

h.2h ft of ogy 2

50 ft spill

.08 ft deep

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.08 ft deep X

12 in/ft 1 in deep

. 1 in deep 3/32 in/ min 2

'10.67 min barn time for 50 ft spill Find burn time for 3 gpm spray or leak 31.75 gallons of oil 3 gallons / min 10.75 minutes burn time for 3 cpm spray or leak Find temperature rise in room Find rate of heat release k,313,78h BTU content of oll 10.58 minutes burn time h07,730 BTU / min rate of heats release into room Find rate of heat removal s

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3 100,000 ft y 30,000 ft3 min s-3.33 min for 1 air change or 0.3 air removed / min 3

100,000 ft X.08018 lb/ft3 8018 lb of air

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8018 lbs of air X

.3 2405.h lbs remived/ min Assume a temperature rise 163 F

.2h BTU /lb F X 163 F 39.12 BTU /lb absorb by air

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,12h05.h lb/ min X 39.12. BTU /lb 9h,099.2 BTU / min rate of heat removal Find remaining heat released

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407,730 BTU / min I

- 9h,099 BT'J/ min f

313,631 BTU / min heating all the air 3

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8018 lb/ air X 39.12 BTU /lb s

313,66h BTU absorbed by air in 1 minute t

313,631 BTU / min released

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- 313,66h BTU / min absorbed 33 BTU / min The air heats to about 1630F above ambient.

Final temperature in room is 163 F

+ 153 F 316 F Valve operatcrs' qualified at 2h5 F 316 F

- 2h5 F 71 F above qualification temperature of valve operators and 18h F below ignition temperature of PVC cable r

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