ML20206T378

Requests Approval of Exemption from Requirement of 10CFR50, App R,Section III.0 Re Reactor Recirculation Pump. Recalculation of Temp Rise in Recirculation Pump Room Due to Oil Fire, Encl

ML20206T378
Person / Time
Site:	Big Rock Point File:Consumers Energy icon.png
Issue date:	07/01/1986
From:	Berry K CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	Office of Nuclear Reactor Regulation
Shared Package
ML20206T383	List: ML20206T378 ML20206T385
References
NUDOCS 8607080103
Download: ML20206T378 (3)

Text

.- > -

.. .o 2

CORSum8IS Power x,,,,,,,,,,,,,,,

av Ekensing 3 AIK m EAW5 PRBEAE55 Generet Othces: 1946 West Pernell Road, Jackson, MI 49201 e (517) 788-1636 July 1, 1986 l

Director, Nuclear Reactor Regulation

! US Nuclear Regulatory Commission Washington, DC 20555' DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT -

FIRE PROTECTION - RECALCULATION OF RECIRCULATION PUMP ROOM TDfPERATURE DUE TO AN OIL FIRE AND ADDITIONAL CLARIFYING INFORMATION By letter dated February 9, 1982, Consumers Power Company requested an exemp-

,f tion from the requirement of 10CFR50, Appendix R, Section 111.0 to install an i oil collection system on the reactor recirculation pump. This exemption i request included a calculation of the temperature rise in the Recirculation

, Pump Room due to a pump lubricating oil fire as additional supporting justifi-cation for the exemption. This calculation was found to be in error over the course of the NRC inspection conducted at the Big Rock Point Plant during the weeks of December 9, 1985, and March 5, 1986. Compensatory actions imple-mented at the Plant until this issue was resolved were specified in our letter dated March 14, 1986. Fy letter dated May 30, 1986, Consumers Power Company i

committed to submit a description of the corrective action resulting from a

recalculation of Recirculation Pump Room temperature rise due to an oil fire or, if no corrective action is found to be necessary (i.e., the original exemption request' remains valid), the recalculation would be submitted to the NRC by July 1, 1986. -

A recalculation has been performed and the results for the various cases considered supports the original exemption request. Furthermore, additional circumstances not previously specified in our exemption request have been identified which provide conclusive justification .for the exemption, i.e. ,

the redundant train of core spray (valves and cables) will remain free of' fire damage. The recalculation provided in Attachment 1 is considered approximate, e.g., the change'in the rate'of heat transfer to the concrete walls of the room was neglected,'and steady state heat transfer was assumed. The recalcu-lation methods were evaluated, however, and'the results are considered'to be conservative. The worst case peak temperature rise which occurs during the burn period of 10.85 minutes was calculated to be 238'F. This value, added to the initial room air temperature of 153*F, yields a peak temperature of 391*F, which is well below the ignition temperature of cables of interest (i.e.,

OC0686-0103-NLO2 8607080103 DR 860701 ADOCK 05000155; PDR f(

. s' Director, Nuclear Reactor Regulation 2 3

Big Rock Point Plant i Fire Protection - Recalculation and Additional Information July 1,' 1986 j i

j cables for the emergency condenser outlet valves and one train of core spray <

valves). Also, because of the short duration of the rise in air temperature l and the fact that the emergency condenser outlet. valves are located approxi-mately 40 feet above the recirculation pumps, we have concluded that the (

temperature of the motor operators for these valves will not reach the peak air temperature.

4

[ Should a Recirculation Pump Room fire render both'the emergency condenser i outlet valves and the one train of core spray' valves inoperable, then the redundant train of core spray valves located outside the Recirculation Pump Room would remain available for use. The cables associated with this redun-

dant train run in a cable tray that passes through a room that is adjacent to j the Recirculation Pump Room, and this room is connected to the Recirculation j Pump Room by two open doorways. Also, the ceiling of this room is approxi-

! mately 50 feet lower and the doorways are approximately 60 feet lower than the

ceiling of the Recirculation Pump Room. Therefore, an oil fire in_the Recir-l culation Pump Room would transfer its heat to the air and surfaces in that j room, and not to the air and surfaces in the adjacent room containing the cables for the redundant core spray valves. Since the Reactor Depressuriza-tion System, which is located outside the Recirculation Pump Room, and a train

of core spray valves will remain free of damage in the event of an oil fire in

! the Recirculation Pump Room, these systems will be available to safety shut-down the Plant.

. The following conditions t.lso support.the original exemption request and were-delineated in our letter of February 9, 1982.

f

! - There are two reactor recirculation pumps. Each pump motor contains i 31.75 gallons of lubrication oil, compared to a typical reactor pump motor which contains 140 to 220 gallons of oil.

' - The pump motor is vertical and has a lower steady bearing and an upper steady and thrust bearing (see the drawings'in Attachment 2).

Each bearing has its own oil supply with the lower reservoir contain-ing 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.

- Only the oil for the thrust bearing is cooled,.and this is accom-plished by a water cooling coil in the oil. No oil' is brought-outside the motor housing for conditioning or cooling.

l - The only locations where the possibility of oil leakage exists are at j the drain plugs and _oi!. level sight glasses for each oil reservoir, 7

and the packing glands for the cooling water inlet'and' outlet of the oil cooler.

- The lubricating oil is not pumped so that 1) except for fracture, the oil cannot leak internally, and 2) no spraying (atomizing) of the oil outside.the housing can occur.

OC0686-0103-NLO2

__r .-m.. _ . _ . - , - . - , , , . . . . , ~ - _

+ . .

Director, Nuclear Reactor Regulation 3 Big Rock Point Plant Fire Protection - Recalculation and Additional Information July 1, 1986 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 switch-es are independently annunciated in the Control Room, and 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 bearings is annunciated in the Control Room, and thereby serve as a backup for the low oil alarms, although thece will be a time delay.

Fire detectors which alarm in the Control Room and a manually actuat-ed suppression system have been installed in the Recirculation Pump Room.

For the reasons described above, Consumers Power Company requests that the NRC reinstate its approval of our request for exemption, submitted by letter dated February 9, 1982, from the requirement of 10CFR50, Appendix R, Section III.0 as it applies to the reactor recirculation pumps, b

Kenneth W Berry Director, Nuclear Licensing CC Administrator, Region III, USNRC NRC Resident Inspector - Big Rock Point Attachments i

)

l oc0686-0103-NLO2