ML20215G730
| ML20215G730 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 10/14/1986 |
| From: | Berry K CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8610210080 | |
| Download: ML20215G730 (5) | |
Text
X Consumers Power x,,,,,,, w %
Director Nuclear Lkensmg MMM M General Offices: 1946 West Pamell Pood. Jackson, MI 49201 + (517) 788-1636 October 14, 1986
- Director, Nuclear Reactor Regulation
.US Nuclear Regulatory Commission Washington, DC 20555
-DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT -
REQUEST FOR EXEMPTION FROM 10CFR50 APPENDIX R SECTION III.G.I.a - SCREEh30USE
- FIRE PROTECTION NRC Inspectors conducted a special inspection at Big Rock Point on December 5-9, 1985; March 5-7, 1986; and May 8, 1986 to determine the status of compli-ance with 10CFR50 Appendix R.
During that inspection, they found that Big Rock Point was incorrectly relying on a previous NRC determination of compli-ance with Appendix A to BTP 9.5.1 to illustrate compliance with 10CFR50 Appendix R, Section 'III with regard to equipment and circuit separation in the Screenhouse; and, that an Exemption Request should have been submitted regard-ing the requirements of 10CFR50 Appendix R, Section III.G.2.
Consumers Power Company filed this Exemption Request on July 1, 1986.
Upon further investigation and study'of various methods to attain hot shutdown after a worst case fire in the Screenhouse, Consumers Power' Company staff determined that, if a worst case fire did occur in the Screenhouse,'a more desirable method to achieve and maintain hot shutdown would be not to rely on any of the equipment in the Screenhouse, but to use the Emergency Condenser (EC) with makeup cooling from the Demineralized Water System (DWS). This method involves the temporary attachment of a hose to maintain hot shutdown.
Therefore, NRC approval is required in the form of an exemption before it can be used for credit in Appendix R compliance.
! is a request for that exemption, and as was discussed in a telephone conference with NRC staff on September 25, 1986, it supersedes and i
withdraws the July 1, 1986 Exemption Request regarding fixed suppression in the plant Screenhouse. Analysis has been performed which shows there is enough water, manpower and time to attain safe shutdown in the manner de-scribed in Attachment 1.
An analysis has also been performed which verifies that no radiation release over allowable limits would take place. A detailed Fire Hazards Analysis has been completed which shows that neither the service water pump nor the overhead crane would be damaged by a worst case fire in the OC1086-0169-NLO2
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Director, Nuclear Reactor Regulation 2
Big Rock Point Plant Exemption Request-- Fire Protection October 14, 1986 Screenhouse. These analyses support the conclusion that, pending approval of the attached exemption request, the Screenhouse will'be in compliance'with Appendix R requirements.
Implementation of procedures covering the safe shutdown method described in Attachment I requires that a spare Service Water Pump motor be purchased beforehand. Compensatory action as described in Consumers Power Company submittal dated April 14, 1986 will remain in effect until a spare motor is obtained.
A check for $150.00, as required by 10CFR170.12(c) is included.
I Kenneth W Berry Director, Nuclear Licensing CC Administrator, Region III, USNRC NRC Resident Inspector - Big Rock Point 9
Attachments l
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ATTACHMENT'1 Consumers Power Company Big Rock Point Plant Docket 50-155 EXEMPTION REQUEST TEMPORARY HOSE CONNECTION TO COOL THE INSTRUMENT AIR COMPRESSORS October 14, 1986 l
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1 2 Pages AT1086-0169-NLO2 l
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ATTACHMENT 1 BIG ROCK POINT PLANT EXEHFrION REQUEST TEMPORARY HOSE CONNECTION TO COOL THE INSTRUMENT AIR COMPRESSORS 10CFR50 Appendix R Section III.G.1.a requires that one train of systems necessary to achieve and maintain hot shutdown be free of fire damage. Normal safe shutdown concurrent with the loss of offsite power involves using the Emergency Condenser (EC) to cool the Primary Coolant System (PCS).
In this process, steam from the main steam drum flows by convection _through the tube side of the EC where it is condensed by cooling water on the shell side. The condensate then flows by gravity back to the main steam drum.
Heat ie removed by boiling off water on the shell side of the EC and the resulting stram is passed directly to the atmosphere. When the plant is at power, there is enough water stored in the shell side of the EC to attain hot shutdown and maintain that condition for four hours. Thus, before four hours have elapsed, makeup water must be applied to the shell side of the EC.
Normal operation is to supply this makeup from the Demineralized Water System (DWS) with additional backup water supplied by the Fire Water System (FW3). Using this procedure, with fire water as the backup, hot shutdown can be maintained for days or weeks. Additionally, if it is desired to go to cold shutdown, service water or fire water can be used to cool reactor cooling water which in turn cools the PCS. Both the fire water pumps and the service water pumps are located in the Screenhouse.
If a worst case fire in the Screenhouse is postulated, although there is twenty feat of separation between the diesel fire pump and the service water pumps, and there is an automatic fire detection system, since there is no automatic suppression, it must be assumed that the diesel fire pump driver, the electric fire pump motor, and both service water pump motors and their power supply cables would be rendered inoperable.
h For this postulated condition, het shutdown would be attained by tripping the reactor to control reactivity and opening the EC outlet valves to operate the EC for removal of decay heat. Additional coolant, required on the shell side of the EC after four hours to maintain hot shutdown, would be provided by the demineralized water pump.
The flowpath from the demineralized water pump to the EC is opened by operat-ing an air-operated valve. Air to open this normally closed valve is supplied by the plant instrument air compressors. The instrument air compressors are l
cooled by service water (SW).
Since both service water pumps and their backup, the fire water pumps, are postulated to be inoperable, cooling would l
be provided to the instrument eir compressors by temporarily connecting a hose I
between the Service Water System where it enters the air compressor cooling l
system and the Demineralized Water System. Appropriate valves would be closed i
to prevent the Demineralized Water System from supplying demineralized water l
to other sections of the Service Water System.
Chicago fittings are perma-nently installed on demineralized water piping and service water piping in the AT1086-0169-NLO2 l
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2 vicinity of the instrument air compressors. The hose for connecting the two systems has Chicago fittings on each end and will be permanently stored'in the same room as the instrument air compressors. Thus, to cross connect the demineralized water system through a portion of the service water system to the instrument air compressors, the operator would go to the Electrical Equipment Room where the instrument air compressors are located and connect the hose to the DWS at either the Chicago fitting located in the adjacent machine shop or the Chicago fitting located in the adjacent boiler room and to the SWS at the Chicago fitting located in the electrical equipment room, close valves isolating the air compressor cooling section of SWS, and open a valve-in the DWS to permit flow to the air compressors. The entire procedure would take less than 10 minutes.
Analyses have been performed to show that when the DWS is connected to the instrument air compressor cooling system, the air compressors started and the flow path opened between the demineralized water pump and the EC, there would be enough cooling water available onsite to permit the EC to operate for a minimum of 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.
During this time the spare SW pump motor would be installed on a SW pump and the spare SW pump motor power cable from the emergency diesel generator connected.to it.
With one SW pump in operation, SW can be supplied to the reactor cooling water (RCW) heat exchangers. The RCW can then cool the PCS in the ahutdown cooling heat exchangers and cold shutdown can be attained within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> of the time the SW pump is operational using the spare motor.
The spare SW pump motor will be stored onsite in an accessible location and-will~be inspected at regular intervals as part of the preventive maintenance program.
It can be transported to the intake structure by crane truck, forklift or pickup truck. After being delivered to the intake structure through the truck door, the spare motor can be transported to the SW pump by using the manually powered overhead crane in the screenhouse. Analysis shows that a worst case fire in the intake structure will not damage the manually l
powered overhead crane nor the service water pump.
Installation of the spare I
motor is a relatively simple task and can be accomplished by three maintenance personnel. The damaged motor is removed and the spare motor is bolted to the pump casing and the shaft bolted to the pump coupling. The electrical connec-l tion is bolted lugs wrapped with tape.
The entire replacement task usually takes less than eight hours.
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Therefore, if a fire occurs in the Screenhouse and fire-induced damage occurs to the fire pumps and both service water pump motors, the plant can be safely shutdown using demineralized water for makeup to the EC shell and for cooling the instrument air co'mpressors and using service water for cooling the reactor cooling water heat exchangers. Accordingly, Consumers Power Company requests an exemption from the requirements of 10CFR50 Appendix R, Section III.G.I.a to the extent that a temporary hose may be installed to enable the DWS to cool the instrument air compressors. This exemption request is eade under the provisions of 10CFR50.12(a)ii in that it has been shown that application of the requirements of 10CFR50, Appendix R, Section III.G.I.a. in prohibiting f
credit for the minor task of making a readily available hose connection would not serve the underlying purpose of the rule.
AT1086-0169-NLO2
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