ML19343C515
| ML19343C515 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 03/17/1981 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19343C516 | List: |
| References | |
| TAC-43320, NUDOCS 8103240417 | |
| Download: ML19343C515 (9) | |
Text
_,
es m SACRAMENTO MUNICIPAL UTILITY DISTRICT C 6201 s street, Box 15330, sacrarnento, Cahfornia 95a13. (916) 452-3211 n,.. --~ 2,
,,,- c t ~ s March 17,1981, y e;.
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. [.,. j Director of Nuclear Reactor Regulation h
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a Attention:
Mr. Darrel G. Eisenhut, Director
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y Division of Licensing N.-
U.S. Nuclear Regulatory Conmission y7 Gj' Washington, D.C.
20555
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Docket 50-312 Rancho Seco Nuclear Generating Station, Unit No. 1
Dear Mr. Eisenhut:
The Sacramento Municipal Utility District, as required by caragraoh (c)(5) of 10 CFR 50.48 and as requested in your letter of February 20, 1981, has prepared this report to describe our plans for implementing the require-ments of Appendix R to 10 CFR 50, Fire Protection Program for Nuclear Power Facilities Operating Prior to January 1,1979, and to provide the reassessment of the design features at Rancho Seco for meeting those requirer.:ents.
In the NRC's Fire Protection Safety Evaluation Report issued February 28, 1973, and letter of Aoril 11, 1980, the NRC accepted our Fire Hazard Analysis and modifi-cations as satisfying the provisions of Appendix A to Branch Technical Position BTP APCSB 9.5-1.
On this basis we have determined that only the requirements of Sections III.G., III.J., and 111.0. are applicable to Rancho Seco Nuclear Generating Station, Unit No. 1.
Section III.G.1 of Appendix R requires licensees to nrovide fire protection features capable of limiting fire damage so that one train of systems necessary to achieve and maintain hot shutdown is free from damage and tnat systems necessary to achieve and maintain cold shutdown can be repaired within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The District has prvided fire protection features to ensure that one train of systems necessary to achieve and maintain cold shutdown is always free from fire damage.
Section III.G.2 requires that cables or equipment including associ-ated non-safety circuits that could prevent coeration or cause maloperation due j
to hot shorts, open circuits, or shorts to ground of redundant trains of Ob systems necessary to achieve and maintain hot shutdown conditions, which are 5
located within the same fire area, be separated in accordance with Section III.G.2.(a), (b), or (c) for areas outside of primary containment and with Section III.G.2.(d), (e), or (f) for areas inside non-inerted containments. The/ l Commission has requested all licensees to reexamine their previously approved fire orotection contigurations to determine if they meet those separation re-quirements or justify their present configurations with a fire hazard analysis.
The District has reexamined each fire area defined in our Fire Haurd Analysis as directed and our conclusions are presented in Enclosure 1.
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Mr.-Darrel G. Eisenhut Page 2 March 17,1981 From our reassessment of Rancho Seco, we conclude that the alter-native or dedicated shutdown capability required by Section III.G.3 is not necessary because our fire protection features, although in some cases not entirely satisfying the requirements of Section III.G.2, are acceptable because of the justification provided in Enclosure 1, and will not be damaged from fire suppression activities or from the rupture or inadvertent operation of the fire suppression systems. For this reason, we request an exemption
'from the requirements of III.G.2.
The District presen;1y has self-contained, battery operated, emergency lighting units rated for eight hours installed throughout the
- Auxiliary Building..We have not-prcvided these units in the Reactor Building, the Control' Room, or the Reactor Building Yard.
To meet the requirements of Section III.J to Appendix R, the District will install units in the Control Room and to provide access to and in the Auxiliary Feedwater Pump area. The District does not plan to install these units in the Reactor Building because:
(1) the-elevated temperature would substantially reduce battery life and require frequent maintenance; (2) the units could be damaged by other postulated design basis events resulting in possible detrimental effects from the spilled electro-lyte; and (3) any design using batteries outsioe witn lights inside would be equivalent to our. existing system and, therefore, subject to the same possible failures. Therefore an exemption in this area'is also requested from the requirements of III.J.
- As required by'Section III.0 of Appendix R, the District is analyzing the design of our existing reactor coolant pump motor lube oil collection system to verify that the catch pans,_ drain piping,__and collection tanks will withstand our Safe Shutdown. Earthquake.
In_ addition to using an oil especially selected for its high~ flashpoint, the District intends to add flame arrestors to the collection' tank vents. Any modifications that may be required, will be completed by the end of the outage' scheduled for April, 1982.
'To complete.any required modifications by the dates established frcm paragraphs:(c)(2) and (c)(3) of 10 CFR 50.48, the-District requests NRC comments and/or approval of.our analysis by May 1, 1981.
-Sincerely, fL? %G John. Mattimoe Assistant General Manager and Chief Engineer Enclosure 1
ENCLOSURE 1 The District has reassessed each fire area at Rancho Seco to determine if the fire protection features for those areas containing redundant systems, equipment, and cables required to achieve and maintain cold shutdown, as detailed in our Fire Hazard Analysis submitted on August 1, 1977, meet the requirements of Section III.G of Appendix R to 10 CFR 50. Any fire area that does not contain redundant cables or equipment required to achieve and maintain cold shutdown, was not considered further. The configurations of the remaining
' fire areas were reanalyzed and our conclusions are presented in this report.
For this reexamination, the District used the same assumptions and conditions use' to make the' first analysis except that modifications made as a result of the -irst analysis were incorporated. Many of the original problem areas were resolved by rerouting redundant cables out of the area of concern. We are aware that as a result of TMI-2, additional equipment and/or systems which we had not previously considered, are now considered necessary to achieve cold shutdown. We will address these during our analysis of associated circuits and when making the modifications required by NUREG 0737 and Regulatory Guide 1.97.
In'our Fire Hazard Analysis associated circuits in Class lE raceway were analyzed to verify that an open or short would not prevent safe shutdown. Any circuit that posed a problem was rerouted or protected.
Due to the concerns expressed by the Commiss' ion, the District is presently analyzing all associated circuits that are. connected to safety related power supplies or equipment required to achieve safe shutdown in the event of a fire, to ensure that neither the power supply nor the required equipment is jeopardized by opens, shorts, or hot shorts.
For tnat analysis,-safety related circuits not required for safe shutdown as a result-of the fire are treated as associated circuits. Any problems that are discovered will be corrected by either rerouting the circuit out of the fire area :or installing an approved thermal barrier to protect the circuit from fire
~ damage. This work will be completed in accordance with the schedule provided in Section 50.48 -(c)(2) or (c)(3),- as applicable.
l
-The following is our assessment of the fire protection features in each fire area containing'. redundant systems, equipment, and cables required to achieve and
[
maintain cold shutdown.
i F.A.'1 - Control and Computer Rooms
. Our analysis of this area. treated the control and computer rooms as one fire-zone, l'
and the offices as another. The control and computer rooms contain vertical control j
boards, cabinets, consoles, and cable for both redundant channels of all systems l
required for safe. shutdown and-cooldewn. A fire in this area could occur in the cable tray or in any one of the cabinets, but not in both simultaneously, and
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the fire will not _ propagate into_ or out of the panels due to the fire stops that l~
'are installed at all. cable tray entrances'to the cabinets. The details of these fire stops,--including test results, were provided in our response to NRC Question j
No. ~10.in Section V of our Fire Hazard Analysis.
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Page 2 ENCLOSURE 1 The probability of a large damaging fire in either the cable tray system or any of the panels is extremely small, since (1) The only significant combustible is cable (refer to the District's August 31, 1979 submittal Item No. 71 for a discussion). All cable in open trays in this area, except for radiation monitoring cable, which is a very small amount, passes the fire resistance tests described in Item No. 28-of the District's August 31, 1976 submittal and as further documented in our response to NRC Question No. 11, included in Section V of our Fire Ha:ard Analysis.
(2)
Ionization detectors are installed in all control and computer cabinets that' contain control pushbuttons and indication required for safe shut-down and cooldown and the panels adjacent to them, and above the cable
- tray system to imediately detect any fire at its incention. The detectors are failsafe in that they go to the alarm condition on failure of the unit or cabling to it.
The system is supplied from a battery-backed source and will alert the operator as to the location of the fire by ~an indicating light and audible alarm on a separate local panel.
(3) Operating personnel are in the control room 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> a day. A fire would be quickly detected by the ionization detectors, but in the improbable event of a failure of the detection system, the operator would definitely detect the fire and initiate action to extinguish the
-fire.
(4) The operator has at his imediate disposal two 2.5 gallon water extinguishers and-two 20p CO2 extinguishers in the control room, three
- 20# CO2 extinguishers in the computer room, and a hose station in the adjacent hall.'
However, the District, in a very conservative approach, analyzed the effects of a fire in the cable tray system that results in a loss of
- all-cables'in tray, and a fire in each of the panels that contain controls for_ redundant systems required to achieve cold shutdown, assuming a total' loss of everything in the panel.
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A1 fire in the cable tray will not result.in loss of ability to achieve cold shutdown because only channel B cables will be lost. Redundant channels A,- C, or-D rec. aired for safe shutdcwn have been routed in conduit.that is protected by a-thermal barrier rated for lh hours con-
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sisting of a two inch layer of-Fiberfrax Hot Board, manufactured by LCarborundum. Company. The design details and documentation were provided in'our letter-dated August 28, 1978, and accepted by your letter of December. 14,.1978.
Page 3 ENCLOSURE 1 The details of our analysis of a fire in each control panel containing redundant controls or instrumentation required for safe shutdown, were provided in our response to NRC Question No. 26 b in Section V of our Fire Hazard Analysis. As a result of tk t study, modifications were made to allow us to isolate certain circuits and take local control of affected
-systems. The details of those modifications were also transmitted in our
. letter dated August 28, 1978, and approved in our meeting with Jerry Zwetzig on September _14, 1978, and by your letter of Jecember 14, 1973.
In analyzing for these fires, the District determined that thile sama operations may have to be performed from outside the Control Room to brir.g the plant to safe shutdown, the Control Room itself would never have to be evacuated and control of 'all operations would be maintained there.
In the event that smoke or fumes from a fire became a problem, 5 M5A self-contained breathing units along with 2-spare air bottles for each are available to the operator.
If a fire occurs in the Control Roca office area or corridor, it would be promptly-extinguished by the wet pipe sprinkler system in this area.
Since there is no safety.related cable or equipment in this area, this fire would not affect our ability to shutdown. Any smoke or fumes generated by a fire
_in this area, would not affect the operators because they have access to the MSA self-contained breathing units.
We_ conclude therefore, that our design and fire protection features meet the intent of Appendix R without further modification because there is no credible
. fire in the Control Room that can prevent us from achieving and maintaining
. cold shutdown.
Fire Area 17 --West Switchgear Room
=This fire area contains-redundant cables for high pressure injection and
. auxiliary feedwater. The west 480V switchgear room is a channel "A" room.
1-The District.has insulated the channel "B" circuits in this room for the high pressure injection system and the auxiliary-feedwater system with two
-inches of Fiberfrax Hot Board manufactured by the Carboruncum Company. The insulation is wrapped with a jacket of.016 inch stainless steel, held in place with stainless steel bands. For a description of the qualifying test performed on the-insulation system refer to Conduit Insulation Fire Test 2, Test Set-Up 1, in Section V of the District's Fire Stop Test Report submitted
'on March 1, 1978. This barrier is rated for lh hours and the area has
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. ionization detectors-and a CO2 suppression system. Therefore, the District concludes that our fire protection features in this area meet.the requirements of Section III.G.2(c)'and comply with Appendix R.
Fire Area 20'- East 480V Switchaear Room
. Fire area 20-is a channel "B" area and contains circuits for channels "A" and "C" RCS -pressure indication, channel. "A" n~uclear instrumentation power supply,
'and the RCS pressure interlock to the channel- ~"A" decay heat valve HV20001.
In addition, both' channels'of the required Class II instrumentation also (run through this area.- To prevent 'any_ fire damage.to these circuits,- the District has installed-the channel "A" cables and one channel of the Class-II J'
Page 4 ENCLOSURE 1 instrumentation cables in conduit and insulated them with two inch s of Fiberfrax Hot Board, manufactured by the Carborundum Company, providing a l$ hour thernal barrier. Refer to the discussion under Fire Area 17 for the design details and the qualifying test information.
This area is' equipped with ionization detectors and a Class I total flooding, low pressure CO Therefore, the District concludes that our fire protection 2 system.
features -meet the requirements of Section III.G.2(c) and comply with Appendix R.
- Fire Area 29 - Mezzanine Main Corridor a
-Both channels of required Class II instrumentation are routed through this area. 'The District has installed one channel in conduit and insulated it with ~ two inches of Fiberfrax Hot Board, manufactured by the Carborundum c
Company,1as. described under Fire Area 17.
This area is protected with ionization; detectors and a wet pipe sprinkler system, four 10# CO 2 1
extinguishers, and four hose stations. There are three alarm pull stations and alarmL bells as well.
Therefore, the District concludes that our fire protection features meet the requirements of Section III.G.2(c) and, amply 1wi th Appendix ~ R.
Fire Area 34 Electrical Penetration Area Both channels of the makeup tank level-indication, source range nuclear instrumentation, and decay heat are in this area. The cables for the makeup-tank level instruments are in close proximity to each other, so
-one was installed in conduit and insulated with two inches of Fiberfrax Hot Board, manufactured by the Carborundum Company, as described under Fire Area:17.-.The redundant source range nuclear instrumentation and decay heat
- circuits'are separated by approximately 70 feet. The District has installed a cable tray fire -stop to prevent a-cable tray fire from bridging this gap.
The design of this' fire stop is shown in Attachment 1 and is constructed of the:same materials that;the District used in its qualified three hour fire stop. iThis area has: ionization detectors and a wet pipe sprinkler system.
Therefore,.theiDistrict-concludes that'our fire protection features in this area-meet the requirements;of Section III.G.2.(b) and (c) and comoly with Appendix R.
.. Fire ~ Area 36 - Ground-Floor Main Corridor
- Cables for., both channels of the required Class II~ instrumentation pass through
'.this area.
.To prevent'possible _ fire damage to both' the District has
' installed one' channel iniconduitiinsulated with -two inches of Fiberfrax
Page 5 ENCLOSURE 1 Hot Board manufactured by the Carborundum Company, as described under Fire Area 17.
This area is equipped with ionization detectors and a wet pipe sprinkler system. Therc a e also tnree hose stations, three 10= C02 extinguishers, four pull stations and three bell alarms.
Therefore, the District concludes that our fire protection features meet the requirements of Section III.G.2(c) and comply wi
.1 Appendix R.
Fire Area 47 - Corridor to El. -47' This area contains redundant cables for the nigh pressure injection system when the "B" high pressure injection pump is out of service and the makeup pump is operating _as the "B" high pressure injection pump, and for the decay heat system. The channel "B" cables are installed in tray which has been wrapped with a Kaowool blanket. The District has installed the
.Kaowool blanket in accordance with the design for Test Number 3 in.
By using this method we have provided a one hour thermal barrier as stated in the test report. This area is equicped with ionization detectors, a 108 CO2 extinguisher, and a hose station. The District's Fire Hazard Analysis shcws that the Design Basis Fire for this area will last less than 15 minutes with a peak temperature not greater than 2500F. The District concludes that our fire protection features in this area ensure that we can achieve and maintain cold shutdown, and therefore comply with Appendix R.
Fire Area 48 "A" High Pressure Injection Pump Room Part of the silver soldered, copper cross-tie between the two nuclear service raw water systems to the makeup pump is located in this fire area.
To prevent a fire in this area from affecting the cooling water to the makeup pump when it is operating as the "B" high pressure injection pump, the District has insulated this piping with one inch of calcium silicate insulation and installed ionization detectors. A hose station and a 10# CO2 extinguisher are located in the corridor outside the room. The District concludes that our fire protection features in this area ensure we can achieve and maintain cold shutdown and therefore comply with Angendix R.
Fire Area 49 - West Containment Valve Area This' area contains redundant cables for the high pressure injection system when the "B" high pressure injection pump is out of service and the
. makeup pump is operating as the "B" high pressure injection pump, and for the decay heat system. The channel "B" cables are installed in tray which have been wrapped with a Kaowool blanket as described under Fire Area 47. Part of the silver soldered copper cross-tie between the two nuclear service raw water systems to supply cooling water to the makeup
Page 6 ENCLOSURE 1 pump when it is operating as a high pressure injection pump, passes through this area. To prevent a failure of this line, the District has insulated it with one inch of calcium silicate insulation.
The area is equioced with ionization detectors, a 10: C09 extinguisher, and a hose station. The District's Fire Hazard Analysis shows that the Design Basis Fire for tnis area will last less than 15 minutes with a peak temcerature not greater 0
than 250 F.
The District concludes that our fire protection features for tnis area ensure that we can achieve and maintain cold shutdcen, and therefore comply with Appendix R.
Fire Area 58 - Makeue Puno Room Part of the silver soldered, copper cross-tie between the two nuclear service raw water systems that supply cooling water to tne nakeup cump whcn it is operating as a high pressure injection pump, is in this area.
To prevent a fire from causing a loss of cooling water to the redundant high pressure injection pump when the makeup pump is ocerating as tne other, the District has insulated this line with one inch of calcium silicate insulation and installed ionization detectors. A hose station and a 10=
CO2 extinguisher are located in the corridor outside the room. The District concludes that our Fire Protection features in this area ensure that we can achieve and maintain cold shutdown, and therefore comply with Appendix R.
Fire Area 68 - Reactor Building The' District has divided the Reactor Building into eleven fire zones.
Analysis shows that a fire in any fire zone will not cause a fire in any other zone because of the spatial separation. To preclude the possibility of a fire propagating from one zone to another along the cable tray, the District has installed fire stops in accordance with the design details provided in our letter of October 17, 1978. Our Fire Hazard Analysis addrcssedeach zone to determine the effects of a fire and found that one redundant channel of equipment required to achieve cold shutdown is always available. Therefore, the District concludes that our fire protection features meet the requirements of Section III.G.2(f) for separation inside non-inerted containments and comply with Appenjix R.
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