ML20054E502
| ML20054E502 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 05/28/1982 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20054E503 | List: |
| References | |
| NUDOCS 8206110286 | |
| Download: ML20054E502 (4) | |
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e suuo SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 S Street, Box 15830. Sacramento, California 95813;(916) 452 3211 May 28, 1982 DIRECTOR OF NUCLEAR REACTOR REGULATION ATTENTION JOHN F STOLZ CHIEF OPERATING REACTORS BRANCH 4 US NUCLEAR REGULATORY COMMISSION WASHINGTON DC 20555 DOCKET 50-312 RANCHO SECO NUCLEAR GENERATING STATION UNIT 1 In our letter of March 17, 1981, the District requested an exemption from providing an automatic suppression system in the control room as required for compliance with Section III.G.2(c) of Appendix R to 10CFR 50.
Having discussed this issue with your staf f, we wish to change our request to exempt our control room from all requirements of Section III.G.2 be-cause the redundant control panels are not separated by the required distance nor by a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> fire barrier. The technical justi-fication for this request was provided in Enclosure 1 to our letter of March 17,1981, and demonstrates that equivalent protection is provided.
The purpose of the requirements in Section III.G.2 is to protect a redundant channel or system long enough for a fire to be detected and extinguished. We have fulfilled this requirement because we have a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> fire watch through constant presence of the control room operators.
Also, in the discussions your Mr. John Stang felt that our analysis was deficient in two areas. We had not addressed a transient combustible
- fire, i.e., 5 gallons of heptane; nor had we provided one hour fire barriers between the panels.
In response to these concerns, we offer the following analysis.
There are no flammable liquids normally stored at Rancho Seco.
As required by special tasks, flammable liquids are brought onto the site and disposed of following that task.
Administrative Procedure, AP-29, already requires that all bulk combustible liquids used on site be handled in specifically designed, approved containers. These are one gallon, UL or FM approved, spillpcoof containers equipped with a self-closing lid and vent.
In addition, we will amend AP-29 to provide for daily inspection of the control room for combustible liquids. Presently, weekly inspections for fire hazards are made by our two, full time, safety technicians. Written reports of these inspections are submitted to the plant superintendent monthly. Also, the fire brigade is trained in the hazards of combust-ible liquids and since the control room operators are the leaders of the
/
fire brigade, we are provided with a constant vigilance for and an aware-f;(SY ness of transient combustibles in the control room.
Rancho Seco has established a reputation as a very sanitary site. When outside agencies such as ANI, INP0, the NRC, and, most recently, SALP conduct inspections, we are always complimented on the cleanliness of our plant. Therefore, you can see that the transient combustible fire that you propose is not a credible event for our control room.
8206110286 820528 PDR ADOCK 05000312 F
PDR A
T John F. - Stolz May'28,.1982L With regard to the lack of one hour barriers between panels we have de-termined that a fire, if one were to occur, would not last an hour due to operator action. 'The ionization detectors installed in the safety :related panels and in the panels on either side of the safety relatedl panels would immediately detect the fire and alert the control' room operator.
Additionally, all wiring inside these panels has passed UL83 flame tests or has been coated with a fire retardant compound to insure that it will pass UL83 requirements.
Fire Area 34, the electrical penetration, ion exchange and storage area, is an extremely. large fire area (6580 square feet) containing redundant penetrations and cables required to shut down. While thetchannel A cables in tray are separated from the redundant channel B cables.in conduit by more than 70' feet there are intervening combustibles in the ' form of cables in open trays. 'The attached drawing shows the raceway layout being de-scribed. The maximum' separation between trays in this area is presently :
19' occurring at the blockouts through the south wall. However, there is a stack of four trays running parallel to the containment building wall that traverses this separation. The District has installed a fi" stop on this stack of1 trays as stated in Enclosure 1 to our March 1; 1981 letter.
Presently.we are adding new trays in this area to support-modifications brought about by the TMI-2 accident. These trays are intended to carry, in part, redundant cables for the EFIC. system which-is required for safe shutdown. Although;the separation is below the 20' required by Section III.G.2(b),;the trays are installed. parallel to each.
other and on opposite sides of.the fire stop in the traversing trays.
Other than the charcoal filter used in the control room air handling.
unit, U545, in the extreme north west corner of the' fire area, the'only other combustible in the area is the cable itself which~has passed fire resistance tests previously documented. The air handling unit will be.
removed during the 1984 outage as part of the control room habitability-upgrade. This fire area is protected with ionization detectors and a wet pipe sprinkler system.
In addition, there are 3-10# CO2 extinguishers, 2-10# dry chemical extinguishers 1 and 2 hose stations in the area. 'There-fore, the District requests' and exemption from the separation requirements of Section III.G.2(b) based cut the extremely low probability of a fire occurring in the area, the lack of combustibles in the area, and_the fire suppression features in the area.
In fire areas 47, 48,'49; and 58,Lthe District has requested an exemption from providing an automatic fire suppression system as required by Section III.G.2(c).
In fire areas 48,'49, and 58, there is a silver brazed, copper cross-connect pipe to supply either train A or train B nuclear service ~ raw water to the make-up pump. This line has been insulated with a 1". layer of calcium silicate insulation jacketed with stainless steel. Attached is an analysis showing the portions of this line which need to be protected and why, as well as the adequacy of the calcuim silicate insulation to provide protection.
John F. Stolz May 25, 1982 The. qualifying fire test (copy attached) demonstrating the protection provided by calcium silicate insulation was performed on insulated conduit with an aluminum jacket.
Conduit internal temperatures were as shown on the graph.
Please note that thermocouple No. 8~ malfunctioned during the test so this discussion relates to the data obtained from the other 5 t he rmocoup les. At 30 minutes into the test, the maximum, recorded tem-perature was approximately 300*F on thermocouple numbers 2 and 5.
This temperature is well below the 600*F maximum service temperature for silver brazed pipe. The 30 minute time is at least double the fire-duration for the affected areas.
Additional conservatisms in this analysis for which no credit is taken include:
1.
The actual piping in the plant contains water which will limit heating unless all the water is boiled away.
If flow is present in the pipe, extreme temperatures will not be possible.
2.
No assumed heat sinks in room.
3.
Room temperature is a step function change to 1400*F.
4.
The lubricating oil is 'of relatively low flammability requiring preheating to 400*F to reach its ' flash point.
5.
The insulation is jacketed with stainless steel (melting tem-perature greater than 2000*F), rather than aluminum (melting temperature 1220*F or less).
It should be pointed out that our original analysis assumed 76 gallons of oil were present in each pump room. Measurements taken while per-forming an overhaul of the make-up pump determined that the capacity of each pump is 20 gallons.
Additionally, in fire areas 47 and 49, there are redundant cables re-quired for safe shutdown, one channel of which has been protected as detailed in our March 17, 1982, letter.
Finally, we wish to withdraw our exemption request from providing emer-gency. lighting inside of containment. Since we do not need to enter the reactor building to manually operate any equipment to achieve hot shutdown, 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> emergency lighting is not required in this building nor would it be available if we need to enter to achieve cold shutdown.
e John F. Stolz May 25. 1982 We trust this information will allow you to complete you evaluation of our exemption request to Appendix R.
Please let us know if we can be of further assistance.
' w
A f
,1 John '. Mattimoe J
Assistant General Manager and Chief Engineer
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