ML20134A749

Safety Evaluation of Addendum 1 to NEDO-10466A, Power Generation Control Complex Design Criteria & Safety Evaluation. Halon 1301 Extinguishing Sys W/Adequate Amount of Halon 1301 Acceptable

ML20134A749
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Issue date:	05/17/1985
From:	Office of Nuclear Reactor Regulation
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ML20134A732	List: ML20134A749
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NUDOCS 8508150408
Download: ML20134A749 (2)

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, Safety Evaluation Repo'rt I

GE Topical Report, NEDO-10466A Adddendum 1 Fower Generation Control Complex Introduction l

InR$ vision 2ofNE00-10466AdatedMarch1978,GeneralElectricrecommended that a Halon 1301 fire extinguishing system would be required to protect l the PGCC. The system would provide a 20 percent concentration of Halen 1301 for a soak time for 20 minutes for deep seated fires.

The staff found it l .'- acceptable.

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By letter dated February 28, 1985, General Electric submitted Addendum 1 to j NEDO-10466A. General Electric requested deviations that would reduce the Halon 1301 <:encentration to be prov.ided to protect the PGCC and the amount of soak time required. For PGCC's with 80 percent or greater Tefzel cable, j General Electric requested that the concentration ano soak time cf Halon 1301 l

be changed to be surface burning fire concentration and soak time, i.e., 6 percent for 10 minutes.

Discussion / Evaluation I

s Based on testing and research performed oncableinsulationsNce1978, General Electric has reevaluated deep seated fires occurring in the PGCC.

l General Electric indicates that Figure 4.2 of NE00-10466, Revision 2, Appendix F, shows that the rate and degree of burning of the Tefzel cable used in the PGCC essentially corresponds with that of the ignition source.

l Because of this, the key to limiting the severity of burning of Tefzel is in l

the capability of extinguishing the ignition source. If the ignition source is extinguished, the fire in the Teftel will self-extinguish, almost simulta-l neously. Tef2el is a thermoplastic material, which means that as its temper-ature is raised it will melt before it burns, that is, the auto ignition temperature is higher than its melting temperature. This characteristic of melting before it burns ensures that burning can occur only at its surface as a liquid.

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The surface burning characteristic of Tefzel have been substantiated in every fire test conducted by General Electric.

' Afte? reviewing the test results in Appendix F of NED0-10466A, we agree with General Electric that Tefzel cable will exhibit surface burning characteristics and not deep seated. Therefore, the amount of Halon 1301 l required to extinguish Tefzel cable fires should be based on surface burning  !

fires in accordance with NFPA 12A,'i.e., 6 percent for 10 minutes, c

Based on the burning characteristics of Tefzel cable, fire test results in non-Tefzel cables, and NFPA for acceptance, for non-Tefzel cable we find that an automatic Halen 1301 extinguishing system with an adequate amount '

of Halon 1301 to achieve a 6 percent concentration for a 10 minute soak time will extinguish cable fires in PGCC's enclosures which contain 80 percent or greater by weight Tefzel cabling.

Conclusion , j Based on our evaluation, we conclude that an automatic Halen 1301 extinguishing j system with an adequate amount of Halon 1301 to achieve a 6 percent concentra-tion for a 10 minute soak time will be acceptable for PGCC's which contain i 80 peretnt or greater by weight Tefzel cabling. Therefore, we find General Electric's request for deviation from NE00-10466A acceptable.

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. NED0-10466 Addendum 1 GENERAL $ ELECTRIC NUCLEAA ENERGY BuslNEss OPERATIONS GENERAL ELECTRIC COMPANY e 175 CURTNER AVENUE e SAN JOSE, CAUFORNIA 95195 MC 682, (408) 925-3392 MFN- 29-85 February 28, 1985 U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington, D.C. 20555 Attention: C. O. Thomas, Chief Standardization & Special Projects Branch Gentlemen:

SUBJECT:

POWER GENERATION CONTROL COMPLEX (PGCC) FIRE SUPPRESSION LICENSING TOPICAL REPORT ADDENDUM 1 The purpose of this letter is to transmit a special report which documents in Addendum 1 to NE00-10466 an additional Halon concentration and soak time option for the PGCC's fire suppression system.

We request a review and safety evaluation report (SER) for referencing and licensing actions by Utility applicants, i.e. Illinois Power Company, Gulf States Utilities, etc. This fire suppression option has been discussed by John Stang, NRC, Ed Maxwell, GE, and various Utility representatives. We request an expedited review schedule, i.e. two to four weeks after receipt of this letter.

Under separate correspondence to William O. Miller, NRC, we have provided the

$150.00 application fee.

Please contact R. D. Hickman on (408) 925-4584 should you have any questions.

Very truly yours, 6 ke- '

H. C. fefferlen Manager 8WR Licensing Programs HCP:csc/102213 Attachments cc: L. S. Gifford, w/Att G. G. Sherwood, w/o Att D. Moran (NRC), w/Att D. C. Scaletti (NRC), w/o Att

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LICENSING TOPICAL REPORT l

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j POWER GENERATION CONTROL COMPLEX DESIGN CRITERIA l AND SAFETY EVALUATION  :

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PGCC FIRE SUPPRESSION CONCENTRATION AND SOAK TIME REQUIREMENTS REQUEST For the GESSAR II design, General Electric requests approval to define an additional Halon concentration and soak time option for the fire suppression system within the PGCC. This option would apply to PGCC floor sections which predominantly contain combustible loadings of cable insulation which only barns on the surface and in the flaming mode.

This request is being made on the basis that GESSAR II, Section 9A.4.2.5, references NED0-10466.A for the fire suppression provisions for the PGCC floor sections. Section 4.1.6.11 of NE00-10466-A contains only requirements for suppression for combustible loadings of cable insulation which is capable of burning in a deep-seated mode. The GESSAR !! design, however, primarily utilizes all Tefzel cable insulation, which burns only on the surface and in the flaming mode. It is appropriate to define a suppression option compatible with surface burning.

We specifically request that for PGCC floor sections containing more than 80%

by weight of Tefzel insulation, the required concentration of Halon 1301 to be EX and the required soak time be 10 minutes.

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' Applicants choosing this option must provide automatic initiation of the initial discharge of the Halon. Discharge may be initiated by either or both  ;

of the product of combustion or rate of temperature rise detectors. It is the responsibility of each applicant to choose the specific wiring methods to be utilized.

JUSTIFICATION Our justification for classifying Tefzel as a surface burning material, recommending a 6% concentration and a 10 minute soaking time for the Halon 1301 l

l and including up to 20% non-Tef2el insulated cable in the fill is as.follows:

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l Tefzel as a Surface Burning Material Tefzel is a thermoplastic material, which means that as its temperature is raised it will melt before it burns, that is, the auto ignition temperature is higher than its melting temperature. This characteristic of melting before it burns ensures that burning can occur only at its surface as a liquid.

l The surface burning characteristic of a thermoplastic contrasts with that of a thermosetting plastic, such as cross-linked polyethylene, which auto-ignites and burns before it melts. Because of this basic characteristic, a fire in a thermal setting material progresses from surface burning to deep-seated as the material is consumed. l l

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The surface burning characteristic of Tefzel as it melts and burns has been substantiated in every fire test conducted by General Electric. Note of it having occurred was reported in the PGCC fire test report, NEDO-10466-A Appendix F. It was also noted in the fire test report contained in the TVA STRIDE Fire Hazard Analysis Report submitted to the NRC in May 1977.

Halon 1301 Concentration of 6% for 10 Minutes NFPA 12A-1972, Section 2420, recommends 5% for 10 minutes as being adequate to completely extinguish a surface fire.

Figure 4.2 of NEDO-10466-A, Appendix F, indicates that the rate and degree of 1

burning of the Tefzel essentially corresponds with that of the ignition source.

Because of this, the key to limiting the severity of burning of Tefzel is in the capability of extinguishing the ignition source. If the ignition source is extinguished, the fire in the Tefzel will self-extinguish, almost simultaneously.

If an ignition source fire is of sufficient magnitude that a 6% concentration

, of Halon 1301 for 10 minutes within the PGCC is not adequate to suppress the fire, the fire would have to be of such magnitude that it would be an area fire. Alternate capability in the form of redundant remote shutdown capability and fire suppression equipment have been provided to make the plant tolerant of area fires in the control room.

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' Twenty Percent Non-Tefzel Cable Due to special requirements, some of the ducts and a few PGCC floor sections may have un to 20% of their cables insulated with materials, usually cross-linked polyethylene, other than Tefzel. A 6% concentration of Halon 1301 for 10 minutes is adequate for these floor sections because:

1. Although the peak temperatures will be elevated above the Tefzel only case (Figure 4.2 of NEDO-10466-A, Appendix F), they will be below those experienced for the 100% non-Tefzel cases shown in Figure 4.2.

This will always be true for two reasons:

I a.., Tefzel does not appreciably increase the severity of the fire above that of the introduced ignition source.

b. The actual cross-sectional area of non-Tefzel cable insulation will be less than the cross-sectional areas for l the non-Tefzel cases for the fire test.

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2. Any fire suppression introduced into the duct within 6 minutes of ignition of the fire would almost immediately extinguish both the ignition source and the surface burning of the cable insulation i

(first peak on the curves of Figure 4.2). Initiation of the l deep-seated mode of burning (second hump on the curves in Figure 4.2) for the non-Tefzel insulated cables would be prevented. )

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3. If discharge of the Halon is delayed 6 minutes or more, the 10 minute soak time would envelope the time required to reach the maximum deep-seated burning rate, which occurred approximately 5 minutes after the ignition source had burned out during the fire test. The action of the Halon would therefore ensure that the burning curve would _ tail down at a much faster rate than experienced in the fire test.

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4. The net effect of items 1 thru 3, above, is that the maximum insulation temperatures for cables in the adjacent cable ducts will be less than those shown on Figure 4.3 of the fire test report. In other words, the maximum insulation temperature for the cables in the cable duct adjacent to the duct containing the fire will be less than 176*C. 'This is less than the 250'C which was deemed to be an accept-able basis for passing the fire test. Cables would not be damaged in a duct adjacent to a duct containing a fire.

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SUGGESTED ADDITION TO NE00-10466-A M Optionally, if the cable insulation for a contr'o1 room is primarily Tefzel, the applicant may choose to provide automatic injection of the Halon in a quantity sufficient to maintain a 6% concentration for 10 minutes. This option may be chosen on an individual floor section basis, but a qualifying floor section  ;

must not contain more than 20% by weight of non-Tefzel insulation. Automatic initiation of the injection of the suppress' ant may be from the product of combustion detectors, the rate of temperature rise detectors or a cross-zoned  ;

combination of the two types of detectors. The choice of the specific method of wiring the detectors is the responsibility of the applicant.

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9 NEDO 10466-A from one area to another. Cables in the control room cables. The fire tests performed on a floor section should be kept to the minimum necessary for plant demonstrated that the separation requirements of operation. Regulatory Guide 1.75 were met (See Appendix F).

The qualification test proved that the limited air flow Cables in underfloor and ceiling spaces should in a normally configured floor section (all floor meet the separation criteria given in Regulatory plates Installed) does not allow a fire to burn and in a Guide 1.75. Air handling functions should be ducted degraded configuration (two floor plates removed) separately from cable runs in such spaces;i.e.,if ca- the fire does not propagate along the cables. Conti-bles are routed in underfloor or ceiling spaces these nuity of cables and dielectric strength of cables in should not be used as air plenums for ventilation of the adjacent raceway (non-fire raceway) were also the control room. Fully enclosed electrical raceways maintained with a substantial safety margin.

In such underfloor and ceiling spaces, if over one square foot in cross-sectional area, should have au- A piping manifold and nozzles for a fixed man-tomatic fire suppression inside. Area automatic fire ual Halon 1301 fire suppression system (as required suppression should be provided for underfloor and by the NRC for the PGCC floor sections)is provided ceiling spaces if used for cable runs unless all cable for suppressant injection.This Halon suppression is is run in 4 inch or smaller steel conduit or if the ca- an additional precaution to control potential fires in bles are in fully enclosed raceways Internally pro- concealed areas. The suppressant will be supplied tected by automatic fire suppression. by the customer to a percent and holding time to ex-tinguish a potential floor section fire. The NRC re-(See Section C.6.b of Reference 7, Regulatory quirement at this time is based on a deep-seated fire Guide 1.120) and their requirement is 20% concentration for 20 minutes.

Optionally, if the cable insulation for a control room is primarily Tetzel, the applicant may choose to provide automatic injection of the Halon in a quanti-ty sufficient to maintain a 6% concentration for 10 minutes. This option may be chosen on an individual floor section basis, but a qualifying floor section must not contain more than 20% by weight of non-Tefzel Insulation. Automatic initiation of the injec-tion of the suppressant may be from the product of combustion detectors, the rate of temperature rise detectors or a cross zoned combination of the two types of detectors. The choice of the specific meth-od of wiring the detectors is the responsibility of the applicant.

4.1.6.11 Computer rooms for computers performing 4.2.6.11 Since the computer panels are also mount-safety-related functions which are not part of the ed on floor sections, the concerns of this guideline control room complex should be separated from oth- apply. These panels do not perform safety-related er areas of the plant by barriers having a minimum functions and therefore are treated the same as any fire resistance rating of three hours and protected by other non safety-related panels in the control room.

automatic detection and fixed suppression. Com- Channel separation is maintained in the routing of puters that are part of the control room complex but computer cables.

not in the control room should be separated and pro-tected as described in Section C.6.b. Computer cabl-nets located in the control room should be protected as other control room equipment and cable runs therein. Non safety-related outside the control room complex computers should be separated from safety related areas by minimum three-hour rated fire barriers and be protected as needed to prevent fire and smoke damage to safety-related equipment.

(See Section C.6.d of Reference 7 Regulatory Guide 1.120) 4 25

NEDO-10466 A ,

Table 41 COLOR CODING OF CA8LE MARKERS Separation Marker Lettering Category Color Lettering Color Division I Yellow Divi Black Division i Associated Yellow Div I A Black Division ll Blue Div 11 White Division ll Associated Blue Div 11 A White Division ill Green Divlil White Division lli Associated Green Div Ill A White Division IV Orange Div IV Black Division IV Associated Orange Div IV A Black Non-Divisional White ND Black The markers are made of colored tape with the letters (1/8-inch characters) printed on it in a repeating pattern. The tape markers are 3/4-inch wide and long enough to go around the cable. The cables are marked 1 foot from each end and at approximately 5-foot intervals.

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