ML20206D414

Exemption from Requirements of 10CFR50,App R,Section III.G.2 Re Enclosure of Cable & Equipment & Associated non-safety Related Circuits of One Redundant Train in Fire Barrier Having 1-hour Rating

ML20206D414
Person / Time
Site:	Three Mile Island
Issue date:	04/20/1999
From:	Zwolinski J NRC (Affiliation Not Assigned)
To:	GENERAL PUBLIC UTILITIES CORP.
Shared Package
ML20206D405	List: ML20206D400 ML20206D414 ML20206D420 ML20206D425
References
NUDOCS 9905040102
Download: ML20206D414 (7)

Text

i 7590-01 P UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION in the matter of )

GPU NUCLEAR, INC. ) Docket No. 50-289 )

ET AL. )

)

0 (Three Mile Island Nuclear )

Generating Station, Unit 1) )

EXEMPTION 1.

GPU Nuclear, Inc., et al. (GPUN or the licensee) is the holder of Facility Operating License No. DPR-50, which authorizes operation of the Three Mile Island Nuclear Generating l Station, Unit 1 (TMI-1 or the facility) at power levels not to exceed 2568 megawatts thermal.

The facility consists of one pressurized-water reactor located at the licensee's site in Dauphin County, Pennsylvania, sad was licensed to operate on April 19,1974. The license provides, among other things, that the licensee is subject to all rules, regulations, and orders of the Nuclear Regulatory Commission (the Commission) now or hereafter in effect.

II.

Appendix R to 10 CFR Part 50 contains specific requirements regarding fire protection features of nuclear power plants operating prior to January 1,1979. Subsection Ol.G.2.c of Appendix R specifies, in part, the enclosure of cable and equipment and associated non-safety-related circuits of one redundant train in a fire barrier having a 1-hour rating. The underlying purpose of Subsection Ill.G.2.c of Appendix R is to provide reasonable assurance 9905040102 990420

PDR ADOCK 05000289

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accordance with the ASTM E-119). In each of the areas / zones that have automatic suppression and/or automatic detection features, the systems installed in the plant meet all I

applicable NFPA codes, specifically the criteria for a Class 1 detection system specified in NFPA 72D and NFPA 13 or NFPA 15 for suppression systems.

Fire zones AB-FZ-4 and FH-FZ-1 contain both automatic suppression and detection features. Fires in these zones are postulated to be slowly developing cable fires, with possible ignition sources including cable overload or transient combustibles, if a fire were to occur in these fire zones, indication of the fire would be received in the control room, through the ionization smoke detection system, and either the automatic pre-nction system (AB-FZ-4) or the wet pipe sprinkler system (FH-FZ-1) would initiate suppression if the fire continued to grow.

If necessary, the fire brigade would be dispatched soon thereafter. The licensee estimPtes 1

i that the fire brigade will respond to these fire zones 15 minutes after receiving an alarm.

Manual fire fighting equipment (hand-held fire extinguishers and hose stations) is available in l

l or adjacent to these fire zones.

I Fire area CB-FA-1 contains both automatic suppression and detection capability. A fire in this area is postulated to be a slowly developing cable fire, with possible ignition sources being overload or transient combustibles. Exposure of the protected envelope to fire is possible through ignition of cable insulation. There is also an acetylene gas line running above the suspended ceiling from an external tank. The licensee committed in its October 14,1998, and December 23,1998, letters to install detectors for combustible gas in this area to provide ,

prompt detection and notification of an acetylene leak, so that the leak could be promptly isolated at the source prior to reaching the lower explosive threshold for acetylene gas. If a fire were to occur in this fire area, indication of the fire would be received in the control room, through the ionization smoke detection system which is above the suspended ceiling. An l

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automatic wet pipe sprinkler system which is below the suspended ceiling would actuate to suppress the fire should it continue to develop. If necessary, the fire brigade would be dispatched soon thereafter, and response has been estimated by the licensee to be 15 minutes. A hand-held dry chemical extinguisher is also available adjacent to this fire area.

Fire zone FH-FZ-6 is provided with automatic detection and will be provided with l automatic suppressior'. The licensee committed to install an automatic wet-pipe sprinkler l suppression system in this fire zone in its letter dated December 23,1998. A fire in this zone is postulated to be a slowly developing cable fire, with possible ignition sources being transient combustibles. If a fire were to occur in this fire zone, indication of the fire would be received in the control room by the ionization smoke detection system or through the actuation of the wet-pipe sprinkler system to be installed. If necessary, the fire brigade would be dispatched soon thereafter, and the licensee estimates a brigade response would occur within 15 minutes.

Manual fire suppression capability (hose stations and dry chemical extinguisher) is available in or adjacent to this fire zone.

Fire zone ISPH-FZ-1 contains both automatic detection and suppression features. A fire in this zone is postulated to be a slowly developing cable fire, with electrical switchgear as a possible ignition source. If a fire were to occur in this zone, indication of the fire would be received in the control room by the ionization smoke detector system. A zone-wide automatic wet-pipe sprinkler system is available to suppress the fire, should it develop, and portable extinguishers (carbon dioxide and dry chemical) are available within the fire zone. The fire brigade would be dispatched, if necessar/, and the licensee estimates a brigade response i time of 25 minutes. A portable extinguisher and yard hydrant are located outside the fire area and are available to fight fires in this fire zone. Protected envelopes consisting of cables and

6-conduits passing through this fire zoae are fire rated at 39 and 50 minutes respectively, and pass within the vicinity of in situ combustibles in only limited instances.

Fire zone ISPH-FZ-2 contains both automatic detection and suppression features. A fire in this zone is postulated to be a slowly developing cable fire, with electrical switchgear as a possible ignition source. If a fire were to occur in this zone, indication of the fire would be received in the control room by the ionization smoke detector system. A zone-wide automatic l wet-pipe sprinkler system is available to suppress the fire, should it develop, and a portable

, extinguisher (carbon dioxide) is available within the file zone. The fire brigade would be I

dispatched, if necessary, and the licensee estimates a brigade response time of 25 minutes. A I

portable extinguisher and yard hydrant are located outside the fire area and are available to i bght fires in this fire zone. Protected envelopes consisting of cables and conduits passing through this fire zone are fire rated at 39 and 50 minutes, respectively, and pass within the vicinity of in-situ combustibles in only limited instances.

The staff is relying on the licensee's commitments made in its October 14,1998, and l

December 23,1998, letters for approval of the exemptions for fire area CB-FA-1 and fire zone FH-FZ-6. Therefore, approval of an exemption for that fire area and zone is contingent upon the licensee completing the modifications described in those submittals. The staff believes that reasonable assurance exists that an adequate level of fire safety has been provided through the availability of automatic suppression and detection in these fire zones / areas to ensure that one division of safe-shutdown components necessary to achieve safe shutdown will remain free of fire damage. Therefore, the underlying purpose of the rule is satisfied and this request for exemption with respect to the foregoing fire areas / zones from the requirements of 10 CFR Part 50, Appendix R, Section Ill.G.2.c meets the special circumstances delineated in 10 CFR 50.12(a)(2)(ii) in that the application of the regulation in these particular

l circumstances is not necessary to achieve the under1ying purpose of the rule. While the l

installed Thermo-Lag barriers in the fire zones demonstrate less than a 1-hour fire endurance rating, they do provide measured resistance to fire. The areas in which the Thermo-Lag envelopes are located have a low combustible loading in the area of the protected envelopes, have available manual suppression capability, and are equipped with automatic suppression I and detection features; the combination of these features and circumstances reflect a level of I

safety that meets the underlying purpose of the rule. Therefore, the staff believes that the exemption should be granted for fire zones / areas AB-FZ-4, FH-FZ-1, CB-FA-1, FH-FZ-6, ISPH-FZ-1, and ISPH-FZ-2.

The staff does not believe the same assurance has been provided for fire zones AB-FZ-3, AB-FZ-5, AB-FZ-7, and FH-FZ-2. Fire zones AB-FZ-3, AB-FZ-5, and AB-FZ-7, have automatic detection but not suppression. Fire zone FH-FZ-2 has automatic suppression but not detection.

The licensee has failed to provide reasonable assurance that one division of safe-shutdown components necessary to achieve safe shutdown will remain free of fire damage in j the four zones immediately discussed above. Accordingly, as discussed above and in the staff's Safety Evaluation dated kril 20, 1999 . the staff has concluded that the licensee's request for an exemption from the technical requirements of Section Ill.G.2.c of Appendix R should be denied for fire zones AB-FZ-3, AB-FZ-5, AB-FZ-7, and FH-FZ 2.

IV.

l Pursuant to 10 CFR 50.12(a)(2), the Commission will not consider granting an exemption from the requirements of a regulation unless special circumstances are present. j Subsection (ii) of 10 CFR 50.12(a)(2) includes as special circumstances situations where

l l application of the subject regulation would not serve the underiying purpose of the rule or is not necessary to achieve the unoorfying purpose of the rule.

The underlying purpose of Section Ill.G of Apportdix R is to provide reasonable assurance that one safe shutdown train and associated circuits used to achieve and maintain

safe shutdown are free of fire damage. As stated above, the staff has determined that the underiying purpose of the rule has been satisfied with respect to fire zones AB-FZ-4, FH-FZ-1,

l. CB-FA-1, FH-FZ4, ISPH-FZ-1 and ISPH-F2 2. Accordingly, the Commission has determined

, that, pursuant to 10 CFR 50.12(a)(2)(ii) special circumstances are present in connection with these fire zone / areas.

The Commission has also determined that, pursuant to 10 CFR 50.12, the exemption requested by the licensee for fire zones / areas AB-FZ-4, FH-FZ 1, CB-FA-1, FH-FZ-6, ISPH-FZ-1, and ISPH FZ-2 is authorized by law, will not present an undue risk to public health and safety, and is consistent with the common defense and security.

Therefore, the Commission hereby grants GPU Nuclear, Inc., an exemption from the technical requirements of Section Ill.G.2.c of Appendix R to 10 CFR Part 50, to the extent that it requires the enclosure of certain redundant safe-shutdown circuits in 1-hour fire-rated barriers, for fire zones / areas AB-FZ-4, FH-FZ-1, CB-FA-1, FH-FZ-6, ISPH-FZ-1, and ISPH-FZ-2 at TMI-1. The exemption for fire area CB-FA-1 and fire zone FH-FZ-6 is contingent upon the licensee completing the commitments identified in its letters of October 14,1998, and December 23,1998, for that fire area and zone. The request for exemption for fire zones AB-FZ-3, AB-FZ-5, AB-FZ-7, and FH-FZ-2 is denied.

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Pursuant to 10 OFR 51.32, the Commission has determined that the issuance of this exemption will have no significant impoet on the quality of the human environment (64 FR 19205 ).

This exemption is effective upon issuance.

l FOR THE NUCLEAR REGU TORY COMMISSION

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John A. Zwolinski, Director Division'of Licensing Project Management Office of Nuclear Reactor Regulation Dated at Rockville, Maryland, this 20th day of April 1999 l

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