ML20034A048

Safety Evaluation Granting Exemption Requests from App R

ML20034A048
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	04/10/1990
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20034A045	List: ML20034A044 ML20034A047 ML20034A048
References
NUDOCS 9004190228
Download: ML20034A048 (5)

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NUCLEAR REGULATORY COMMISSION y,

t WASHINGTON, 0; C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION EXEMPTION RE0 VESTS FP,0M APPENDIX R TO 10 CFR 50 i

CONNECTICUT YANKEE ATOMIC POWER COMPANY I

HADDAM NECK PLANT

'l DOCKET NO. 50-213 1

1.0-- Auxiliary Feedwater' Pump Room By letter dated October 27, 1989, Connecticut Yankee Atomic Power Company (the-licensee) requested approval of an exemption from the technical requirenents:

of Section III.G.I.(a) of Appendix R to 10 CFR 50 to the extent:that;it i

requires that one train of. systems necessary-to' achieve. and maintain hot shutdown conditions remain free from fire damage. Specifically, motor j

operators for redundant-auxiliary feedwater valves in the auxiliary feedwater i

pump roon (Fire Area R-2)-are vulnerable to fire' damage.

J 1.1 Discussion I

h Motor-Operated Valves FH-MOV-35 and FW-MOV-160 are located in the auxiliary feedwater pump room. These valves are used to direct auxiliary -feedwater ~ flow to the steam generators along either the preferred path-through'the auxiliary fee &ater regulating valves or along the alternate path, directly to the steam generators. The valves are aligned in their d uign hot shutdown position-during rermal plant power operations and would not be required to change i

position in the event of an Appendix P, fire scenario'.- However, fire in the auxiliary feedwater pump room could damage these. valve motor operators.

Despite any damage, these valves will fail at is. Therefore, there would be no impact on the ability of the plant to achieve and maintain hot shutdown.

The cables to the valve operators are routed through the fire area in-conduit. However, the licensee stated that the c_ircuits are not subject to damage that may result in a spurious signal induced by a fire which would-cause the valve to realign.

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1.2 Evaluation m

oshj The technical requirements of Section III.G.I.(a) of Appendix R have no.t been

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met in this area because the circuits and valve operators for redundantauxiliary fe o.o

. damage.

M The subject valves are aligned in their desired het shutdown position during

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$8 normal plant operation. The licensee has indicated that their desion is ge-such that damage to the motor operators will cause the valves to fail as is.

Consequently, the staff's only remaining concern was that a fire could damage e

,;88 the circuit associated with the automatic operation of the valves in such a M.k -

manner that a spurious signal could result in a re-alignment of the valve.

In response to this concern, the licensee performed a spurious signal analysis in accordance with the guidance issued in Generic Letter 81-12. The results

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of this analysis indicated that only a hot short on all three phases of the circuits in' proper sequence _would cause a~ spurious signal. The staff considers.this scenario incredible, except for high-low pressure piping interfaces. Because these-valves are not in a high-low pressure interface and a

because the circuits.are-in conduit, the staff concerns regarding spurious signals _.are considered resolved.

j 1.3': Conclusion Based on the above evaluation, the staff concludes that' the existing plant condition achieves.an equivalent level of safety to that achieved.by conformance with Section III.G.1 of the Rule. Therefore, the licensee's request.for exemption from the technical requirements of_ Appendix RLto 10'CFR 50 applicable to the redundant valves -in.the' auxiliary feedwater pump room should be approved.'

2.0 Men's Locker Room, Fire-Area S R.H.R. Pump Pit Area', Fire Area A-1 In safety evaluation reports dated November.27, 1987 and November 14, 1984, the staff approved exemptions from-the technical requirements of Section III.G of Appendix R to 10 CFR 50 in the above plant locations. By letter dated-October. 27 ~, ~1989,- the licensee described modifications to be performed.in these areas 'which change ~ the physical configuration and protection of safe shutdown cables. Separation of the cables will not be in strictz conformance with the provisions of Appendix R.

Consequently, revised exemption requests-have been submitf.ed.

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-2.1 Discussion a.

Men's Locker-Room:

l-With the construction of the new switchgear building, he power supply for Service Water Pump "D" will be moved from the old switchgear room to the new.switchgear. building. Accordingly, the cables for Pump "D" will be re-routed, and will now pass beneath-l the service building floor before entering.the old duct bank.

L The cables will join in a new concrete junction box' located-below l

the floor of the men's locker room.

In this-junction box,~a new cable will' be spliced onto'the existing "0" service water pump cable; and travel out to the intake structure in its'own conduit (in the

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duct bank)'

The only separation at this point to the intake structure will be the conduits 11n a concrete duct bank which is considered a new junction box. This new route will eliminate the need to have all four service water cables in' the same vertical cable chase, as presently configured.- The licensee justified the-exemption request on the basis of the enhanced: separation between.

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service water cables, the limited fire. hazard in the area and the L

presence of an automatic sprinkler system which protects the men's L

locker room.

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RHR Pump Pit Area:

The staff's approval of the original exemption in the RHR pump pit area was based on credit for a partial height wall which separated redundant: shutdown-cables and components, and the rerouting ofJ redundant RHR cables to enhance physical-separation.- At this. time, the licensee; proposes to protect one division of RHR-pump cables by

.a 3-hour fire rated cable wrap, as described in the.subje'ct letter,-

in lieu of rerouting cables. Additional modifications include installation of-curbing at the access to the-pump rooms to mitigate the effect of a-lube oil spill and potential fire, and sealing the access hatchway from operating = floor, elevation 21 feet 6 inches.-

2.2 Evaluation The technical requirements-.of Section III.G of Appendix'R have not been met in the. subject areas.because the redundant cables and components have not been.

separated and protected in accordance with the. fire protection options

-delineated in Appendix R.

The ' staff was initially concerned that a fire of sufficient magnitude and intensity could develop in these areas and.dr,e both shutdown trains.

However, the men's locker area is protected b'

-n. automatic sprinkler-system.

If a fire were to-occur,-the system would act..:e to both control-the fire and protect +he shutdown circuits in the area.x ' Concurrently, an alarm.would be-transmitted automatically to the control room. -The plant fire brigade would be dispatched and would put out any residual combustion with available manual-fire fighting equipment.

In the RHR pump-pit area, the in-situ combustible loading is minimal. 1The.

most likely fire scenario-is a lube oil spill and-fire. The curb at.the entrance to the cubicle would prevent oil from spreading 'beyond. the immediate spill area.

If ignition of the oil' occurs, it would be-detected in its.

initial stages by plant operators. or the existing fire detection-system. An alarm from the detection ~ system would be transmitted automatically to.the control room. The plant fire brigade would arrive within minutes to=put out the fire manually.

Pending. arrival of the-brigade, the RHR pump cubicle.

walls would shield the redundant pumps from direct flame impingement and radiant energy. The smoke and hot gases from a fire would collect at the ceiling,.and not encompass vulnerable cables or the redundant pump until'well i.

'after the arrival of the brigade. The staff, therefore, concludes-that the-existing. fire protection features with the proposed modifications in these two areas is sufficient to provide reasonable assurance that at least one shutdown division will remain free of fire damage.

2.3 Conclusion Based on the above evaluation, the staff concludes that the licensee's alternate fire protection configuration provides an equivalent level of fire safety to that achieved by compliance with the requirements of Appendix R.

4 Therefore the licensee's request for exemption from the requirements of Section-III.G of Appendix R to 10 CFR 50 in the subject-areas should be granted.

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-6 3.0 Containment Cable Vault By-letter dated November 14, 1984, the staff granted approval of an exemption in the containment cable vault area from the requirements of section a

III.G.(2)(c)ofAppendixP,. Specifically,. redundant-shutdown circuits were-

,1 separated by 20 feet, but the intervening space contained combustible-1 materials. - The licensee's justification for the original exemption was based, l

in part, on a proposal to protect certain shutdown cables in a 1-hour

'l fire-rated cable wrap.

At this time, the licensee has proposed to utilize fire-rated cables in lieu -

l of a 1-hour cable wrap. However, because certain redundant shutdown cables will still be separated by spatial separation with intervening combustibles, l

an exemption for the area is necessary.

3.1 Discussion i

Fire-rated mineral insulated (MI) cables will be.used to transmit one ' set (Train B) of Appendix R safe shutdown process monitoring parameters through the cable vault. This set of safe shutdown parameters will be utilized during cable vault fires.

The MI cable has been successfully tested in accordance i

with ASTM Standard E119 for_a three-hour fire rating. This MI.. cable has been i

previously approved by the staff.

The. transition from containment to the cable vault wi11 be made via special welded penetrations which incorporate' the fire qualified'MI cable. The routing.of the cable will be such that falling debris resulting from a cable j

vault fire will not affect the integrity of the MI cable. The HI; cable will be fastened to the cab'e vault surfaces using unistrut and tubing clips. This fastening method has been qualified-as part of the MI cable fire qualification.

The transition from MI cable to organic cable will take place within a one-hour fire-rated enclosure. This enclosure and the conduit transition to the duct bank will have a one-hour wrap and will carry the Appendix R, Train B instrument cables from the-cable vault. This enclosure and the cable runs from the duct bank to the enclosure will be fire protected.to meet Appendix R,Section III.G.2.c. This enclosure and the cable runs have also been evaluated:

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with respect to falling-debris resulting from a cable vault fire and have been determined to retain their integrity.

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3.2 Evaluation 4

The-licensee's proposal to utilize 3-hour fire-rated MI cable in lieu of 1-hour' fire-rated cable wrap as discussed in the subject letter is considered I

an enhancement over the fire protection configuration approved in our' November 14, 1984 safety evaluation. Since no other significant change is being proposed at this time, the staff concludes that the original justification for-granting the exemption for containment cable vault remains valid.

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. 5-3.3 Conclusion.

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Based on the above review, and the previously granted exemptions in this crea, the staff. concludes that the licensee's alternate fire protection configuratien provides an equivalent.. level of safety to that. achieved by

. compliance'with Appendix R to 10 CFR 50.

Therefore, the licensee's request for exemption from Section III.G.2 of Appendix R to 10 -CFR:50 in the cable vault should be granted.-

l Principal Contributor:

D. Kubicki~

Dated:

April 10, 1990 h

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