ML20212L084
| ML20212L084 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 10/01/1999 |
| From: | Zwolinski J NRC (Affiliation Not Assigned) |
| To: | ENTERGY OPERATIONS, INC. |
| Shared Package | |
| ML20212L066 | List: |
| References | |
| NUDOCS 9910070152 | |
| Download: ML20212L084 (9) | |
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m 7590-01-P UNITED STATES OF AMERICA.
NUCLEAR REGULATORY COMMISSION r in the Matter of )
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ENTERGY OPERATIONS, INC. ) Docket No. 50-368
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(Arkansas Nuclear One, Unit 2) )
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EXEMPTION 1.
Entergy Operations, Inc. (the licensee), is the holder of Facility Operating License No. NPF-6, which authorizes operation of Arkansas Nuclear One, Unit 2. The license provides, among other things, that the licensee is subject to all rules, regulations, and orders of the Commission now or hereaf ter in effect.
The facility is one of two pressurized-water reactors at the licensee's site located in Pope County, Ar' kansas.
II.
in its letter dated October 8,1997, as supplemented by letter dated February 25,1999, the licensee requested an exemption from the Commission's regulations. Title 10 of the Code ;
of Federal Regulations (10 CFR), Part 50, Appendix R, Section Ill.G.2, is designed to ensure that adequate fire protection features are provided for redundant cables or equipment located in the same fire area outside of primary conWame 7 2uch '. hat at least or.e of the redundant trains of safe shutdown equipment will remain available during and after any postulated fire in the 9910070152 991001 PDR ADOCK 05000368 p PDR L
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i l piant to achieve and maintain safe shutdown conditions. Section Ill.G.2.c requires the following means of assurance:
1 Enclosure of cable and equipment and t.ssociated non-safety circuits of one redundant train in a fire barrier having a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> fire rating. In addition, fire detectors and an automatic fire suppression system shall be installed in the fire I area [.) l The licensee has requested an exemption from the requirements of 10 CFR Part 50, Appendix R, Section Ill.G.2.c, for cables and equipment located below the 354-foot elevation of the ANO 2 intake structure. The licensee is requesting an exemption from the specific 1
requirement to provide fire detectors and an automatic fire suppression system to protect i redundant trains of safe shutdown equipment that are located in the same fire zone. The l licensee has demonstrated that one redundant train of cable and equipment, required to l achieve and maintain safe shutdown conditions, is protected with a fire barrier having an equivalent 1-hour fire rating.
111.
l Pursuant to 10 CFR 50.12, the Commission may, upon application by any interested person or upon its own initiative, grant exemptions from the requirements of 10 CFR Part 50 l (1) when the exemptions are authorized by law, will not present an undue risk to public health or safety, and are consistent with the common defense and security; and (2) when special circumstances are present. Special circumstances are present whmever, according to 10 CFR 50.12(a)(2)(ii)," Application of the regulation in the particular circumstances would not serve the underlying purpose of the rule or is not necessary to achieve the underlying purpose of the rule...."
i The underlying purpose of 10 CFR Part 50, Appendix R, Section Ill.G.2, is to provide reasonable assurance that at least onu of the redundant trains of safe shutdown equipment will
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i remain available during and after any postulated fire in the plant to achieve and maintain safe shutdown conditions.
The ANO-2 intake structure is about 32 feet by 26 feet on three levels. There are no rated fire barriers between the three levels. Below the 354-foot elevation there are three intake I
bays, which contain service water (SW) piping and conduits. The bays are approximately 7 feet {
i by 32 feet and are separated from one another by 2-foot thick, non-rated concrete walls. The bays are separated from the ground level by an 18-inch thick, non-rated concrete slab on metal decking. The floor of the bays is typically covered with water 16 feet deep. The ceiling height is approximately 14 feet above the normal poollevel. Of the three bays, only the "A" SW intake bay contains redundant cables. The licensee stated that the total in-situ combustible loading is j I
3,469,060 BTUs, which is equivalent to a fire severity to a standard fire duration of less than !
4 minutes. Each bay is administratively controlled as a " confined space," thus limiting access by personnel during rou'.ine operations and precluding the accumulation of combustibles, in addition, the licensee's administrative procedures limit the transient combustibles to 5 pounds unless personnel are continuously present in the area, in such case's, the personnel could be either the craft personnel responsible for using the combustible materials or a continuous fire watch. Water to the bay is normally provided through a sluice gate for the bays where the circulating pumps take suction.
SW is required to be available to supply cooling water for various safe shutdown components including the diesel generators and the shutdown cooling heat exchangers.
Additionally, SW can be aligned to the emergency feedwater system in the event that the desired condensate source is depleted. The time critical function is to supply cooling for the diesel generators. The licensee stated that, on the basis of its calculations, the diesel generators (and therefore the SW system components) are not required to be operated during l
! the first 30 minutes of a postulated fire event. The licensee allows the operators to manually i
r align the SW system because the diesel generators are not required during the first 30 minutes of a fire event and sufficient time is available to complete the alignment.
The SW system consists of two independent seismic category 1 flow paths, which !
furnish cooling water to two independent trains of 100 percent capacity engineered safety feature equipment, and two nonseismic category 1 flow paths. The SW system has three 100 percent capacity pumps. One pump is dedicated to each of the two SW trains while the I
third pump is designated as a swing pump and can be aligned to either train. The two loops of i
the SW system are also electrically independent with two separate divisions of electrical power designated as the red and green train. The red train power for SW is aligned to either SW pump 2P4A or SW pump 2P48, while the green train power is aligned to either SW pump 2P4C
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or SW pump 2P4B.
The four power cables associated with the 2P4A,2P4B, and 2P4C SW pumps interface with the "A" SW intake bay During plant operations (Modes 1 through 5), the ANO-2 technical specification requires that two SW trains be operable. The possible SW pump alignments are SW pumps 2P4A and 2P48, SW pumps 2P4A and 2P4C, or SW pumps 2P4C and 2P48. The power cable arrangements are as follows: conduit EA 1007 contains the red train power supply cable to SW pump 2P4A; conduit EA2036 contains the greese tidi power supply cable to swing SW pump 2P4B; and conduit EA2007 contains the green train power supply cable for i
SW pump 2P4C. Conduits EA1007 and EA2036 are protected by separate 1-hour fire-rated Hemyc fire barriers. Below the 354-foot elevation, these conduits are also encapsulated in a common galvanized sheet metal moisture barrier. Conduit EA2007, which is located about i 6 feet from the moisture barrier containing conduits EA1007 and EA2036, is covered by a Thermo-Lag barrier. The licensee stated that it does not take credit for the Thermo-Lag barrier i
to meet the requirements of Appendix R. Conduit EA1008, which contains the red train power supply to swing SW pump 2P48,is embedded in the concrete slab at the elevation of 354 feet I
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and does not enter the bay. Therefore, based on the preceding discussion, this area would L ' require the addition of fire detectors and an automatic fire suppression system to comply with p the requirements of 10 CFR Part 50,- Appendix R, Section Ill.G.2.c.
The "A" SW intake bay contains redundant cables required to support post fire safe shutdown. .The licensee stated that the 2P4C/2P48 SW pump combination with SW pump 2P4B aligned to the red train power is the only pump alignment that would be utilized during normal operations in Modes 1 through 5 with the "A" SW intake bay isolated and drained.
. During the recovery from a fire, the time critical function is to supply cooling water to the diesel
. generators. The licensee ~ stated that,'on the basis of its calculations, the diesel generators (and therefore the SW system components) are not required to be operated during the first 30 minutes of a fire event. The licensee allows the operators to manually align the SW system.
' because sufficient time is available to complete the alignment.
Power and control cables for the sluice gates are also located in the SW intake bays.
Sluice gate valves 2CV1470-1,2CV1472-5, and 2CV1474 2 are normally open, which u
corresponds to the safe shutdown position. The redundant control cables are separated horizontally by approximately 8 feet. As stated previously, the time critical function of the SW ;
system is to provide cooling to the diesel generators. The licensee stated that if a fire were to cause the sluice gates to spuriously close, adequate time would be available before the SW l was required to manually realign any affected component.
The in-situ combustibles in "A" SW intake bay and the administratively allowed quantity :
I of transient combustibles (5 pounds) do not pose a credible fire threat to the SW pump cables.
In the staff's view, a fire involving transient combustibles in excess of the administratively allowed quantity is the only type of fire that could damage redundant SW pump power cables.
The licensee has addressed this threat by protecting both the red train power supply cable for SW pump 2P4A and the green train power supply cable for swing SW pump 2P4B with 1-hour
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4 0 6-fire rated barriers, by embedding the red train power supply cable for SW swing pump 2P4B in
= concrete, and by administratively requiring the presence of craft personnel or a fire watch, if the
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administrative transient combustible limit is exceeded.
A fire involving transient combustibles could be extinguished by the craft personnel or the f. ire watch during its incipient stage. In the event the fire grows beyond the incipient stage before it is extinguished, the craft personnel or the fire watch could summon the plant fire 4
brigade, in addition, the smoke and hot gases would be directed upwards into the higher elevations of the intake structure, which are equipped with an automatic fire detection system.
Therefore, in the event that a fire in the intake bay is not discovered by the craft personnel or the fire watch, it would be detected by the automatic fire detection system and the plant fire brigade would be dispatched. If the fire exposes the redundant conduits, the 1-hour fire-rated l barriers and the concrete embedding, with an equivalent 1-hour fire rating, would provide fire resistive protection, with margin, for the expected fire hazards and, therefore, provide reasonable assurance that the power cables would not be damaged before the fire either burns itself out or is extinguished by the craft personnel, the fire watch, or the fire brigade. On this basis, the staff conclu' des that the existing fire protection design features, coupled with the ;
administrative controls, provide reasonable assurance that a fire in the "A" SW intake bay would not damage the redundant SW pump power cables and, therefore, would not adversely affect the ability to achieve and maintain post-fire safe shutdown. The staff also concludes that the ;
installation of fire detectors and an automatic fire suppression system in the area below the 354-foot elevation of the ANO-2 intake structure would not result in a significant increase in the
- level of fire safety for the redundant SW pumps. Additional details concerning the exemption are provided in the staff's Safety Evaluation dated October 1 1999.
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For the forgoing reasons, the NRC staff has determined that there is a low probability of l
occurrence for a fire event in the ANO-2 intake structure below the 354-foot elevation. This low probability of occurrence combined with the lack of combustible material, administrative controls, and the fire protection features provided, as stated in the licensee's submittals, is sufficient to reasonably ensure adequate protection for redundant equipment in the SW system, i
such that there is reasonable assurance that at least one means of achieving and maintaining i
safe shutdown conditions will remain available during and aftcr any postulated fire. Therefore, !
i the addition of fire detectors and an automatic fire suppression system is not necessary to I achieve the underlying purpose of Appendix R, Section Ill.G.2.c. i The Commission has determined that, pursuant to 10 CFR 50.12, this exemption is authorized by law, will not endanger life or property or the common defense and security, and presents no undue risk to public health and safety. In addition, the Commission has determined that the special circumstances under 10 CFR 50.12(a)(2)(ii) are present. Therefore, the Commission hereby grants Entergy Operations, Inc., an exemption from the requirements of 10 CFR Part 50, Appendix R, Section Ill.G.2.c, for the area below the 354 foot elevation of the -
ANO-2 intake structure, such that fire detectors and an automatic fire suppression system need not be installed in the fire area.
8-Pursuant to 10 CFR 51.32, the Commission has determined that the granting of this exemption will have no significant impact on the environment ( 64 FR 52804 ).
This exemption is effective upon issuance.
Dated at Rockville, Maryland, this 1st day of October 1999.
FOR THE NUCLEAR REGULATORY COMMISSION ORIGINAL SIGNED BY John A.Zwolinski, Director Division of Licensing Project Management Office of Nuclear Reactor Regulation i
- See Previous Concurrence l To receive a copy of this document, indicate "C" in the box g,o UV OFFICE PDIV-1/PM C, PDIV-1/l.A , L 'SPLB/BC OGChM PDIV-1/SC L i NAME C.Nolan:db M L. Berry h k') J.Hannon* h,[N R.Gramrk DATE 7 / fJ /99 h /Mhh99 7/ 9 /99 4/'k)( /99 #
C) / t1/99 j OFFICE PDIV-1/PD (, DLPM/D NAME S.Ricbcf J.Zwolin[kf DATE S /&?l/99 10 / \ /99
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i Pursuant to 10 CFR 51.32, the Commission has determined that the granting of this exemption will have no significant impact on the environment ( 64 FR 52804 - ).
This exemption is effective upon issuance.
Dated at Rockville, Maryland, this 1st day of October 1999.
l FOR THE NUCLEAR REGULATORY COMMISSION
}, J G. - v ;
John . Zwolinski, Director Division of Licensing Project Management Office of Nuclear Reactor Regulation i
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