ML20202B875
| ML20202B875 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 11/24/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20202B881 | List: |
| References | |
| NUDOCS 9712030203 | |
| Download: ML20202B875 (5) | |
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NUCLEAR REGULATORY COMMISSION g *... /j WASHlhoYON, D.C. seteHopi SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION DENIAL OF LICENSEE REQUEST FOR EXEMPTION FROM SECTION lli.G.2.f 0F APPENDIX R TO 10 CFR PART 60 SURRY POWER STATION. UNITS 1 AND 2. NORTH ANNA POWER STATION. UNITS 1 AND 2 DOCKET N05. 50 280. 50 281. 50-338. AND 50 339 1.
INTRODUCTION Appendix R. " Fire Protection program for Nuclear Power Facilities Operating Prior to January 1, 1979 " to Title 10 of the Code of Federal Reaulations (10 CFR Part 50), establishes fire protection features required to satisfy General Design Criterion 3, " Fire Protection," of Appendix A to 10 CFR Part 50 with respect to certain generic issues for nuclear power plants licensed to operate prior to January 1, 1979.
Surry Power Station, Units 1 and 2 (Surry) were licensed to operate on May 25, 1972, and January 29, 1973, respectively.
North Anna Power Station, Units 1 and 2 (North Anna) were licensed to operate on November 26, 1977, and August 21, 1980, respectively.
By letter dated December 15, 1995, Virginia Electric and Power Company (the licensee) submitted a request for exemation from the technical requirements of Section Ill.G.2.f. of Appendix R for T1ermo Lag radiant energy heat shields inside containment at Surry and North Anna.
By letter dated October 15, 1996, the staff ',ent 'a request for additional information regarding the December 15.
1995, exemption request.
The licensee responded by letter dated April 22, 1997.
Since North Anna Unit 2, was licensed to operate in 1980, the licensee is not required to meet the requirements of Appendix R as a regulatory requirement.
Therefore, the staff has treated the licensee's request for North Anna. Unit
- 2. as a deviatic,n request from the guidance contained in Appendix A to Branch Technical Position (BTP) Auxiliary Power Conversion System (APCSB) 9.5-1 rather than a request for an exemption from Appendix R.
2 EXEMPTION REOUESTED ine licensee requested an exemation from the technical requirements of III.G.2.f. of A:oendix R for T1ermo Lag radiant energy heat shields inside containment to ne extent that, when separation of cables and equipment and associated circuits of redundant trains by a horizontal distance of 20 feet
. ithout intervening combustibles cannot be achieved, inside noninerted w
containments, these cables and equipment and associated circuits of redundant trains are to be separated by noncombustible radiant energy heat shields.
The fire barrier material used for radiant energy heat shields at Surry and North Anna is Thermo Lag 330-1 (Thermo-Lag), a conibustible material.
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DISCUSSION At Surry and North Anna. Thermo Lag is used as a radiant energy heat shield for equipment and instrumentation located inside containment.
The equipment and instrumentation that are the subject of the exemption reauest are:
At Surry. Unit 1. the reactor coolant system (RCS) pressure indication circuits (3 feet 6 inches elevation), the pressurizer level indication circuits (18 feet 4 inches elevation), and the residual heat removal (RHR) pump motors (13 feet 0 inches elevation).
1 At Surry Unit 2. the RCS pressurizer level indication circuits (18 feet 4 i
incnes elevation), the steam generator level inaication circuits (3 feet 6 inches. 18 feet 4 inches and 27 feet 7 inches elevations), and the RHR pump motors (13 feet 0 inches elevation).
At North Anna. Unit 1. the RCS pressure indication circuits (262 feet 10 inches elevation), the pressurizer level indication circuits (292 feet 10 inches elevation), the neutron flux 1'dication cirmits (231 feet 6 inches elevation), and the RHR pump motors (231 feet 6 i crc 4 elevation).
At North Anna. Unit 2. the RCS pressurizer level indication circuits (262 feet 10 inches and 292 feet 10 inches elevations), and the RHR pump motor; (231 feet 6 inches-elevation).
At Surry, fire areas 15 and 16 are the primary containments for Units 1 and 2.
respectively.
Primary and alternate trains of instrumentation are routed through two different penetration areas within each containment.
There is an electrical penetration area into the cable vault / tunnel area at approximately the 15 feet 0 inches elevation and another electrical penetration area into the fuel building at the 47 feet 4 inches elevation.
These two penetration areas, at each unit, are separated by more than 20 feet horizontally and 30 feet vertically.
At North Anna, fire areas 1-1 and 1-2 are the primary containments for Units 1 and 2. respectively.
Primary and alternate trains of instrumentation are-routed through two different penetration areas within each containment.
There is an electrical penetration area into the cable vault / tunnel area and another electrical penetration area into the fuel building.
These two penetration areas, at each unit, are each separated by more than 20 feet horizontally and 30 feet vertically.
Free standing radiant energy shields or box enclosures are installed to-provide separation between primary and alternate instrumentation or components that are less than 20 feet apart horizontally.
Thermo Lag preformed half rounds protect conduits until a distance of 20 feet of horizontal separation-is achieved or until a barrier which is constructed of heavy-concrete is encountered.
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3 The radiant energy shields 3rotecting conduits are fabricated from 1/2 inch thick Thermo Lag preformed lalf-rounds. The boxes around cable penetrations and transmitters, and the panels between transmitters and between the RHR motors are fabricated from 1/2-inch thick Thermo Lag panels.
Intervening combustibles in the form of cable trays exist between primary and-alternate trains of instrumentation separated by more than 20 feet or by
' Thermo-Lag radiant energy shields.
Fire detection has not been provided in the immediate vicinity of the equipment and conduits protected by the radiant energy shields, with the exception of the reactor coolant pumps that are provided with heat detectors that alarm in the control room.
Fire extinguishers are located outside of the containment-at the personnel access hatch and dry hose stations. in the case of Surry, and stand)1 pes in L
the case of North Anna, for use by the fire brigade are located wit 11n the containment annulus.
4.
EVALUATION The licensee states the combustible radiant energy shields inside containment i
will perform their intended function on the basis of a combination of factors that include:
(1) ncgligible amounts of intervening combustibles near the shields: (2) the flame resistant nature of the cables: (3) the automatic fire detection: (4) the defense in depth: (5) the limited ignition sources: (6) the lack of transient combustibles: (7) a containment that is a multi-level open structure; and (8) the fact that Thermo-Lag requires large heat fluxes or high temperatures to ignite.
i BTP APCSB 9.5-1 and its Appendix A define non combustible materials as
" materials, no part of which will i The definition of. "non combustible"gnite and burn when subjected to fire "
used by the NRC in its Standard Review Plan (NUREG 0800. SRP 9.5-1. Fire Protection) was derived from National Fire Protection Association (NFPA) Standard 220. " Standard on Types of Building Construction." NFPA 220, which is referenced by the SRP. defincs noncombustible material as "[a] material which in the form in which it is used and under the conditions anticipated, will not ignite, burn, support combustion, or release flammable vapors when subjected to fire or heat.-
Materials which-are reported as >assing ASTM E136... shall be considered noncombustible materiais." On tlat basis, the staff used the test meth. s specified in ASTM E136 to assess the combustibility of Thermo Lag. As-reported in NRC Information Notice-92 82, the NRC concluded that Thermo-Lag is 4 combustible as defined in the aforementioned NRC fire protection guidelines.
The staff views combustibility as a material property which is independent of.
the fire loading in the area of the material and, therefore, the use of
- Thermo Leg as a radiant energy shield inside containment is unacceptable.
NRC-Informatico Notice 92-82 also; recommended that-licensees reevaluate their use of Thermo Lag radiant energy. shields inside the containment and seek other solutions such as. exemptions.where technically justified.
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For Surry in a letter dated February 25, 1988, the staff granted an exemption i
from Section Ill G.2.d. for the fire areas that are the subject of this request to the extent that it requires redundant cables and equipment inside a noninerted containment to be separated by 20 feet horizontally with no intervening combustibles. The staff based its approval of this exemption on the adequacy of fire sto)s used on vertical cable trays (intervening combustibles) and noncom]ustible N diant energy heat shields in the area of the redundant train interactions associated with the RCS hot and cold leg temperature, steam generator level, neutron flux monitoring. RCS pressure and pressurizer level instrumentation.
For North Anna, in a letter dated November 6, 1986, the staff ranted an exemption from Section III.G.2.d for the fire areas that are t e subject of this request to the extent that it requires redundant cables and equipment 1
inside a noninerted containment to be seaarated by 20 feet horizontally with no intervening cumbustibles.
The staff Jased its approval of this exemption on the adequacy of the fire stops used on vertical cable trays (intervening combustibles) and noncombustible radiant energy heat shields in the area of i
the redundant train interactions associated with RCS hot and cold leg temperature, steam generator level neutron flux monitoring. RCS pressure and pressurizer level instrumentation.
Therefore, the combustibility of the radiant energy heat shields was not factored in the overall evaluation.
On December 28. 1994, the staff issued a request for additional information regarding Generic letter 92 08 pursuant to 10 CFR 50.54(f).
One of the i
questions addressed Thermo Lag material consistency.
To help resolve this question.-the Nuclear Energy Institute (NEI) coordinated a generic chemical
-analysis program.
NEI analyzed the Thermo Lag samples sent by licensees and based on the results of the analysis, concluded that all of the samples were similar in chemical composition.
The licensee, however, did not participate e
in the chemical consistency program. As a result, the licensee is unable to establish with reasonable assurance that the Thermo Lag in use at Surry and North Anna is represented by the population of simples that were tested.
Generic letter 86-10 responds to a question in regard to the issue of limited amount of intervening combustibles and what would be sufficient justification to support an exemption request as follows:
If more than negligible quantities of combustible materials (such as isolated cable runs) exist between redundant shutdown division, an exemption request should be filed.
[ Negligible quantity is an admitted judgmental criterion.
- and this judgement should be made by a qualified fire protection engineer and documented for later NRC audit.) Justifications for such exemptions have been based on _the following factors:
1.
A relatively large horizontal spatial separation between redundant divisions; all cables qualified to IEEE-383:
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The presence of an automatic fire sup)ression system over the intervening combustible (such as a ca)le tray fire suppression system):
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3.
The presence of fire stops to inhibit fire propagation in intervening cable trays:
l 4.
The likely fire propagation direction of burning intervening combustibles in relation to the location of the vulnerable i
shutdown division:
5.
The availability of compensating active and passive fire l
protection.
containment constitute intervening combustibles:y shields inside the(2) additiona In view of the fact that:
(1) the radiant energ combustible! in the form of cable trays are also present in containment:
(3) there is no automatic fire suppression system over the intervening combustibles in question: and (4) manual suppression would be delayed due to the time required to enter containment, the use of Thermo Lag radiant energy shields inside containment is unacceptable. The licensee's request for t
exemption from Section Ill.G.2.f. of Appendix R for Thermo-Lag radiant energy heat shields inside containment for Surry Units 1 and 2. and North Anna. Unit
- 1. to the extent that it requires that inside rioninerted containmht, redundant trains of equiament needed to achieve and maintain safe shutdown conditions be separated )y a horizontal distance of more than 20 feet with no intervening combustible or fire hazards or a noncombustible radiant energy shield, should be denied.
in regard to North Anna. Unit 2. a deviation from the guidance contained in Appendix A to BTP APCSB 9.5 1 should not be granted.
5.
CONCLUSION On the basis of its evaluation, the staff has concluded that the use of combustible radiant energy heat shields inside containment at Surry and North i
Anna is unacceptable. Therefore, the licensee's request for an exemption from i
the requirements of Section III.G.2.f. of Appendix R to 10 CFR Part 50-for Surry. Units 1 and 2 and North Anna. Unit 1. is denied.
A deviation from the guidance contained in Appendix A to BTP APCSB 9.5-1 for North Anna. Unit 2. is also denied.
Reviewers:
Pat Madden and Daniele Oudinot Date: Nw enber 24, 1997 i
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