ML19242B305
| ML19242B305 | |
| Person / Time | |
|---|---|
| Issue date: | 07/01/1979 |
| From: | NRC OFFICE OF STANDARDS DEVELOPMENT |
| To: | |
| Shared Package | |
| ML19242B301 | List: |
| References | |
| REGGD-01.XXX, REGGD-1.XXX, NUDOCS 7908070846 | |
| Download: ML19242B305 (6) | |
Text
O DRAFT VALUE/ IMPACT STATEMENT 1.
THE PROPOSED ACTION 1.1 Description In the course of construction of a nuclear power plant, cables and cable raceways penetrate barriers such as walls, floors, or floor-ceiling assemblies throughout the plant.
When these barriers are ratea as fire resistive barriers, the catle penetrations should have the same resistance to fire as the barriers.
The fire rating for a barrier witn no penetrations is arrived at by testing it according to the procedure outlined in ANSI / ASTM Standard Fil9-71, " Methods of Fire Tests of Building Construction and Materials."
This rating is expressed in hours and represents the ability of the barrier tc withstand exposure to a stand-ard fire for that length of time without faiiure (acceptance cr#teria are given in ANSI / ASTM Standard E119-71).
Up to r.ow there has not been 2 standard quali-fication test for rating a rated fire barrier with a cable penetration.
The proposed action will provide guidance for establishing a standard type test for qualifying cable penetration fire stops when mounted in rated fire barriers used in the constr uction of nuclear power plants.
- 1. 2 Need for the Proposed Action There is no detailed or formal staff position on a standard qualification test for cable penetration fire stops utber than a reference made in Regulatory Guide 1.120 to a draft standard being developed by Task Force 12-40 of the IEEE Insulated Conductors Committee on testing cable penetration fire stops.
This draf t is now an approved standarc' (IEEE Std 634-1978, "IEEE Standard Cable Penetra-tion Fire Stop Qualification Test"), and a definite need exists for an established NRC position on the use of ti.is standard for quoi;fication testing cable penetra-
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- 1. 3 Value/ Impact of the Proposed Action There will be less time spent by the staff in licensing actions if a standard qualification test of cable penetration fire stops is endorsed by the NRC.
This will relieve the staff of determining a special test for each facility application on a case-by-case basis.
The value/ impact of each regulatory position supplement-ing the endorsed IEEE standard is discussed below:
1.3.1 Regulatory Position C.1 - This 70sition provides information to the user of the guide on how to apply referenced standards and has no impact.
1.3.2 Regulatory Positica C.? - The IEEE standard states that the test assembly should be representative of an actually installeJ cable penetration fire stop.
Regulatory po:ition C.2 lists items that might not normally be considered in constructing the test assembly.
Value - This positi n will ensure more nearly representative conditions in i
the qualification test.
Impact - Test assemblies will be more difficult +
construct, especially the type having a differential pressure with the high pressure on the exposed side, since test furnaces are normally operated at a pressure belnw atmospheric.
- 1. 3. 3 Regulatory Position C.3 - The IEEE standard does not discuss the case of iritentional modification of a fire stop to add additional elements and the subse"; ant resealing of that fire stop.
Regulatory position C.3 provides for requalification of a fire stop that undergoes the above procedure if the proto-type was not successfully tested under such conditions.
Value - This position will ensure that fire stop resealing procedures are adequate to prevent a reduction in the effectiveness of the fire stop.
Impact - This position will require the preparation and t : ting of an addi-tional reprejentative assembly.
1.3.4 Regulatory Position C.4 - Section 5.3.3 of the IEEE standard states that the cable on the exposed side shall protrude a minimum of 1 foot.
This distance of 1 foot is considered an artificial reduction in the combustible load-ing for fire stops rated at 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or less.
Regulatory position C.4 states that 1"
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3 feet of cable should be used on the exposed side for such applications to provide a more representative deviation from the standard time-temperature curve during the initial burning of ti.e cable jacket.
Value - This position will ensure more nearly representative testing of fire stops rated at 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or less.
Impact - The use of an additional 2 feet of cable
'xpected to have little impact on the complexity of design or testing of the representative assembly.
1.3.5 Regulatory Position C.5 - Section 5.3.5 of the IEEE standard states that cable penetration fire stop designs that are unsymmetrical may require testing on both sides for qualification.
Regulatory position C.5 calls for testing on both sides of fire stops that are unsymmetrical with respect to the use and appli-cation of fire stop materials.
Value - This position will ensure adequate symmetrj of fire spreading resistance for unsymmetrical fire stops.
Impact - More testing will be required, since tach fire stop that is unsymmetrical with respect to the use and application of fire stop materials will have to be tested twice.
1.3.6 Regulatory Position C.6 - Section 5.3.10 of the IEEE standard states that a minimum of three thermocouples shall be used (a the unexposed sioe and designates the minimum distribution pattern for these thermocouples.
Regulatory position C.6 provides for more reliable temperature measurements on the unexposed side by requiring three thermocouples for each point of interest.
Value - This posit. ion will preclude the inherent unreliability of single-point measurements and will ensure that the temperature at each possible point of interest is sampled.
Impact - The complexity of the instrumentation layout will be increased s l ightl;,
1.3.7 Regulatory Position C..
- Section 6.1.1 of the IEEE standard contains some ambiguity on the passage of flame.
Specifically, the phrase " hot enough to ignite
" could be ir.terpreted to modify the noun " flame" as well as the noun
" gases."
Regulatory position C.7 provides clarification by stating that any passage of flame should be considered to termis te the endurance of the fire stop.
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Value - This position will prevent errors in endpoint determination caused by misinterpretation of the IEEE standard.
Impact - This position is merely a clarification and has no impact.
1.3.8 Regulatory Pos' tion C.8 - Section 6.1.2 of the IEEE standard states that the transmission of heat through the cable penetration fire stop shall not raise the temperature on its unexposed surface above the self-ignition temperature of various listed materials and states that the maximum temperature measurement sha:1 not exceed 700 F.
Regulatory position C.8 adds conservatism to this maximum temperature by stating that it should not exceed 600 F or o00 F depending on the location of the thermocouple.
The 600 F limit is baseo on the self-ignition temperature of various materials that could pass through the penetration.
The 400 F limit is placed on thermocouples located 1 inch away from the 600 F thermocouples and is based on the self-;g..ition temperature of common shipping containers that could be placed in the proximity of the fire stop in the floor / ceiling application.
Value - This position will ensure that the maximum allowable temperature on the unexposed side is well below the self-ignition temperature of materials expected to pass through the fire stop and will ensure that common violations of good housekeeping procedures will not contribute to the spreading of fire between compartments separated by a fire t'arrier.
Impact - The complexity of the instrumentation layout will be increased slightly.
Increased cost in fire stop construction because of the lowering of the temperature limit is not expected.
2.
TECHNICAL APPROACH 2.1 Technical Alternativg A fire-rated barrier is qualified in accordance with ASTM Standard E119-71,
" Methods of Fire Tests of Building Construction and Materials."
The prrposed action involves qualifying, by testing, a rated fire barrier that has '>een changed by the addition of a physical penetration (i.e., a cable or c.ible tray).
The technical approach should provide guidance that will, as a ninimum, result in testing equal to the testing of the rated fire barrier, since the rating of i
the qualified fire barrier with the penetration should equal the rating of the g (; U
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qualified fire barrier.
Since the rated fire barrier, tested to E119-71, is accepted by the staff as an acceptable technical approach taken in lieu of attempting to simulate the design basis fire for every cable penetration in the plant and then testing t-it, it appears technically feasible to modify the method and acceptance criteria of the ASTM E119-71 test for the purpose of testing a fire stc in a cable penetration that penetrates a rated fire barrier.
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- 2. 2 Discussion and Comparison of Technical Alternatives Not applicable as thore are no other reasonable approaches available at this time.
3.
PROCEDURAL APPROACH 3.1 Procedural Alternatives Potential SD procedures that may be used to nromulgate proposed action and technical approach include the following:
O 1.
Regulatory Guide 2.
Branch Technical Position 3.
ANSI Standard, endorsed by a Regulatory Guide 4.
NUREG 5.
Regulation 3.2 Value/ Impact of Procedural Alternatives A regulatior, requiaing that the design of safety-related equipment be veri-fied by such measures as the performance of a suitable testing program is already in effect.
However, detailed methods for qualifying a particular item of equip-ment are not appropriate for a regulation.
A NUREG is nat a viable alternative because the guidance will contain positions.
An ItEE (Institute of Electrical and Electronics Engineers) standard (IEEE Std 634-1978, dated April 19, 1978, "IEEE Standard Cable Penetration Fire Stop Qualification Test") is in existence and could be endorsed by a regulatory guide.
There are no branch technical
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positions that address the specifics on how to qualify cable penetration fire stops.
- 3. 3 Decision of Procedural Approach A regulatory guide that endorses, with appropriate exceptions, IEEE standard 634-1978 dated April 19, 1978, should be prepared.
4.
STATUTORY CONSIDERATIONS 4.1 NRC Authority Authority for this guide would be derived from the safety requirement. of the Atomic Energy Act through the Commission's regulations, in particular, General Design Criterion 3, " Fire Protection," of Appendix A, " General Design Criteria for Nucloar Power Plants," to 10 CFR Part 50, " Domestic Licensing of Production and Utilization Facilities," which requires that structures, systems, and components important to safety be designed and located to minimize, con istent with other safety requirements, the probability and effect of fires and explosions.
In addition, Criterion III, " Design Control," of Appendix B, " Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants," to 10 CFR Part 50 requires, among other things, that design control measures provide for verifying the adequacy of design by such measures as the performance of a suitable test program.
Where a test program is used to verify the adequacy of a specific design feature, it is required to include suitable qualification testing of a prototype unit under the most adverse design conditions.
4.2 Need for NEPA Assessment No environmental impact statement is required.
5.
RELATIONSHIP TO OTHER EXISTING PROPOSED REGULATIONS OR POLICIES This guide will supplement Regulatory Guide 1.120, " Fire Protection Guide-lines for Nuclear Power Plants."
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