ML19250B041
| ML19250B041 | |
| Person / Time | |
|---|---|
| Issue date: | 10/01/1979 |
| From: | Grimes B Office of Nuclear Reactor Regulation |
| To: | Morrison W NRC OFFICE OF STANDARDS DEVELOPMENT |
| References | |
| RTR-NUREG-75-087, RTR-NUREG-75-87 NUDOCS 7910260019 | |
| Download: ML19250B041 (3) | |
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OCT 11973 MEMOR.MDUM FOR:
W. M. Morrison, Assistant Director for General Engineering Standard:, Division of Engineering Standards FRCM:
Brian K. Grimes, Assistant Director for Systems Engineering, Division of Operating Reactors
SUBJECT:
STANDARD REVIEW REQUEST (TAC 33)
The Plant Systems Branch has reviewed the proposed revision to IEEE Std. 384-1977. As a result of our review, we recommend a negative ballot. Those items which must be corrected in order to make the revised standard acceptable are identified in our enclosed aments.
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Brian K. Grimes, Assistant Director for Systems Engineering Division of Operating Reactors
Enclosure:
As stated Con tact:
R. Scholl X-27162 cc w/ enclosure:
D. Eisennut R. Satterfield F. Scnroeder D. Tondi D. Vassallo V. Senaraya D. Muller V. Thomas J. Norterg R. Ferguson G. Lainas J. Knign:
F. Rosa PSB, Section A 881 02 7 910260 o t et
ENCLOSURE COMMENTS ON IEEE STD. P384/01 1.
" Low energy", as used in Section 4.6.l(4), is undefined and, therefore, this section does not give the guidance which shculd be provided by an industry standard.
It is recommended that a footnote be added which cites Article 725-B (Class 1 Circuits) of the National Electric Codes for a definition of and the requirements for "Icw energy" circuits.
2.
The one inch separation distance that is specified in Section 5.1.5 is not acceptable because it does not offer any protection from the effects of an exposure fire.
It is recommended that this specificatien be eliminated.
3.
The use of fuses as isolation devices, specified in Section 6.2.2.3, is unacceptable because fuses do not satisfy the requirements of 10 CFR 50.55a(h) nor 10 CFR 50 Appendix A with regard to the requirements for testing. Consequen tly,
and in accordance with IEEE Std. 379, all circuits that use fuses as isolation devices must be subjecter to a single failure analysis which assumes a second failure (in ddition to the non-tested, non-detectible, failure of the fuse to operate).
It is recommended that this section be deleted.
4.
The material presented in Sections 4.7, 4.8, 4.9 and 4.10 does not provide adequate separation criteria for the designer.
They are restataments of 4.1 for certain events but are not adequate to define the events or give iny significant guidance to the designer.
5.
Section 5.1.1.2 does not give separation criteria for non-IEEE 383 cable. All plants contain some non-IEEE 383 cable.
Provide separation criteria for non-IEEE 383 cable.
6.
Section 5.1.3 should require a 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> fire barrier between redundant systems where practicable because no area can be deemed free of potential exposure fires caused by breakdown of acministrative controls or; combustibles.
7.
The difference between a "non-hazard" and a " limited hazard" area is not discernable.
The note in Section 5.1.4 misleads the designer because no area can be deemed free of a potential exoosure fire.
8.
The separation distances of Sections 5.1. 3, 5.1. 4, anc 5.1. 5 are meaningless unless the zone of influence of the specific ha:ard is known. Therefore, eacn separation distance should be justified based on the known hazards and this justification should be docurented in the hazards analysis.
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.. 9.
Section 5.1.6 does not cover pipes containing flammables or combustibles.
- 10. The separation distance of 50 ft. is without basis.
Such distance depends upon the nature of the fire hazard.
The variation of the fire barrier rating is without basis. Such rating also depends upon the ne ure of the fire hazard.
11.
The special provisions required for cables to meet the single failure criteria should be defined in Section 5.1.8.3.
- 12. There is no basis for 6" separation in Section 5.6.2.
Fire barriers should be required in all cases.
- 13. The difference between 4.7 and 7.1 is not obvious and should be clarified.
14 Sections 7.2.1 and 7.2.2 are inconsistent and must be corrected.
15.
Section 7.2 is an inadequate attempt to define a fire design basis event. No other design basis events pipes break, missile etc., are defined.
Indicate, by reference, where criteria for defining design basis events is stated.
- 16. The criteria for associated circuits in Section 4.5 permit redundant safe shutdown circuits to be isolated and run in the same conduit. This is unacceptable when redundancy is requi red.
17.
Neither Section 4.5 nor 5.1.7.2(2) explicitly requires that, in the case of circuits and equipment that is required to mitigate the consequences of failure (including false operation) of other equipment and circuits, the former be physically seoarated from the latter.
13.
Sections 5.1.1.3 and 7.3.4 should also state that there are, at present, no accepted methods of analysis.
- 19. Section 5.4.1 does not adequately address the separation of redundant equipment that is connected t: the same offsite sources.
There has been at least one instance whe hot gases have passed tnrough ducting from a cubicle in one div fon to the cubicle of a second division and resulted in break ' (isolator) damage in two divisions as a result of a single fire.
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