ML040640752

3.1.5 Fire Zones, Appendix R Questions & Answers

ML040640752
Person / Time
Site:	Arkansas Nuclear
Issue date:	02/20/2004
From:	Entergy Operations
To:	NRC Region 4
References
FOIA/PA-2003-0358
Download: ML040640752 (2)

Text

3.1.5 Fire Zones QUESTION Appendix R,Section III.G.3 states "alternative or dedicated shutdown capability and its associated circuits, independent of cables, systems or components in the area room or zone under consideration...." What is the implied utilization of a room or zone concept under Section III.G of Appendix R? The use of the ,

phraseology "area, room or zone under consideration" is used again at the end of the Section III.G.3. Does the requirement for detection and fixed suppres-sion indicate that the requirement can be limited to a fire zone rather than throughout a fire area? Under what conditions and with what caveats can the fire zone concept be utilized in demonstrating conformance to Appendix R?

RESPONSE

Section III.G was written after NRC's multi-discipline review teams had visited all operating power plants.' From these audits, the NRC recognized that it is not practical and may be impossible to subdivide some portions of an operating plant into fire areas. In addition, the NRC recognized that in some cases where fire areas are designated, it may not be possible to provide alternate shutdown capability independent of the fire area and, therefore, would have to be evaluated on the basis of fire zones within the fire area. The NRC also recognized that because some licensees had not yet performed a safe shutdown analysis, these analyses may identify new unique configurations.

To cover the large variation of possible configurations, the reqL rements of Section III.G were presented in three parts:

o Section III.G.1 requires one train of hot shutdown systems be free of fire damage and damage to cold shutdown systems be limited.

o Section III.G.2 provides certain separation, suppression and detection requirements within fire areas; where such requirements are met, analysis is not necessary.

o Section III.G.3 requires alternative dedicated shutdown capability for configurations that do not satisfy the requirements of III.G.2 or where fire suppressants released as a result of fire fighting, rupture of the system or inadvertent operation of the system may damage redundant equip-ment; If alternate shutdown is provided on the basis of rooms or zones,

'the provision of fire detection and fixed suppression is only required in the room or zone under consideration.

Section 11I.G recognizes that the need for alternate or dedicated shutdown capability may have to be considered on the basis of a fire area,.a room or a fire zone. The alternative or dedicated capability should be independent of the fire area where it is possible to do so (See Supplementary Information for the final rule Section Ii1.G). When fire areas are not designated or where it is not possible to have the alternative or dedicated capability independent of the fire area, careful consideration must be given to the selection and location of the alternative or dedicated shutdown capability to assure that the performance requirement set forth in Section III.G.1 is met. Where alternate or dedicated shutdown is provided for a room or zone, the capability must be physically and 'da APPENDIX R QUESTIONS & ANSWERS 6 'il?

v l electrically independent of that room or zone. The vulnerability of the equip-(Pit ment and personnel required at the location of the alternative or dedicated shutdown capability to the environments produced at that location as a result of the fire or fire suppressant's must be evaluated. These environments may be due to the hot layer, smoke, drifting suppressants, common ventilation systems, common drain systems-or flooding. In addition, other interactions between the locations may be possible in unique configurations.

If alternate shutdown is provided on the basis of rooms or zones, the provision of fire detection and fixed suppression is only required in the room or zone under consideration. Compliance with Section III.G.2 cannot be based on rooms or. zones.

See also Sections #5 and #6 of the "Interpretations of Appendix R."

3.1.6 Documentation QUESTION In Generic Letter 83-33 at pg. 2, the NRC Staff referred to the guidance in Appendix A to BTP 9.5-1 to establish the rating of the barrier. What level of documentation must be provided to verify that the fire area meets the require-ments of Appendix R?

-RESPONSE The documentation required to verify the rating of a fire barrier should in-clude the design description of the barrier and the test reports that verify

• its fire rating. Reference can be made to UL listed designs.

3.2 Fire Barrier Qualification 3.2.1 Acceptance Criteria QUESTION Recently the Staff has applied a 3250 F cold side temperature criterion to its evaluation of the acceptability of one-hour and three-hour fire barrier cable tray wraps. This criterion is not in Branch Technical Position (BTP) APCSB 9.5-1, Appendix A as an acceptance criterion for fire barrier cable tray wraps and is not contained in Appendix R. It appears to represent post-Appendix R guidance.

What is the origin of this criterion and why is it applicable to electrical cables where insulation degradation does not begin until jacket temperatures reach 450'F to 650'F?

RESPONSE

Fire barriers relied upon to protect shutdown related systems to meet the re-quirements of III.G.2 need to have a fire rating of either one or three hours.

§ 50.48 references BTP APCSB 9.5-1, where the fire protection definitions are found. Fire rating is defined:

t "Fire Rating - the endurance period of a fire barrier or structure; it defines the period of resistance to a standard fire exposure before the first critical point in behavior is observed (see NFPA 251)."

APPENDIX R QUESTIONS & ANSWERS 7