ML20204A274

Forwards Request for Addl Info,By 860530,re 850614 Analysis of Structural Steel Supports for Fire Related Assemblies Submitted in Support of Request for Exception to 10CFR50 App R Requirements

ML20204A274
Person / Time
Site:	Grand Gulf
Issue date:	05/01/1986
From:	Butler W Office of Nuclear Reactor Regulation
To:	Kingsley O MISSISSIPPI POWER & LIGHT CO.
References
NUDOCS 8605090556
Download: ML20204A274 (5)

Text

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MAY 1 1986 Docket ~Nos.'50-416/417 Mr. Oliver D. Kingsley, Jr.

Vice President, Nuclear Operations Mississippi Power & Light Company P.O. Box 23054 <

Jackson, Mississippi 39205

Dear Mr. Kingsley:

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SUBJECT:

GRAND GULF NUCLEAR STATION, UNITS 1 AND 2, STRUCTURAL STEEL SUPPORTS FOR FIRE RELATED ASSEMBLIES By letter dated June 14, 1985, Mississippi Power & Light Company provided results of an analysis of the structural integrity of unprotected steel support members for fire rated assemblies protecting safe shutdown cable '

raceways when subjected to elevated temperatures from postulated fires.

This analysis was submitted to support the licensee's request for an exception .

to the requirements of 10 CFR 50 Appendix R.  ;

The NRC staff is reviewing this submittal and finds that the additional information described in the Enclosure is needed to complete our evaluation.

In order to meet the schedule for completion of our review, you are requested to provide this additional information by May 30, 1986. If you cannot meet this date, please advise the staff project manager, L. L. Kintner, within 7 days of receipt of this letter.

The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents; therefore, OMB clearance is not required under P.L.95-511.

Sincerely,

/s/R.Coruso g Walter R. Butler, Director BWR Project Directorate No. 4 Division of BWR Licensing

Enclosure:

As stated DISTRIBUTION Docket Files M0'Brien cc: See next page NRC PDR LKintner Local PDR ACRS (10)

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/ g gg Docket Nos. 50-416/417 Mr. Oliver D. Kingsley, Jr.

Vice President, Nuclear Operations Mississippi Power & Light Company P.O. Box 23054 Jackson, Mississippi 39205

SUBJECT:

GRAND GULF NUCLEAR STATION, UNITS 1 AND 2, STRUCTURAL STEEL SUPPORTS FOR FIRE RELATED ASSEMBLIES l

By letter dated June 14, 1985, Mississippi Power & Light Company provided results of an analysis of the structural integrity of unprotected steel support members for fire rated assemblies protecting safe shutdown cable raceways when subjected to elevated temperatures from postulated fires.

This analysis was submitted to support the licensee's request for an exception to tne requirements of 10 CFR 50 Appendix R.

The NRC staff is reviewing this submittal and finds that the additional information described .a the Enclosure is needed to complete our evaluation.

In order to meet the schedule for completion of our review, you are requested to provide this additional information by May 30, 1986. If you cannot meet this date, please advise the staff project manager, L. L. Kintner, within 7 days of receipt of this letter.

The reporting and/or recordkeeping requirements contained in this letter affect ,

fewer than ten respondents; therefore, OMB clearance is not required under P.L.95-511.

Sincerely,

(,

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\ 41/N l Walter R. Butler, Director l 4 8WR Project Directorate No. 4 Division of BWR Licensing Encicsure:

As stated cc: See next page l

1 l

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V Mr. Oliver D. Kingsley, Jr.

Mississippi Power & Light Company Grand Gulf Nuclear Staiton cc:

Robert B. McGehee, Esquire The Honorable William J. Guste, Jr.

Wise, Carter, Child, Steen and Caraway Attorney General P.O. Box 651 Department of Justice Jackson, Mississippi 39205 State of Louisiana Baton Rouge, Louisiana 70804 Nicholas S. Reynolds, Esquire Bishop, Liberman, Cook, Purcell Office of the Governor and Reynolds State of Mississippi 1200 17th Street, N.W. Jackson, Mississippi 39201 Washington, D. C. 20036 Attorney General Mr. Ralph T. Lally Gartin Building Manager of Quality Assurance Jackson, Mississippi 39205 Middle South Services, Inc.

P.O. Box 61000 Mr. Jack McMillan, Director New Orleans, Louisiana 70161 Division of Solid Waste Management Mississippi Department of Natural Mr. Larry F. Dale, Director Resources Nuclear Licensing and Safety Bureau of Pollution Control Mississippi Power & Light Company Post Office Box 10385 P.O. Box 23054 Jackson, Mississippi 39209 Jackson, Mississippi 39205 Alton B. Cobb, M.D.

Mr. R. W. Jackson, Project. Engineer State Health Officer Bechtel Power Corporation State Board of Health 15740 Shady Grove Road P.O. Box 1700 Gaithersburg, Maryland 20877-1454 Jackson, Mississippi 39205 Mr. Ross C. Butcher President Senior Resident Inspector Claiborne County Board of Supervisors U.S. Nuclear Regulatory Commission Port Gibson, Mississippi 39150 Route 2, Box 399 Port Gibson, Mississippi 39150 Mr. Ted H. Cloninger Vice President, Nuclear Engineering Regional Administrator, Region II and Support U.S. Nuclear Regulatory Commission, Mississippi Power & Light Company 101 Marietta Street, N.W., Suite 2900 Post Office Box 23054 Atlanta, Georgia 30323 Jackson, Mississippi 39205 Mr. J. E. Cross Grand Gulf Nuclear Station Site Director Mississippi Power & Light Company P.O. Box 756 Port Gibson, Mississippi 39150 Mr. C. R. Hutchinson GGNS General Manager Mississippi Power & Light Company Post Office Box 756 Port Gibson, Mississippi 39150

y Request for Additional Information Grand Gulf Nuclear Station (GGNS),

Units 1 and 2 By letter dated June 14, 1985, the licensee submitted the results of an analysis of the structural integrity of the steel support members when subjected to elevated temperatures from postulated fires. In conjunction with the analysis, the licensee requested an exception to the requirements of Section III.G.2.a of Appendix R to 10 CFR Part 50. The licensee's evaluation of unprotected steel cable tray supports utilized a heat transfer analysis to determine if postulated fires within certain plant locations would produce temperatures sufficiently high to adversely affect the integrity of the steel. The scope of the evaluation was limited to those supports which are associated with cable trays encased in a fire-rated tarrier. The evaluation featured a " bulk fire analysis" which, using a computer program, calculated the heat loads that would result in temperatures less then those necessary to adversely affect the steel.

It also featured a summary of calculations to predict localized temperatures produced by a fire involving a " pool" of flammable liquids. The results of these calculations let the licensee to conclude that either a potential fire would not produce elevated temperatures sufficient to damage the steel supports, or that the damage would be limited so as not to affect the structural integrity hf the fire barrier. The licensee stated that this approach is "similar" to an analytic method that the staff found acceptable during the staff reviews of the timerick and Peach Bottom fire protection programs.

Section III.G.2.a of Appendix R to 10 CFR 50 requires that structural steel <

supporting fire barriers be protected to provide fire resistance equivalent to i that required of the barrier. The reason for this requirement is that if a significant fire occurred, the unprotected steel may fail. In GGNS, this  :

could lead to the collapse of the cable tray system and damage of the fire '

barrier that protects one of two shutdown divisions in these locations. The licensee has employed an analytic technique to establish that such a scenario is not possible. The staff accepted an analytic technique during the evaluation of unprotected structural steel at Limerick and Peach Bottom. However, the

previously accepted analysis differs from the licensee's submittal. If the licensee could establish that this technique is as conservative snd complete as what was previously accepted, then a basis for acceptance of an exception to 10 CFR 50 Appendix R Section III.G.2.a could be established.

1 Provide the following additional information regarding the analytic technique  !

used to obtain the results provided in the June 14, 1985 submittal.  !

1. Provide the details of the computer program used in the bulk fire model and the method used to calculate the plume temperatures. Compare the GGNS methods with the methods used in the Limerick / Peach Bottom evaluation.

2. Identify all of the assumptions used in the bulk fire and fire plume analyses, including heat loses through all of the openings in the fire area.

3. Provide results of calculations assuming that heat release rate is not ventilation-limited, similar to the Limerick / Peach Bottom analyses.

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4. Justify the quantities of flammable liquid used in the fire plume analysis, or the quantities of transient combustibles cons 1dared.

5. Provide results of calculations that take into account the contribution of combustible cable insulation in the plume fire analysis.

6. Provide results of analyses that consider the effect of cable tray fires on localized temperatures.

7. Provide the method, assumptions and results of the structural analysis wnich forms '.he basis for the conclusion that the failure of individual steel supports would not result in structural failure of the fire-protected cable tray.

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