ML20211B455

Summary of 860507 Meeting W/Util to Discuss Spent Fuel Pool Cooling for Fuel Stored in High Density Spent Fuel Racks. List of Meeting Attendees & Handout Encl

ML20211B455
Person / Time
Site:	Grand Gulf
Issue date:	05/21/1986
From:	Kintner L Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 8606110666
Download: ML20211B455 (11)

Text

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MAY 21 W Docket No. 50-416 -

LICENSEE: Mississippi Power & Light Company (MP&L)

FACILITY: Grand Gulf Nuclear Station, Unit 1

SUBJECT:

SUMARY OF MAY 7,1986 MEETING REGARDING SPENT FUEL POOL COOLING The purpose of the meeting was to discuss spent fuel pool cooling for spent fuel stored in high de nity spent fuel racks. Enclosure 1 is a list of attendees. Enclosure 2 is a handout prepared by the licensee.

The licensee provided in Enclosure 2 the heat loads for various cases of off load plans. The licensee also provided results of its calculated fuel pool temperature for the 14th refueling outage based on a 12 month fuel cycle. This calculation resulted in a peak pool temperature of about 140*F. The licensee described its method of calculating pool temperature. NRC staff agreed that the heat loads and method of calculating fuel pool temperature appeared to be conservative.

The licensee plans to file supplemental information regarding decay heat loads and temperature calculations. In addition, changes to Technical Specifications will be submitted to limit the number of fuel assemblies which can be stored in the spent fuel pool and to limit the pool temperature to 140 F. The specification will require the plant to be in shut down condition if temperature less than 140*F cannot be maintained without the use of the residual heat removal system to supplement spent fuel pool cooling. The spent fuel pool cooling capability will be increased prior to the fifth refueling outage to ensure the spent fuel pool will be kept below 140 F and this commitment will be included in the supplemental information filed on the docket.

Originalsigned by L. L. Kintner, Project Manager BWR Project Directorate No. 4 Division of BWR Licensing

Enclosures:

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\ . . . . . * .f may 21986 Docket No. 50-416 LICENSEE: Mississippi Power & Light Company (MP&L)

FACILITY: Grand Gulf Nuclear Station, Unit 1

SUMMARY

OF MAY 7, 1986 MEETING REGARDING SPENT FUEL P0OL COOLING The purpose of the meeting was to discuss spent fuel pool cooling for spent fuel stored in high desnity r pent fuel racks. Enclosure 1 is a list of attendees. Enclosure 2 is a handout prepared by the licensee.

The licensee provided in Enclosure 2 the heat loads for various cases of off load plans. The licensee also provided results of its calculated fuel pool temperatu' a for the 14th refueling outage based on a 12 month fuel cycle. This calculation resulted in a peak pool temperature of about 140*F. The licensee descriLcd its method of calculating pool temperature. NRC staff agreed that the heat loads and method of calculating fuel pool temperature appeared to be conservative.

The licensee plans to file supplemental information regarding decay heat loads and temperature calculations. In addition, changes to Technical Specifications will be submitted to limit the number of fuel assemblies which can be stored in the spent fuel pool and to limit the pool temperature to 140'F. The specification will require the plant to be in shut down ::ondition if temperature less than 140*F cannot be maintained without the use of the residual heat removal system to supplement spent fuel pool cooling. The spent fuel pool cooling capability will be increased prior to the fifth refueling outage to ensure the spent fuel pool will be kept below 140'F and this commitment will be included in the supplemental information filed on the docket.

L. L. Kintner, Project Manager BWR Project Directorate No. 4 Division of BWR Licensing

Enclosures:

As stated cc: See next page

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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, Steea 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 i _ _ _ _

. Enclosure 1 4 ATTENDEES May 7, 1986 M(eting Between NRC Staff and Mississippi Power & Light Co.

Name Affiliation Steve Thomas MP&L

, Dan Marshall MP&L Matt Crawford MP&L

John Ridgely NRC L. Kintner NRC

W. Butler

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. . Enclosure 2

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PMI j h Page 1 of 1 RESPONSE TO THE NRC CONCERNS ABOUT THE SPENT FUEL POOL BULK -

TEMPERATURE ANALYSIS FOR THE HIGH DENSITY SPENT FUEL RACKS

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l The NRC requested that the Pool Bulk Temperature Analysis for the high j density spent fuel storage racks be reanalyzed assuming the failure of a

spent fuel pool heat exchanger train at a time when RHR was not available i to supplement fuel pool cooling. The NRC also expressed concern that the heat loads for the pool bulk temperature analysis were not correctly

. calculated.

l To verify that spent fuel decay heat loads have been correctly .

calculated the NRC requested that the heat loads be calculated for two i offload scenarios prescribed by the NRC. The spent fuel off-load scenarios l and their associated heat loads are delineated in Tables 4 and 5.

l The reanalysis of the spent fuel pool bulk temperatures was performed

. using Revision 2 of Branch Technical Position ASB 9-2 to calculate decay j heat loads and the failure of cne spent fuel cooling train. Analysis of the i spent fuel pool bulk temperatures for the projected refueling outages show l that Fuel Pool and RHR Cooling Systems can keep the bulk temperatures at or ~

i below 140*F for the first fourteen refueling outages. Tables 1 and 2

! delineate the refueling scenario and heat loads for the fourteenth projected

, refueling outage. The pool bulk temperature, the decay heat, and the heat i removed by the cooling systems for the fourteenth refueling scenario are

, delineated in Table 3 and Figure 1. All spent fuel discharged to the spent j fuel pool in the analyzed outages is assumed to be moved over a three hour

period starting at 110 hours0.00127 days <br />0.0306 hours <br />1.818783e-4 weeks <br />4.1855e-5 months <br /> after shutdown. Time zero in Figure 1 repre-

sents the start of fuel movement 110 hours0.00127 days <br />0.0306 hours <br />1.818783e-4 weeks <br />4.1855e-5 months <br /> after shutdown. The fourteenth projected refuelin'g scenario was analyzed assuming that one fuel pool l' cooling hest exchanger is in continuous service and RHR train is used for 35 days starting at shutdown.

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! The analysis of the spent fuel pool bulk temperatures (Figure 1) shows i that the heat removed by the cooling systems varies with pool temperature, since the heat transfer rate of the heat exchanger is increased with the

! increase in the temperature difference between the pool water and the i cooling water. The maximum pool bulk temperature is reached when the heat i removed from the pool equals the decay heat load of the spent fuel. The i actual maximum pool bulk temperature calculated was 140.04*F.

As a conservatism to the pool bulk temperature analysis, the number of l' fuel assemblies which can be off-loaded to the spent fuel pool will be limited to the number projected through the ninth refueling outage (which is i - 2096 assemblies). This limit will be observed until equipment modifications l have been made which will enable the cooling systems to keep the temperature associated with greater amounts of spent fuel below 140'F. Design changes j for the modifications to the cooling systems will be defined before the third refueling outage and implemented prior to restart after the fifth refueling outage.

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TABLE 1 Heatloads for the First 13 Projected Fuel Cycles on the Eve of the Fourteenth Refueling Outage -

Batch Shutdown No. of Fuel Heat Load / Bundle Batch Heat Load No. Time (yrs) Bundles (Btu /hr) (8tu/hr) 1 13 280 1306.0 365680 2 12 240 1337.7 321048 3 11 208 1370.2 285002 4 10 228 1403.8 320066 5 9 228 1438.8 328046 6 8 228 1476.3 336596 7 7 228 1518.6 346240

8 6 228 1572.2 358462 -

9 5 228 1652.9 376861 I 10 4 228 1801.5 410742 ..

i i1 3 228 2122.0 483816 12 2 228 2896.9 660493 13 1 228 5312.4 1211227 TOTAL

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• All fuel is assumed to have 4 years of reactor operating operating time and 12 month fuel cycles.

TABLE 2 Decay Heat Loads of 228 Fuel Bundles for Shutdown Times UD to 1000 Hours Shutdown Decay Heat Load

• Time (Hours) (Blu/hr x 10-6 )

0 322.70 50 18.33 100 1401 150 11.78 200 10.48 250 9.63 300 9.00 350 8.50 400 8.07 450 7.69 --

500 7.36 550 7.06 ,

600 6.78 650 6.53 700 6.29 750 - 6.08

( 800 5.88 850 5.70 900 5.53 950 5.37 1000 5.22 l

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• All fuel is assumed to have 4 years of reactor operating time and 12 month fuel cycles.

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TABLE 3 Pool Bulk TemDerature Analvsis of the Fourteenth Offload of the Actual Projected Refueling Scenario Heat Removed Shutdown Pool Temp. Decay Heat from Pool Time (Hrs) (Deg.F) (Btu /hrX 106) (Btu /hr X 106 )

114 110.54 19.00 21.45 118 109.88 18.80 20.72 122 108.50 18.62 19.19 130 107.81 18.28 18.43 150 107.10 17.55 17.65 170 106.55 16.97 17.04 210 105.73 16.08 16.13 310 104 45 14.69 14.72

-410 103.63 13.79 13.81 ..

510 103.00 13.09 13.11 610 102.48 12.53 12.54 710 102.05 12.05 12.06 810 101.68 11.64 11.65 822 101.64 11.60 11.61 826 ,101.63 11.59 11.60 830 101.61 11.57 11.58 834 112.37 11.56 4.38 838 120.16 11.54 6.34 842 125.81 11.53 7.76 846 129.90 11.51 8.79 858 136.53 11.47 10.46 870 138.97 11.43 11.08 878 139.62 11.40 11.24 890 139.99 11.36 11.33 894 140.02 11.35 11.34 898 140.04 11.34 11.35 902 140.03 11.32 11.34 906 140.01 11.31 11.33 914 139.95 11.28 11.32 922 139.87 11.26 11.30 950 139.54 11.17 11.22 990 139.07 11.05 11.10 5

TABLE 4 Heat load Analysis of the Normal Discharge Scenario Prescribed by the NRC Batch Shutdown No. of Fuel Batch Heat Load

• No. Time (Years) Bundles (BTU /Hr) 1 18 252 291967 2 17 240 284808 3 16 208 252803 4 15 228 283834 5 14 228 290700 6 13 228 297768 7 12 228 304996 8 11 228 312406 9 10 228 320066 10 9 228 328046 11 8 228 336596 12 7 228 346241 13 6 228 358462 14 5 228 376861 15 4 228 410742 16 3 228 483816 2 228 660493 17 l

18 1 228 1211227 i 19 150 Hrs 228 11780000 TOTAL 4348 TOTAL 18931832 l

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TABLE 5 Heat Load AnalvsIs of the Abnormal Discharge Scenario Prescribed by the NRC Batch Shutdown No. of Fuel Batch Heat Load

• No. Time (Years) Bundles (BTU /Hr) 1 16 128 155576 2 15 228 283834 3 14 228 290700 _

4 13 228 297768 5 12 228 304996 6 11 228 312406 7 10 228 320066 8 9 228 328046 9 8 228 336596 10 7 228 346241 ._

11 6 228 358462 12 5 228 376861 13 4 228 410742 14 3 228 483816 15 2 228 660493 16 1 228 1211227 17 150 Hrs 800 41330000 TOTAL 4348 TOTAL 47807830 l

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• All fuel is assumed to have 4 years of reactor operating operating time and 12 month fuel cycles.

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