AECM-86-0077, Forwards Revised Spent Fuel Loading Pattern Developed to Maintain Dose Rate Contribution from Spent Fuel in Auxiliary Bldg Spent Fuel Pool Area Below 2.5 Mrems/H for Routinely Accessible Areas

Forwards Revised Spent Fuel Loading Pattern Developed to Maintain Dose Rate Contribution from Spent Fuel in Auxiliary Bldg Spent Fuel Pool Area Below 2.5 Mrems/H for Routinely Accessible Areas

ML20140E525
Person / Time
Site:	Grand Gulf
Issue date:	03/14/1986
From:	Kingsley O MISSISSIPPI POWER & LIGHT CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
AECM-86-0077, AECM-86-77, TAC-57619, NUDOCS 8603280027
Download: ML20140E525 (5)

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EehilAllddB MISSISSIPPI POWER & LIGHT COMPANY Helping Build Mississippi P. O. B O X 184 0, J AC K S O N, MIS SIS SIP PI 39215-1640 March 14, 1986 O. D. KINGSLEY, J R.

YtCE PREllDENT NUCLE AR OPERAtlONS U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington, D. C. 20555 Attention: Mr. Harold R. Denton, Director

SUBJECT:

Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No NPF-29 High Density Spent Fuel Racks Loading Pattern AECM-86/0077 By letter dated December 18, 1985 (AECM-85/0410), Mississippi Power &

Light submitted a response to a request for additional information regarding occupational exposures associated with operation of Grand Gulf Nuclear Station (GGNS) Unit I with high density spent fuel racks (HDSFR). On February 5, 1986, Mr. L. L. Kintner and Mr. M. A. Lamastra of your staff visited CGNS to discuss results presented in AECM-85/0410 and to tour the HDSFR installation.

During the discussion, MP&L identified several conservative assumptions utilized in determining dose rate contributions from the HDSFR in the areas surrounding the pools. These conservatisms resulted in relatively high dose rates in certain areas as reported in AECM-85/0410. At the exit briefing, MP&L committed to perform a more realistic dose assessment and develop a revised loading pattern. Specifically, MP&L committed to the following:

1. Develop and submit a revised HDSFR loading pattern to maintain occupational dose rate contribution from HDSFR below 2.5 mR/hr.

2. Reassess dose rates based on the revised loading pattern.

3. Survey actual radiation levels in the fuel pool areas during the first refueling. outage and provide the results to Nuclear Plant Engineering (NPE) for comparison with calculations. The results of the engineering evaluation will be available for inspection by NRC Region.II personnel.

K 6 P 90 J14AECM86031301 - 1 Member Middle South Utilities System l

AECM-86/0077 Pags 2 In response to the above commitments, a revised spent fuel loading pattern (attached) was developed to maintain dose rate contribution from spent fuel.in the Auxiliary Building spent fuel pool area below 2.5 mR/hr j for routinely accessible areas. This loading pattern was determined utilizing the methodology described in the February 5, 1986 meeting. It should be recognized that by utilizing this methodology other. loading patterns may be developed to achieve the same results.

, If you have any additional questions, please contact this office.

Yours truly, i

. 0DK:dmm Attachment cc: Mr. T. H. Cloninger (w/a)

Mr. R. B. McGehee (w/a)

Mr. N. S. Reynolds (w/a)

Mr. H. L. Thomas (w/o).

Mr. R. C. Butcher (w/a) 1 Mr. James M. Taylor, Director (w/a)

Office'of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Dr. J. Nelson Grace, Regional Administrator (w/a)

U. S. Nuclear Regulatory Commission Region II 101 Marietta St., N. W., Suite 2900 Atlanta,. Georgia 30323

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J14AECM86031301 - 2

Attachmsnt to 4

AECM-86/0077 1

'e AUXILIARY BUILDING HIGH DENSITY SPENT FUEL RACKS LOADING PATTERN +

Analyses show that the following storage conditions apply with respect to loading of the HDSFR in order to maintain dose rate contributions below 2.5 mR/hr in routinely accessible areas. Refer to Figure.1 for the revised HDSFR. loading pattern.

1. There are no dose related restrictions on the storage of spent fuel in 4 ' racks,AS, A6, A8, A9, All and'Al2 of the spent fuel pool.

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2. There are no dose related restrictions on the storage of spent fuel in racks A4,.A7 and A10. It should be noted that dose rate contributions on the South wall of the Fuel Transfer Canal and transfer gate area are expected to be approximately 600 mR/hr. 'However, this area is under water and is not routinely accessible.

3. Certain locations in racks A1, A2, A3, B1, C1, and Dl- are restricted from storage of freshly discharged fuel regardless of the fuel loading pattern in the rest of the pool. Those locations with no dose related restrictions are as follows:

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a. All storage locations in rows 4-16 from the East wall of racks A1, A2, A3 and B1 of the spent fuel pool.

b. All storage locations in rows 8-16 from the South wall of rack B1 of the spent fuel pool.

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All storage locations in rows 4-12 from the South wall of racks 1 C1 and D1 of the spent fuel pool.

4. The loading pattern described be' low would result in all dose related loading restrictions being removed from the spent fuel pool.

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a. The 264 fuel bundles discharged at the end of Cycle 1 should be

! stored in any pattern in the unrestricted rack locations defined above for 1 year (365 days) after discharge (Cycle I shutdown)-

prior to their movement' to a permanent storage location.

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b. After 1 year of' decay, the Cycle 1 discharged fuel, Batches 1 and.2, should be positioned as follows:

1) The Batch 1 (natural uranium bundles) fuel will;be positioned in the following manner:

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1) fill rows 1 and 2 of rack D1 (rows closest to South wall).

ii) fill rows 1 and 2 of rack C1 (rows closest to South wall).

iii) fill' row.6 of rack B1 (from the South wall).

iv) load the last 2 bundles from Batch I in any location. 1

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AttcchmInt-to:

AECM-86/0077

2) The Batch 2 fuel should be positioned in the following manner:

i) fill row 1 of racks A1, A2 and A3.(adjacent to the East wall) with Batch 2 bundles.

ii) load the row of cells of rack Bl' adjacent to:the East wall with Batch 2 bundles.

iii) load the remaining bundles of Batch 2 in any available location.

5. Prior to loading spent fuel in the spent fuel pool, administrative controls will be implemented to ensurt the above guidelines are followed. Prior to deviating from any of.the above guidelines,Lan evaluation of the impact will be performed.

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