AECM-85-0088, Submits Info Re Elevated Groundwater Level Recorded on 850228 for Dewatering Well 8.Elevation Caused by Equipment Failure & Above Average Precipitation.Tables Listing Precipitation Measurements & Groundwater Elevations Encl

Submits Info Re Elevated Groundwater Level Recorded on 850228 for Dewatering Well 8.Elevation Caused by Equipment Failure & Above Average Precipitation.Tables Listing Precipitation Measurements & Groundwater Elevations Encl

ML20112J555
Person / Time
Site:	Grand Gulf
Issue date:	03/25/1985
From:	Dale L MISSISSIPPI POWER & LIGHT CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
AECM-85-0088, AECM-85-88, TAC-54498, TAC-M54498, NUDOCS 8504050216
Download: ML20112J555 (5)

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MISSISSIPPI POWER & LIGHT COMPANY

] Helping Build Mississippi EdiMhMMS P. O. B O X 16 4 0, J AC K S O N, MI S SIS SIP PI 39215-1640 March 25, 1985 NUCLEAR LICEN5lNG & 5AFETY DEPARTMENT 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 Units 1 and 2 Docket Nos. 50-416 and 50-417 License No. NPF-29 File: 0260/15320 Groundwater Level at Grand Gulf AECM-85/0098 References (1) AECM-85/0020, March 9,1984 (2) AECM-85/0035, February 14, 1985 On February 28, 1985, a groundwater elevation of 109.1 ft Mean Sea Level (MSL) was recorded for Grand Gulf Nuclear Station (GGNS) Dewatering Well 8 (DW-8). This exceeded the design basis groundwater elevation for GGNS of 109.0 f t MSL by 0.1 f t. Elevated groundwater levels for this well have been previously reported to the Nuclear Regulatory Commission (NRC) in Reference (1).

An analysis of this situation indicated that the DW-8 pump had not operated properly due to clogged screens. Repairs to DW-8 were completed on March 4, 1985, and the groundwater level at DW-8 dropped to 106.6 ft shortly after activation.

Precipitation measurements and dewatering well groundwater elevations (Tables 1 and 2 respectively) indicate DW-8 functioned properly prior to February 28, 1985, even during periods of nhove average precipitation experienced in October and November 1984. Equipment failure coupled with the above average precipitation for February 1985 seem to be the cause of the groundwater elevation rise at DW-8 to 109.1 ft. This conclusion is further supported by the fact that the February 28 well reading was preceded by a 4.24 inch rainfall on February 25.

As stated in the High Groundwater Level Study, Grand Gulf Unit I submitted to the NRC in Reference (2), "the high groundwater level experienced in DW-8 can probably be attributed to excessive precipitation at the site and subsequent infiltration and migration of groundwater through the grandular backfill around the circulating water pipeline in areas not covered by the clay seal." Based on this study and the data presented in this letter, MP&L beliaves that high groundwater elevations in the vicinity of DW-8 cre loca'.ized and not representative of the perched aquifer in this area.

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8504050216 850325 \g PDR ADOCK 05000416

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J0P OAECM85030607

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+- AECM-85/0088

. Page 2 In' addition, as requested in a teleconference held on March 8, 1985,,

between MP&L and members of your staff, MP&L confirms that the groundwater i study submitted via Reference (2) considered combined seismic loadings in the determination of the effects of high groundwater on Unit 1 seismic Category I buildings.

If you have any questions, please contact this office.

Yours truly, L. F. Dale Director EBS/SHH:vog Attachment cc: Mr. J. B. Richard (w/a)

.Mr. O. D. Kingsley, Jr. (w/a)

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

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

Mr. G. B. Taylor (w/a)

Mr. James M. Taylor (w/a)

Office of Inspection & Enforcement

.U. S. Nuclear Regulatory Commission.

Washington, D. C. 20555 Mr. J. Nelson Grace, Regional Administrator (w/a)

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

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. AECM-85/0088 Pzga 3 bec: ~ Mr. L. E. Ruhland'(w/o)

Mr. R. W. Jackson (w/a)

Mr. R. D. Couse (w/o)

Mr. J. F. Hudson, Jr. (w/o)

Mr. T.:H.'Cloninger1(w/a)-

Mr. T. E. Reaves'(w/o)

Mr.'J.'E. Cross (w/a)"

-Mr. S. M. Feith (w/a)

Mr. A. R.-Smith (w/a)

Mr;-R. C. Butcher (w/a)

Mr. C. C. Hayes (w/a)

Mr. L. L. Kintner (w/a) -

Mr. M. D. Archdeacon (w/a)

Mr. W. E. Edge (w/2)

Mr. J. C.' Roberts (w/o).

Mr. L. F. Daughtery (w/a)

Mr. J..D. Barlow (w/a)

Mr. G. O. Smith (w/a)

-Dr. L. R. McKay (w/a)

Ms. R. R. Jackson (w/a)

MSS Nuclear Activities (w/a)

File (LCTS) (w/2) -

File (NS) (w/a)

File (Central) (w/a) [ 7 ]

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Attachment to

.c AECM-85/0088 r

TABLE I

_;e 1-I PRECIPITATION MEASUREMENT

' . GRAND GULF AND JACKSON, MISSISSIPPI w

OBSERVED AT SITE LONC-TERM

! YEAR 1984-85(1) MEAN(2)

' PERIOD' INCHES INCHES h

September 0.74 2.87

- 1 October 15.86 .2.33 L i

i- - November 8.68 3.80

~

December 1.47 5.47 t

January; 3.92 4.97

) February 8.54 4.69 l

3 (1) Rainfall-measurements from GGNS Meteorological Data 1

(2) U. S. Weather Bureau Station, Jackson, Mississippi (1909 through 1981) i n

1 I

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' - g; Attach 3snt to

~ AECM-85/0088 TABLE II DEWATERING WELL GROUNDWATER ELEVATIONS 9-27-84 10-12-84 11-29-84 12-11-84 1-30-85 2-28-85 DW-1 90.0 91.9 91.5 88.4 90.1 88.8 DW-2 100.0 100.5 100.7 100.7' 100.6 100.6 DW-3 99.8 99.5 98.4 96.4 96.1 99.8 DW-4 99.8 99.5 98.7 -99.2 98.9 99.9 DW-5 100.9 '100.7 101.7 101.6 101.4 102.0 DW-6 104.0 104.5 105.7 105.3 105.4 105.2 DW-7 92.9 95.0 94.9 95.0 93.7 97.6 DW-8 105.6 105.6 107.5 107.8 107.0 109.1 9

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