ML20092C259

Notifies That on 910829,0927,1001 & 920103 Measurements of Groundwater Level at Dewatering Well (DW) DW-8 Exceeded 109.0 Ft Msl,Per NRC .Groundwater Program Presently Evaluating High Groundwater Level Issues

ML20092C259
Person / Time
Site:	Grand Gulf
Issue date:	02/07/1992
From:	Cottle W ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GNRO-92-00001, GNRO-92-1, NUDOCS 9202110374
Download: ML20092C259 (2)

Text

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Mk i d ENTERGY FM". ,4"""""** '"*-

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U.S. Nuclear Regulatory Commission  ;

Mail Station P1-137 Washington, D.C. 20555 Attention: Document Control Desk

SUBJECT:

Grand Gulf Nuclear Station Unit 1 Dacket No. 50-416 License No. NPF-29 Groundwater Level Exceeds 109.0' MSL in Dewatering Well 8 GNR0-92/00001 Gentlemen:

Monthly groundwater level readings taken at dewatering well 8 (DW-8) on August 29, 1991 indicated a level of 109.9 feet mean sea level (MSL).

Other measurements of groundwater level at DW-8 en September 27, 1991, October 1, 1991, and January 3, 1992 indicated levels of 109.0 feet MSL, 109.1 feet MSL, and 109.5 feet MSL respectively. DW-8 is located near the southeast corner o_f the Radwaste Building. These occurrences of groundwater level exceeding 109.0 feet MSL are being reported as requested by your letter dated August 19,1985(MAEC-85/0284).

The August 29 occurrence was caused by fouled dewatering well level probes which control operation of the pump. The September 27 and October 1 occurrences were caused by the puinp's power supply circuit breaker being opened inadvertently when personnel deenergized some yard lighting via an adjacent breaker. The January 3 incident occurred as a result of sump pump motor failure.

Response to these events has increased the preventive maintenance (PM) program frequency for DW-8 to 2 month intervals. In addition, level setpoints on all dewatering wells will be verified as part of the PM

)rogram on dewatering well work ta ks. Dewatering well circuit breakers lave also been labeled. Future changes to the dewatering well program equipment may reinstate the previous PM program frequency.

An engineering study performed in 1985 concluded that groundwater levels

-up to 114.5 feet MSL would not impair the structural integrity of Unit 1 buildings as previously submitted by letter dated February . 14, 1985 (AECM-85/0035).

SPRPTJAN --1 9202110374 920207 j ;', O J 1 g PDR ADOCKOSOOg6 S

'O February 7. 1992 GNR0-92/00001-Page 2 of 3 A grouedwater program is presently evaluating issues associated with high groundweter levels. A final report of the groundwater program is schedule 1 for issuance by April 30, 1992,

-Yours troly, eo rc<

WTC/BAB/cg cc: Mr. D. C. Hintz Mr. J. L. Mathis Mr. R. B. McGehee Mr. N. S. Reynolds Mr. H. L. Thomas Mr. Stewart D. Ebneter Regional Administrator.

U.S. Nuclear Regulatory Comission Region II 101 Marietta St., N.W., Suite 2900 Atlanta, Georgia 30323 Mr. P. W. O'Connor, Project Manager Office of Nuclear Reactor. Regulation <

U.S. Nuclear Regulatory Comission Mail Stop 13H3 Washington, D.C. 20555 L

SPRPTJAN - 2 l