ML20249B902

NPDES Noncompliance Notification:On 980603,release of Small Amount of Low Ph Water from Plant.Caused by acid-water Solution Being Spilled Into Sump.Operator re-diverted Plant Wastewater Discharge & Flushed Outlet Ph Monitor'S Probe

ML20249B902
Person / Time
Site:	Rancho Seco
Issue date:	06/18/1998
From:	Redeker S SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Merschoff E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
MPC&D-98-097, MPC&D-98-97, NUDOCS 9806250017
Download: ML20249B902 (2)

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y. j O' suun SACRAIMENTD MUNICIPAL UTIUTY DISTRICr O R O. Box 15830, Sacramento CA 95852-1830, (91m 452-3211 AN ELECTRIC SYSTEM SERVING THE HEART OF CALIFORNIA MPC&D 98-097 June 18, 1998 U. S. Nuclear Regulatory Commission Attn: E. W. Merschoff, Regional Administrator Region IV Parkway Central Plaza Bui; ding 611 Ryan Plaza Building, Suite 400 Arlington, Texas 76011-4085 Docket No. 50-312 Rancho Seco Nuclear Station License No. DPR-54 REPORT OF LOW pil WATER RELEASE FROM RANCIIO SECO; NPDES PERMIT NUMBER e40004758

Dear Mr. Merschoff:

In accordance with a condition specified in the NRC Safety Evaluation Report for License Amendment No. 45 to Facility Operating License No. DPR-54, the District is required to notify the NRC cencerning Rancho Seco NPDES wastewater discharge permit violations. Below, the District provides information concerning the release of a small amount of low pH water from Rancho Seco in violation of NPDES permit number CA0004758.

On June 3,1998. while a contractor cleaned some chemical system lines to prepare the lines for dismantlement, approximately 16 gallons of an acid-water solution spilled into a sump. This sump is connected to a drain that is connected to the plant wastewater discharge st ;am. At 2:31pm on June 3"', the plant Control Room received an alarm, which indicated the plant wastewater discharge stream had automatically diverted into one of two 500,000-gallon Retention Basins due te low pH (less than 6.5). After the alarm activated, plant personnel implemented the casualty procedure for a hazardous material spill and release. The Control Room Shift Supervisor dispatched a nuclear plant equipment operator to investigate the alarm and requested a Ranche Seco laboratory technician take wastewater samples and perform appropriate analyses. O The automatic diversion of wastewater to a Retention Basin is a Rancho Seco wastewater process monitor protective feature that occurs when a preset water quality limit is exceeded (e.g.,

pH less than 6.5 or greater than 8.5). i,.

9906250017 990618 PDR ADOCK 05000312 S PDR RANCHO SECO NUCLEAR GENERATING STATION O 14440 Twin cities Road, Herald. CA 95638-9799; (209) 333-2935 b _ _ _ ____ _____ __

Mr. Merschoff MPC&D 98-097 The nuclear plant equipment operator arrived at the Retention Basins in about five minutes. The operator, believing the probe was faulty, took manual control of the automatic diversion system, re-divened the plant wastewater discharge stream, and flushed the outlet pH monitor's probe.

After about five minutes, the operator noted the inlet stream pH probe increase and the outlet pH probe decrease. The operator then diverted the plant wastewater discharge stream back to a Retention Basin. During the five minutes, approximately 2,500 gallons of low pH water, which contained a stiiall portion of the 16 gallons of spilled acid, flowed into the combined plant effluent wastewater stream and mixed with Folsom South Carial dilution water before going off-site.

The great majority of the combined plant effluent wastewater stream that leaves the Rancho Seco site is comprised of Foisom South Canal dilution water. The combined plant effluent wastewater stream flow rate during the approximately five minutes of low pH water flow off-site was about 5,000 gallons per minute.

The Rancho Seco laboratory technician took water quality samples immediately after the nuclear plant equipment operator completed his activities. The sample analysis results are as follows:

Sample Point Collection Time pH units Plant Wastewater Mixing Box Inlet June 3,1998 @ 1450 2.75 Con,bined Plant Effluent June 3,1998 @ 1455 6.93 Off-site Receiving Water June 3,1998 @ 1530 6.9 Also, Rancho Seco laboratory personnel conducted a tour of the receiving water pathwg oct to the confluence of Clay and Hadselville creeks. Laboratory personnel could find Eo evidcace of harmful impact on the aquatic environment.

Members of your staff requiring additional information or clarification may contact Mr. Richard Mannheimer at (916) 452-3211, Extension 4916.

Sincerely

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n Steve J. Redeker Manager Plant Closure and Decommissioning cc: V. Everett, NRC, Arlington, Texas L

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