ML20101S618

Forwards NPDES Discharge Monitoring Rept for June 1992 for North Anna Power Station. High Ph Problems in Turbine Bldg Sumps May Be Due to Residual Effects of Earlier Hydrazine Spill

ML20101S618
Person / Time
Site:	North Anna
Issue date:	07/09/1992
From:	Marshall B VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	VIRGINIA, COMMONWEALTH OF
Shared Package
ML20101S619	List: ML20101S618 ML20101S620
References
NUDOCS 9207170243
Download: ML20101S618 (4)

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4 July 9, 1992 CERTIEIED_ MAIL N En RETURN RECEIFT REQUESTED Virginia Water Control Board Valloy Regional Office

-116 North Main Street P. O. Box-268 Bridgewater, VA 22812 Gentlemen:

RE: NORTH ANNA POWER STATION - DISCHARGE MONITORING REPORT FOR JUNE 1992 Attached is the original of tho June 1992 Discharge P.onitoring Report for North Anna Power Station. .

Thic report is required by and prepared specifically for the Virginia Water Control Board. It presents truly, accurately, and completely the observed results of measurements and analyses required by the Virginia Water Control Board to be performed or submitted, but only such observed resultc. It is not intended as an assertion of the accuracy of any instrument, reading or analytical result, nor is it an endorsement of the suitability of any_ analytical or measurement procedure.

The measurements of specific pollutants and whole effluent toxicity '

were obtained by employing methods of analysis listed in this facility. Those . measurements are subject to the accuracy limitations associated with those methods in the subject sample matrices at the concentrations present in the sample. All values above the Method Detection Limit but below the Limit of Quantitation by definition (52 Fed. Reg. 25, 699-700 July 8,,1987) ,

do not provide adequate confidence as to the actual. concentration appropriate Limit of Quantitation. All values reported below the Method Detection Limit,-by definition 40 C.F.R. 136.2 (f) (1990),

do not provide adequate confidence as to whether or not the constituent being measured is present and are recorded as "not detectable."

According to EPA, Method Detection Limits are not necessarily reproducible over time in a given laboratory, even when the same analytical procedures, instruments, and sample matrix are used. 50 Fed.-Reg. 46,906 ~(November 13, 1985). All values reported above the Method Detection Limit but below a reasonable detection level calculated on an interlaboratory basis in the matrix of concern do not_ provide adequate confidence as to whether or not the constituent being measured is present and are recorded as "not l

detectable."

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!~rginia Water Control Board July 9, 1992 Page 2 After a spill of hydrazine on June 13, 1992, and the actions taken in reaction to the spill, which were discussed in my followup letter of June 19, the station has experienced problems with pH control in the impacted sumps. On June 20, 1992, due to a high pH condition in the common and Unit 2 turbine building sumps, station personnel suspected that the discharge at internal outfall 004 may exceed the maximum permit limitation of 9.0 pH units. Although the two per month samples for the outfall had previously been taken, the discharge was sampled and a pH of 9.25 was measured. The sump pumps, normally on automatic operation, were switched to manual control and the sump pH corrected prior to further discharge.

Following the excursion on June 20, and the corrective actions taken, pH measurements at the 004 discharge were back within the permit's limitations on June 21. However, the sum 7 conditions were still in the higher end of the acceptable pH rrnge and excursions of the 9.0 limit were experienced on June 27, 28 and 30. Measurements made are shown on the attachment to this letter. In response to the additional excursions, station personnel continued to monitor the sump pH and maintain manual control of the sump pumps, when high pH was measured in the sump, through the following days in order to provide pH correction of further discharges to acceptable values.

It appears that the high pH problems in the turbine building sumps may be due to residual effects of the earlier hydrazine spill. The causes of the high pH conditions in the sumps are undergoing further evaluation to determine if additional measures are needed to prevent recurrence of the problem. Should any changes in facilities or processes be necessary to ensure that no future excursions of the pH limitations occur, you will be notified. Meanwhile, monitoring of the sump pH, and pH correction prior to discharge if needed, will continua.

The pH excursions at Outfall 004 did not result in any detectable impact in the discharge canal, or downstream, and would not have adversely affected state waters or endangered public health. It is expected that the station will be able to control the pH of the discharge until the conditions in the sumps are stabilized, or until any additional remedial actions identified can be carried out.

We are including a copy of the Report of Operation for the sewage treatment f acility (Outf all 011) . If you have any questions or desire additional information concerning this submittal, please contact Mr.

Daniel James at (804) 273-2996.

Sincerely,

/

B. M. arshall, P.E.

Manager Water Quality 1

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Virginia Water Control Board July 9, 1992 Page 3 cc: U.S. Nuclear Regulatory Commission Docket No. 50-338/50-339 101 Marietta St., NW Suite 2900 Atlanta, GA 30323 U.S. Nuclear Regulatory Commission Attn: Docket Control Desk Docket No. 50-338/50-339 Washington,,DC 20555 Mr. M. S. Lesser NRC Sr.- Resident Inspector North Anna Power Station

4 Attachment to DMR letter.

Corrected pH at sump prior to discharge Date Time pH at 004 Unit 2 Commen 6-20 1945 9.25 2035 8.88 2250 8.97 6-21 1535 8.96 6-26 1430 8.91 6-27 1019 9.12 1240 8.87 8.71 6-28 1040 9.22 1329 8.93 1425 8.89 1450 9.02 1525 8.77 6-30 0923 9.12 1720 8.56 _

2350 8.97

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