ML19210A095

Environ Incident 50-289/75-01:on 750124,chlorine Concentration at Plant River Water Discharge Exceeded Ets. Caused by Lack of Guidelines to Determine Variance in Chlorine Feed Rate

ML19210A095
Person / Time
Site:	Three Mile Island
Issue date:	01/31/1975
From:	Arnold R METROPOLITAN EDISON CO.
To:
References
GQL-0721, GQL-721, NUDOCS 7910240815
Download: ML19210A095 (4)

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FILE: NO8 O FROM: Met. Edison Compary DATE OF DOC DATE REC'D LTR TWX RPT OTHER Reading, Pa. 196o3 o_r_ wa 1-31-75 2-8-75 X ORIG CC OTHER SENT AEC PDR 77 TO:

H J.P. O'Reilly 1 SENT LOCAL PDR CLASS UNCLASS PROPINFO INPUT NO CYS REC'D DOCKET NO:

CCCC 1 50-289 DESCRIPTION: Ltr reportin6 Enviro Incident 50:289/75-01on1-24-75reexcessivetotal chlorine concentration at the plant river water discharge . . . .

PLANT NAME: Three Mile Island Unit 1 FOR ACTION /INFORMATION DHL 2-8-75 BUTLER (L) SCHWENCER (L) ZIEMANN (L) 8TEG AN (E)

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CASE PAWLICKl SEALLARD P. KREUTZER (E)

GIAMBUSSO SHAO SPANGLER J. LEE (L) PLANS BOYD STELLO . MAIGRET (L) MCDONALD MOORE (L) HOUSTON ENVIRO . REED (E) CHAPMAN DEYOUNG (L) NOVAK WMULLER M. SERVICE (L) DUBE (Ltr)

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Dear Mr. O'Reilly:

kg D Operating License DPR-50 Docket #50-289 In accordance sith the Environ = ental ' Technical Specifications for Three Mile Island Nucl' ear S tation Unit 1, we are reporting the following Environmental Incident:

(1) Reporting Number: E.I. 50-289/75-01 (2a) Report Date: JAN 311975 (2b) Occurrence Date: January 24, 1975 (3) Facility: Three Mile Island Nuclear Generating Station Unit 1 (4) Identification of Incident:

Excessive total chlorine concentration at the plant river water dis-charge, which is a violation of the Environmental Technical Specifications ,

paragraph 2.2.la, and constitutes exceeding a limiting condition for operation.

(5) Conditions Prior to Occurrence:

- The reactcr was at Hot Stand'oy with majer plant parameters as follows :

Power: Core: 0%

Elec.: 0 hG (Gross) 1489 063 RC Flow: 1.37 x 108 lb/hr RC Pressure: 2155 psig

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. RC Temp.: 5360F PRZR Level: 230 in.

PRZR Temp.: 630 F-(6) Discriptica of Occurrence:

During a periodic evolution conducted to chlorinate the systeas cooled by the lhchanical Draf t Cooling Tower, the plant river discharge sample taken 30 minutes af ter co==ence=ent of the evolution indicated a total chlorine residual of 0.29 pps. The plant river discharge sample taken 50 minutes after co==en ecent of the evolution indicated a total chlorine residual of 0.23 ppa.

In that chlorine addition had been ter=inated about 15 minutes af ter the co==encement of the evolution, it was determined that there were no additional actions which could be taken to get the reading within the specification ll=it.

(7) Designation of Apparent Cause of Occurrence:

Procedure is thought to be the apparent cause of the occurrence in that there are no guidelines to aid in determining how the chlorine feed rate should be varied as a fuaction of existing conditions. Some of the conditions which can affect the a=ount of total chlorine consumed as it passes through the syste=s are:

1. _ River cooling water transit time from the river cooling water pump discharge to the cooling tower discharge which is in turn a function of the number of systens and pumps in use.

2. Various river water conditions such as temperature, pH, and organic composition.

Operator error is not thought to be the cause of the incident in that the technician who performed the analysis was trained in the analytical technique.

(8) Analysis of Occurrence:

It is believed that the total chlorine level did not exceed the 0.2 ppm limit by a sufficient degree to cause environ = ental damage or to have endangered the health and safety of the public because

a. During the course of the subject chlorination period, free chlorine residual recained less than the 0.1 ppa specification li=1t.

b. The chlorine residuals are =easured prior to discharge to the river. The actual plant discharge is s=all in comparison to total river flow resulting in an enormous dilution of the chlorine residual. It is believed that the effective chlorine residuals actually established in the river would be below environmentally hazardous values.

1489 064

(9) Corrective Action:

Immediate corrective action involving termination of chlorine was not feasible as chlorination had already been terminated by the ti=e it was realized that the limit for f ree chlorine had been exceeded. However, prior to the next chlorination period following the incident, the chlorination rate at the river water screen house was reduced from 450 lbs/ day to 300 lbs/ day.

It should be noted that in our letter of January 24, 1975, we stated that the chlorination rate would be reduced to 200 lbs/ day. On attempting to reduce chlorination to this level, it was discovered that the minimum chlorination rate achievable through the system was 300 lbs/ day due to a malfunctioning control valve. This rate proved to be satisfac;ory and within all specification limits as evidenced by chlorine analyses taken during subsequent chlo rination periods. The malfunctioning flow control valve will be repaired within 30 days.

It should also be noted that previous Environmental Incidents had reported a series of reductions in chlorination feed rate to o point to where it had been decreased to less than 150 lbs/ day. The gradual increase to 450 lbs/ day, the initial rate for this incident, was f elt to be justified based on the set of conditions that existed prior to the incident together with additional studies conducted by our consultants.

Long term corrective' action includes a continuing investigation of the chlorination program and its associated systems, procedures, and equip-ment. A part of the investigation will consist of utilizing the 90 day period referenced in the Environcental Technical Specifications ,

paragraph 2.2.1.6 to better determine if and how chlorine addition rate limits should be established as a function of existing conditions.

The Plant Operations Review Co=nittee and the Station Superintendent reviewed and approved these corrective actions.

(10) Failure Data:

a. Previous Failures: Although the incident is not thought to have resulted from equipment failure, similar incidents were reported as E.I. 50-289/74-2, 74-3, 74-4, 74-5, 74-6, 74-7 and 74-9.

b. Equipcent Identification: Not Applicable Sincerely, Signed - R. C. Anmid RCA/RSB/tas R. C. Arnold cc: Director Vice President Directorate of Licensing Nuclear Regulatory Commission Washington, D.C . 20555 File: 20.1.1 / 7.7.3.11.1 1489 065