ML19319E102
| ML19319E102 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 05/16/1975 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| References | |
| NUDOCS 8003310611 | |
| Download: ML19319E102 (2) | |
Text
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SACRAMENTO MUNICIPAL UTILITY DISTRICT C 1703 59tti Street, Box 15830 Sacramento. California 95813 (916)452-3211 May 16, 1975e W-.n y-~
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Director f-i Division of Reactor Licensing
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Re: Operating License DPR-54 s-Docket No. 50-312 N
I' Unusual Event 75-4
Dear Sir:
As defined by Technical Specifications " Appendix B", Section 5.6.2.C, we are reporting the following Unusual Event as UE-75-4.
Since operation has resumed at 92% rated full power on April 15, 1975, the al le growth in the Circulating Water Syste:r. has steadily in-t creased. Algae has been controlled by a planned program of chlorine injection into the Circulating Water System. The program was discussed in detail in A0-75-1.
However, a new program was initiated on May 9,
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X 1975, to investigate better chlorine injection sequences.
The program
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required a five-minute chlorine injection into the Plant Cooling Water System at a rate of 1000 lbs. per day, followed by a five-minute flush, a twenty-minute chlorine injection into the suction of the A and B cir-culating water pumps at a rate of 6000 lbs. per day, followed by a five-minute flush and a twenty-minute chlorine injection into the suction' of the C and D circulating water pumps at a rate of 6000 lbs. per day, followed by a five-minute flush. This program was repeated twice daily.
Simultaneous with the initiation of the new injection scheme, the sampling frequency was increased to closely monitor the system chlorine level due to the circulating water blowdown to the effluent discharge. On May 12 the effluent sample taken at 10:45 showed an increase to 0.3 ppm and the dilution water was increased. The chlorine effluent concentration was reduced to 0.14 at 11:15, one-half hour later.
To prevent reoccurrence of this event, the program was terminated at the chlorine injection rates of 6000 lbs. per day. A revised program using an injection rate of 800 lbs. per day into the Plant Cooling Water System and ten-minute injections into A,B and C.D circulating water pumps at a rate of 3000 lbs. per day was started May 13.
This program is repeated four times a day.
The continuation of closely monitoring the plant effluent chlorine concentrations has indicated controlled releases at satisfactory levels, not exceeding the 0.2 ppm limit. New programs may be investigated if the present schemes do not adequately control algae. During each test, the injection rate will be limited and a monitoring program will be re-accelerated to determine the effluent discharges.
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Director Division of Reactor Licensing May 16, 1975 There was no plant transient associated with this event.
Respectfully,
[,9N b d J. J. Mattimc,e Assistant General Manager and Chief Engineer cc:
R.H. Engelken, Region V O
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