ML17266A022

Reportable Occurrence 335-B-78-08 on 781117:condenser Temp Rise Exceeded 24 F,Caused by Circulating Water Sys Fouling, But Discharge Canal Temp Did Not Exceed 111 F Degrees

ML17266A022
Person / Time
Site:	Saint Lucie
Issue date:	12/14/1978
From:	Robert E. Uhrig FLORIDA POWER & LIGHT CO.
To:
Shared Package
ML17266A021	List: ML17266A020 ML17266A022
References
NUDOCS 7901040157
Download: ML17266A022 (3)

Text

FLORIDA POWER & LIGHT COMPANY ST. LUCIE UNIT NO. 1 REPORTABLE OCCURRENCE NO. 335-B-78-08 TITLE Maximum Condenser Temperature Rise s

A. Descri tion, Anal sis and Evaluation Reportable Occurrence Nos. 335-B-78-03,-'04, and -07 described occasions on which the condenser temperature rise at St. Lucie Unit No. 1 was observed to be in excess of 24'F. Further in-stances of this type occurring in November are as follows:

DATE TIME 6T POWER FLOW 11-17-78 2000 24. loF 100% 490,000 gpm 11-26-78 0200 24.1 F 100$ 485,000 gpm 11-27-78 0700 24.3'F 100% 482, 000 gpm As was described in the earlier R.O.'s cited above, the circu-lating water system at the St. Lucie Plant has been experiencing conditions of system fouling which have caused the condenser temperature rise to slightly exceed 24'P. These conditions of fouling make the temperature rises which have been experienced acceptable as per ETS 2.1.2. These events are being reported, however, as a continuing item of potential public interest concerning environmental impact from plant o'peration in accor-dance with ETS 5.6.2.a.

No instance of discharge canal temperature exceeding the limit of ill'F (ETS 2.1. 1) was observed at a time correspondingis to it the eported condenser temperature rise. Therefore, believed that no adverse environmental impact has resulted from this event. Also, the discharge area thermograph recorders which are located in the vicinity of the hot spot have shown no times at which the maximum allowable instantaneous temperature in the hot spot was exceeded.

B. Cause The conditions of the circulating water system which caused these events have been described in the previous R.O.- reports which were cited in Section A above.

C. Corrective Action Operation of the condensers at greater-than-design flow has been undertaken occasionally to help prevent exceeding the condenser hT limit and can continue up to some point. However, 780'M40157

this mode of operation is considered undesirable for long term operation since it will affect the integrity of the Aluminum-Brass condenser tubes.

By letter dated August 29, 1978 (L-78-281) we requested that the allowable condenser hT be increased to 26'F for an interim period. Ne are awaiting licensing action on this request.

At this time, it is planned to replace the existing Aluminum-Brass condenser tubes with titanium tubes during the cycle 3 refueling outage for St. Lucie 1, expected to begin in April, 1979. Although this is expected to restore some of the opera-ting margin to the system, such that the condenser dT can be maintained at or below 24'F for some period of time, it does not address any anticipated future degradation in system per-formance. FPL therefore plans to request a permanent modifi-cation of the ETS to allow operation at a higher condenser hT upon completion of the necessary environmental assessments.

4