ML19274D343
| ML19274D343 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 01/05/1979 |
| From: | Jeffery Grant TOLEDO EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 1-40, NUDOCS 7901230214 | |
| Download: ML19274D343 (3) | |
Text
D *O C
,,_ _g, A TOLEDO EDISON January 5, 1979 JAMES S. GRANT
%ce President Serial No.1-40
[*,'['((31 Docket No. 50-346 License No. NPF-3 Mr. James G. Keppler Regional Director, Region III Of fice of Inspection and Enforcement U. S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137
Dear Mr. Keppler:
Enclosed are two copies of Reportable Occurrence NP-09-78-03, which are beir.g sub-mitted to you in accordance with Technical Specification 6.9 to provide 30 day written notification of this occurrence.
~Y Yrurs truly, L
y/W
- JSG/ljk Enclosure cc:
Mr. William G. Mcdonald, Director Office of Management Information and Program Control Encl:
2 Ohio Environmental Protection Agency Northwest District Office Encl:
1 J.l 1 0 1979 THE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEDO, OH10 43652
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- a TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEME'*TAL INFOR'uTION FOR LER NP-09-78-03 DATE OF EVENT: December 9 and 10, 1978 FACILITY: Davis-Besse Unit 1 Discharge Temperature for-Station Liquid Effluents IDENTIFICATION OF OCCURRENCE:
Exceeded 200F Limit Above Lake Temperature Tbe unit was in Mode 1, with Power (MUT) = 1358, Conditions Prior to Occurrence:
and Load (Gross MWE) = 420.
On December 9, 1978, at 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br />, the Circulating Water Description of Occurrence:
The combina-System had been operating in bypass mode; bypassing the cooling tow the cooling tower) and the low lake temperature caused the indicated temperature diff 2rential between the lake and effluent discharge to increase and exceed the 200F limit.
1733 hours0.0201 days <br />0.481 hours <br />0.00287 weeks <br />6.594065e-4 months <br /> on December 9, 1978, indicating a Computer alarm T191 was receivcd at the operator diverted service 190F temperature differential. Upon receiving the alarm, vator from the coolf ; tower makeup to the collection box and reduced cooling tower to decrease the temperature differential.
blowdown flow in an effort The temperature differential reached approximately 210F at 1737 hours0.0201 days <br />0.483 hours <br />0.00287 weeks <br />6.609285e-4 months <br /> on December 9, The temperature differential decreased below the 1978, before starting to decrease.
20 F limit at 1755 hours0.0203 days <br />0.488 hours <br />0.0029 weeks <br />6.677775e-4 months <br /> on December 9, 1978.
0000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />, the circulating water flow had been operating in On December 10, 1978 at Again, the cambination of the cooling tower bypass mode bypassing th r cooling tower. basin' tenperature increasing and the lo tqre dif ferential between the lake and effluent discharge to increase and exceed the 20 F limit.
10, 1978, indicating a Computer alarm T191 was received at 0950 hours0.011 days <br />0.264 hours <br />0.00157 weeks <br />3.61475e-4 months <br /> on Decemberthe operator stopped all 190F temperature differential. Upon receiving the alarm, The tempera-cooling tower blowdown flow to reduce the ef fluent discharge temperature.
The tempera-ture diff erential reached approximately 22 F before starting to decrease.
10, 1978.
ture differential decreased below 20 F at 1026 hours0.0119 days <br />0.285 hours <br />0.0017 weeks <br />3.90393e-4 months <br /> on December The apparent cause of the occurrence was Desienatien of Aeoarent Cause of Occurrence:
(1) There is a design deficiency in the system used to determine the station The location of the resistance temperature threefold.
effluent liquid discharge temperature.
detector (RTD) which measures the statica effluent discharge temperature, TE2696, d l
is not respond accuratel" to effluent discharce temocrature when the north samp e pump in operation.
. ~*
s TOLEDO EDIS0N CO:!PAST DAVIS-BESSE NUCLEAR PONER STATION C;1T ONE PAGE 2 g
SUPPLDIE:;TAL I'; FOP 24ATION FOR LER NP-09-78-03 i
l (2) The combined ef fect of the high cooling tower basin temperature caused by opcrat-to be exceedcd.
ing in bypass mode and low leak temperature caused the 20 F limitthe i
the indicated temperature differential could be higher than the actual temper.1ture (3) Also, differential.
It is believed this slight increase in temperature above Analysis of Occurrence:for the short period of time did not cause environmental damage.
the discharge licit An investigation into the occurrence discovered a design defi-Corrective Action:
ciency in the system which ceasures the station liquid effluent discharge t ture. The liquid effluent The RTD is located such that piping of the Radiation Monitor RE 8433 sample pu=ps.
If the north the south pump cust be operating in order to obtain flow past the RTD.
pump is running, the RTD reading doesn't accurately respond to the discharge tempera-ture.
Facility Change Request 78-020 was submitted to eliminate the existing design defi-ciency by relocating the ther=occuple. TE 2696 and revise the heat tracing to eliminate the indicated tenperature differential error.
n investigation is being made into cocling tower operation and blowdown rates to determine if guidelines for cooling tower blowdown rates need to be revised.
An additional tecperature differentini alarm is being added to provide the operators more time to take corrective action.
There have been no previously reported incidents of discharge tempera-Failure Data:
ture dif ferential limit being exceeded.
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