ML19345G173
| ML19345G173 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 02/28/1974 |
| From: | Hartley F CONNECTICUT YANKEE ATOMIC POWER CO. |
| To: | Anthony Giambusso US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| AO-74-01, AO-74-1, CYH-2578, NUDOCS 8103100182 | |
| Download: ML19345G173 (2) | |
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CONNECTICUT YA N K EE ATO MIC POWER COMPANY
)I HADDAM NECK PLANT
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RR # 1 BOX 127E. EAST HAMPTON, CONN. 06424 January 28, 1974 CYH-2578
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v g g/ /y Mr. A. Giambusso 50-213
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'4(y'Ogh Deputy Director for Reactor Porjects r
Nu Directorate of Licensing United States Atomic Energy Commission
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Office of Regulation
'pc, I A Washington, D. C. 20545
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Dear Mr. Giambusso; b/
As defined by Technical Specifications for Connecticut Yankee Atomic Power Station, Section 5.3, the following incident involving an unsatisfactory test of timers associated with the emergency diesel generator / core cooling systems is hereby submitted as Abnormal Occur-rence 74-1.
While conducting routine surveillance tests of the core cooling equipment initiation timers, No. 3 containment recirculating fan timer failed to actuate within the required time. The criteria for this timer is 43 1 5 seconds; however the timer actuated at 31.5 seconds. The timer also failed to operate properly on two subsequent tests.
Since these timers function to sequentially load the emergency diesel gen-erators during a simultaneous loss of AC power and core cooling actuation, operation outside the permissible time band is considered to constitute an Abnormal Occurrence.
Redundant back up timers were satisfactorily tested to insure proper response capability and the affected timer was replaced.
However, the replacement timer also failed to operate properly and further investigation revealed the problem to b6 inalfunction of an SV relay located in the timer circuitry. The SV relay monitors 480V Bus 6 voltage and actuates the timer for the containment t ecirculating fan provided the necessary core cooling signal is present. The SV relay appeared to be sticking and would not operate consistently.
The affected SV relay was replaced and successfully tested several times. The Plant Operations Review Committee investigated the incident and recommended an investigation to see if any other event is causing the relay failure. The committee also racormiended a study to determine if SV relays need to be upgraded with a more reliable device.
Previous difficulty was experienced with the SV type relays in the timer circuitry during testing. in October 1973 and was reported as Abnormal Occurrence 73-9.
Additionally, during the refueling interval Loss of AC/ Core Cooling Test conducted on 12/1/73, SV relay 59-6 did not respond normally and was replaced with a relay of similar function.
After each of these problems the affected relays and their associated timers were successfully tested and returned to service, as f'/0 5/OOff A
t Mr. A. Giambusso January 28, 1974 Presently the equipment timer surveillance test and the SV relay continuity checks are being conducted on a weekly basis to insure satisfactory operation. With weekly tests, plus redundant back-up equipment it is felt that the system capability is adequate.
Very truly yours,
/ftus l
. W. Hartley Plant Superintendent l
RHG/bn cc: Mr. James P. O'Reilly, Director Region 1 Directorate of Regulatory Operations U. S. Atomic Energy Commission King of Prussia, Pennsylvania 19406 1
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