ML20086H449

AO 50-271/72-01:on 720406,after Inadvertent Low Reactor Water Level Initiation,Standby Gas Treatment Sys Fan a Failed to Run.Caused by Inadequate Heater Size.Larger Heaters Installed & Fans Tested

ML20086H449
Person / Time
Site:	Vermont Yankee
Issue date:	04/14/1972
From:	Riley B VERMONT YANKEE NUCLEAR POWER CORP.
To:	Morris P US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086H450	List: ML20086H449 ML20086H457
References
AO-50-271-72-01, AO-50-271-72-1, VYV-1929, NUDOCS 8401170157
Download: ML20086H449 (2)

Text

{{#Wiki_filter:- [. . .- - . . 7 O O l 1 VERMONT YANKEE NUCLEAR POWER CORPORATION SEVENTY SEVEN OROVE STREET RUTLAND, Vensoxr osvoi VYV-1929 ,

                                                                                  "P.".O*O B X  157 VE.1NON. VERMONT oS354 April 14, 1972 4

United States Atomic Energy Commission fg/v , ,. ,p  %

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Division of Reactor Licensing i hshington, D.C. 20545 '

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ATTENTION: Dr. Peter A. Morris, Director - f.c c. Dg j

REFERENCE:

Operating License DPR-28 sy fb'kW4 ' s n Docket No. 50-271 <E'+s q *fe / Abnormal Occurrence No. A0-72-1 ( , C{i /

Dear Mr. Morris:

As defined by Technical Specifications for the Vermont Yankee Nuclear Power Station, Section 6.7.B.d, we are reporting the following Abnormal Occurrence as A0-72-1. On April 6, 1972, at 1615, a low reactor water level initiation of the Standby Gas Treatment System was inadvertently imposed by an Instrument Technician performing maintenance work on a line common to the low side reference for the reactor vessel level Yarway instruments. This caused initiation of the Standby Gas Treatment System (SBGT) which called for auto start of both A and B SBGT fans. At this time Fan B was observed to have started and was running; however, Fan A was observed not to be running. It is believed that Fan A did start but tripped prior to operator verification of its operation. Subsequent investigation revealed that although the installed _ motor _over-lond heater size was within the correct range as prescribed by the manuf ac'turer,

     ;)(         in certain cases it becomes necessary to install a higher value heater to
   !             accomodate the magnitude and duration of motor inrush current. In this regard, cg[',          the heater sizing was reviewed by plant personnel and larger heaters were g             determined necessary and therefore installed.

NE Following the installation of larger heaters, a series of satisfactory f [-{ demonstrations of both manual and auto start were performed on each f an. These were followed by a successful four hour test run of both units. f ! s h 7 720414 0500oa73 f.p f PDR MN COPY SENT REGION T i L:---~ m -- .r- - ~ p ~ Y

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gJ I VERMONT Y6%/ ,EE NUCLEAR POWER CORPORATik, Dr. Peter Morris . April 14, 1972 Page 2 It is germain to this report to point out that at the time of failure there was no requirement by Technical Specifications for cperation of the SBGT system due to the ' existing plant status. However, this occurrence was a discovery that under' previous plant conditions when SBGT System was required to be fully operational that the SBGT may not have performed as required by Technical Specifications. Respectfully submitted, VERMONT YANKEE NUCLEAR POWER CORPORATION o Bradford W. Riley A Assistant Plant Superintendent BWR/kib l l 1

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