ML20112E086

Informs of Unusual Event on 761112.During Attempt to Open Reflector Drain Valves,Neither Drain Valve 5A or 5B Opened. Solenoid Showed Evidence of Dirt or Trash Presumably from Air Supply to Valves.Procedure 2006 Will Be Modified

ML20112E086
Person / Time
Site:	Neely Research Reactor
Issue date:	01/14/1977
From:	Kirkland R Neely Research Reactor, ATLANTA, GA
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20112E009	List: ML20112E021 ML20112E086 ML20112E088 ML20112E096 ML20112E109 ML20112E128 ML20112E146 ML20112E171 ML20112E184
References
NUDOCS 9606050142
Download: ML20112E086 (3)

Text

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GEORGIA INSTITUTE OF TECHNOLOGY , .

ENGINEERING EXPERlWENT STATION

, , . ATLANTA. GEORGIA 3o332

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.B U.S. Nuclear Regulatory Commission, Region II / T E B 1 1 W /. "?

230 Peachtree Street, N.W. Suite 818 2' u,3, q M *'; f * " j Atlanta, GA 30303 I , ';j b

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Reference:

Docket 50-160 h

Gentlemen:

This letter is a report of an unusual event that occurred at the Georgia Tech Research Reactor. On Friday, November 12, 1976, the reactor was i operated at 1 MW from 0857 hours0.00992 days <br />0.238 hours <br />0.00142 weeks <br />3.260885e-4 months <br /> to 1123 hours0.013 days <br />0.312 hours <br />0.00186 weeks <br />4.273015e-4 months <br /> when it was shutdown for  !

the week. Subsequent to the shutdown, the reactor operator began follow-ing GTRP. Procedure 2006, " Weekly Reactor Shutdown Checklist" (copy enclosed).

Near.the end of the procedure, the operator attempted to open the reflec-tor drain valves. When the OPEN switch was operated, neither drain valve SA or 5B (installed in parallel) opened. The operator pushed the CLOSE l switch and then the OPEN switch which caused the reflector to be drained.

Field inspection revealed that valve SA was open and SB was still closed.

Valves SA and 5B are air operated butterfly valves in the top reflector i drain line to storage tank TD-1. The control system is such that air must be supplied through an electro-pneumatic solenoid valve to maintain l the valves in the closed position. The loss of either the electric signal l or plant air will cause the valves to open and drain the top D,0 reflec-tor of the reactor. The valves are installed in parallel so tHat either one will drain the reflector.

When the solenoid on the still closed valve 5B was lightly tapped, valve 5B immediately opened. Subsequently, both valves were opened and closed l for 6 complete cycles without the reflector and an additional 3 complete cycles with the top reflector pumped up. In all 9 cases, both valves op-erated normally. On Monday, November 15, 1976, the solenoids from both drain valves were removed. Each was disassembled and thoroughly cleaned.

The internals of both solenoids showed evidence of some dirt or trash pre-sumably from the air supply to the valves. We believe it was this foreign material that caused failure of both solenoids to operate which in turn i

caused both drain valves to remain closed when the OPEN switch was oper-ated. After reassembling the solenoid valves and installing them on the

! drain valves the drain system was operated for 8 complete cycles. The valves performed normally. Following the testing, the reactor was start-ed up.

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e U.S. Nuclear Regulatory Commission, Region II Page Two January 14, 1977 , -

^~ To prevent'this from occurring again we are making two changes. On an .

annual-basis, both solenoid valves will be inspected and cleaned. Addi-l tionally, Procedure 2006 will-be modified so that the field operator is l present when the drain valves are opened. This will alert us to the occur- i rence of a single failure.

Should you require any additional information on this matter, please con- 1 tact me. -

s Sincerely yours, i

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Robert S. Kirkland, l Reactor Supervisor l l l l

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Enclosure:

GTRR Procedure 2006 cc: Members, Nuclear Safeguards Committee L. D. McDowell .

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• l hapter CEORCIA TECH RESEARCH REACf0R

'4 Procedure 2006

[ .' Approved l w Nomal . -

5/2/74 Revised-

. Opera ti,on-

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5/8/75

'~ - Weekly Reactor Shutdown Check List. Page 1 of 1 L

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M e ,st run ECCS pump Close valve 8 -

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• WeeEiy.it ower calibration j

Re-establish' ~overflow -

. completed date and time' Remove Jump *er from TBA-82 to Shutdown by stopping MD-3 -

TEA-69 and from TBA-89 to TEA-98

-or'MD-4'and wait for No .

D 0.. overflow scram Reset ECCS -

2 Open spray block valve "

~ Observe the following: s do D2 0 V ffl W Plate Reset-. Mag. Act.' Amp. t. I Rod low limit lights 1-4 Energize clutches 1-4 Magnet current 0.18A Close spray block valve Re-establish overflow Manually close reactor isolation valves Install jumpers from TBA-89 to TDA-98 (Isola tion . valves Observe the following:

not open scram) and TEA-82 Reactor isolation valves not P n Pl ate to TBA-69 (D9 0 level Reset L

Switch) Lowo? Scram Set d magnet indicat rs 1-4.od, L' point'on FRA-H1 to zero and- MD-3 (4) stopped

. then stop MH-2A (MH'-1) Switch ."*E' ^ * " " * " '

• pottermeter recorder off and - Open Reacto.r isolation valves. -

install scram jumpers from (ECCS override)

^

TEA-29 to TEA-30. (D2 0 flow -

Open ECCS spray' block valve -

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l scram 1.& 2)

'Stop MD-2A e-es a sh b,e d om j l-Reset ECCS *

!. (Close Spray Block Valve Reset Mag. 'Act. Amp.

L Lowcr Reactor tank level Reset clutches 1-4

- slot!1y 'by draining through

. valve S Cooldown requirements met

' NOTE: Vnicliever icvol channel trips -8** *

• i: first. the reactor isolation valves ' Open reflector drain valves

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close. Stop draining, Override to ' '

7 reopen the valves and recommence drain. Observe the following indications:

Drain valves open place ,_

Observe the following: #8 ' ^ # ^*E' #" * "

• Reactor tank low level plate #" * * * -

Rod mgnet indicators 1 & 2 Switch pottermeter recorder 4

g - on and remove jumpor from-Rod magnet indicators 3 & 4 TBA-29 to N 30 _

!. off .

I Magnet current 0.18A' Low 1cyc1 channel trip -

Security System Test Date Time

-indicators'1 & 2 on *

!' MD-3'(4) stopped Reactor isolation valves; closed Operacor Spray valves open Date'

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