ML20141M046

Dow Triga Research Reactor Annual Rept - 1991

ML20141M046
Person / Time
Site:	Dow Chemical Company
Issue date:	12/31/1991
From:	Kocher C DOW CHEMICAL CO.
To:
References
NUDOCS 9203310245
Download: ML20141M046 (5)

Text

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i 26 hivth 1992 .

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Director, Office of Nuclear Reactor Regulation ArlN: Document Contzol Desk U. S. Nuclear Regulatory Comrnlasion Washington,DC 20555 DOW TRIGA RESEARCilllEACTOR 90( KET NO.50 2M .;

he 1991 annaal report for the Dow TRIG A Research Reactor Facility is attached.

Yours, a

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C. W. Kocher Restar Supemsor '

1602 Building 9203310245 911231 i i-DR ADOCK 05000264 3 j *\

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i' DOW TRIG A RESEARCis REACTOR-

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ANNUAL REPORT.1991 The ivxtor has seen more use this year !han in the par', partly duS to incicased sample load and partly

- due to increased analytical sensitivity resulting from the increased power level. Problems w4.h the new console, installed in late Decemter 1990, prevenul opacation uuring the flat week of January and for a

- time in October, but some hardware changes have led to smoother operations. A raajor problern seems to be rehted to the operation of the .NM 1000 digital channel which provides information about, among '

oter things, the reactor period: at low power !cvels, from source level'.o abaut 150 milliwartz, the noise n the period channel has caused an inordinate number of unintentiona! shutdowns. Sorae of this is related to tlx digital smoothing algtrithm.

- New fuel elemenu have cepbced two dummy clernents; the 300 kw power level has been activated; and two persons have been newly licensed as Senior Reactar Oyrators.

A. Staff, Licenses, and TrainMg '

Tbc staff consists of live persoru:

C. W. Kocher Senior Rextor Operttor ReactorSupervisor W. L Rigot Senior Reactor Operator Assistant Reactor Supervisor T. L Quinn Senior Rextor Open:or Assistant Reactor Su[rrvisor M E.Buchmann Senior Rextec Operatcr

.~. D. Rooick Senior Reactor Operator Licenses of the SROs ne c nent, with rr newals exp cred in 1993 (Rigot and Quinn),1995 (Xochu), and 1997 ('Buctmann and Romickt Medical examinations are current.

The cmwnt two year requahlication program was started in the second quarter of 1990 and seven sessions have been held. The SROs are current with operaticg experience and participr. tion in hypothetical emettency drilla,Rexter Operatioru Committee meetings and the annual fuel inventory.

The Rextor Operrtiont Curaniace continues with five members:

1L Havel Facility Director C. W. Krher Reactor Surervisor and Senior Reactor Operator S. W. Maxey ' Radiation Safety Oflicer W. L. Rigot Senior Rexto Operator T. D. Lickly B. Reactcs Opciating Experience The reactor was operawd for about 0.8fs megawatt-days during the yect, and from 2491 through 12-3.t.91 (the time during v htch the new console was used to accumulate operating hours) the reactor wu operated for a total time of aboat 251 hours0.00291 days <br />0.0697 hours <br />4.150132e-4 weeks <br />9.55055e-5 months <br />. The crerators perfonned over 1500

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reactivity manipulatians,lachding the daily, monthly and annual checxouts, the training a-d i operating examinations for two SROs, anu the irradiatien of sampics.

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C. Majer Clanges Two new fuel elements were added to the core in January 1991, seplacin,1 two graphite loaded dummy clerc.ents in te F-ring. His brought a core excess to abcut $2.30 (0.01615k/k).

The ree.or was cperated at power levels above 100 kilowacs for the first time on 30 lanuary 1991, utdizira the higher power levds allowed by the liccese of May 1989.  ;

The stactor was opente A e'.250 kilowatts for the first time to irradiate ampler for neutron activation analysis on 5 February 1931. i D. Unscheduled Shutdown) -

During the period 1 January 1991 and 31 December 1991 there were seveuty-two unintentional shutdowne. Many of these *vwe the remh of the installation and tr# tining procce but a number were *clated to problems with the new console.. Some of these problems have t>cca solved but une at least still remains to oc solved.

1. Forty-thre[urdrantional shutoowns ocrwed tceause the period setpoir,t (3 seconds) wns reochort.

Of tlem 5 txcurred during pess.Sg of the eutonmuc mode of operution; maillication of the actpoints of the automatic mode climinated tNs pro 5!cin in April 199 and it has not recuned.

Four more occuned during ti.e crossover between the count-rate mode and the P.MS mode of.he wide range log channel which suppliu the geriod signal. We setpoints for this chxmel were improved to provide a smoot:.cr crovover and this has not recurred since June.

- Oac u;cerred at a power level of I kilowatt in Janury and can be attributed to the operator % attempt to evaluate the noise in the period .-ircuit at this level.

Thirty two other unintentional shutdowns due to the period setpoint occurred at rawer lewis less than one watt, during startup of the reactor from the normal source level of about 1 milliwr.tt. Of diese, eleven occum d at a level which is recognind by the manufacter:r us a switchmg-point c<f the digital amoothing algorithrn. The manufasurer has so far been unabic tc modify the alt sorithm 'o climinate this problem.

All of these low level penod shutdowne seem to xcur becarne of the noisiness of the perimi signal f rom the digital nu mthing algorithm.- his censole is t!c first to ba operated at a 1RIGA remtcc which has such u hig' minimum period requiruneat - sevcu seconds.

Other'1RIGA reactors, licensed to be puised, do not have period scrarns; a ccatol rod run-down system suffices.

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, f10W TRIGA RESEARCil REACTOR The manufacturer is suggesdug that we ask :or a lower period requirement, of the order of one to three seconds. We woukt thus he able to operate at a uominal period of 10 to 13 seconds and the rolse of the period circuit would not activate the period shutdown circuit.

Unless the digital algorithrn is modified or the period setpoint is changed we expct to continue to observe tMsc uninterational shutdowns.

2. Eleven urJntemional sht*hvms omttred while thJ ruictor was at power. Five of .hese occurred during the Itrst month of operation, including three immediately following the implementrtion of the 300 kw operation, and these are attributed to learning experiencas.  ;

Two others occurred while te reactor was in J.e automatic mode; modifications of this mode have been r,wde and this is not expecteo to recur. One othet xcurred on a day when the reactor Lad three period scrams nd one co.npu*cr crash, and is mtributed to colse in the comper system.

nree unintentional shutdowns are attributed to operator error lack vf attention to the power ievel while watching other parts of the svstem, including making cruriet in the ,

loglxiok.

3. Tv.o u untentional dutdowns wear caused by a faulty connection in the cornole keyswitch; the conNction was repaired and no funher probleras me expected.

4. Seven uni.ctentional shutdowns occur.dl because thc computer stopped opemting or taause th computer rmted. Th power supply of one of the computers was replaced in September and the problem has not recaired.

5. Nine unintentional shutdowns occurred when the watchdog circuits timed out, indi:ating that the network was not functioning. Six of these occurred with!n four day s late in October; the network cable was replaced and the problem has not recurred.

Of Ae twen:y~uine unintcutional shutdowns widch did not invc!ve the perist circuit eighteen resulted in irtrdware changes that appear to havr: climinated these events, two resultea in softwa e changes, five were attributed to the start.up exercises, and one was probtb!y due to a computer malfunct'on. 'It.e t.:rnaining tlure, due to operator error, have been addressed in the training ,

progium.

E, Major Preventive and Corxctive Maintenanc,c af Safety Signific ance The Continuous Air Manitor (CAM) was replaced in hcember following a Inise illGH RADIATION ALARM. The new C AM is an Eberline AMS 3A, a slight modification of the ,

Ebarline AMS.3 that hasi; con used here since 1980. The AMS 3 was returned to the man ifacturer to be rebuilt and calibrated; it will be used as a backup sysxm.

The power supply of one uf the two computers was replaced and the network cable connecting the computets was repbced to provide more reliabie scivice.

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.s h The hard disc of one of the computers was repired following a power f.illure.

The keyswitch v.as repaired to eliminate unintentional shutdowt4s.

F. Radioactive Flfinents The oMy radioactive material released to the environment frtun this fxility it, argon 41, which is produced from activadon of the natural argon dissolved in the pool water, and wl.ich subsequently c.tcapes from the pool into the reactor room and fiorn them to the outside of the heilding, and from the natural argon present in the ait used to transport sampics from a laboratory into a terminus is the com of the reactor.

• Die m eroge release after dilutiori or diffusion i; estimated to le less than 25% of the allowcd or ,j recommended concentration.

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O. Radiation Exposures Radiation exposures received by facility personnel and visitors are monitored using film badges d and theimoluminescent deta s. No persens have icccived exposures approaching 25% of those allowed or recommended in 1 AfR20.

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( ,. & f b.ic. A +- J C. W. Kocher .

Feactor Supeniscr 8

25 March 1992

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25 Much 1992 4

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