ML20096A712

Advises That in FY90-91,univ Awarded Grant to Purchase Gaseous Effluent Monitor for Stack Which Exhausts Air from Reactor Room to Measure Radioactive Noble Gases.Requests That Project Be Extended Until 920831

ML20096A712
Person / Time
Site:	University of Virginia
Issue date:	03/04/1992
From:	Benneche P, Mulder R VIRGINIA, UNIV. OF, CHARLOTTESVILLE, VA
To:	ENERGY, DEPT. OF
References
NUDOCS 9205110188
Download: ML20096A712 (4)

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U.S. Department of Energy aggggggggggggggggggg Chicago Field Office soa.9e2 544o m 8o4 982 5473 9800 South Cass Avenue Argonne, Illinois 60439 Re: Grant No: DE-FG07-90ER12983 (Univ. Reactor Instrumentation Program)

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Dear Sir:

In the 1990-91 fiscal year the University of Virginia Reactor Facility was awarded a grant of $60,000 to purchase a gaseous effluent monitor for the stack which exhausts the air from the reactor room. As outlined in a letter from Robert Mulder, Reactor Facility Director, we were not able to purchase this monitoring system for several reasons, the most important being that the actual bids received exceeded suppliers the previously quoted prices by about 5096 and the fact that upon further analysis we concluded that such a system would not be able to measure the concentration of the exhaust air during all anticipated circumstances.

An extension to the end of the project period from September 1991 to December 31,1991 was obtained in order to resolve these problems.

The conclusions reached were:

(1) A stack monitor, no matter how sophisticated, will not measure the concentration of radionuclides in the exhaust air from the UVAR reactor room during

" accident" situations when the room is automatically scaled and the stack turned off, as required by procedure.

(2) The presene of an instrument which measures the concentration of noble gas radionuclides in the reactor room air, along with the particulate monitor (with minor (

upgrading) that is already in use, would provide more useful information than provided by a stack monitor. It will measure the concentrations in the room both during normal operations and during acciden' conditions.

(3) A room moniter is Ir u costly, cas;er to calibrate and maintain, and of greater benefit than a stack monitor.

Therefore, we intend to purchase a ioom monitor to measure the indioactive noble gas levels in the reactor room. This instrument will cost around $12,000 and has j 0 been ordered. It is manufactured by EG & G instruments and it should be delivered j within two months.

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Reactor Room Noble Gas Monitor $12,000 This instrument monitors operationally produced argon 41 Ambient sadiation levels in the reactor room are less than 0.5 mr/hr. During accident conditions this instrument would monitor fission product gasses in much higher radiation fields.

Therefore, some means must be provided to monitor and compensate for the ambient radiation level near the detector to determine the actual noble gas activity.

Iastrument characteristics are:

(1) Continuous flow, non pressurized chamber (2) Means of subtracting signal from ambient radiation (3) Sensitive enough to detect 2E-7 uCi/ml of argon 41 in the sampled air.

(4) Allow remote reading via serial computer interface (5) Ilave analog output for driving strip chart recorder (6) - Read out in Engineering units such as uCi/ml (7) llave outputs for remote alarms The proposed new allocation of the balance of the $60,000 grant is as follows:

Item #1- Upgrade Electronics for Existing Continuous Flow $5.000 Airborne Particulate Monitor The existing airborne particulate monitor in use at the UVA reactor facility has been in use for about 15 years. It has a number of minor drawbacks that could be overcome with an upgrade of the electronics. First, the instrument is time-consuming and difficult to calibrate. With the small number of staff members and the high volume of work at the UVA reactor facility, staff time is at a premium. Secondly, the output from the instrument is currently displayed only in units of counts per minute on a simple-analog meter and strip chart recorder, which is not a very useful method of conveying this information to the reactor operator. The desired replacement equipment will make this instrument compatible with other equipment we intend to purchase. Also, it will display the rate of change.of the radioactivity collected on the filter in the system, which is a desired parameter. - Additionally, the ability to monitor the instrument output remotely through an RS-232 connection would allow this instrument to be used for monitoring the airborne activity in the reactor room during both operational accident situations.

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A replacement system which encompasses the detection system and the rod control system is commercially available and should reduce maintenance activities and enhance tafe operation.

Item #2 Wide Rance 1.inear Neutron Channel with Servo $30.000 Rod Control The existing linear neutron channel and rod control mechanism utilius some 1950's vintage equipment in a system designed in house in the early 1960's. The current system consists of:

(1) A compensated ion chamber, manufactured by either Westinghouse or Reuter Stokes. The instruments we utilize are typically used, second hand models that are 10-20 years old.

(2) Compensation voltage power supply, part of an 'old Bailey Instruments /

Stromberg Carlson nuclear instrumentation drawer.

(3) Keithley 410 model picoammeter. This particular instrument has been modified over the years to meet our needs and no instrument of current manufacture has the output functions required to operate our servo system. Also, this instrument has needed many minor repairs in the past and there is no good indication of how long it might actually last.

(4) The power supply for the servo control mechanism is an old tube type model. Repair parts a ' available but because of its age there is no way of telling how much longe the entire instrument will continue to be operaule.

(5) The actual input signal to the servo control system is from one of the two channels on a two pen chart recorder. This channel receives its input from the linear power picoammeter. Recently, this recorder has not been exceptionally reliable.

Item #3 Strip Chart Recorders for Radiation Monitors $ 3.000 The output from the new noble gas monitor, the constant flow particulate monitor and a monitor measuring the argon 41 concentration in the exhaust duct need to have a hard copy record of their output. With this amount three pen recorders will be

. purchased. The recording of the output allows the observation of the rate of change of the signal as well as the analysis of trends in the absolute reading.

Item #4 Reactor Core Differential Temperature Monitor - $ 6.000 The absolute thermal power generated by the UVAR reactor is measured b, performing a heat balance across the core Currently. this is done with an instrument designed and built about 15 years ago by a former reactor staff member. This

(page 4, cont.)

. instrument needs to be replaced with a commercial instrument to provide better reliability and accuracy. - This upgrade will enhance safety and iegulatory compliance.

Item #5 Contincencies $ 4.000 The original grant was for the amount of $60,000. This $4,000 balance will be used to offset unforseen expenses in the purchase or installation of the items.

~In order to apply the balance of the original grant of $60,000 to other safety

- related instrumentation we would like to request project period extension to August 31,- ,

1992. This is the second extension requested for this project; an extension was granted through December 31,1991. This new date will correspond to the date of the end of a second instrumentation grant of $35,000. All monies will be spent by August 31,1992.

Sincerely, h(u(f<h.L(wCf t Paul E. Benneche Supervisor. U.Va. .

, Reactor Facility

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.'_w Robert U. Mulder Director, U.Va.

Reactor Facility cc: Mr. Craig Basset, NRC, Atlanta l

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