ML19221A537
| ML19221A537 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/24/1979 |
| From: | Stoddart P Office of Nuclear Reactor Regulation |
| To: | Jay Collins Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7905230152 | |
| Download: ML19221A537 (2) | |
Text
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NUCLEAR REGULATORY COMMISSION
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April 24, 1979 MEMORANDUM FOR:
John T. Collins FROM:
P.
itoddart
SUBJECT:
EFFLUENT AND PROCESS GAS MONITORING SYSTEM The basic monitoring unit is a Victoreen air monitor, featuring a moving tape filter for particulates, a charcoal adsorber cartridge for iodine, and a shielded gas volume for detection of noble gases.
Particulates are measured by detecting B radiations from particles collected on the moving tape filter.
Tape moves at about 1" per hour, but can be advanced if a hot slug needs to be moved away from the detector so that subsequent releases can be evaluated, lodine collected on the charcoal (or zeolite) cartridge is detected and measured by a sodium iodide scintillation detector set te exami.ne pulses ir. a 20 kev window centered on the 364 kev l-131 peak.
Noble gates are detected and measured by a plastic beta-sensitive crystal scintillation counter.
In each case, sample lines run approximately 100 to 150 feet from the point of collection to the monitor.
Additionally, as many as four lines service each monitor, and can be valved in or out to sample from any one point or up to four points simultaneously.
The sample collection points have not been tested for representative sampling.
They are located generally in the middle of duct runs, but no confirmatory testing has been done.
R. Dubiel says that he does not consider either the particulate or iodine channel measurements to be valid as far as quantitative values are concerned.
He feels the noble gas measurements could be reasonably valid; the only calibration, however, was.not made against a gaseous source.
Ca!ibration consisted only of solid source measurements at the location of the main monitors.
No calibration has ever been made to estimate line losses.
On monitors 221A and 2218, pump problems have occurred in that 221A does not run, 221B cuts off very quickly on thereal ove rl oad.
On m,nitors 227 and 228, variations in flow rate have been observed.
All of these monitors have a constant flow device built-in.
I feel that the problem lies in a defective flow-regulating device, rather pumps will cure the problem -
than with the pumps.
Dubiel hopes that new
! can't buy this; based on past experience, the pr3bable cause of flow variation is the constant flow device rather than the pump.
7 9 0 3 2 3 o 15 L 164 042 i/
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John T.
Collins April 24, 1979 The normal
.'l ow rate in the air monitors is 2 scfm.
This has been varying, in the above cited cases, to up to 6-1/2 cfm, with no change in setting of the constant flow device.
I would agree with Dubiel that the noble gas section of the inonitors is probably working OK (subject to pump failure).
Va r i a t i on in flow would have no effect on noble gas readings, except for some variatior. in time of the sample to reach the detector.
There appears to be no practical way to calibrate the noble gas monitor except by use of a solid source - or calibration against a grab sample.
However, at this time, Xe-133 is so low in concentration as tn be near background and therefore not useful.
In my coinion, the particulate and iodine monitor sections are not useful for anything more than indication of trends.
As far as Tech Specs are concerned, should we be considering a T/S on these process monitors? We have HPR-si9 on the final release point, which siould provide the necessary release concentrations for the Tech Specs.
The typical rances of the Victoreen m:.iitor channels are:
Particulate:
2x 10~II to 2 x 10-6 uCi/cc
-10 lodine:
10 to 10-5 uCi/cc 2x 10-7 to 1 x 10-2 uCi/cc Noble Gas:
(106 cpm on scale)
/
P. Stoddart e
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.