ML20155E237
| ML20155E237 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 10/04/1988 |
| From: | Schnell D UNION ELECTRIC CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737 ULNRC-1839, NUDOCS 8810120198 | |
| Download: ML20155E237 (4) | |
Text
I901 Ca nt 5 rryt e
o e cwb m St Im V : c0 s 31I t $1IMO Donaldf Schnelt Eurn[(u)N e
october 4, 1988 323 U.
S. Nuclear Regulatory Commission ATTN Document Control Desk Washington, DC 20555 Gentlemen ULNRC-18 39 CALLAWAY PLANT DOCKET NUMBER 50-483 WIDE RANGE GAS MONITOR ISOKINETIC SAMPLING During our NUREG-0737 post-implementation compliance review, we have identified an issue which requires clarification by Union Electric and your concurrence.
This issue involves the sizing or' the normal vent flow /high radiation sample flow isokinetic nozzle and its inability to collect an isokinetic sample per ANSI N13.1-1969 guidelines.
This requirement is referenced in NUREG 0737,Section II.F.1,, Clarification 3.
The Callaway Plant unit vent wide range gas monitor (WRGM) uses four sample lines with associated isokinetic nozzle assemblies for sample collection.
Two sample lines are provided to allow collection of unit vent samples at low radiation activities.
These lines are fitted with nozzle assemblico for collecting isokinetic samples at normal and accident unit vent flow rates.
Two additional sample lines are provided to allow collection of unit vent samples at high radiation activities.
These lines are also fitted with nozzle assemblies for collecting isokinetic canples at normal and accident unit vent flow rates.
The isokinetic nozzle assemblies associated with the WRGM were designed by G. A. Technologies per ANSI N13.1-1969, except for the normal vent flow /high radiation sample isokinetic nozzle.
In this case the single nozzle ID is too large to allow the nozzle velocity to be approximately equal to the unit vent velocity.
This causes non-isokinetic and non-representative sampling per ANSI N1".1-1969 guidelines.
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Technologies standard design practico for low flow, high radiati.on sampling systems has been to use a minimum nozzle ID of 0.150 inches becauce of the potential for plugging at smaller ID's.
If a single nozzle is used, most calculated nozzle ID's are less than 0.150 inches with some as small as 0.070 inchec.
If an increased number of nozzles were selected per ANSI N13.3-1969 guidelines, nozzle ID'c as small as 0.020 inches result.
Therefore, a single 0.150 inch ID nozzle is used on most WRGM low flow campling systems.
Por vents with a well developed turbulent flow (cuch an at Callaway), a single nozzle campling point pulls a well-mixed, nearly reprocentative cample.
When the vent flow has been filtered upstream of campling as in the care at Callaway, only cmaller particles are being campled.
In this case, the effect of non-isokinetic sampling is minimized and, because nozzle velocity is less than unit vent velocity, the cample collected by the nozzle will have a higher particulate concentration than the unit vent.
Therefore, the sample collected would be biased in the conservative direction.
naced on the above discussion, Union Electric is requecting a variance from the requirements ac referenced in NUREG 0737,Section II.T.1, Attachment 2, Clarification 3.
We propose to use the normal vent flow /high radiation cample isokinetic nozzle as designed.
We believe that the nozzle is sized to create a practical nozzle ID for sampling particulates in our unit vent.
Redesign of the nozzle to meet ANSI N13.1-1969 guidelines would produce an impractical "hypodermic needle" type nozzle which would be casily damaged or plugged caucing this cample path to be less reliable.
If you have any questionc regarding this request or if additional information is required, please let me know.
Very truly yours,
/
ts Donald P.
Schnell DP!l/ckn
STATC OF f1ISSOURI )
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Donald F.
Schnell, of lawful go, being first duly sworn upon oath says that he is Senior Vice President-Nuclear and an officer of Union Electric Company; that he has read the foregoing document and knows the content thereof; that he has executed the same for and on behalf of said company with full power and authori&.y to do no; and that the facts therein stated are true and correct to the best of his knowledge, information and belief.
By
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Donald F.
Schnell Senior Vice President Nuclear SUBSCRIBED and sworn to before me this [ W day of d[//av', 198[-
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cc:
Gerald Charnoff, Esq.
Shaw, Pittman, Potts & Trowbridge 2300 N. Street, N.W.
Washington, D.C.
20037 Dr. J. O. Cormak I
CFA, Inc.
f 4 Professional Drive (Suite 110) i Gaithersburg, MD 20879
[
R. C. Knop Chief, Reactor Project Branch 1 U.S.
Nuclear Regulatory Commission Region III 799 Roosevcit Road Glen Ellyn, Illinois 60137 Bruce Little Callaway Resident Office i
U.S.
Nuclear Regulatory Commission t
RR$1 Steedman, Missouri 65077
[
Tom Alexicn (2)
Of f!ce of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 316 i
7920 Norfolk Avenue f
Bethesda, MD 20014 l
f Manager, Electric Department Missouri Public Service Commission P.O. Box 360 Jefferson City, MO 65102 U.S.
Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D.C.
20555