ML20040C309
| ML20040C309 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 11/20/1981 |
| From: | Leasburg R VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-SSINS-6830 327, IEC-81-07, IEC-81-7, NUDOCS 8201270512 | |
| Download: ML20040C309 (1) | |
Text
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USNRC REGION."
VIRGINIA ELucinIc Axn POWEH 'CO3fP5Y. 'l C O P I, j A
'IIICIIMOND, VInUINIA 20 261 31 nov 23 Alu: 1I November 20, 1981 H. II. Lna mn n uo G
Vace Pamnsnant Noca.EAm oFEmmONS Mr. James P. O'Reilly, Director o
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Serial No. 327 Office of Inspection and Enforcement 4
N0/WC:rhh U. S. Nuclear Regulatory Commission Docket Nos. 50-280 Region II 50-281 101 Marietta Street, Suite 3100 9
R6CEMp p
Atlanta, GA 30303 2
jgg 261982> 7 0 n y.e arm W fl?
9 0 aas& TATE NC
Dear Mr. O'Reilly:
'?w
= ' '
/ rg--p s We have reviewed IE Circular 81-07, " Con o
Radioactively Contaminated Material", and believe that an error has been made regarding the sensitivity limits for portable beta-gamma instrumentation referenced in the discussion section of the circular.
In the referenced article by Mr.
J.
F.
Sommers, " Sensitivity of Portable Beta-Gamma Survey Instruments", the experiment and recommendations were limited to small area (less than one square centimeter) sources.
Mr. Sommers' determination of 5000 betas / minute as the minimum practical sensitivity limit for portable beta-gamma survey instruments is only applicable to small area
" hot spots" of contamination.
Experiments performed by Vepco, using Eberline's Model RM-14 Counter with the HP-210 or HP-260 probe, indicate that approximately 5000 betas / minute per 20 square centimeters is the lowest sensitivity. limit.
Radioactivity of 5000 betas / minute spread over an area of 100 square centimeters is ur. detectable by current available portable survey instruments.
Our experiments and subsequent discussions with Mr. Sommers indicate that _the extrapolation of his findings to support the t,RC's proposed limit of 5000 dpm/100 square centimeters is inappropriate and invalid.
A response to our findings will be most appreciated.
Very trul yours, e
. Leasbur i
8201270512 811120 PDR ADOCK 05000280 G
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