ML20008D487
| ML20008D487 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 06/15/1989 |
| From: | Thurlow R PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| To: | Dodge S PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| References | |
| OL-I-MAG-118, NUDOCS 9003050245 | |
| Download: ML20008D487 (5) | |
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SS# 43289 IMSV02.02 KETED SNRC New Hampshire Yankee Olveion mmAcoMPANYBUSINESSMEM90 JN 18 P4:39 Subject S3PREEZING 'IESTI!G OF ME APTEC FT126 DETICIOR prrtCE OF $ECi1ETARY 900K1,194G 4 S!i<VICf.'
From R. M. Thuric,
Distnct Dale January 26,19EI8W CH P
To S. L. Dodge Morence i
. is the study to determine the response characteristics cf the Aptec FT126 G. M.
probe at very low tanparatures.
. /w
. M. Thurlow Health Physicist Reagme Attachment cc:
J. J. Rafalowski E. L. Darois W. T. Cash R. Mayes F. Straccia J. Murphy NLICLEAR REGULATORY COMMISSION 56 'H3 -OL Docket No. 5034V. d4_ Official Exh. No,. [ / N In the matter of OffdcMge b ay d Al, M,yffg, p
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IDENTiflED 2.5 M3 App icant I ECEIVED.__3 7 8 9'S Intervenor M[,t*
_ REJECTED Cont'c Off'r Contra: tor _flfRlfd52_ DATE (C //5/99 Other -
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Reporter 9003050245 090615 PDR ADOCK 05000443 jf. I,(.
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A.
Response Charactaristics Of The Aptec 126BH Probe At Very Iow Tenpartures i
i 1.
Discussion The APTEC FT-126BH is a wide area, flat G4 detactor used to survey various surfaces for beta and gamna contamination. The specifica-tions of 32*provided by the manufacturer indicate an cparating tanperatare to 1220 Fahrenheit. This tanparature range is of concern because the instrument may be used outside in cold tam-paratures.
A review of the fundamental principles of GM detectors and the speci-fications of other G4 detectors indicate that the instrunent should function at the tanparatures of concern (lower than the manufacturer specifications). 7b verify this, testing was performed at tam-paratures well below 320 Fahrenheit.
2.
Mutinqr The APr!E detector is normally used with the BICRON Frisk Tech A769K and there-fore was tasted as a system (detector ard scaler placed in the fresser). Two systems were randomly selected from the inventory and were tasted using two sources at three different tanparatures. To ensure the detector had reached the tasting tenparature, the systems i
were placed in the freezer for at least 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> prior to taking l
measurements. The systems were operated an battery power while being l
tasted in the freezer. The testing involved placing the sources 1
directaly on the detector grid cover, allowing the count rate to sta-l bilise and recording the average count rata. A stamary of the testing equipment can be found in Figure 1.
l 3.
Conclusion l
L The testing data, found in Figure 2 indicate the APTBC FT-126BH can be used at very low taaparatures. The data show that tamparature (within the range of -10 to 70 degrees Fahrenheit) has no adverse effect on the performance of the detector.
h The slight changes in count rates are acceptable given the positioning of the sources, slight novemant of the notar needla and the relatively low count rates. Although the APTEC FT-126BH can aparate at low tam-paretures, care should be taken when the system is noved fra a cold environment to a warmar one as condensation will form on the outside of the detector and on the BICRON Frisk Tech.
It is r===narided that during a given use period the system be used either in a cold environ-nent or a warm environannt but not repeatedly brought into and out of a mld environment. leien the system is moved fran cold to warm, l
sufficient time should be given for the systen to dry out, i
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I FIGGRE 1 Testing Equipment System 1 APTI!C FT126BH, Serial thnbar 3H137 I
BICRON Frisk Tech. A791K Calibrated 10-26-87 System 2 APr!!C FT126BH, Serial Number 3H136 BICION Frisk M. A769K Calibrated 10-23-87 Ther:occuple Type K, Model A2301, Serial Number FLS-1502 Calibrated 12-9-87 Source 1 Tc-99, Serial Number E-85-74 Source 2 Ca-137, Serial Number E-83-5 i
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ii FIGURE 2 Tasting Data J
J Trial F'
System 1 System 2 Source (cpm)
(cpm) l s
1 70 1700 1700 Tc-99 7
0 1700 1700 Tc-99 t
3
-10 1650 1700 Tc-99 4
70*
1700 1700 Tc-99 5
70 4500 Cs-137 6
0 4800 4500 Cs-137 7
-10 4800 4700 Cs-137 8
70*
4800 4500 Cs-137 Mansurement performed several hours after the system had been renoved feczn the freezer.
- The Cs-137 source was not available until after System i had been placed in the freezer.
tore - All O' and -10' measurements were parformed using the Prisk
% built in batteries, e
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'FT Series G-M Tube Sensitivity i
Minimum detectable activity (MDA) for Aptec large area sealed Ceiger Mueller tubes (FT series), based on source site of 100 cm2 Note:
5000 dpa/100 cm2 = 2.25 nC1/100 ca:
"A" vindov = 14 ag/ck2; "B" vindov = 7 ag/ce2 MDA - vith background of 15 uR/h 952 confidence of alara (5% false alara) j i
FT Series Tube (Active Area) isotope FT-126B FT-252B FT-3468 FT-366A i
l (126 cm2)
(252 cm2)
(366 cm2)
(366 cm2) l 137Ca 0.36nci(est) 0.49 nC1 1.1 nci 1.7 nci 60 o 0.75 (est) 1.0 2.3 6.3 C
s SBCo 1.0 (est/
)
1.3 2.8 4.3
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13'Cs 0.5 (est) 0.69 1.6 2.4 i
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- MDA - with background of 0.1 at/h 951 confidence of alarm (51 false alars)
FT Series Tube (Active Area)
Isotope-FT-1263 FT-2523 FT-3663 FT-366A (116 ce2)
(252 cm2)
(366 es2)
(366 es2) 137Cs 0.6 nci(est) 0.9 nci 2.5 nci 4 nci 60Co 1.2 (est) 1.8 5.6 15 58Co 1.5 (est) 2.3 6.3 10 13'Cs 0.9 (est) 1.3 3.8 5.7 01/86
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