ML20008D487

Intervenor Exhibit I-MAG-118,consisting of New Hampshire Yankee Div 880626 Memo Forwarding Results of Study to Determine Response Characteristics of Aptec 126BH Probe at Very Low Temps

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)

Text

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KETED IMSV02.02 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

Attachment 1 is the study to determine the response characteristics cf the Aptec FT126 G. M. probe at very low tanparatures.

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. 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 OffdcMgep b ay d fAl , M,yffg, Staff -

App icant IDENTiflED 2.5 M3 I ECEIVED .__3 7 8 9'S

. Intervenor M[,t* _ REJECTED Cont'c Off'r Contra: tor _flfRlfd52_ DATE Other -

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Attachment 1 Response Charactaristics Of The Aptec 126BH Probe At Very Iow Tenpartures  ;

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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 to 1220 by the manufacturer Fahrenheit. indicate an This tanparature cparating range is tanperatare -

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 i

ensure the detector had reached the tasting tenparature, the systems 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.

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 ,

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.. i 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

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'FT Series G-M Tube Sensitivity

. i Minimumtubes Mueller detectable (FT series),activity (MDA) for Aptec large area sealed Ceiger 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 l FT-366A (126 cm2) (252 cm2) (366 cm2) (366 cm2) i l

137Ca 0.36nci(est) 0.49 nC1 1.1 nci 1.7 nci 60Co 0.75 (est) 1.0 2.3 s -

6.3 SBCo 1.0 (est/ -

1.3 2.8 4.3

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13'Cs 0.5 (est) 0.69 i 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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