ML19224B181
| ML19224B181 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 02/25/1977 |
| From: | Metropolitan Edison Co |
| To: | Mullinix W NRC/IE |
| References | |
| 1704, TM-0111, TM-111, NUDOCS 7906140173 | |
| Download: ML19224B181 (5) | |
Text
-
s s
- ~ s.
'IMI DOCUMEttrS 7///-0///
D - NT NO:
COPY MADE oil 0F DOCUMENT PROVIDED BY METROPOLITAN EDISON COMPMiY.
Wilda R. Mullinix, NRC 79061401B I
9 190 265 e
1704 J-Revision 2 02/25/77 THREE MILE ISLAND NUCLEAR STATION STATION HEALTH PHYSICS PROCEDURE 1704
~
EFFICIENCY DETERMINATION FOR GM DETECTORS Table of Effective Pages Pace Date Revision Pace Date R evision Pace Date Revision 1.0 02/25/77 2
26.0 51.0 2.0 09/19/75 1
27.0 52.0 3.0 09/19/75 1
28.0 53.0
'29.0 CONTROLLED COPY 54 o 4.0 09/19/75 1
5.0 a 0. 0 55.0 6.0 31.0 j"u;/\\ Q 7 r d, p p,ipg/
56.0
-'.v i C.
srv 1
57.0 7.0 32.0 80 33 0
\\!OT REMOVE 59.'0 58 9$0 34 O
10.0 35.0 60.0 11.0 36.0 61.0 12.0 37.0 62.0 13.0 38.0 63.0 14.0 39.0 64.0 15.0 40.0 65.0 16.0 41.0 66.0 17.0 42.0 67.0 18.0 43.0 68.0 19.0 44.0 69.0 20.0 45.0 70.0 21.0 46.0 71.0 22.0 47.0 72.0 23.0 48.0 73.0 24.0 49.0 74.0 25.0 50.0 75.0 Unit 1 Staff Recommends Approval Unit 2 Staff Recommends Ap royal Date 2 /19 /77 Approval t
/
Date 2 /ta /77 Approval o
Ccgnizant Oept. Head Cognizant Dept. Head Unit 1 PORC 9ecomSen Approval Unit 2 PORC F mommehds Ap roval
\\
/
Date i
Date i
I Ch rrr n of f0 Chairnbn c PORd PORC comrt.nts f
?
included PORC comment ; of.
included
~
(dae)
{dap)
By
\\,
Date By 1
ate 100
?/4 Approval
, M M' DatE S # N Approval Date Appro I./S
_D[eY"O M;r.. operatiena:
(t 'Su p'e ri ritancen ts Quality As:;urance
o 1704 Revision 2 THREE MILE ISLAND NUCLEAR STATION 02/25/77 STATION HEALTH PHYSICS PROCEDURE 1704 Efficiency Determination For Gi Scalers 1.0 Purcose The purpose of this procedure is to list the steps taken to determine the counting efficiency of the Gi Scaler.
2.0 Discussion Determination of cour.ing efficiency is necessary to check the condition of a counting instrument on a monthly basis.
The reliability of the GM or the consistency of the degree of efficiency may change for various reasons.
The efficiency is used in the determination of radioactivity in a sample.
3.0 References 3.1 ORTEC Manuals for the following units.
1.
Model 456 - High Voltage Supply 2.
Model 719 - Timer 3.
Model 775 - Counter 4.0 Ecuipment 4.1 Lead Shield containing open end GM tube.
4.2 ORTEC - Model 456 High Voltage Supply 4.3 ORTEC - Model 719 Timer 4.4 ORTEC - Model 775 Counter 4.5 Beta gamma calibration source 5.0 Ooeratino Instructions 5.1 Insure cabinet power supply is on.
I 5.2 Insure High voltage supply (0RTEC 456) is on.
5.3 Insure Timer preset is set to 1.
190 267 1.0
1704 ke'vs' ion 1 5.4 Insure Timer multiplier is set to X100.
5.5 Insure Timer time base is set to 0.01.
5.6 Adjust Power supply high voltage to that posted on the instrument (as determined by most recent plateau) by adjusting the course switches.
5.7 Insure discriminator on 775 Counter is set to 0.1 Volt (minimum).
5.8 Place the Beta-gamma source on the sliding tray (activity side facing detector) in the geometry to be used for counting, and close the door.
5.9 Depress the RESET button on the counter.
5.10 Cepress the START button on the timer.
The interval indicator light should light, and remain lit for the duration of the count time.
5.11 Read and record the total counts displayed at canpletion of counting (indicated by interval light out) in the background and efficiency log book.
5.12 Calculate the counting efficiency using the formula of section 6.0.
5.13 Plot and record the efficiency determined on the Efficiency Curve located in the background and Efficiency Log Book.
5.14 Insure that the current efficiency is within the + 2o operating range.
If not, contact the Radiation Protection Foreman.
5.15.
Return the source to the source storage area.
(The scaler and its power supply are normally left energized.)
- 6. 0 Cal cula tions 6.1 Efficiency (%) = Source counts-x 100 min Source Dis.
Min.
1?0 268 2.0
09-19-75 1704 Revision 1 WHERE:
Source counts
= Total counts obtained in step 5.11 divided
- I"'
by the counting time (1 minute).
Source Dis.
Min * = Disintegration rate of the sources (may be mod 1-fied by step 6.2) 100 = Conversion constant, Decimal to Percent.
6.2 Source Dis correction:
Min A = A e
.693 t g
tS WHERE: A = disintegration rate corrected to current date Ao = original activity (disintegration rate) obtained frcm source certificate.
e = base of natural log t = elapsed time (days) since original certification date.
t = Isotopic half life (same units as t)
NOTE:
If Ao (original activity) is given in pC; convert to Dis / Min by multiplying the pC value by 2.22E6.
6.3 Examples 6.3.1 Efficiency Calculation Source counts / min. = 7781 Source dis./ min. = 3.37E4 Efficiency % = cou.nts/ min.
x 100 dTs./ min
=7 x 100 = 23.1 3 7E4 6.3.2 Source Decay Correction Calculation
}
A = Ace
.693t
.h t
3-190 269
~
a 09-19-75 1704 Revision 1 A = Present Source Activity, Dis./ Min.
Ao = Source.'ctivity at Certificate Date
= 3.37E4 dis./ min.
Certificate Date = 3/7/67 Present Date = 1/1/74 t = time ' rom certificate date to present date
= 2.48E3 days th = Source half life
= 22 years x 3.6425E2 tays/ year
= 8.01E3 days A = (3.37E4) e - (.693)(2.48E3)
(8.01E3)
= 2.72E4 dis./ min.
4.0
'~
1?0 270
__