ML19224B184
| ML19224B184 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 02/25/1977 |
| From: | Metropolitan Edison Co |
| To: | Mullinix W NRC/IE |
| References | |
| 1705, TM-0112, TM-112, NUDOCS 7906140179 | |
| Download: ML19224B184 (6) | |
Text
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TMI DOCUMENTS DOCUMENT NO:
!h,!7 OF DOCUMENT PROVIDED BY COPY MADE ON METROPOLITAN EDISON COMPANY.
Wilda R. Mullinix, IRC 7906140171 e
191 032
L.
r 1705 S
Revision 2
02/25/77 THREE MILE ISLAND NUCLEAR STATION STATION HEALTH PHYSICS PROCEDURE 1705
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EFFICIENCY DETERMINATION FOR PCC-llT 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
{Q[,
53.0 3.0 09/19/75 1
28.0 Q((
4.0 09/19/75 1
29.0 54.0 5.0 09/19/75 1
30.0 ON/
55.0 C,.li 6.0 31.0 56.0 hh k D 7.0 32.0 EMOWC57.0 8.0 33.0 58.0 9.0 34 59.0 10.0
- 35. ~
60.0 11.0 36.0 61.0 12.0 37.0 62.0 13.0
'18.0 63.0 14.0 39.0 64.0 15.0 40.0 65.0 16.0 41.0 66.0 17.0 4?.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 Approval 3.I Date 2 /t4/T7 Approval
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J.E Date 2 /t 9 [77 Approval o
Cognizant Dept. Head Cognizant Dept. He.d Unit 1 PORC Re mmerdis spproval Unit 2 PORC f tommendi Approval 1
Date I
Date Chair % o POfl Chairrran fP0RC I
PORC comment < of I I -
included PORC commen so included
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' (late) l(da )
I 1 013 By Date Av Approval D dea [
Date d -M-7 7 Approval Date. _
Approval r/[b Dateb*YN Mgr.. O peration:1
( StfpYrTntendents Quality Anurance
8 3
1705 Revision 2 G?/25/77 THREE MILE ISLAND NUCLEAR STAT'un STATION HEALTH PHYSICS PROCEDURE l'.)5 Efficiency Determination For NMC Proportional Counter Model PCC-llT 1.0 PURPOSE The purpose of this procedure is to list the steps taken to determine the counting efficiency of the PCC-llT Proportional Counter.
2.0 DISCUSSION Determination of counting efficiency is necessary to check the condition of a counting instrument on a monthly basis. The eliability of the detector or the consistency of the degree of efficiency may change for various reasons. The efficiency obtained is used in the determination of radioactivity in a sample.
(TEXT CONT'D ON NEXT PAGE) 4 4
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191 034 1.0
N05-09-]9 75 7
Revision 1 3.0 REFEREt1CES 3.1 PCC-llT Manual 3.2 ORTEC MAtiUAL for the following instruments:
- 1) Model 456-High Voltage Supply
- 2) !!adel 451-Amplifier
- 3) Model 719-Timer
- 4) Model 770-Counter 4.0 EOUIPMEtiT 4.1 PCC-llT Proportional Counter 4.2 456 High Voltage Supply 4.3 451 Spectroscopy Amplifier 4.4 719 Timer 4.5 770 Counter 4.6 Beta and Gamma Calibration Svurces 5.0 OPERATIt1G ItlSTRUCTI0tlS 110TE: Fully open the gas supply valve located on the wall behind the instrument. Check for flow in the bubbler window.
If none is apparent, the gas cylinder may require replacement. This instrument is used for Alpha and Beta Counting, therefore an officiency for each Plateau must be determined.
5.1 Beta Efficiency 5.1.1 Turn ORTEC Cabinet Power Supply ON.
E,1.2 Tu n on High Voltage Power Supply.
5.1.3 Insure Spectroscopy Amplifier fine gain is at 5.80 and course gain is set at 5.
191.035
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2.0
I705 09-19-75 Revision 1 5.1.4 Insure that discriminator on 770 Counter is set at 2.
5.1.5 Insure Power Supply High Voltage is set at posted value for Beta count.
5.1.6 Turn detector toggle switch to ON.
Set timer to two (2) minute count as follows:
5.1.7 Insure Preset is set to two (2).
Insure Multiplier is set to 100.
Ins e Time base is set to 0.01 min.
5.1. 8 Depress RESET button on counter.
5.1.9 Turn drawer latch to left and pull out.
Insert Beta Source in the Planchet holder with activity side up, in the appropriate counting geometry.
Close and latch the drawer.
Push PURGE button.
Purge light will light.
5.1.10 After purge light goes off, depress Start button on timer. The interval light should light. Completion of counting is indicated by the interval light going out.
5.1.11 Record the total counts in the Background and Efficiency log book.
6.1.12 Calculate efficiency as per Section six (6).
5.1.13 Recora efficiency in the Background and Efficiency log book.
5.1.14 Plot the efficiency determined on the efficiency curve located in the Background and Efficiency log book.
5.1.15 Check that current officiency is within the + 2 sigma operating range.
If not, contact the Radiation Protection Foreman.
5.1.16 Return source to the source cabinet.
The Scaler and its Power Supply are normally left energized.
19.1.036 3.0
'1705' 09-19-75 Revision 1 5.2 Alpha Efficiency 5.2.1 Repeat steps 5.1 through 5.1.16 using the Alpha Source instead of the Beta Source. Note that in Step 5.1.5 the High Voltage adjustment will be changed to agree with the required value (on front of instrument) for Alpha Counting.
6.0 CALCULATIONS
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6.1 Efficiency (%) =
Source Counts Min.
i Source Dis X 100 Min.
Where: Source Counts = Total Counts obtained in Step 5.1.11 divided Min.
by Counting time of Step 5.1.7.
Source Dis Disintegration rate of source (may be modified Mis.
by Step 6.2) 6.2 Source Dis correction Min.
s A = A e.693t c
I WHERE:
A = disintegrations rate corrected to current date.
A = original activity (disintegration rate) caained from Source g
Certificate.
e = base of natural log t = elapsed time (days) since original Certificate date.
T = isotopic half life (same t, nits as t) 4 191 037 4.0
5705-09-19-75
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Revision 1
,tt0TE:
If A is 9.ven in Mc1, to convert to Dis./ Min., multiply the o
J(ci value. '
2EE6.
6.3 Examples 6.3.1 Efficiency Calculation Eificiency % = Counts / Min.
X 100 Dis./ Min.
Sourca Counts / Min. = 8191 Source Dis./ Min.
= 2.72E4 8191
= 30.1 2.72E4 6.3.2 Source Decay Correction Calculation A = Ac
.693t e
tis A = Present Source Activity, Dis./ Min.
Ao = Source Activity at Certificate Date
= 3.37E4 Dis./ Min.
Certificate Date = 3/7/67 Present Date = 1/1/74 t = Time from Certificate Date to Present Date
= 2.48 E3 Days th = Source Half Life
= 22 years x 3.6425E2 Days / Year
= 8.01E3 Days A = (3.37E4)e- (.693)(2.48E3)
(8.01E3)
= 2.72E4 Dis./ Min.
5 191 038 5.0