ML19224B208
| ML19224B208 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 02/25/1977 |
| From: | Metropolitan Edison Co |
| To: | Mullinix W NRC/IE |
| References | |
| 1713, TM-0120, TM-120, NUDOCS 7906140217 | |
| Download: ML19224B208 (5) | |
Text
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TMI DOCUMENTS DOCUME!rr NG:
COPY MADE CN
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0F DOCUw_NT PROVIDED BY METROPOLITAN EDISON COMPANY.
Wilda R. Mullinix, IRC 79061402Il
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1713
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02/25/77 THREE t.t!LE ISLATJD NUCLE AR STATIOf4 STATICH HEALTH PHYSICS PROCEDURE 1713 EFFICIENCY DETERMIriATI0tl FOR LUDIUt1 2000 Tabie of Effective Pages Pcge Date Revision Pace Date R evision Page Date Revitior 27.0 CONTpm i cD COPY si o 1.0 02/25/77 2
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a 52.0 3.0 09/19/75 1
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1713 Revision 2
02/25/77 THREE MILE ISLAND NUCLEAR STATION STATION HEALTH PHYSICS PROCEDURES 1713 - Efficiency Determination for Ludlum 2000 1.0 PURPOSE The purpose of this procedure is to list the steps take7 to determine counting efficiencies of various detectors used with the Ludlum 2000.
2.0 DISCUSSION Detennination of efficiency is necessary to ascertain the condition of a counting instrument when a change is suspected or on a periodic basis. The counting efficiency determined by this procedure is used in the calculation of radioactivity concentration.
3.0 REFERENCES
3.1 Ludlum Model 2000 Instruction Manual 3.2 H.P.P. 1712 4.0 EQUIPMENT 4.1 Cs Beta-Gamma source or equivalent 230 4.2 Th Alpha source or equivalent 4.3 Graph Paper 4.4 Ludlum 2000 Instrumer.t 4.5 Detectors 4.5.1 Alpha scintillation detector Model 43-2 or equivalent.
4.5.2 Eberline Instrument Ct aration (EIC) Model HP-210 G.M. detector or equivalent.
4.5.3 End Window G.M. Pig unted detector.
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192 312 7
J1713 09-19-75 Revision 1 5.0 OPERATING INSTRUCTIONS NOTE:
Line voltage should be used when available since the internal batteries are not rechargable.
5.1 Install the desircd Alpha or Beta-Gamma detector in its appropriate sample holder to obtain reproducible counting geometry.
o.2 Attach the probe lead to the PROBE connection on the scaler.
5.3 Fiace the selector switch in BAT, or LINE if line voltage is available.
If BAT position is selected, depress BAT button and check " BAT OK" indication.
If battery replacement is required, refer to Instruction Manual.
5.4 Depress the H.V. button and note the detector voltage.
Adjust the voltage as required to agree with the previously determined setpoint.
This voltage setpoint should be obtained from the Plateau Curve Book.
5.5 Set Minutes selector to.01.
5.6 Set Multiplier selector to X100.
137 O
5.7 Place Cs or Th in sample holder in geometry to be used under detector (source side facing detector).
5.8 Depress the RESET button on the Counter.
5.9 Depress the START button on the Timer.
The interval indicator light should light, and remain lit for the duration of the count time.
5.10 dead and record the total counts disp. 7yed at the completion of counting (indicated by interval light out) in the Background and h
Efficiency Log Book.
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2.0 ;
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192-313
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1713 09-19-75 Revision 1 5.11 Calculate the Counting Efficiency using the formula of Section
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6.0.
5.12 Plot and record the efficiency determined on the Effeciency Curve located in the Background and Efficiency Log Book.
5.13 Insure that the current efficiency is within the I 2c operating range.
If not, contact the Radiation Protec+. ion Foreman.
5.14 Return the source to the source storage area.
(The scaler and its Power Supnly are normally left energized.)
6.0 CALCULATI0 tis Counts 6.1 Efficiency (%) = Source Min.
X 100 Source Dis.
fii n.
Counts Where:
Source
= Total counts obtained in Step 5.10 divided by the Counting Time (1 minute).
D s; = Disintegration rate of the sources (may be Source g n modified by Step 6.2) 100 = Conversion Constant, Cecimal to Percent Source,D ;
correction:
6.2 A = Ao e
.693t tk2 Where:
A = disintegration rate corrected to current date Ao = original activity (disintegration rate) obtained from source certificate e = base of natural log h
i
= elapsed time (days) since original certificate date t
tk =
isotopic half life (same units as t) 2 fl0TE:
If Ao (original activity) is given in uci convert to Dis./ Min. by multiplying the pci value by 2.]2g 3
4 3.0 3
, 1713 09-19-/5 Revision 1
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6.J EXAMPLE-
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6.3.1 Efficiency Calculation Source Counts / Min. = 8578 Source Dis./ Min. = 3.37E4 Efficiency " = D
/ti n. ' X 100 X 100 = 25.5 3 E4 6.3.2 Source Decay Correction Calculation 6 t A = Ao e-4 A = Present Source Activity, Dis./ Min.
Ao = Source Activity of Certificate Date
= 3.37E4 Dis./ Min.
Certificate Date = 3/7/67 Present Date = 1/1/74 t = Time from Cer+.ficate Date to Present Cate
= 2.48E3 Days t13= Source Half Life
= 22 years x 3.64.15E2 Days / Year
= 8.01E3 Days
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A = (3.37E4) e ~
8.01E3
= 2.72E4 Dis./ Min.
2 e-192 315 4.0 m
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