ML19224B210
| ML19224B210 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 06/25/1976 |
| From: | Metropolitan Edison Co |
| To: | Mullinix W NRC/IE |
| References | |
| 1714, TM-0121, TM-121, NUDOCS 7906140220 | |
| Download: ML19224B210 (4) | |
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METROPOLITAN EDISON CCMPANY.
Wilda R. Mullinix, IEC 79061402Ro e
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1HREE MILE ISLAND NUCLE AR ST ATION F:
CON, TROL t STATION HEALTH PHYSICS PROCEDURE 1714 PLATEAU DETERMINATION FOR LUDIUM 2000 Table of Ef fective Pages Pace Date R ev isio n Pace Date R evision Paoe Date R evision 1.0 09/17/75 1
26.0 51.0 2.0 06/25/76 2
27.0 52.0 3.0 C6/25/76 2
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1714 Revision I kO THREE MILE ISLAND NUCLEAR STATION HEALTH PHYSICS PROCEDURE 1714 Plateau Cetermination for Ludlum 2000 1.0 PURPOSE The purpose of this procedure is to list the steps taken to determine the operating voltage plateau for the Ludlum 2000.
2.0 DISCUSSION 2.1 A plateau is the flat portion of the count rate vs. voltage curve where changes in operatina voltage introduce minimum changes in counting rate.
2.2 The Ludlum 2000 scaler is a portable counting instrument which operates on 110 volts A.C. Line or in integral D.C. battery power supply.
2.3 This instrument with the use of various detectors may be used for alpha or beta-gamma counting.
A voltage plateau must be determined with each detector used.
3.0 REFERENCES
3.1 Ludlum Model 2000 Instruction Manual 4.0 ECUIPMENT 4.1 Ludlum 2000 Instrument 137 4.2 Cs Beta-gamma source or equivalent 230 4.3 Th alpha source or equivalent 4.4 Semilog graph paper 4.5 Detectors t
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1714 Revision 2
'A 06/25/76 4.5.1 Alpha scintillation detector Model 432 or equivalent.
4.5.2 EIC Model HP210 G.M. detector or equivalent.
4.5.3 End Window pig mounted G.M. detector or equivalent.
5.0 CPEPATING INSTRUCTIONS NOTE:
Line voltage should be used whenever availaale since the internal batteries are not rechargeable.
5.1 Beta-Gamma Plateau Determination 5.1.1 Place the selector switch in SAT or LINE if line vcitage is available.
If battery pcwer is used, depress BAT and check " Bat OK" indication.
If battery replacement is required, refer to Instruction Manual.
5.1.2 Insure the desired probe is attached to the PROBE connection.
5.1.3 Set the toggle switch to 1.
5.l.4 Set the minutes selector to 01.
5.1.5 Insert the Beta-Gamma source in the sample holder, activity side up, in the geometry to be used.
L.l.6 Depress the Count button on the counter, this resets the counter to zero (0) and initiates the count.
5.1.7 Beginning at 0 Volts, slowly increase the power supply voltage until a count rate is observed on the scaler.
5.1.8 When counts are observed, round off the high voltage setting to the nearest 20 units as indicated on the HV pot and record as the starting voltage.
_e 5.1.9 Prepare a sheet of semi-log graph paper labeling the X (horizontal) axis with voltage, and the Y (vertical) axis in counts per minute. A previously obtained Plateau Curve may be used for reference as necessary.
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n6/25/76 6.i.10 Record the name, date, scurce used, and operating voltage setpoint determined on the semi-log granh paper and place in the Plateau Curve Book.
5.1.11 Repeat 1.0 minute counts at starting voltage setpoint determined in Step 5.1.8 and at 20 unit increments until a good plateau curve, or a maximum of 1000 volts is obtained.
5.1.12 Record and plot on the plateau curve each voltage and its corresponding counts per minute.
5.2 Aloha Plateau Determination 5.2.1 Ensure the Alpha scintillation probe is attached to the PROBE connection.
5.2.2 Place the alpha source in the sample holder, activity side up, in the geometry to be used.
5.2.3 Repeat Steps 5.1.1 through 5.1.12, excluding step 5.1.5.
6.0 CPERATING VOLTAGE SECTION 6.1 Select from the curve the approximate beginning and ending point of the plateau.
6.2 Take one-third of the difference between the beginning and ending voltages of Step 6.1 and add to the beginning voltage.
Round off this figure to the nearest 50 volts.
Use this value as the operating voltage setpoint ur.til another plateau determination indicates a different voltage is best for optimum operation.
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