manual

PYLON MODEL

6000

RADON CHECK SOURCE MANUAL

MANUAL NUMBER: 7940007

Revision 1 Draft 5

Copyright 2011 Pylon Electronics Inc. (ALL RIGHTS RESERVED)

Registered Trademark Canada and U.S.A.

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Manual Number: 7940007 Rev 1 Draft 5

WARNING This Pylon product contains radioactive material. Although the amount of radioactive material is small, care should be exercised. The following guidelines should be adhered to at all times: 1) Most countries have regulations covering the ownership of radioactive sources. Please refer

to the local authorities for more information. 2) Only knowledgeable users should handle these sources. 3) Observe the operating instructions listed in this manual. 4) Observe the maintenance instructions listed in this manual. 5) Observe the packing and shipping instructions listed in this manual. 6) Observe the health and safety instructions listed in this manual.

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CAUTION 1) DO NOT attempt to thread the Model 6000 Radon Check Source onto older Pylon products

such as the AB-5, AB-5R, and AB-4. The threads are incompatible. Forcing the Model 6000 Radon Check Source onto any of these older products will damage the source and PMT assembly threads.

2) Do not force the Model 6000 Radon Check Source onto the AB6A PMT assembly since this

may damage the check source and / or PMT assembly threads. A small amount of lubricating grease may be applied to the threads to assist with installation. This may be renewed when necessary.

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IMPORTANT 1) Read this instruction manual thoroughly before using the product. Be especially certain

to read the section on health and safety. 2) Be familiar with, and consult, the instruction manual(s) that came with the equipment

with which the product is to be used. 3) Many of the terms and abbreviations used in this manual are described in Pylon manual

number 7940018 - Glossary of Selected Pylon Terms. 4) The following symbols may be used throughout this manual:

WARNING The Warning symbol is use to identify notes that are used to warn of potential hazards that could cause injury or death to personnel as well as damage to the equipment.

CAUTION The Caution symbol is use to identify notes that are used to warn of potential hazards that could damage the equipment.

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WARRANTY PYLON ELECTRONICS INC. products are warranted against defects in material and workmanship for a period of one year from the date of shipment. Our warranty obligation is limited to the repair of products or parts thereof which, on our examination, prove to be defective during the warranty period. The warranty shall not apply to any equipment which has been subject to accident, incorrect wiring not of our own, or operation not in accordance with manufacturer's written instructions. PYLON ELECTRONICS INC. repairs are warranted against defects in material and workmanship for a period of 90 days from the date of shipment. Our warranty obligation is limited to the repair of the unit returned prepaid, to our factory and which, on our examination, prove to be defective during the warranty period. Equipment which has work performed under Warranty will be returned to the user or Distributor freight prepaid. The warranty shall not apply to any equipment which has been subject to accident, incorrect wiring not of our own, or operation not in accordance with manufacturer's written instructions. This warranty is given by PYLON in lieu of all other warranties arising in law or otherwise in respect of the goods, and this Company shall not be liable under any circumstances for consequential damage. Note: All product(s) must be returned prepaid, to our factory. All warranty claims shall be addressed to: Pylon Electronics Inc. 147 Colonnade Road, Ottawa, ON K2E 7L9 CANADA Phone: (613) 226-7920 Fax: (613) 226-8195 Email: [email protected]

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DISCLAIMER Pylon Electronics Inc. has attempted to ensure that this manual is complete and accurate. However, Pylon will not be held responsible for any errors and omissions in this manual including consequential damage due to the information contained herein. Please forward all comments and suggestions for improvements on the product or this manual to: Pylon Electronics Inc. 147 Colonnade Road, Ottawa, ON K2E 7L9 CANADA Phone: (613) 226-7920 Fax: (613) 226-8195 Email: [email protected] For technical support contact us at the above address. Please visit us on our website at www.pylonelectronics.com. Click on the Products icon.

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TABLE OF CONTENTS WARNING ................................................................................................................................................................... 2CAUTION .................................................................................................................................................................... 3IMPORTANT .............................................................................................................................................................. 4WARRANTY ............................................................................................................................................................... 5DISCLAIMER ............................................................................................................................................................. 61.0 INTRODUCTION ............................................................................................................................................. 8

1.1 PURPOSE ........................................................................................................................................................... 81.2 DESCRIPTION .................................................................................................................................................... 81.3 SPECIFICATIONS ................................................................................................................................................ 91.4 THEORY OF OPERATION .................................................................................................................................... 9

2.0 OPERATION ................................................................................................................................................... 102.1 DETERMINING AN OPERATING POINT ................................................................................................................ 102.2 VERIFYING OPERATING POINT .......................................................................................................................... 112.3 RADIUM D INGROWTH ...................................................................................................................................... 12

3.0 MAINTENANCE & TROUBLESHOOTING .............................................................................................. 143.1 MAINTENANCE ............................................................................................................................................... 143.2 TROUBLESHOOTING ........................................................................................................................................ 15

4.0 PACKING & SHIPPING ................................................................................................................................ 155.0 HEALTH AND SAFETY ................................................................................................................................ 15

5.1 SAFETY FEATURES .......................................................................................................................................... 165.2 PRECAUTIONS ................................................................................................................................................. 165.3 SPILL OR LEAK PROCEDURE ........................................................................................................................... 165.4 DISPOSAL ........................................................................................................................................................ 17

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1.0 INTRODUCTION 1.1 Purpose The Model 6000 check source is primarily used for determining or verifying the operating

point of measurement instruments such as the Pylon Model AB6A monitor. The operating point is the combination of the PMT High Voltage (HV) setting and Discriminator (DISC) setting which optimizes the alpha detection of the monitor versus the rejection of background noise.

1.2 Description The Model 6000 source is similar in shape, size, and construction as the scintillation cells

(such as the Pylon Models 600A, 610A, and 600P active and passive Lucas type detection cells) that are used to measure radon gas with the AB6A monitor. The Model 6000 source is equivalent in size to the Pylon Model 600A Lucas Cell. Since the optimum operating point is dependent on the shape, size, and construction of the detector, the Model 6000 source can be used in place of the scintillation cell detector and another radioactive source when determining the optimum operating point.

The primary difference between the Model 6000 source and the AB6A scintillation cells is

that the source contains a radioactive source and is completely and permanently sealed. The radioactive source material is in the form of dry radium (Ra-226) powder having a nominal activity of 18.5 Bq (0.5 pCi). The source material is located at one end of the Model 6000 inside an aluminum chamber and is contained in the chamber by glass fibre and polyethylene filters. The inside wall of the Model 6000 is coated with a scintillator and the bottom of the Model 6000 has a clear Plexiglas window. This window has a lightproof cap for protecting the Model 6000 from light when it is not in use. No radioactive material leaves the Model 6000.

There are several advantages in using the Model 6000 as the means of determining or

verifying the monitor operating point: i) The user does not need to have a device which generates radon gas for delivery

outside the device. ii) The user does not need to transfer or dilute the radon gas delivered from a generating

device.

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iii) The Model 6000 can be used immediately. No wait time is needed for the radon gas to reach equilibrium.

iv) No compensation is needed for decay before or during counting. 1.3 Specifications The following table lists the nominal specifications for the Model 6000 check source. Alpha Activity 1, 2: 3150 dpm Efficiency: 0.745 0.02 Calibration Accuracy 3: 4% Parent Nuclide: Radium (Ra-226) Source Activity: 18.5 Bq (500 pCi) Scintillator: ZnS (Ag) Operating Temperature: -20 C to +40 C (-4 F to +104 F) Dimensions: Diameter: 6.1 cm (2.4") Length: 15.5 cm (6.1") Weight: 226 g (0.50 lb.) 1 Loaded activity tolerance: -10 to +25% of nominal value. E.g., If 3150 dpm is the specified

nominal activity, the actual loaded activity will be between 2835 dpm and 3937.5 dpm. 2 Other activities are available. Please contact Pylon. 3 Calibration accuracy of the loaded activity. E.g., If the nominal activity is 3150 but the

loaded activity is 3500 dpm, the calibration accuracy is 3500 dpm 140 dpm. 4 All specifications are nominal. 1.4 Theory of Operation The radium in the Model 6000 source decays into radon gas. The radon gas decays,

producing daughter products (progeny) and releasing alpha energy particles. The daughter products further decay and release more alpha particles. Some of the alpha particles strike the scintillator which in turn generates light pulses. The rate of light pulses generated by the scintillator is constant because the rate of generation and decay is at equilibrium (constant).

The light pulses generated by the scintillator can be counted through the window by

measurement equipment such as the AB6A. The AB6A uses a photomultiplier tube (PMT) to detect and convert the light pulses into electronic pulses which are then amplified further.

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These pulses are then amplified further, discriminated to remove background noise, and counted over user-defined time intervals by the AB6A.

The HV setting on the AB6A determines the degree to which the pulses are amplified. The

DISC setting determines the pulse rejection level. The optimal combination of HV and DISC settings will result in the highest percentage of alpha particles being counted with the least amount of background. The optimal combination of HV and DISC dial settings is known as the AB6A operating point. These are programmed into the AB6A.

Because the radium powder in the Model 6000 generates new radon gas at the same rate that

the old radon gas decays, the number of alpha particles being generated per minute in the Model 6000 is statistically constant. The number of alpha pulses being generated per minute has been determined for each Model 6000. The value is printed as the DPM (Disintegrations per Minute) value on the label on the Model 6000.

However, over time there will be an increase in the number of pulses in the Model 6000.

This is due to the ingrowth of Lead-210 (Radium D or RaD). The effect of RaD and how to re-calculate the DPM value is described more fully in Section 2.3.

Counts are made using the Model 6000 source in order to determine or verify the monitor's

operating point. Section 2.1 describes how to determine the operating point and Section 2.2 describes how to verify the operating point.

2.0 OPERATION 2.1 Determining an Operating Point The Model 6000 can be used for determining the radon gas scintillation cell operating point

of measurement instruments such as the Pylon Model AB6A. The operating point is the combination of High Voltage (HV) and Discriminator (DISC) settings that provides the best measurement results.

The operating point of the monitor should be determined a minimum of once per year or

more frequently, depending on use. The detailed procedure for determining the optimal setting of the AB6A DISC and HV

settings using the Model 6000 for Pylon scintillation cells is described in Pylon manual number 7940013 - AB6A Operating Point Determination Instructions. The general procedure is described below.

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General Procedure: The general procedure consists of: 1) Attaching the Model 6000 to the AB6A monitor and allowing time (approximately

30 seconds) for recovery from exposure to light. 2) Taking counts over a range of HV settings for various DISC settings. 3) Plotting the counts in Counts per Minute (CPM) against the HV settings for each

DISC setting. 4) Plotting the Model 6000 activity in CPM based on a 0.745 efficiency for each HV

setting on each DISC setting curve. 5) Selecting the DISC setting curve that meets the following criteria: The best plateau (based on background, slope, and plateau length). The point on the curve at the approximate midpoint of the plateau where the

Model 6000 activity in CPM crosses the curve. 6) Selecting the HV point where the source activity crosses the curve and programming

the HV and DISC settings into the AB6A monitor as the operating point. 7) Verifying the operating point by measuring the Model 6000 activity again with the

programmed operating point set in the AB6A monitor and calculating the efficiency. The efficiency is determined by dividing the average counts in CPM

measured with the AB6A by the Model 6000's activity in dpm. The result should be 0.745 0.02.

8) Performing a system background check and verifying that the system background is

less than 0.4 CPM. 2.2 Verifying Operating Point The Model 6000 can be used for quick verification of the scintillation cell operating point of

the monitor. The operating point of the monitor should be verified periodically to ensure that the measurement equipment's operating point is acceptable.

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The Pylon manual number 7940013 - AB6A Operating Point Determination Instructions describes in detail how to the AB6A DISC and HV settings for scintillation cell used when using the Model 6000. The general procedure is described below.

General Procedure: The general procedure consists of: 1) Attaching the Model 6000 to the AB6A monitor, allowing time for recovery from

exposure to light (approximately 30 seconds), and ensuring that the AB6A monitor is set at the operating point.

2) Making a count and converting it to a CPM value. 3) Converting the CPM value into an efficiency value by dividing it by the Model

6000's activity in DPM. 4) The efficiency value should be 0.745 0.02. If it is not, the operating point may need

to be re-determined or there may be a problem with the measurement equipment. 2.3 Radium D Ingrowth Over time, Po-210 (RaF) will start being produced in the Model 6000. This new daughter

product (progeny) is the result of Pb-210 (RaD) ingrowth. Po-210 (RaF) emits alpha energy particles that will increase the activity of the source.

This increase in activity can be calculated. The first step in the calculation is to determine the

activity of the RaC'. When this isotope decays it produces RaD. Since, 1) There were originally 3 alpha emitters in the source, 2) Only one of the alpha emitters (the RaC') produces RaD, and 3) The 3 alpha emitters are in equilibrium, The activity due to RaC' can be easily calculated as follows: ARaC' = A0 / 3

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Where: ARaC' = Activity of the RaC' isotope in DPM. A0 = Original calibrated activity of the source in DPM. 3 = Number of alpha emitters in the source in equilibrium. Now the increase in activity due to RaD can be calculated, as follows: ARaD = ARaC' * (1 - e-t) Where: ARaD = Activity of the RaD isotope in DPM. ARaC' = Activity of the RaC' isotope in DPM. (Calculated above.) = Decay constant for RaD. = ln(2) / T1/2 = 0.031 year-1 = 0.00259 month-1 = 0.0000851 day-1 T1/2 = Half Life of RaD = 22.3 years = 267.6 months = 8145 days t = Time from the original calibration to the time of calculation

in the appropriate units of measure. The total activity of the source at time t after the original calibration can now be calculated

as follows: At = A0 + ARaD The following provides an example of the above calculations: A0 = 3300 DPM t = 1 year

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Therefore: ARaC' = 3300 / 3 = 1100 ARaD = 1100 * (1 - e-(0.031 * 1)) = 1100 * 0.0306 = 33.66 34 DPM Therefore, the activity of the source at 1 year after the calibration is At = 3300 + 34 = 3334 DPM 3.0 MAINTENANCE & TROUBLESHOOTING 3.1 Maintenance

WARNING THE PRODUCT SHOULD NOT BE USED IF THERE ARE

ANY DISCREPANCIES NOTED DURING INSPECTION OR IF THERE IS A LEAK TEST FAILURE.

The product should be visually inspected for cracks, faults, etc., before being

used. Leak tests should be performed in accordance with the requirements of local

regulations. As a minimum, the following tests should be performed and records maintained:

Wipe tests should be made of the external surface of the source every six

months. Wipe tests should be made of the surrounding equipment every month. The product may be wiped clean of dirt with a dry cloth.

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3.2 Troubleshooting No user troubleshooting can be performed. 4.0 PACKING & SHIPPING The source falls under the dangerous goods regulations due to the radioactive material in

the source. Refer to the Dangerous Goods Regulations for more information and instructions. However, the following provides information and guidelines on some of the requirements.

The source must be packed in accordance with the regulations for Type A

packages. Due to the low activity and emanation rates of the source and if packed in

accordance with the appropriate requirements, the packaged source is considered an excepted package. (Refer to paragraph 6.2.1 of the 34th Edition, 1 Jan 1993 or the equivalent paragraph of more recent editions.)

Following the above instructions also means that the package conforms to the

conditions and limitations specified in 49CFR 173.421 for excepted radioactive material, limited quantity, n.o.s. UN2910.

A Dangerous Goods Declaration must be completed and shipped with the unit. A wipe test of the source must be performed prior to shipment and the results

must be provided with the shipment. Contact your local carrier for specific instructions on packing and shipping the

source. Provide the information indicated above. 5.0 HEALTH AND SAFETY Although of small quantity, the product does contain radioactive material. It is therefore

recommended that the user read this section on health and safety. Section 5.1 briefly describes some of the safety features incorporated into the product.

Section 5.2 lists precautions to be undertaken with the product. Section 5.3 describes what to do in the event of a spill or leak from the product. Section 5.4 provides some information and guidelines for disposal of the product.

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5.1 Safety Features Source material is protected from escape by rugged body and source holder

construction. Rupture is only likely to occur under accident conditions of explosion, fire, or

crushing. In the event of fire, meltdown of source holder and source material will occur

only at temperatures above 100 C (212 F). The product body will melt only at 600 C (1112 F). No radioactive material or gas is delivered outside the product. 5.2 Precautions Do not attempt to open the product. The product should be stored upright in a designated storage area when not in use. Do not subject the product to shock. Avoid temperatures above 50 C (122 F). Use in a well ventilated location. Physical contact with the product should be minimized. Conduct leak tests every six months. Observe appropriate licensing regulations. Allow only trained personnel to operate the product. Do not eat or smoke when using the product. Do not immerse in water or other liquids. Follow the maintenance and operating instructions which are presented in this

manual. 5.3 Spill or Leak Procedure Spillage or leakage is unlikely. However if spillage or leakage should occur: Filter air with respirators and air cleaners. Wear appropriate personal protective equipment such as gloves, etc. when

performing the clean up. Wash down surfaces. Filter washings to remove solids. Enclose solids in a sealed capsule for delivery to a designated authority. Dispose of personnel protective equipment appropriately.

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5.4 Disposal When the product is no longer required: Do not throw the product in the garbage. Check with local authorities for regulations regarding the disposal of radioactive

materials. Do not sell or give this product to anyone who does not meet local regulations or

is not authorized by local authorities to own or use radioactive materials.

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