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Ludlum Measurements 334A Operation Manual

Alpha air monitor
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LUDLUM MODEL 334A
ALPHA AIR MONITOR
January 2021

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  • Page 1 LUDLUM MODEL 334A ALPHA AIR MONITOR January 2021...
  • Page 3 Model 334A Operations Manual...
  • Page 4 Ludlum Measurements, Inc. 501 Oak Street, Sweetwater, Texas 79556 Trademarks Ludlum, the Ludlum logo, and Model 334A are trademarks of Ludlum Measurements, Inc. Microsoft, Windows CE, ActiveSync, Excel and the Windows logo are registered trademarks of Microsoft Corporation.
  • Page 6 RETURN OF GOODS TO MANUFACTURER If equipment needs to be returned to Ludlum Measurements, Inc. for repair or calibration, please send to the address below. All shipments should include documentation containing return shipping address, customer name, telephone number, description of service requested, and all other necessary information.

  • Page 8: Table Of Contents

    Table of Contents GETTING STARTED ...................... 1 ....................1 ENERAL ESCRIPTION ................... 1 NPACKING AND EPACKING 334A ..................... 2 ARTS OF THE ODEL ................3 NDERSTANDING THE ETECTOR ..................... 4 URNING THE Charging the Batteries....................4 Power Button Functions ....................4 ....................
  • Page 9 .................... 31 ESPONSE HECK OUTINE Source Requirements ....................31 Running the Response Check ..................32 ................33 ORMAL EASUREMENT PERATION Minimum-Detectable Levels & Window Times ............33 Display: Meter/Spectrum/Log ..................33 Operational Duration ....................34 MEASUREMENT CALCULATIONS ................. 35 & C .................

  • Page 10: Getting Started

    Getting Started General Description The Model 334A is a portable alpha air monitor designed to function both as a workplace monitor and a Continuous Air Monitor (CAM) for measurements. Spectral analysis is conducted via a 1024-channel analyzer that feeds data to the embedded processor. Factory configuration provides either special nuclear materials (SNM) or radon progeny measurements of potential alpha energy concentration (PAEC).

  • Page 11: Parts Of The Model 334A

    In addition to the Model 334A itself, the package it comes in contains an AC Adapter for charging the Model 334A, a USB sync cable for exchanging data with a PC, a flow calibration aid, and a CD with software, certificates and training videos.

  • Page 12: Understanding The Detector Head

    Model 334A Operations Manual Understanding the Detector Head The Model 334A has an integrated head that houses the detector. Also, an In-Line Sample Head on an umbilical is available as an option. The detector head has several components that function together to be able to accurately detect the decay of radioactive particulates.

  • Page 13: Turning The Unit On

    Also the Model 334A application will be stored on a non-volatile SD card and will be restored once power is returned to the unit. So after the battery is fully discharged, all that is needed is to reconnect the unit to AC power and allow the battery to charge again.

  • Page 14: Starting The Program

    Understanding the Display The basic display for the Model 334A includes a Menu bar across the top, a Meter in the upper half of the screen and a Log entry in the lower half that toggles to view the current Spectrum.

  • Page 15: How To Change The Filter

    Channel has its own set of four units, while the Flow channel only has one unit, LPM. How to Change the Filter After a Model 334A has been monitoring for some time, the filter will become laden with dust and need to be replaced. Do this regularly; either by a specific schedule or when the flow rate declines and indicates Lo Flow (see section 3 on configurations).

  • Page 16: Password Security

    Always reset the instrument after a filter change. Password Security The Model 334A supports password security to prevent unauthorized users from changing the instrument configuration or calibration. By default, password security is turned off and all menus and functions are accessible.

  • Page 17: Setting The Clock

    Setting the Clock The Model 334A is configured with a real-time clock which can be manually set or set automatically when connected via the USB port to a PC. The unit is factory calibrated to the correct customer time-zone before shipment. Whenever the battery and external power are disconnected from the main processor board during maintenance or repair, the clock will be reset to a default date.

  • Page 18: Calibration

    If the radon peaks appear too far from the expected locations, the peak-fitting algorithm will fail (POOR FIT status) and the unit will fail to alarm properly. Flow calibration is important, as it determines if the Model 334A is converting the pump current into the measured flow rate correctly.

  • Page 19: Calibration Overview

    Calibration Expiration The Model 334A program keeps track of the last time the alpha energy calibration was performed and will indicate that the unit is out of service if one of two conditions is met: ...

  • Page 20: Set Source Parameters

    Several vertical red lines are scattered along the alpha spectrum. The number of lines depends on the operating configuration of the Model 334A. These lines indicate the position of the alpha peaks, and can be adjusted by dragging to match up with the peak location.
  • Page 21 Model 334A Operations Manual There are either zero, one or two alpha isotopes-of-interest, plus the Po-218, Po-214 and Po-212 radon-progeny peaks. In radon mode, a peak marker for Po-210 will also appear. The lower reference line(s) on the spectrum coincide with the isotope(s)-of-interest.

  • Page 22: Performing The Calibration

    Alpha Energy Calibration window open on the screen before leaving the Model 334A to collect the radon spectrum. Leave the Model 334A operating in a high radon area for 8-12 hours so that a well-defined radon spectrum can be accumulated.
  • Page 23 Model 334A Operations Manual NOTE: After a few hours, if the 3 peaks are not all visible, the Offset needs to be increased by 8, 16, or 24 channels to shift the peaks further left. Click Reset Spectrum and run the unit again for several hours to accumulate another spectrum.

  • Page 24: Alpha Efficiency Calibration

    This efficiency is used to produce accurate exposure and concentrations in units of measure meaningful to the user (e.g. DAC-h and mWL). It also makes sure that the Model 334A is counting at an acceptable rate. To begin the Alpha Efficiency Calibration, select Calibrate—Advanced—Alpha Efficiency…...

  • Page 25: Automatic Alpha Calibration

    Model 334A Operations Manual After the calibration has completed, it will report the efficiency. Typical 4pi efficiency is 20- 30% for Am-241. If the efficiency falls outside these parameters, either Repeat Calibration or call a Ludlum Technician for assistance. If the efficiency is acceptable, remove the source from the detector, place the filter back, and close up the detector head.

  • Page 26: Response Check

    Model 334A Operations Manual In the Calibrate Energy step, the peak fitting process occurs. This is where the red lines that correspond to the isotopes’ energy levels (peak channels) line up with the peaks displayed by the spectrum. The peak should appear with the calibration source still inserted in the detector head.

  • Page 27: Flow Calibration

    Model 334A Operations Manual Flow Calibration The Model 334A sample flow rate is estimated by monitoring the pump’s electrical current. Flow calibration is necessary to insure that the Model 334A program is correctly monitoring and converting the pump current into a flow. This relationship is not linear. As a result, a three-point flow calibration is used, with validation at a fourth flow rate.

  • Page 28: Performing The Calibration

    Model 334A Operations Manual Performing the Calibration To begin, make sure the pump is ON (Monitor–Pump–On… in the menu). Then, open up the flow calibration dialogue under Calibrate–Flow… The flow calibration is a three-point calibration, meaning it takes measurements at three different flow rates (low, medium, and wide open), and the program then uses those measurements to create an equation for a curve.
  • Page 29 Model 334A Operations Manual In the third step, adjust the flow restriction device until it is completely open, providing maximum flow. Again, input the LPM indicated on the flowmeter into the Measured Flow box on the screen. Continue with the same process as before.

  • Page 30: Configuration

    This dialog controls the operation of the of the user interface aspects of the program. Tap the File – Properties… menu item to access the Instrument Properties dialog. Voice Update Frequency Voice output is not implemented in the Model 334A, so the settings are disabled. Ludlum Measurements, Inc January 2021...

  • Page 31: Instrument Options

    Alarm Ack button on the face of the Model 334A. When paired with the Use Password Security option, the user must have at least a config-level password in order to acknowledge and silence the alarm.

  • Page 32: General Tab

    Calibration Expiration Settings Calibration expires—This non-editable item displays the latest date on which the Model 334A calibration will expire. The expiration could occur sooner if the maximum runtime hours are exceeded. Calibrations are valid for XXX days—This field sets the maximum number of days between calibrations.

  • Page 33: Logging Tab

    SD Card—this setting causes log data to be saved to the non-volatile SD memory card in the Model 334A. Note: data saved to the SD Card is accessible from an attached PC/laptop, but data is not automatically synchronized with the PC as are files in the My Documents folder.

  • Page 34: Isotope Tabs

    Model 334A Operations Manual Isotope Tabs The Iso 1 and 2 tabs define the parameters concerning the primary and secondary isotope- of-interest measurements. By default, the first isotope of interest is Pu-239, however, this isotope may be changed to support the measurement of other alpha-emitting isotopes.
  • Page 35 Model 334A Operations Manual Alarm Settings…—This button calls up the alarm settings dialog to configure the alarm limits for the isotope-of-interest. See the dialog description under Alarm Settings below. Iso 2 Tab This page defines the parameters concerning the second isotope-of-interest measurements.

  • Page 36: Alarm Settings

    Model 334A Operations Manual Alarm Settings This dialog allows configuration of the acute and chronic alarm set points for dose and concentration alarms. Separate Alarm Settings dialogs are applied for each Isotope. Chronic Alarms Chronic Dose—This setting determines the alarm set point for a chronic dose alarm.

  • Page 37: Flow Tab

    It also offers a Fixed Flow setting for externally plumbed units. Low Limit—This setting defines the limit in liters per minute below which the Model 334A will indicate a LO FLOW status. A low flow status can indicate a loaded or wet filter. Default is 6.0 LPM High Limit—This setting defines the limit in liters per minute above which the Model...

  • Page 38: Radnet Tab (With Wifi Option)

    RadNet Tab (with WiFi option) This page contains the settings for RadNet Protocol broadcasts for Model 334A units with the WiFi Option installed. This page will only appear for wireless-enabled instruments. Use WAN IP Address—When checked, a specific WAN IP address can be entered.

  • Page 39: Ascii Tab (With Rs-232 Or Wifi Option)

    This page contains the settings for ASCII Communications Protocol broadcasts for Model 334A units with either the RS-232 Option or the WiFi Option installed. The RS-232 option offers a DB-9 or RJ-9 connector on the side panel, while the WiFi option provides an internal antenna or broadcasting.

  • Page 40: Starting A Dose Measurement

    Starting a Dose Measurement Response Check Routine Before starting a dose measurement, the Model 334A should be tested using the Response Check routine to make sure that it is operating properly and in calibration. The purpose of the Response Check is to verify the following: ...

  • Page 41: Running The Response Check

    Model 334A Operations Manual Running the Response Check After starting the Model 334A program, the Response Check dialog is automatically initiated. It may also be initiated from the menu by tapping Monitor – Response Check…. There are four edit fields in the upper portion of the screen: Source—This list box displays the applicable sources that can be used for the response...

  • Page 42: Normal Measurement Operation

    The minimum-detectable levels of concentration and dose will be elevated until the Acute and Chronic Window times have elapsed, defaulted to 120sec and 240min respectively. Until the full window times have elapsed, the Model 334A is using incomplete spectrum accumulations to calculate the dose and concentration and has elevated statistical fluctuations of the results.

  • Page 43: Operational Duration

    Return to the log entry view by tapping View—Log. In the event that a dose or concentration reading exceeds alarm limits, the Model 334A will alarm visually and audibly, automatically display the channel of the chronic or acute reading that caused the alarm, and the status will be changed to High Alarm.

  • Page 44: Measurement Calculations

    Model 334A Operations Manual SECTION Measurement Calculations Acute & Chronic Moving-Windows In order to calculate a concentration, the counts for each counting channel are saved—along with the flow rate and volume—in a history array, so that the increase in counts over time can be used to determine the net count rate.
  • Page 45 Model 334A Operations Manual known, the calibration constant and flow volume are used to derive the concentration in the specified measurement units. An additional term is included in the concentration calculation to account for the expected count rate losses due to activity that has decayed off during the last interval. For longer half- lived isotopes the term Net λ...

  • Page 46: Minimum Detectable Measurement Calculations

    In the Model 334A, the minimum detectible concentration (MDC) is not directly related to the spectrum counts, but to the uncertainty in the peak fit.
  • Page 47 Model 334A Operations Manual Uncertainties in Flow Rate The measurement of the flow rate and volume has a statistical variance that contributes to the MDC and MDD. This statistical variance is calculated by the program and applied in the MDC and MDD calculations.

  • Page 48: Radon Mode Considerations

    Bi-212 before the ultimate energy yield of 13.69 MeV of Po-218 are summed. While its contribution is not included in the PAEC result, the Model 334A does monitor for and report the concentration and dose estimate from Po-210.

  • Page 49: Retrieving & Analyzing The Data

    SECTION Retrieving & Analyzing the Data The log files stored on the Model 334A may be retrieved and analyzed on a PC, laptop or workstation. The data can be imported into a spreadsheet or database and saved for future use.

  • Page 50: Connecting To Apc

    To connect to your Model 334A, plug the USB sync cable from the computer to the mini- USB connection on the side of the unit. If the unit is turned on, the Model 334A should automatically connect with the computer.

  • Page 51: Syncing Log Files

    PC in the My Documents folder or desktop with a name corresponding to the Model 334A name (e.g. M334A_303 My Documents) and includes all the Model 334A log files. Files will continue to sync each time the unit is plugged in to the PC.

  • Page 52: Graphing Data In Excel - Manually

    Microsoft Excel. Once the Model 334A log data has been retrieved, you may disconnect the USB cable from the computer to the unit. Disconnecting the USB cable will not affect the operation of the unit nor the files copied or synced.

  • Page 53: Spectrum Chart

    Model 334A Operations Manual Spectrum Chart Open the Excel document labeled Data Charting Template. You should see a chart of the spectrum, showing mostly the Radon daughter counts in three peaks on the right side. This first chart in the template is called the Spectrum Animate Chart which displays the spectrum data over time in a moving graph.

  • Page 54: Chronic & Acute Charts

    Model 334A Operations Manual Chronic & Acute Charts The subsequent tabs are charts for the Acute and Chronic windows for both Alpha data. You can follow the same instructions as above to refresh the template with new data from your unit.

  • Page 55: Radnet Operation

    Ludlum, using the default UDP Port 16367. A wireless access point (WAP) is required to receive the transmissions from the Model 334A and relay those transmissions either via an Ethernet cable or via a second wireless link to the RadNet Client workstation.
  • Page 56 RadNet Client Workstation Configuration In order to communicate with the Model 334A and wireless access point, the client workstation must be configured with a compatible IP Address in the 192.168.0.xxx Class-C range. Choose an address that does not conflict with the addresses of the Model 334As or the wireless access point.

  • Page 57: Ascii Operation

    Configuration of RS-232 Connections The serial RS-232 port on the Model 334A is a 2-wire output-only serial connection using an RJ-9 connector (TXD, GND signals). Terminal emulators should be configured for 19,200 baud, 8 data bits, no parity, and 1 stop bit (19,200 bps, 8, N, 1).
  • Page 58 Model 334A Operations Manual Standard Log Data Format The log data is reported in comma-delimited format. Each channel is transmitted in a string of data, with multiple strings each minute depending on the unit configuration. The text fields are terminated with a <cr><lf> sequence. Below is an example of 1 minute of strings.

  • Page 59: Status Conditions

    Model 334A Operations Manual Appendix Status Conditions Status Description Initializing Model 334A program initialization (momentary) Normal Operating normally, alarm levels below limit High Alarm Dose or Concentration set point has been exceeded Low Flow Flow rate is below Low Limit...

  • Page 60: Specifications

    Model 334A Operations Manual Appendix Specifications Sampling Head and Flow  37 mm Filter holder, masking to 25 mm  Detector: Solid-state silicon 300-µm-depleted (450 mm² active area)  Pump: diaphragm-type, 7.0 LPM with no load Alpha Data Analysis  MCA: 1024-channel analyzer binned to 256 channel spectrum ...

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