- UF6 cylinder verification system implemented on the ORTEC Micro-trans-SPEC HPGe Portable Spectrometer with a reinforced structural frame.
- All-in-one instrument with software designed to follow the current procedures for UF6 cylinder inspection by safeguards inspectors.
- High precision, rapid results through combining tried-and-tested methodology with the latest advances in HPGe spectrometry.
- Solves spectral interference problems encountered with NaI-based systems.
- Micro-trans-SPEC hardware can be used for other related applications.
- Operating time of up to 5 hours on a single battery.
- “Snap-open” battery door for rapid battery exchange with minimal down-time.
- New improved silent running, low-power cryocooler.
The ORTEC Micro-trans-SPEC is a field deployable LN2-free HPGe spectrometer. The Micro-trans-SPEC, weighing in at less than 7 kg (excluding additional hardware such as collimators), is small and compact yet rugged enough for field operations.
The instrument features a long life Stirling cycle cryocooler and digital electronics. It can be powered from a variety of sources, including worldwide mains, automobile and other DC sources, which means it is ideal for safeguards inspections where an inspector may arrive at a facility with the instrument in the operational state and ready for use.
The internal battery provides up to 5 hours operational life and is easily replaced minimizing down time. The powerful built-in data processing capabilities make it ideal for onboard custom data analysis, and its bright clear screen makes it a pleasure to use, even in bright outdoor conditions.
The UF6 Cylinder Verification System
For the UF6 cylinder verification application, the Micro-trans-SPEC is supplied with a custom-designed tungsten collimator, and a reinforced structural frame. (The collimator may be removed if not required).
The UF6 software application is based on the classical enrichment meter method and executes on the Micro-trans-SPEC without the need for the inspector to carry an extra computer.
The user interface is similar to the Micro-trans-SPEC basic GUI software and uses identical methods for such tasks as hardware setup and storage of spectra and display. In addition, many of the data entry fields are stored in a configuration file that may be created and edited on a 32-bit Windows 7 or Windows XP computer and subsequently copied to the built-in data processor using Windows Mobile Device Center or Microsoft ActiveSync.
The basic operation of the software is an automated sequential process of the following tasks:
• Acquire spectral data
• Store the data
• Analyze the data
• Report results to file and screen
Program operation is designed so that a minimal amount of information is required to acquire, store, analyze and report a finding.
Uranium enrichment is determined by a variation of the “classic” infinite thickness method. Originally the method was developed for use with NaI(Tl) detectors and suffered from potential spectral interferences. Because an HPGe detector is used, the area of the 186 keV gamma-ray peak can be derived by a method less susceptible to interference from nearby peaks.
The startup screen presents the inspector with a number of choices. The first choice is Verification, which is the most straightforward inspection measurement when all other system parameters are set up.
The verification mode is composed of the following sequential steps:
• Select an Item ID from the Item Database,
• Enter the Inspection Data for the acquisition and analysis,
• Acquire and Analyze data,
• Store results to a spectrum file and create an analysis report.
The Item Database is typically loaded before the start of the measurement program at the facility in question. It is a standard text file that may be edited on the PC using the Notepad application and transferred to the built-in data processor using the Windows Mobile Device Center or Microsoft ActiveSync. It can contain standards which may be used to check correct operation of the system.
The second step of the verification process is the entry of “bookkeeping data”. This minimum set of data is required for each verification measurement. The count preset fields are initialized from default values, that are the last values used for the Verification mode acquisition. The wall thickness is also required and is entered via the keypad.
Real Time Results
Once data acquisition has begun, the screen to the right appears. This screen shows a portion of the spectrum (150 keV to 210 keV) with an ROI marked around the 185.7 keV peak. ROIs are also marked around the low and high background ROIs. During the acquisition, the ROIs, count rate, and enrichment results are periodically updated and displayed.
Both Atom% or Wt% displays are available.
The Calibration mode is similar to the Verification mode, but the calibration constant is set based on expected results from a standard definition. It is composed of the following sequential steps:
• Select an Item ID Standard from the Item Database,
• Enter the Inspection Data for the acquisition and analysis,
• Acquire and calibrate from spectrum,
• Store the calibration constant to the Configuration File.
The Item Database mode permits editing of the contents of the Item Database. This includes modification, addition and deletion of items in the database. The Item Database is a standard text file (UF6.ISL) that is located in the Program Files\UF6 folder. The inspector may choose an existing Item ID for modification or deletion. (Note that the asterisk [*] in the item selection list denotes a “standard” setting that may be used for calibration and validation of correct system operation.)
Inspection Data mode manages the Inspection Data file contents: inspector data, such as the inspector name, country codes, facility name, inspection number and other optional comments. The data file is a standard text file that may be edited on the PC and transferred to the built-in data processor using the Windows Mobile Device Center or Microsoft ActiveSync prior to starting the series of measurements. All data are stored in the Inspection Data file (UF6.IDB) that is located in the Program Files\UF6 folder.
The Settings mode manages the hardware settings of the instrument and includes hardware setup, cooler control, energy calibration, state-of-health, etc., all selectable from a single screen.
The energy calibration procedure is specific to the UF6 application. The hardware settings are adjusted to position the U-235 peak at 185.7 keV in channel 2476 as required by the method.
The Spectra option allows the user to define “bookkeeping” options such as where spectra are to be saved and if the user is to be asked for descriptive input on saving a file. A “recall mode” allows spectra to be retrieved for scrutiny in a convenient MCA display mode, reminiscent of the MAESTRO MCA display. Users may use MAESTRO
to view spectra on a laptop once files have been transferred via the Windows Mobile Device Center or Microsoft ActiveSync. The MCA display mode features log/lin vertical scale, moveable cursor and zoom in/zoom out. The cursor position displays counts and energy.