Charles W. Hubbard

Automated separation and measurement of radioxenon for the Comprehensive Test Ban Treaty

A fully automatic radioxenon sampler/analyzer (ARSA) has been developed and demonstrated for the collection and quantitative measurement of the four xenon radionuclides,131mXe(11.9 d),133mXe(2.2 d),133Xe(5.2 d), and135Xe(9.1 hr), in the atmosphere. These radionuclides are important signatures in monitoring for compliance to a Comprehensive Test Ban Treaty (CTBT). Activity ratios of these radionuclides permit source attribution. Xenon, continuously and automatically separated from the atmosphere, is automatically analyzed by electron-photon coincidence spectrometry providing a lower limit of detection of about 100 μBq/m3. The demonstrated detection limit is about 100 times better than achievable with reported laboratory-based procedures for the short-time collection intervals of interest.

Field testing of collection and measurement of radioxenon for the Comprehensive Test Ban Treaty

Pacific Northwest National Laboratory, with guidance and support from the U.S. Department of Energys NN-20 Comprehensive Test Ban Treaty (CTBT) Research and Development program, has developed and demonstrated a fully automatic sampler-analyzer (ARSA) for the collection and quantitative measurement of the four xenon radionuclides,131mXe (11.9 d),133mXe (2.19 d),133Xe (5.24 d), and135Xe (9.10 h), in the atmosphere. These radionuclides are important signatures in monitoring for compliance to a CTBT, and may have applications in stack monitoring and other areas where xenon radionuclides are present. The activity ratios between certain of these radionuclides permit discrimination between radioxenon originating from nuclear detonations and that from nuclear reactor operations, nuclear fuel reprocessing, or from medical isotope production and usage. With the ARSA system, xenon is continuously and automatically separated from the atmosphere at flow rates of about 100 lpm by sorption-bed techniques. Samples collected in 8 hours are automatically analyzed by electron-photon coincidence spectrometry to provide detection sensitivities as low as 100 μBq/m3 of air. This sensitivity is about 10-fold better than achieved with reported laboratory-based procedures1 for the short time collection intervals of interest. Gamma-ray energy spectra and gas analysis data are automatically collected.

A description of the DOE Radionuclide Aerosol Sampler/Analyzer for the Comprehensive Test Ban Treaty

Radionuclide monitoring, though slower than vibrational methods of explosion detection, provides a basic and certain component of Comprehensive Test Ban treaty (CTBT) verification. Measurement of aerosol radioactive debris, specifically a suite of short-lived fission products, gives high confidence that a nuclear weapon has been detonated in or vented to the atmosphere. The variable nature of wind-borne transport of the debris requires that many monitoring stations cover the globe to insure a high degree of confidence that tests which vent to the atmosphere will be detected within a reasonable time period. To fulfill the CTBT aerosol measurement requirements, a system has been developed at PNNL to automatically collect and measure radioactive aerosol debris, then communicate spectral data to a central data center. This development has proceeded through several design iterations which began with sufficient measurement capability (<30 μBq/m3140Ba) and resulted in a system with a minimal footprint (1 m×2 m), minimal power requirement (1600W), and support of network infrastructure needs. The Mark IV prototype (Fig. 1) is currently the subject of an Air Force procurement with private industry to partially fulfill US treaty obligations under the CTBT. It is planned that the system will be available for purchase from a manufacturer in late 1997.

Automating communications with and developing user interfaces for remote data acquisition and analysis systems

Many remote sensor applications require the deployment of automated data acquisition systems. These systems must provide a reliable and robust method of transferring acquired data to an appropriate data center. Remote users also require a means to verify the state-of-health of the sensors and a method of installing improved control software as needed. Research at PNNL on automated radionuclide systems for the Comprehensive Test Ban Treaty has developed a robust and automated method of data transmission. User interfaces for these systems allow one to use simple text-based communication protocols (kermit, telnet) or the X Windows environment. The use of TcI/Tk aided in the rapid development of the X windows user interfaces.

Automated aerosol sampling and analysis for the Comprehensive Test Ban Treaty

Detecting nuclear debris from a nuclear weapon exploded in or substantially vented to the Earths atmosphere constitutes the most certain indication that a violation of the Comprehensive Test Ban Treaty has occurred. For this reason, a radionuclide portion of the International Monitoring System is being designed and implemented. The IMS will monitor aerosols and gaseous xenon isotopes to detect atmospheric and underground tests, respectively. The monitoring network will be composed of a number of manual or automatic stations which have the capacity to sample large volumes of air each day and make sensitive gamma-ray spectroscopy measurements of the samples collected. In addition, a number of Certified Laboratories will perform confirmatory measurements on samples that show detectable quantities of fission products. This may be accomplished by measuring (instrumentally or by radiochemical means) certain isotopes which discriminate weapons debris from reactor accidents and other releases of fission products. An automated system, the Radionuclide Aerosol Sampler/Analyzer (RASA), has been developed at Pacific Northwest National Laboratory to meet CTBT aerosol measurement requirements. This is achieved by the use of a novel sampling apparatus, a high-resolution germanium detector, and very sophisticated software.

Environmental measurements with a Comprehensive Nuclear Test Ban Treaty radionuclide particulate monitor

A Radionuclide Aerosol Sampler/Analyzer (RASA Mark 4) has been developed at PNNL for use in verifying the Comprehensive Nuclear Test Ban Treaty (CTBT). The RASA Mark 4 collects about 20,000 m3 of air per day on a 0.25 m2 filter. This filter is automatically decayed for 24 hours, then advanced to a germanium detector for a 24 hour count. This system has been operated in Richland, WA for a limited period of time in a predeployment testing phase. The germanium-detector gamma-ray spectra have been analyzed by automatic spectral analysis codes to determine Minimum Detectable Concentrations (MDC) for a number of isotopes of interest. These MDCs have been compared to other atmospheric measurements in the field and in the laboratory.

Selective, high-energy beta scintillation sensor for real-time, in situ characterization of uranium-238 and strontium-90

A novel scintillating-fiber sensor for detecting high-energy beta particles has been designed and built at the Pacific Northwest Laboratory to characterize238U and90Sr in surface soils. High-energy betas generate unique signals as they pass through multiple layers of scintillating fibers that make up the active region of the detector. Lower-energy beta particles, gamma rays, and cosmic-ray-generated particles comprise the majority of the background interferences. The resulting signals produced by these latter phenomena are effectively discriminated against due to the combination of the sensors multi-layer configuration and its interlayer coincidence/anti-coincidence circuitry.

Requirements for Xenon International

This document defines the requirements for the new Xenon International radioxenon system. The output of this project will be a Pacific Northwest National Laboratory (PNNL) developed prototype and a manufacturer-developed production prototype. The two prototypes are intended to be as close to matching as possible; this will be facilitated by overlapping development cycles and open communication between PNNL and the manufacturer.

Data communications and management of a distributed network of automated data acquisition and analysis systems

Several research applications require the deployment of a distributed network of automated data acquisition and analysis systems. These systems must provide a reliable and robust method of transferring acquired data to an appropriate data center. The data center must be capable of forwarding the acquired data to a potentially large group of researchers. The networks system operators need robust tools that allow them to easily manage and verify the state of health of the individual systems within the data acquisition and analysis network. Research at PNNL on automated radionuclide systems for the Comprehensive Nuclear Test Ban Treaty has shown that existing Internet protocols and software applications can be leveraged in the deployment of a functioning network of automated data acquisition and analysis systems. Specifically e-mail, FTP, and network news can be used to transmit data, while SNMP based management tools can be used to manage the systems within the network.

An extension of the CAMAC standard for increased data transfer rates

This report describes a proposed extension to the CAMAC data acquisition standard (FASTCAMAC), which substantially increases the data transfer rate of CAMAC systems while retaining compatibility with standard CAMAC. There have been previous proposals to increase the CAMAC transfer rate, but these have usually been proprietary or not compatible with standard CAMAC. None has achieved widespread acceptance by CAMAC users.