Radionuclide measurements of the international monitoring system.

The International Monitoring System (IMS) is a unique global network of sensors, tuned to measure various phenomenology, with the common goal of detecting a nuclear explosion anywhere in the world. One component of this network collects measurements of radioactive particulates and gases (collectively known as radionuclides) present in the atmosphere; through this, compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT) can be verified. The radionuclide sub-network consists of 120 sensors across 80 locations, supported by 16 measurement laboratories. All radionuclide stations make use of a form of γ-ray spectroscopy to measure radionuclides from samples; this remains largely unchanged since the network was first established 25 years ago. Advances in sampling and spectroscopy systems can yield improvements to the sensitivity of the network to detect a nuclear explosion. This paper summarises the status of the IMS radionuclide network, the current suite of technology used and reviews new technology that could enhance future iterations, potentially improving the verification power of the IMS.

Enhancing the detection sensitivity of a high-resolution ß - γ coincidence spectrometer.

A high-resolution ß - Î³ coincidence spectrometry system has been set-up and calibrated at the UK CTBT Radionuclide Laboratory (known as GBL15) at AWE. The system has been configured specifically to measure the signatures of radioxenon isotopes that can be indicative of a nuclear explosion. The high purity germanium (HPGe) and PIPSBox detectors have been placed in an ultra-low-background lead shield to reduce the background count-rate and new software allows the combination of signals from four detectors (two HPGe detectors and two silicon-based detectors) to cover a larger solid angle. Measurements of samples of radioxenon isotopes are used to realise an improved detection efficiency and background acquisitions have demonstrated the achievable detection limits to reach 1.3 mBq for 133Xe and ≤0.3 mBq for the metastable isomers 131mXe and 133mXe. Due to the improved energy resolution in both photon and electron detectors, the detection sensitivity remains high in the presence of interfering signals from other radioxenon isotopes, such as those that may be present due to the significant levels of atmospheric radioxenon in parts of the world. This paper summarises the detector setup, efficiency calibration measurements and determination of the limits of detection. This work demonstrates the benefits of high-resolution coincidence detector systems for re-measurement of samples from the CTBT International Monitoring System (IMS) - improved detectability of metastable isomers 131mXe and 133mXe in the presence of 133Xe, compared to the current laboratory system.

Analysis of radionuclide detection events on the International Monitoring System.

The United Kingdom (UK) National Data Centre (NDC) operates a series of custom-developed software tools for the automatic processing, analysis, archiving and interpretation of radionuclide (RN) data from the International Monitoring System (IMS) - the primary instrument for verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The software in-use at the NDC includes an RN Pipeline for the retrieval, analysis, categorisation and archiving of noble gas and particulate radionuclide data. On the identification of a treaty-relevant radionuclide detection or plume of radioxenon, a 'radionuclide detection event' is formed. A series of atmospheric transport and dispersion simulations are activated, and the data is added to the 'RN Event' database where the detection is compared with forward simulations from known or suspected radionuclide emitters. The field of regard for a radionuclide detection event is cross-checked with others to identify possible associated detections, and finally a source reconstruction tool (known as FREAR) is used to determine the source parameters - location, magnitude, emission start time and emission stop time.

Production and measurement of fission product noble gases.

Gaseous fission products have been produced via thermal neutron irradiation of a highly-enriched uranium target and extracted using a custom gas processing system for measurement on a prototype, high-resolution ß - Î³ coincidence detection system. The gas was extracted and measured in two stages in order to measure the prompt and ß--delayed fission products. This paper presents an overview of the system used to produce gaseous fission products, and the results of the advanced coincidence spectrometry techniques used to identify and quantify decays from the radionuclides produced, including the noble gases 85Kr, 85mKr, 88Kr, 133Xe, 135Xe, 133mXe and 135mXe, as well as 133I and 88Rb. The measurements were validated by determination of the nuclear decay half-lives, specifically for the ground state decay of 135Xe, which was found to be 9.15(49) hours and consistent with the literature value. This work demonstrates the UK capability to produce gaseous radionuclides for quality assurance and calibration purposes in Radionuclide Laboratories supporting the Comprehensive Nuclear-Test-Ban Treaty (CTBT).

Analysis of environmental radioxenon detections in the UK.

Radioxenon activity concentrations are monitored globally using the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organisation, improving the monitoring community's ability to detect radionuclide signatures from an underground nuclear test (UNT). An IMS-like noble gas system is in operation at AWE (Aldermaston, UK) and can collect and measure radioxenon isotopes in environmental air samples. When operated in this mode, data produced is analysed at the UK National Data Centre (NDC) and significant detection events are flagged for further investigation. This work discusses a number of significant detection events analysed using the operational system deployed at the UK NDC, which includes atmospheric transport simulations and a real-time stack-monitoring data feed from the nearest medical isotope production facility in Belgium. A comparison of the expected radionuclide contributions with measured detections is presented, including a comparison of the isotopic ratios for the radioxenon isotopes of interest (133Xe, 131mXe, 133mXe, 135Xe).

Mandatory presuit mediation: 5-year results of a medical malpractice resolution program.

The Florida Patient Safety and Presuit Mediation Program (FLPSMP) is a mandatory mediation program designed to provide deserving patients with fast, fair compensation while limiting the healthcare provider expenses incurred during traditional litigation. Mediation occurs before litigation begins; therefore, patients with meritorious claims receive compensation often years earlier than they would with extended litigation. This early mediation fosters confidential and candid communication between doctors and patients, which promotes early fact-finding and candid discussion. The program went into effect across the University of Florida (UF) Health system on January 1, 2008. In an article previously published in this journal, we discussed the positive trend observed 2 years after the implementation of the FLPSMP. This article incorporates 5 years of data, which includes new benchmarks with state and national data, to demonstrate that the program can be used successfully as a medical malpractice solution.