Conveners
T2.4 e-poster session: e-poster session - T2.4 - Atmospheric and Subsurface Radionuclide Background and Dispersion
- Robin Riedmann (CTBTO Preparatory Commission, Vienna, Austria)
- Jonathan Bare (CTBTO Preparatory Commission, Vienna, Austria)
T2.4 e-poster session: T2.4 - Atmospheric and Subsurface Radionuclide Background and Dispersion
- Robin Riedmann (CTBTO Preparatory Commission, Vienna, Austria)
- Jonathan Bare (CTBTO Preparatory Commission, Vienna, Austria)
Description
T2.4
Understanding the radioxenon background at the radionuclide stations in the IMS network is important to improve the verification capability of the network. The background at the IMS station SEX63 in Stockholm Sweden has been studied in the time period between 2012 to 2019 using data from the IMS SAUNA II system. From 2017 data have also been evaluated from the co-located SAUNA III system....
This paper evaluates the desirability of noble gas stations network coverage in the International Monitoring System of the CTBTO for the detection of 1 kt nuclear explosions. It was assumed all the 39 noble gas stations become active, the annual average of MDC was used for each certified station and the MDC of Non-Operational Stations was considered 0.24 mBq/m3. In this regard, the daily...
An IMS-like noble gas system is in operation at AWE (Aldermaston, UK) and can collect and measure the radioxenon content in environmental air samples. When operated in this mode, data produced is analysed at the UK National Data Centre (NDC) as part of the in-house radionuclide (RN) analysis pipeline. This work discusses a number of significant detection events analysed using the operational...
The atmospheric dispersion modeling of radionuclides is used to obtain responses to emergencies by estimating radiation effects, associated with the atmospheric release of radioactive materials. Nowadays, almost all software used for these purposes, is based on the Gaussian model, which provides fast and conservative means that consider regions free of obstructions and simple weather...
A general code has been developed to describe two phase flow, tracer transport and thermal effects through a fractured porous medium on the Darcy scale under the action of constant or time dependent pressure fluctuations. The fractures are modeled as surfaces with specific properties. The fluid properties can depend on pressure and temperature.
The equations for flow, tracer concentration...
Xenon emissions from medical isotope production facilities (MIPFs) and other nuclear installations affect the verification capability of the International Monitoring System (IMS) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO). In an effort to minimize the impact of this radioxenon and in order to mitigate, in general, the radionuclide emission, Atmospheric Transport Models...
The concentrations and distributions of natural and anthropogenic radionuclides and heavy metals in surface water, groundwater, and soil samples of the site of Rooppur Nuclear Power Plant which is being constructed were investigated with the aim of evaluating the environmental radioactivity and radiation hazard and associated health risk assessment. Water and soil samples were collected and...
Worldwide monitoring of radioxenon is a necessary component of the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The current IMS design foresees 40 radioxenon stations around the world to provide a 90 % detectability of a 1 kt nuclear explosions within 14 days. Radioxenon stations have the capability to measure four radioxenon isotopes; 131mXe,...
A variety of factors influence the atmospheric background of ubiquitous radionuclide signatures, like xenon-133, measured at International Monitoring System (IMS) stations. Variability in the radionuclide background obscures the categorization and discrimination of signals from nuclear weapons testing and civilian and industrial activities tied to medical radioisotope production and nuclear...
Countries seeking a quick bomb or would-be nuclear terrorists have eyes on poorly secured sites that contain significant quantities of high enriched uranium, (HEU). HEU is the material of choice for states or terrorists that seek to proliferate stealthily without testing their weapons. It is therefore critical to make current stocks of HEU as inaccessible as possible. One of the most effective...
The global atmospheric dispersion and deposition of radionuclides released from the Fukushima Dai-ichi nuclear power plant accident was modelled using the EMAC atmospheric chemistry – general circulation model at different esolutions (equivalent to ∼50 km and ∼110 km Gaussian grid). The model accounts for emissions and transport of the radioactive isotopes 131I and 137Cs, and removal...
Radioisotope Production Facility in Serpong, has produced and processed I-131 which can be dispersed to residential areas and the environment around the Serpong Nuclear Zone (SNZ). Measurement of the air release dispersion I-131 using an old analogue tool is not functioning, and only a charcoal filter is functioning in the stack of the isotope production facility. Measurement of the I-131...
The Fission Radioisotope Production Plant of Argentina, located at the Ezeiza Atomic Center, produces 99Mo since 1985 irradiating targets with High Enrichment Uranium. In 2002 the targets have been changed by Low Enrichment Uranium.
Facilities that produce radioisotopes by fission increase the background of noble gases in the environment, especially radioactive xenon.
This background could...
Wildfires broke out on the 3rd of April 2020 in the Chernobyl exclusion zone, and the fires lasted for several weeks. As a consequence, measurable amounts of Cs-137 were re-suspended into the atmosphere and observed through the IMS network. Over the period of April - May 2020, the International Data Centre reported a significant increase in the number of Cs-137 detections compared to the same...
The potential benefit of ensemble dispersion modeling for CTBTO applications was investigated using input data from the ECMWF-Ensemble Prediction System (EPS). Five different test cases - among which are the ETEX-I experiment and the Fukushima accident - were run. For those test cases run in backward mode and based on a puff release it became evident that Probable Source Regions (PSRs) can be...
A general description of INVAP STAX monitor final status is shown, including calibration and software/hardware configuration.
First measurements results obtained in a real Noble Gas emission environment (MIPF plant at Ezeiza Atomic Center, CNEA, Buenos Aires, Argentina) are presented. Equipment measurement ranges, mainly focused to low flow rate and high activity concentration emissions,...
The goal of the third ATM challenge is to perform atmospheric transport modelling in order to estimate radioxenon observations at selected IMS stations in the northern hemisphere for an extended period in the year 2014 (June to November). This estimation is needed for calibration and performance assessment of the verification system as described in the Treaty. The best estimates for Xe-133...
Radionuclide observations made by the International Monitoring System are an important part of the CTBT verification regime, as it allows to discriminate between conventional and nuclear explosions. Atmospheric transport and dispersion modelling can link known sources with such observations. However, sometimes observations are made for which the source parameters (such as the release amount,...
The “Flexible Lagrangian particle dispersion model” FLEXPART is used in the IDC as well as by many of the participants in the Atmospheric Transport Modelling Challenges. As a truly flexible model, it may be used in forward and backward mode and it has many other parameters that can be set by users. All of these options influence the CPU and memory requirements as well as the accuracy of the...
Strong neutron sources may generate significant amounts of radioxenon by activation of stable xenon. Radioxenon emission from some nuclear research reactors and from spallation neutron sources are dominated by neutron activation as the production process. The isotopic ratios are different from fission gases. Activation generates Xe-135 to Xe-133 activity ratios like fission but the activated...
As gaseous and particulate signatures are produced during an underground nuclear explosion, it is important to understand their transport to the surface for subsequent atmospheric transport and detection. By understanding the transport throughout the subsurface, the atmospheric measurements have the potential to allow for a better understanding of the fractionation and total release fraction...
Atmospheric dispersion modeling and radiological safety analysis is performed for the public outside a radioisotope production facility (RPF) in case of hypothetical radioactive Iodine spilling and leakage from a hot cell. Potential human error is expected and the column that holds iodine may be broken causing it to spill on the radioactive cell floor. The ventilation exhaust system is...
The project ABC-MAUS is undertaken by a collaboration of the Austrian Ministry of Defense, Joanneum Research, the Austrian national weather and geophysical service Zentralanstalt für Meteorologie und Geodynamik (ZAMG), including the Austrian National Data Center (NDC), as well as the private company GIHMM. The aim is to develop a strategy of protection for chemical, biological, radiological...
The aim of this work is to apply a non-parametric statistical methodology to the radioxenon activity concentrations measured at noble gas stations of the International Monitoring System of the CTBTO, in order to investigate the radioxenon atmospheric background and the radioxenon anomalous values. The proposed non-parametric statistical methodology does not require any assumption on the...
NDC Preparedness Exercises (NPE) are regularly performed to practice the verification procedures for the detections of nuclear explosions in the framework of CTBT monitoring. In the event of NPE2019, a fictitious state RAETIA announced that a reactor had an incident and some radionuclides were released into the atmosphere. Both the IMS data and data from a fictitious neighbour state, EASTRIA,...
The aim of this work is to apply a parametric statistical methodology to the radioxenon activity concentrations measured at noble gas stations of the International Monitoring System of the CTBTO, in order to investigate the radioxenon atmospheric background and the radioxenon anomalous values. The proposed parametric statistical methodology is based on the “Statistical Process Control” method...
In 2017, the Government of Japan has decided to make a voluntary contribution to further enhance the capabilities of the CTBTO verification regime. In that framework, two transportable noble gas systems were deployed in Horonobe and Mutsu. They respectively started operating in February 2018 and March 2018. Continued operation of the two systems is now financially supported with funding from...
The most common mussel species in Rio de Janeiro State is Perna perna. It is an edible Mylilidae that has been cultivated in many places at Brazilian coast from Espirito Santo to Rio Grande do Sul States. Ten kilograms of flesh of mussels with a size of 5 to 8 cm were collected annually in the town of Arraial do Cabo, Rio de Janeiro State (23o S and 42o W) from 2002 to 2009. These organisms...
Half-lives of radioisotopes are thought of as absolute constants of Nature. However, since the 1980s several experiments indicated that small percent or sub-percent level temporal modulations may exist, potentially correlated to variations of the solar neutrino flux. The issue has been debated by the nuclear theory community, since it would imply some new mechanism influencing weak decays,...
This work describes the determination of the shielding against ionizing radiation from atmospheric dispersion arising from a radiological accident in a small nuclear reactor (SMR). Among the radionuclides from the inventory of this reactor, the contribution of Cs-137 was considered for simulation in HotSpot (analytical modeling) and ANSYS (numerical modeling), of the concentration and total...
The National Institute For Radioelements (IRE), located at Fleurus in Belgium, is an important emitter of radioactive xenon into the atmosphere. These emissions are not harmful to the environment, but can interfere with the very sensitive noble gas detection stations that are part of the verification regime of the Comprehensive Nuclear-Test-Ban Treaty Organization. Radioxenon stack emission...
Measuring airborne radioactivity typically requires large, static installations, limited in number and geographical distribution. By measuring the activity of matter deposited to the ground (by dry settling or wet scavenging), one can complement detections of airborne activity and improve overall data availability.
Many ways exist to detect deposited activity, such as using rain basins...
The source-term estimation of the radionuclides detected at IMS stations by using adjoint atmospheric transport modeling (ATM) is a vital part in the CTBTO monitoring and verification Regime. Webgrape software was developed by CTBTO International data center to assist the state signatories in the verification purposes of radionuclides detections. However, the source determination of an event...
Anthropogenic radionuclides of fission and activation products are frequently detected by most IMS stations located on the African continent with varying concentrations in the years 2011 to 2020. This study assesses the spatial and temporal variation of Cs-134 and Cs-137 in ground-level air at IMS stations located on the African continent from 2011 to 2020. Spatial and temporal base analysis...
The STAX (Source Term Analysis of Xenon) project aims at the development of a worldwide network to measure radioxenon isotopes released from medical isotope production facilities. A software package has been developed to fully process STAX data from secure data acquisition at the back end, to interactively viewing data at the front end. This presentation focusses on the analysis of data and on...
The most important indicators for an underground nuclear explosion during a CTBT on-site inspection are the radioactive xenon isotopes 131mXe, 133Xe and 133mXe and the radioactive argon isotope 37Ar. Knowledge of how these isotopes vary and potentially correlate in different types of soil is essential to be able to discriminate between the natural background and a signal from a nuclear...
Two ultra-sensitive gamma-spectrometry systems are being used to measure environmental samples collected from the Hartlepool Nuclear Power Station in the United Kingdom. The work is being performed as part of the Xenon Environmental Nuclide Analysis at Hartlepool (XENAH) collaboration between Pacific Northwest National Laboratory (PNNL, USA), the Atomic Weapons Establishment (AWE, UK) and EDF...
Scientists from the U.K. and the U.S. are collaborating to perform measurements involving three different radionuclide monitoring techniques with the collective goal of better characterizing radionuclide emissions of a nuclear power reactor and how those might affect the International Monitoring System. The Xenon Environmental Nuclide Analysis at Hartlepool (XENAH) collaboration will perform...
