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Title: International challenge to predict the impact of radioxenon releases from medical isotope production on a comprehensive nuclear test ban treaty sampling station

Abstract

Abstract The International Monitoring System (IMS) is part of the verification regime for the Comprehensive Nuclear-Test-Ban-Treaty Organization (CTBTO). At entry-into-force, half of the 80 radionuclide stations will be able to measure concentrations of several radioactive xenon isotopes produced in nuclear explosions, and then the full network may be populated with xenon monitoring afterward (Bowyer et al., 2013). Fission-based production of 99Mo for medical purposes also releases radioxenon isotopes to the atmosphere (Saey, 2009). One of the ways to mitigate the effect of emissions from medical isotope production is the use of stack monitoring data, if it were available, so that the effect of radioactive xenon emissions could be subtracted from the effect from a presumed nuclear explosion, when detected at an IMS station location. To date, no studies have addressed the impacts the time resolution or data accuracy of stack monitoring data have on predicted concentrations at an IMS station location. Recently, participants from seven nations used atmospheric transport modeling to predict the time-history of 133Xe concentration measurements at an IMS station in Germany using stack monitoring data from a medical isotope production facility in Belgium. Participants received only stack monitoring data and used the atmospheric transport model and meteorologicalmore » data of their choice. Some of the models predicted the highest measured concentrations quite well (a high composite statistical model comparison rank or a small mean square error with the measured values). The results suggest release data on a 15 min time spacing is best. The model comparison rank and ensemble analysis suggests that combining multiple models may provide more accurate predicted concentrations than any single model. Further research is needed to identify optimal methods for selecting ensemble members and those methods may depend on the specific transport problem. None of the submissions based only on the stack monitoring data predicted the small measured concentrations very well. The one submission that best predicted small concentrations also included releases from nuclear power plants. Modeling of sources by other nuclear facilities with smaller releases than medical isotope production facilities may be important in discriminating those releases from releases from a nuclear explosion.« less

Authors:
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Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1254565
Report Number(s):
PNNL-SA-114075
Journal ID: ISSN 0265-931X; 400809000
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Environmental Radioactivity; Journal Volume: 157
Country of Publication:
United States
Language:
English
Subject:
Medical isotope production; 133Xe; source-term estimation; atmospheric modeling; CTBTO

Citation Formats

Eslinger, Paul W., Bowyer, Ted W., Achim, Pascal, Chai, Tianfeng, Deconninck, Benoit, Freeman, Katie, Generoso, Sylvia, Hayes, Philip, Heidmann, Verena, Hoffman, Ian, Kijima, Yuichi, Krysta, Monika, Malo, Alain, Maurer, Christian, Ngan, Fantine, Robins, Peter, Ross, J. Ole, Saunier, Olivier, Schlosser, Clemens, Schöppner, Michael, Schrom, Brian T., Seibert, Petra, Stein, Ariel F., Ungar, Kurt, and Yi, Jing. International challenge to predict the impact of radioxenon releases from medical isotope production on a comprehensive nuclear test ban treaty sampling station. United States: N. p., 2016. Web. doi:10.1016/j.jenvrad.2016.03.001.
Eslinger, Paul W., Bowyer, Ted W., Achim, Pascal, Chai, Tianfeng, Deconninck, Benoit, Freeman, Katie, Generoso, Sylvia, Hayes, Philip, Heidmann, Verena, Hoffman, Ian, Kijima, Yuichi, Krysta, Monika, Malo, Alain, Maurer, Christian, Ngan, Fantine, Robins, Peter, Ross, J. Ole, Saunier, Olivier, Schlosser, Clemens, Schöppner, Michael, Schrom, Brian T., Seibert, Petra, Stein, Ariel F., Ungar, Kurt, & Yi, Jing. International challenge to predict the impact of radioxenon releases from medical isotope production on a comprehensive nuclear test ban treaty sampling station. United States. doi:10.1016/j.jenvrad.2016.03.001.
Eslinger, Paul W., Bowyer, Ted W., Achim, Pascal, Chai, Tianfeng, Deconninck, Benoit, Freeman, Katie, Generoso, Sylvia, Hayes, Philip, Heidmann, Verena, Hoffman, Ian, Kijima, Yuichi, Krysta, Monika, Malo, Alain, Maurer, Christian, Ngan, Fantine, Robins, Peter, Ross, J. Ole, Saunier, Olivier, Schlosser, Clemens, Schöppner, Michael, Schrom, Brian T., Seibert, Petra, Stein, Ariel F., Ungar, Kurt, and Yi, Jing. Wed . "International challenge to predict the impact of radioxenon releases from medical isotope production on a comprehensive nuclear test ban treaty sampling station". United States. doi:10.1016/j.jenvrad.2016.03.001.
@article{osti_1254565,
title = {International challenge to predict the impact of radioxenon releases from medical isotope production on a comprehensive nuclear test ban treaty sampling station},
author = {Eslinger, Paul W. and Bowyer, Ted W. and Achim, Pascal and Chai, Tianfeng and Deconninck, Benoit and Freeman, Katie and Generoso, Sylvia and Hayes, Philip and Heidmann, Verena and Hoffman, Ian and Kijima, Yuichi and Krysta, Monika and Malo, Alain and Maurer, Christian and Ngan, Fantine and Robins, Peter and Ross, J. Ole and Saunier, Olivier and Schlosser, Clemens and Schöppner, Michael and Schrom, Brian T. and Seibert, Petra and Stein, Ariel F. and Ungar, Kurt and Yi, Jing},
abstractNote = {Abstract The International Monitoring System (IMS) is part of the verification regime for the Comprehensive Nuclear-Test-Ban-Treaty Organization (CTBTO). At entry-into-force, half of the 80 radionuclide stations will be able to measure concentrations of several radioactive xenon isotopes produced in nuclear explosions, and then the full network may be populated with xenon monitoring afterward (Bowyer et al., 2013). Fission-based production of 99Mo for medical purposes also releases radioxenon isotopes to the atmosphere (Saey, 2009). One of the ways to mitigate the effect of emissions from medical isotope production is the use of stack monitoring data, if it were available, so that the effect of radioactive xenon emissions could be subtracted from the effect from a presumed nuclear explosion, when detected at an IMS station location. To date, no studies have addressed the impacts the time resolution or data accuracy of stack monitoring data have on predicted concentrations at an IMS station location. Recently, participants from seven nations used atmospheric transport modeling to predict the time-history of 133Xe concentration measurements at an IMS station in Germany using stack monitoring data from a medical isotope production facility in Belgium. Participants received only stack monitoring data and used the atmospheric transport model and meteorological data of their choice. Some of the models predicted the highest measured concentrations quite well (a high composite statistical model comparison rank or a small mean square error with the measured values). The results suggest release data on a 15 min time spacing is best. The model comparison rank and ensemble analysis suggests that combining multiple models may provide more accurate predicted concentrations than any single model. Further research is needed to identify optimal methods for selecting ensemble members and those methods may depend on the specific transport problem. None of the submissions based only on the stack monitoring data predicted the small measured concentrations very well. The one submission that best predicted small concentrations also included releases from nuclear power plants. Modeling of sources by other nuclear facilities with smaller releases than medical isotope production facilities may be important in discriminating those releases from releases from a nuclear explosion.},
doi = {10.1016/j.jenvrad.2016.03.001},
journal = {Journal of Environmental Radioactivity},
number = ,
volume = 157,
place = {United States},
year = {Wed Jun 01 00:00:00 EDT 2016},
month = {Wed Jun 01 00:00:00 EDT 2016}
}
  • After performing a first multi-model exercise in 2015 a comprehensive and technically more demanding atmospheric transport modelling challenge was organized in 2016. Release data were provided by the Australian Nuclear Science and Technology Organization radiopharmaceutical facility in Sydney (Australia) for a one month period. Measured samples for the same time frame were gathered from six International Monitoring System stations in the Southern Hemisphere with distances to the source ranging between 680 (Melbourne) and about 17,000 km (Tristan da Cunha). Participants were prompted to work with unit emissions in pre-defined emission intervals (daily, half-daily, 3-hourly and hourly emission segment lengths) andmore » in order to perform a blind test actual emission values were not provided to them. Despite the quite different settings of the two atmospheric transport modelling challenges there is common evidence that for long-range atmospheric transport using temporally highly resolved emissions and highly space-resolved meteorological input fields has no significant advantage compared to using lower resolved ones. As well an uncertainty of up to 20% in the daily stack emission data turns out to be acceptable for the purpose of a study like this. Model performance at individual stations is quite diverse depending largely on successfully capturing boundary layer processes. No single model-meteorology combination performs best for all stations. Moreover, the stations statistics do not depend on the distance between the source and the individual stations. Finally, it became more evident how future exercises need to be designed. Set-up parameters like the meteorological driver or the output grid resolution should be pre-scribed in order to enhance diversity as well as comparability among model runs.« less
  • The current status of the ongoing establishment of a verification system for the Comprehensive Nuclear-Test-Ban Treaty using radioxenon detection is discussed. As an example of equipment used in this application the newly developed fully automatic noble gas sampling and detection system SAUNA is described, and data collected with this system are discussed. It is concluded that the most important remaining scientific challenges in the field concern event categorization and meteorological backtracking.
  • Fission gases such as 133Xe are used extensively for monitoring the world for signs of nuclear testing in systems such as the International Monitoring System (IMS). These gases are also produced by nuclear reactors and by fission production of 99Mo for medical use. Recently, medical isotope production facilities have been identified as the major contributor to the background of radioactive xenon isotopes (radioxenon) in the atmosphere (Saey, et al., 2009). These releases pose a potential future problem for monitoring nuclear explosions if not addressed. As a starting point, a maximum acceptable daily xenon emission rate was calculated, that is bothmore » scientifically defendable as not adversely affecting the IMS, but also consistent with what is possible to achieve in an operational environment. This study concludes that an emission of 5×109 Bq/day from a medical isotope production facility would be both an acceptable upper limit from the perspective of minimal impact to monitoring stations, but also appears to be an achievable limit for large isotope producers.« less
  • The use of the xenon isotopes for detection of nuclear explosions is of great interest for monitoring the CTBT.
  • The Nuclear Non-Proliferation Treaty (NPT) is the most important international security arrangement that we have that is protecting the world community and this has been true for many years. But it did not happen by accident, it is a strategic bargain in which 184 states gave up the right forever to acquire the most powerful weapon ever created in exchange for a commitment from the five states allowed to keep nuclear weapons under the NPT (U.S., U.K., Russia, France and China), to share peaceful nuclear technology and to engage in disarmament negotiations aimed at the ultimate elimination of their nuclearmore » stockpiles. The most important part of this is the comprehensive nuclear test ban (CTBT); the thinking by the 184 NPT non-nuclear weapon states was and is that they understand that the elimination of nuclear weapon stockpiles is a long way off, but at least the NPT nuclear weapon states could stop testing the weapons. The CTBT has been ratified by 161 states but by its terms it can only come into force if 44 nuclear potential states ratify; 36 have of the 44 have ratified it, the remaining eight include the United States and seven others, most of whom are in effect waiting for the United States. No state has tested a nuclear weapon-except for complete outlier North Korea-in 15 years. There appears to be no chance that the U.S. Senate will approve the CTBT for ratification in the foreseeable future, but the NPT may not survive without it. Perhaps it is time to consider an interim measure, for the UN Security Council to declare that any future nuclear weapon test any time, anywhere is a 'threat to peace and security', in effect a violation of international law, which in today's world it clearly would be.« less