Global emission inventory of Xe, Xe, Xe, and Xe from all kinds of nuclear facilities for the reference year 2014.

Global radioactivity monitoring for the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) includes the four xenon isotopes Xe, Xe, Xe and Xe. These four isotopes are serving as important indicators of nuclear explosions. The state-of-the-art radioxenon emission inventory uses generic release estimates for each known nuclear facility.

Overview of temporary radioxenon background measurement campaigns conducted for the CTBTO between 2008 and 2018.

The Comprehensive Nuclear-Test-Ban Treaty (CTBT) specifies that an overall network of at least 40 International Monitoring System (IMS) stations should monitor the presence of radioxenon in the atmosphere upon its entry into force. The measurement of radioxenon concentrations in the air is one of the major techniques to detect underground nuclear explosions. It is, together with radionuclide particulate monitoring, the only component of the network able to confirm whether an event originates from a nuclear test, leaving the final proof to on-site inspection.

On the usability of event zero time determinations using radioxenon isotopic activity ratios given the real atmospheric background observations.

This work focuses on the usability of event zero time determination using xenon isotopic activity ratios. Two data sets from Nevada underground nuclear test and Fukushima accident debris were used to calculate the age of radioxenon release by considering three kinds of radioactivity release radionuclide sources: nuclear explosion scenarios, nuclear power reactor release and medical isotopes production facilities release. Typical nuclear power reactor releases were characterized and reference values are proposed for six isotopic activity ratios, which data can be considered as reference point of nuclear reactor effluents at the time of their release obtained from real observations.

Nuclear event zero time determination using analytical solutions of radioxenon activities under in-growth condition.

Motivated by simplifying the calculation process of radioxenon isotopic activity used by scientist community in nuclear event characterization, the analytical formulas of the numbers of nuclides and isotopic activities of CTBT relevant radioxenon Xe-135, Xe-133m, Xe-133 and Xe-131m proposed in this work can be useful and incorporated in the calculation algorithms for nuclear event studies. The calculated ages using analytical formulas and radioxenon activity data from real observations compare well with the reported ages and show good results of event timing precision.

Setting the baseline for estimated background observations at IMS systems of four radioxenon isotopes in 2014.

Worldwide monitoring of radionuclides is an essential part of the verification system of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) as it can provide a direct evidence of the nuclear nature of an explosion. In the case of underground nuclear testing, the radioactive noble gases, specifically radioxenon, have the highest probability to escape to the atmosphere. The detection capability of the CTBT noble gas network, which is being built, is weakened due to the presence of a worldwide civilian radioxenon background.

Fast and accurate dating of nuclear events using La-140/Ba-140 isotopic activity ratio.

This study reports on a fast and accurate assessment of zero time of certain nuclear events using La-140/Ba-140 isotopic activity ratio. For a non-steady nuclear fission reaction, the dating is not possible. For the hypothesis of a nuclear explosion and for a release from a steady state nuclear fission reaction the zero-times will differ.

Update and improvement of the global krypton-85 emission inventory.

Krypton-85 is mainly produced in nuclear reactors by fission of uranium and plutonium and released during chopping and dissolution of spent fuel rods in nuclear reprocessing facilities. As noble gas it is suited as a passive tracer for evaluation of atmospheric transport models. Furthermore, research is ongoing to assess its quality as an indicator for clandestine reprocessing activities.

A novel vacuum ultra violet lamp for metastable rare gas experiments.

We report on a new design of a vacuum ultra violet (VUV) lamp for direct optical excitation of high laying atomic states, e.g., for excitation of metastable rare gas atoms.

Characterisation of prompt and delayed atmospheric radioactivity releases from underground nuclear tests at Nevada as a function of release time.

A database with information on about 500 cases of atmospheric radioactivity releases from underground nuclear tests is analysed. The data are statistically evaluated and systematically aggregated in order to characterise prompt uncontrolled as well as delayed operational releases of radioactivity into the atmosphere. The focus is put on the latter.

Global radioxenon emission inventory based on nuclear power reactor reports.

Atmospheric radioactivity is monitored for the verification of the Comprehensive Nuclear-Test-Ban Treaty, with xenon isotopes 131mXe, 133Xe, 133mXe and 135Xe serving as important indicators of nuclear explosions. The treaty-relevant interpretation of atmospheric concentrations of radioxenon is enhanced by quantifying radioxenon emissions released from civilian facilities. This paper presents the first global radioxenon emission inventory for nuclear power plants, based on North American and European emission reports for the years 1995-2005.

Isotopic signature of atmospheric xenon released from light water reactors.

A global monitoring system for atmospheric xenon radioactivity is being established as part of the International Monitoring System to verify compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The isotopic activity ratios of (135)Xe, (133m)Xe, (133)Xe and (131m)Xe are of interest for distinguishing nuclear explosion sources from civilian releases. Simulations of light water reactor (LWR) fuel burn-up through three operational reactor power cycles are conducted to explore the possible xenon isotopic signature of nuclear reactor releases under different operational conditions.

Conclusions on plutonium separation from atmospheric krypton-85 measured at various distances from the Karlsruhe reprocessing plant.

For wide-area atmospheric monitoring, krypton-85 is the best indicator for clandestine plutonium separations. The detection and false alarm rates were determined from weekly samples at five different distances from the Karlsruhe reprocessing plant between 1985 and 1988. The detection rate for the separation of 4 kg of plutonium per week was found to be as high as 80-90% at a distance of less than 1 km, 70% at 5 km, 40% at 39 km, and 15% at 130 km.