Paul R. J. Saey

A long distance measurement of radioxenon in Yellowknife, Canada, in late October 2006

[1]xa0Between 21–25 October 2006, elevated levels of atmospheric xenon-133 were observed in Yellowknife (Canada). This station is located in an area where the background level of radioxenon is very low. The few measurements of xenon-133 above background in the last three years have been traced back to known nuclear facilities. The measurements in late October could not be linked to them. According to backward atmospheric transport models (ATM), the air that contained the measured radioxenon could have originated from the Korean Peninsula. On 9 October 2006, seismic networks world-wide recorded an event with characteristics of an underground explosion in the Democratic Peoples Republic of Korea. Forward ATM was performed using these coordinates. The results were consistent with the measurements in Yellowknife, more than 7000 km away. The order of magnitude of the amount measured is consistent with simple leak scenarios assumed for a low yield underground nuclear explosion on the Korean peninsula.

Radioxenon background at high northern latitudes

[1]xa0As part of the International Noble Gas Experiment (INGE) two stations were deployed in remote regions at high northern latitudes: Longyearbyen, Spitsbergen, Norway (78.2°N), and Yellowknife, Canada (62.5°N). With one exception, both stations are 2000 km or more from any single known stationary nuclear facility. Nevertheless, the short-lived anthropogenic radionuclide = 5.24 days) has been detected on a regular basis at both stations, and also = 11.84 days) was found at the Yellowknife station. Measuring these very low concentrations (∼0.1 mBq/m3) has been possible because of the introduction of new and sensitive equipment developed specifically for the verification of the Comprehensive Nuclear-Test Ban Treaty. By means of atmospheric transport modeling, it was determined that the measurements at both sites are broadly consistent with reported releases from reactors in North America and Europe and that the Spitsbergen station is much more susceptible to this influence than the Yellowknife station. Especially at Spitsbergen, the simplified assumption of a continuous bulk release across Europe could well explain the month-to-month variation of the time series. A future radioxenon event classification scheme for treaty verification purposes thus needs to consider the actual meteorological situation and large-scale transport processes.

WOSMIP II- Workshop on Signatures of Medical and Industrial Isotope Production

Medical and industrial fadioisotopes are fundamental tools used in science, medicine and industry with an ever expanding usage in medical practice where their availability is vital. Very sensitive environmental radionuclide monitoring networks have been developed for nuclear-security-related monitoring [particularly Comprehensive Test-Ban-Treaty (CTBT) compliance verification] and are now operational.

Measurements of Worldwide Radioxenon Backgrounds - The "EU" Project

Under the Comprehensive Nuclear-Test-Ban Treaty (CTBT), radioactive xenon (radioxenon) measurements are one of the principle techniques used to detect nuclear underground nuclear explosions, and specifically, the presence of one or more radioxenon isotopes allows one to determine whether a suspected event was a nuclear explosion or originated from an innocent source. During the design of the International Monitoring System (IMS), which was designed as the verification mechanism for the Treaty, it was determined that radioxenon measurements should be performed at 40 or more stations worldwide. At the time of the design of the IMS, however, very few details about the background of the xenon isotopes was known and it is now recognized that the backgrounds were probably evolving anyhow. This paper lays out the beginning of a study of the worldwide concentrations of xenon isotopes that can be used to detect nuclear explosions and several sources that also release radioxenons, and will have to be accounted for during analysis of atmospheric levels. Although the global concentrations of the xenon isotopes are the scope of a much larger activity that could span over several years, this study measures radioxenon concentrations in locations where there was either very little information or theremorexa0» was a unique opportunity to learn more about emissions from known sources. The locations where radioxenon levels were measured and reported are included.«xa0less