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

Abstract

Between 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.

Backtracking of Noble Gas Measurements Taken in the Aftermath of the Announced October 2006 Event in North Korea by Means of PTS Methods in Nuclear Source Estimation and Reconstruction

“…To better understand the flow and resulting dispersion conditions on the event day, a higher-resolution forward model simulation based on ECMWF wind field analysis was conducted (Run 3, Table 1). Compared with the standard simulation (Run 4) already discussed by SAEY et al (2007), the horizontal resolution was increased five times. At this resolution the forward modelling and three-dimensional wind field analysis show that a continental cold air outflow took place after 12:00 UTC on 10 October (Fig.…”

“…It is worth noting in this context that the Democratic Peoples Republic of Korea already televised at 3 October, 2006 an announcement that it would conduct a nuclear explosion. For further detail see SAEY et al (2007).…”

“…This would be three to four orders of magnitudes more sensitive than required to detect the approximately 10 15 Bq release of an immediate venting of 10% of the 133 Xe fission yield mentioned above. In a previous study published after the event (SAEY et al, 2007), a data analysis was made based on measurements from the IMS network. It was determined that the measurements would be consistent with the assumption that 10 15 Bq of 133 Xe was released at the DPRK event location within the first days.…”

North Korean nuclear test of October 9th, 2006: The utilization of health Canada’s radionuclide monitoring network and environment Canada’s atmospheric transport and dispersion modelling

“…This paper discusses the radioxenon background in the Ottawa region in terms of its distribution as a source of radioxenon background in Yellowknife, Canada. This turned out to be a key piece of information in regards to determining the source of radioxenon observed in Yellowknife in October of 2006 [7]. This paper describes the radioxenon distributions measured in two different ways: 1) the NaI(Tl) network, and 2) by through yearly safety reports by Chalk River Laboratories.…”

“…This paper describes the radioxenon distributions measured in two different ways: 1) the NaI(Tl) network, and 2) by through yearly safety reports by Chalk River Laboratories. All of this together was done in order to determine whether or not Chalk River was the source of Radioxenon measured at Yellowknife after the announced nuclear test by North Korea [7].…”