Background Study Locations

Transcription

1 Figure of Merit for Choosing Xe Background Study Locations Justin McIntyre, Paul Eslinger, Derek Haas, Harry Miley S&T Meeting, June 2011 Disclaimer: The views expressed here do not necessarily reflect the opinion of the United States Government, the United States Department of Energy, or Pacific Northwest National Laboratory. 1

2 Why do we need to consider new locations for Xe background study? The world s xenon background is more complex than envisioned when the network was designed. Understanding medical isotope facility emissions is key to discriminating civilian releases from Treaty-relevant relevant signals The situation as it is will take many years to allow us to perform confident discrimination. Conclusion: place xenon monitoring equipment at key locations to study medical isotope signatures on a temporary basis But where? 2

3 Technical Approach HYSPLIT calculations using an entire year of meteorological data Calculate xenon transport from existing and proposed medical isotope production facilities Calculate coverage of IMS noble gas network Develop a figure of merit for additional xenon sampling locations based on two questions: Do medical isotope releases reach the location? Is the production site not covered by IMS xenon samplers? If both yes, FOM is high. 3

4 Existing and Possible Future Producers of Medical Isotopes Source (Bq/event) Location Country Status MDS Nordion Canada Existing Mallinckrodt Medical The Netherlands Existing IRE Belgium Existing NTP South Africa Existing CNEA Ezeiza Argentina Existing ANSTO Australia Existing Islamabad Pakistan Existing Saskatoon, Saskatchewan Canada Media Announcement Rabat Morocco Media Announcement Otwock Poland Media Announcement Inshas Egypt Media Announcement Tehran Iran Media Announcement Jakarta Indonesia Media Announcement Yongbyon North Korea Media Announcement Itaguaí Brazil Media Announcement Dimitrovgrad Russia Media Announcement Charlottesville, Virginia United States Hypothetical Location Idaho Falls, Idaho United States Hypothetical Location Columbia, Missouri United States Hypothetical Location 4 Source per release event for 133 Xe and 135 Xe Source of 133m Xe is assumed at 10% of 133 Xe Unknown sources for 133 Xe are set to Bq

5 Medical Isotope Detection Coverage Maps for 19 Release Locations Xe-133 Releases vary MDC 300 μbq/m 3 Xe-133m Releases Vary MDC 100 μbq/m 3 Xe-135 Releases Vary MDC 600 μbq/m 3 5

6 Locations of IMS Radionuclide Sampling Stations with Noble Gas Capabilities 3 Stations Certified 24 Stations Operational 13 Stations Planned 6 Source:

7 Detection Coverage for 27 IMS Stations for Release Magnitudes Compatible with 99m Tc Production Xe-133 Release Bq MDC 300 μbq/m 3 Xe-133m Release Bq MDC 100 μbq/m 3 Xe-135 Release Bq MDC 600 μbq/m 3 Coverage limited to the 27 stations currently certified or operational. 7

8 Detection Coverage for 40 IMS Stations for Release Magnitudes Compatible with 99m Tc Production Xe-133 Release Bq MDC 300 μbq/m 3 Xe-133m Release Bq MDC 100 μbq/m 3 Xe-135 Release Bq MDC 600 μbq/m 3 Only 39 stations modeled because coordinates for RN35 have not been established 8

9 Detection Coverage for 80 IMS Stations for Release Magnitudes Compatible with 99m Tc Production Xe-133 Release Bq MDC 300 μbq/m 3 Xe-133m Release Bq MDC 100 μbq/m 3 Xe-135 Release Bq MDC 600 μbq/m 3 Only 79 stations modeled because coordinates for RN35 have not been established 9

10 Figure of Merit Desirable figure of merit attributes: Low value: If medical isotope concentrations are always too low to detect If IMS stations can reliably detect releases from the medical facility High value: If medical isotope concentrations are always high enough to detect but no IMS station will detect the release Metric Eliminate medical facilities where IMS coverage of releases from the facility is greater than 0.30 Choose sampling locations within high coverage area of the remaining medical facilities (based on forward transport runs) 10

11 Figure of Merit for Xe133 for 27 Xenon Stationsti Coverage from Medical Releases Coverage from Medical Releases for Locations with IMS coverage <0.3 11

12 Figure of Merit for Xe133 for 40 Xenon Stationsti Coverage from Medical Releases Coverage from Medical Releases for Locations with IMS coverage <0.3 12

13 Figure of Merit for Xe133 for 80 Xenon Stationsti Coverage from Medical Releases Coverage from Medical Releases for Locations with IMS coverage <0.3 13

14 Conclusions Case for extra measuring locations is compelling The development of new medical isotope locations will result in a significant scientific challenge in understanding Results are heavily dependant on locations that are missing or not yet installed in the IMS network This work shows a scientifically-motivated approach to choosing locations 14

15 Thank you! Questions? 15

16 Modeling Assumptions for Medical Isotopes Hysplit 14-day forward transport runs Meteorology (GDAS Global data assimilation system archive) from October 2009 through September hour time resolution 110 km data spacing (nominal 1 by 1 spacing) ~7,000 Hysplit version 4.9 runs (365 days by 19 release locations) Low resolution transport t runs (10, particles) to limit it compute times Top layer of the model reaches to 10,000 m above ground level Concentration calculated in the lower 100 m of the atmosphere Used 94 compute nodes on a Linux cluster Source Sources vary in size by facility (see previous slide) Concentration detection limit varies by isotope 300 μbq/m 3 for 133 Xe 100 μbq/m 3 for 133m Xe 600 μbq/mb / 3 for 135 Xe 16

17 Display Assumptions for Contour Plots Coverage is defined as the fraction of releases where the xenon concentration exceeds the detection limit at each grid location at least one time during the first 14 days after the release occurred Assume a release occurs each day at each facility Each plume is tracked separately (no overlap) Detections (yes/no) are accumulated over the 365 different release days Contours Each contour level e is a difference e in 10% on coverage Darkest purple is >90% detections Lightest purple is >50% detections Darkest green is >40% detections lightest green is >10% detections 17

18 IMS Station Coverage Modeling Assumptions Hysplit 14-day backcast transport runs Meteorology from Oct through Sep ~30,000 Hysplit runs (380 days by 79 locations) Low resolution runs (25,000 particles) to limit compute times (greater than 50,000 CPU-hours) Used 94 compute nodes on a Linux cluster Source Source size assumed to be: Bq for 133 Xe and 135 Xe Bq for 133m Xe Concentration detection limit varies by isotope 300 μbq/m 3 for 133 Xe 100 μbq/m 3 for 133m Xe 600 μbq/m 3 for 135 Xe 18

19 Discussion ATM modeling of both IMS sampling station coverage and existing/future medical isotope facilities coverage provides the basis for selecting locations for additional sampling stations Relative merit for new stations (based on IMS sampling locations) North and South America: All medical isotope production locations are well covered by 27 xenon stations Europe: All medical isotope production locations are well covered by 27 xenon stations Africa: NW, NE and S regions of the continent are not well covered even by 80 xenon stations Asia Northern Asia: All medical isotope production locations are well covered by 27 xenon stations Eastern Asia: All medical isotope production locations are well covered by 27 xenon stations Southern Asia: A number of regions are not well covered even by 80 xenon stations Australia: All medical isotope production locations are well covered by 80 xenon stations 19