1 Optimizing the network coverage of the IMS radioxenon component. CVT WORKSHOP 2015 CONSORTIUM FOR VERIFICATION T ECHN OLOGIES 16 OCTOBER 2015, ANN ARBOR, USA MICHAEL SCHOEPPNER PROGRAM ON SCIENCE AND GLOBAL SECURITY, PRINCETON UNIVERSITY SCHOEPPNER@PRINCETON.EDU
CTBT verification 2 Confidence building measures International Monitoring System Consultation and clarification On-Site Inspection
CTBT verification 3 Confidence building measures International Monitoring System 3x waveform (seismic, hydroacoustic, infrasound) 1x airborne radionuclides and radioxenon Consultation and clarification On-Site Inspection
INTERNATIONAL MONITORING SYSTEM Radioxenon network 39+1 stations 4
Standard modelling 5 conditions 1kt yield underground / underwater 3h Xe-133 max Underground 1% release at maximum of Xe-133 activity (after about 100h) Underwater 100% release of activity within 3h Source: Kalinowski, 2011
Standard modelling 6 conditions (cont.) 1kt yield underground / underwater Xe-133 with half-life of 5.25 days Background emissions from 200 Nuclear Power Plants and 5 Medical Isotope Production Facilities 14 days transport time 40 noble gas stations Atmospheric transport modelling with Flexpart 8.23 and 0.5deg NCEP data
7 IMS RADIOXENON NETWORK Purpose and conditions 1. Detection of unusual radioxenon emissions CONDITION: Any release of radioxenon should reach a monitoring station (and be detectable). 1. Localization of event through inverse modelling CONDITION: More samples lead to better localization capability.
Standard conditions 8 Average detection probability 100 % 75 % 50 % Average number of samples 25 % 0 % Regional gaps in the network coverage exist. Detection probability and localization 10 + 9 8 7 6 5 4 3 2 1 capability do not fully correlate.
Without background 9 Average detection probability 100 % 75 % 50 % 25 % 0 % With background Average number of samples With background Reducing the background would greatly increase regional capabilities. 10 + 9 8 7 6 5 4 3 2 1
Increased yields 20 kt TNT 10 Average detection probability 100 % 75 % 50 % 25 % 0 % Higher yields (/higher leakage or lower MDC) 1 kt TNT yield greatly increases the detection and localization capability. 10 + Average number of 9 8 samples 1 kt TNT yield 7 6 5 4 3 2 1
Transport time 7 days 11 Average detection probability 100 % 75 % 50 % 25 % 0 % In many locations more detections are to 14 days transport be expected more than 7 days after 10 + release. Average number of 9 8 samples 14 days transport 7 6 5 4 3 2 1
12 Other radioxenon isotopes Xe-133 and Xe-131m, Xe-133m, Xe-135 Stand-alone tracers Combined detections for isotopic activity ratios Different ratios for discrimination of reactor emissions and nuclear tests
Other radioxenon isotopes 13 100 % 75 % 50 % 25 % 0 % Xe-131m Xe-133 Other isotopes are less likely to be detected, but... Xe-133m Xe-135
Other radioxenon isotopes at 20 kt TNT yield 100 % 75 % 50 % 25 % 0 % 14 Xe-131m Xe-133 For higher yields (/lower MDC) other isotopes can be a realistic option. Xe-133m Xe-135
INTERNATIONAL MONITORING SYSTEM Noble gas & radionuclide network 40 + 40 stations 15
Extended network 60 stations 16 Average detection probability 100 % 75 % 50 % 25 % 0 % 40 stations Average number of samples 40 stations The 20 equatorial RN stations would fill the biggest NG detection gaps. 10 + 9 8 7 6 5 4 3 2 1
Extended network 80 stations 17 Average detection probability 100 % 75 % 50 % 25 % 0 % 60 stations Average number of samples 60 stations Most mid-latitude RN stations are in regions of already good NG coverage. 10 + 9 8 7 6 5 4 3 2 1
Scenarios With and without background 1kt and 20kt yields 7 days and 14 days transport time Four radioxenon isotopes 40, 60 and 80 stations Summary and Recommendations Differentiation between detection probability and localisation capability Good coverage for most parts of the globe Gaps due to background and equatorial meteorology Other radioxenon isotopes are secondary means (needed for activity ratios) Last detection of event can take time (transport time) Overall improvement from lowering MDC for low background regions Initial extension of 20 stations would yield most benefit