The complexity of CTBT verification. Taking noble gas monitoring as an example

Abstract

Verification of the Comprehensive Nuclear-Test-Ban Treaty is a complex undertaking. A monitoring system comprising a global network of 321 seismic, hydroacoustic, infrasound and radionuclide stations is used to detect signals that could indicate a possible nuclear explosion. This system daily sends more than 10 GB of raw data to the Vienna based International Data Centre for further processing and analysis to answer a simple question: have any indications for a possible nuclear explosion been sensed? We will focus on the 40 stations in charge for global radioxenon monitoring and discuss the complexity of solving the nuclear source attribution problem.2008 Wiley Periodicals, Inc. Complexity 14: [89][90][91][92][93][94][95][96][97][98][99] 2008 INTRODUCTION T he verification of international agreements is often a highly complex undertaking. First of all, the cultural gap between scientific analysis and diplomatic thinking has to be bridged. Furthermore, even within the process of measurement, data processing, and analysis, many different methodologies are applied in an interdisciplinary cooperation.The Comprehensive Nuclear-Test-Ban Treaty (CTBT) bans all nuclear explosions. It has not yet entered into force, but its verification system is being established by the Provisional Technical Secretariat (PTS) of the CTBTO PrepCom (CTBT Organisation Preparatory Commission) in Vienna. This verification system consists of three elements: global monitoring, consultation and clarification as well as on-site inspections. The main component is the International Monitoring System (IMS) that will be used to verify compliance with the CTBT once it has entered into force. This system will consist of 321 measurement stations all over the world (see Figure 1). Seismic, hydroacoustic, infrasound, and radionuclide sensors are used to detect signals that could indicate a possible nuclear explosion. Every day, more than 10 GigaByte of raw data will be transmitted through a Global Communication Infrastructure (GCI) system to the International Data Centre (IDC) of the PTS in Vienna. The GCI consists of a network of five satellites that links the data measured at IMS stations directly to Vienna, This is an invited paper for the Special Issue-Security and Complexity, Guest Editor: Jü rgen Scheffran. The views expressed herein are those of the authors and do not necessarily reflect the views of the CTBTO Preparatory Commission. where it is also controlled and managed. The task of the IDC is to process and analyze this huge amount of data in order to break this information down to a simple message: have any indications for a possible nuclear explosion been sensed? This is reported in a daily executive summary bulletin that refers to more elaborate lists and reports. The IDC reports do not contain any interpretation or prejudice. The final judgement is left to the states parties. The raw data and the reports are sent out to the customers, which are authorized users in the member states. National data centers (NDCs) make use of the reports a...

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

“…167, (2010) Backtracking of Noble Gas Measurements Table 1 List of forward and backward modelling runs performed with the LPDM FLEXPART 5.0 (STOHL et al, 1998(STOHL et al, , 2005 BECKER et al, 2007). In addition, taking the source location information provided by the seismic part of the IMS, the same SRS fields were also utilized for a source reconstruction conducted by means of a multiple regression analysis method introduced and elaborated by WOTAWA et al (2006, 2009) and KALINOWSKI et al (2008. Finally, forward dispersion modelling was applied to predict the activity concentrations for the location and sampling times of the 133 Xe measurements with the parabolic kernel method of ULIASZ (1994) serving modelled activity concentrations with a method complementary to the SRS folding method.…”

“…Backtracking was performed for all five samples based on ATM results calculated at 1.0°(Run 5) and 0.2°horizontal resolutions (Run 6, Table 1). The respective backtracking results were evaluated by means of a multiple regression analysis introduced and elaborated by WOTAWA et al (2006, 2009) and KALINOWSKI et al (2008 in order to identify the most consistent singular source hypothesis that would best explain the activity concentrations encountered in those five (four) 133 Xe samples in ROK that covered at least once the DPRK event location. Interestingly, a 3-day persistent release of 15 9 10 12 Bq (Run 5) or 60 9 10 12 Bq (Run 6) from 10 to 13 October, 0 UTC was shown to be most consistent with the measurements taken from the many possible release scenarios examined (Fig.…”

“…In its final build-up, the IMS will have 80 highly sensitive particulate RN stations (SCHULZE et al, 2000) with 40 of these stations scheduled to also measure the CTBT relevant radio-xenon isotopes 131m Xe, 133m Xe, 133 Xe, 135 Xe ( Fig. 1; AUER et al, 2004;KALINOWSKI et al, 2008) that are known to be created in substantial amounts after a nuclear explosion. These four isotopes are most interesting as their respective half-life times of 11.94, 2.19, 5.24 days and 9.14 h (ENSDF, 2009) are long enough to allow for detection and also clocking of their time of production by evaluation of the isotopic ratios.…”

Bayesian inverse modeling and source location of an unintended <sup>131</sup>I release in Europe in the fall of 2011

“…FLEXPART (FLEXible PARTicle dispersion model) is a scientific model used worldwide by many research groups and also operationally, e.g., at the Comprehensive Nuclear-TestBan Treaty Organization for routine atmospheric backtracking (Kalinowski et al, 2008). In this work we used version 9.2 (Stohl et al, 2005).…”

Radioxenon Time Series and Meteorological Pattern Analysis for CTBT Event Categorisation

“…In order to ensure the quality and accuracy of the IMS noble gas measurement capabilities, it is of eminent importance to characterise the noble gas background (BOWYER et al, 1997;WEISS et al, 1997;IGARASHI et al, 2000;STOCKI et al, 2005;KALINOWSKI and PISTNER, 2006;KALINOWSKI et al, 2008;SAEY, 2009). It is important for the assessment of measurements also to calculate and analyse the source-receptor relationships (WOTAWA et al, 2003;STOHL et al, 2005;BECKER et al, 2007).…”