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The Wendelstein 7-X (W7-X) safety instrumented system (SIS) ensures personnel safety and investment protection. The development and implementation of the SIS are based on the international safety standard for the process industry sector, IEC 61511. The SIS is based on a distributed and hierarchically organized architecture consisting of a central safety system (cSS) on the top and many local safety systems (lSS). Each technical component or diagnostic system potentially hazardous to staff or the device is equipped with an lSS, which is responsible for the safety of the component. On the other hand, the cSS ensures safety of the W7-X device as a whole and is part of the central control system of W7-X. For every operation phase of the W7-X experiment, hardware and software updates for the SIS are mandatory. New components with additional lSS functionality and additional safety signals have to be integrated. Already established safety functions must be adapted and new safety functions have to be implemented in the cSS. Finally, the safety programs of the central and lSS have to be verified for every development stage and validated against the safety requirement specification. This paper focuses on the application of a model-based simulation system for the whole SIS of W7-X. A brief introduction into the development process of the SIS and its technical realization will be given followed by a description of the design and implementation of the SIS simulation system using the framework SIMIT (Siemens). Finally, the first operational experience of this simulation system for the preparation of the SIS for the upcoming operation phase OP 1.2b of W7-X will be discussed. [ABSTRACT FROM AUTHOR]

The Wendelstein 7-X superconducting stellarator is a fusion experiment designed for processing of plasma discharges in the range of some seconds up to 30 min in a quasi-steady state operation mode. The first plasma experiment was conducted in December 2015. Since this first plasma experiment, more than 100 experimental days with about 3500 plasma experiments were successfully performed within three operational phases. The operation of W7-X requires the handling of many different sources of hazards with different hazardous potentials for persons and for the device. To identify critical hazards, risk analyses and risk assessments are carried out at an early stage in the development process for all W7-X technical components and diagnostics, so that measures for risk mitigation can be taken into account already in the design. The main objective of this process is to ensure safe operation for the personnel and to protect the investment in the W7-X device. In this work, we present the safety model for W7-X operation. After a brief introduction to the architecture of the W7-X control system, the process of regarding the safety requirements will be discussed. In addition, the multi-shell safety model for the technical implementation of risk mitigation functions at the various levels of the W7-X control system is described. The experiences at W7-X during the previous operating phases obtained with the implemented safety concept will be described. Finally, a preview of the enhancements and modifications of the safety systems for the next operation phase OP2, which will start in 2021, is given. [ABSTRACT FROM AUTHOR]