Safety Issues and Approach to Meet the Safety Requirements in Tokamak Cooling Water System of ITER
- ORNL
- ITER Organization, Saint Paul Lez Durance, France
The ITER (Latin for 'the way') tokamak cooling water system (TCWS) consists of several separate systems to cool the major ITER components - the divertor/limiter, the first wall blanket, the neutral beam injector and the vacuum vessel. The ex-vessel part of the TCWS systems provides a confinement function for tritium and activated corrosion products in the cooling water. The Vacuum Vessel System also has a functional safety requirement regarding the residual heat removal from in-vessel components. A preliminary hazards assessment (PHA) was performed for a better understanding of the hazards, initiating events, and defense in depth mechanisms associated with the TCWS. The PHA was completed using the following steps. (1) Hazard Identification. Hazards associated with the TCWS were identified including radiological/chemical/electromagnetic hazards and physical hazards (e.g., high voltage, high pressure, high temperature, falling objects). (2) Hazard Categorization. Hazards identified in step (1) were categorized as to their potential for harm to the workers, the public, and/or the environment. (3) Hazard Evaluation. The design was examined to determine initiating events that might occur and that could expose the public, environment, or workers to the hazard. In addition the system was examined to identify barriers that prevent exposure. Finally, consequences to the public or workers were qualitatively assessed, should the initiating event occur and one or more of the barriers fail. Frequency of occurrence of the initiating event and subsequent barrier failure was qualitatively estimated. (4) Accident Analysis. A preliminary hazards analysis was performed on the conceptual design of the TCWS. As the design progresses, a detailed accident analysis will be performed in the form of a failure modes and effects analysis. The results of the PHA indicated that the principal hazards associated with the TCWS were those associated with radiation. These were low compared to hazards associated with nuclear fission reactors and were limited to potential exposure to the on-site workers if appropriate protective actions were not used. However, the risk to the general public off-site was found to be negligible even under worst case accident conditions.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); ITER Organization, St. Paul Lez Durance (France)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 1000888
- Resource Relation:
- Conference: The Ninth International Symposium on Fusion Nuclear Technology, Dalian, China, 20091011, 20091016
- Country of Publication:
- United States
- Language:
- English
Similar Records
Drain Tank Information for Developing Design Basis of the Preliminary Design - R00
Chemical Hazards and Safety Issues in Fusion Safety Design