The introduction of passive systems is regarded as one of the most important factors for safety increase of Gen III/III+ reactors, as well as for the development of small reactor size or the SMR (Small Modular Reactors). However, more detailed studies reveal how such an advantage deriving from the use of passive safety systems than the active ones is not so obvious: thus the assessment of the benefits and the challenges that the adoption of the two types of systems in the various reactors pose. The study is aimed at developing the methodical approach in order to identify the criteria suitable to drive the assessment process at the system level, regardless, in any case, of economic factors. For this reason both active and passive systems designed to accomplish the required safety functions, as the decay heat removal, have been deeply investigated mainly in terms of their safety performance and reliability shaping factors. Through a qualitatively conducted analysis, factors of both active and passive design are identified and compared on a reliability plane. The analysis points out the relevance of the reliability figure of merit as the most important criterion in the process of opting out of one system in favour of the other alternative. In particular any aspects like the functional failure probability and the large amount of uncertainties, are identified as most relevant factors affecting the system performance assessment in passive design. © 2017 by American Nuclear Society. All rights reserved.
Comparative assessment of passive and active systems for the development of advanced reactors
Burgazzi, L.
2017-01-01
Abstract
The introduction of passive systems is regarded as one of the most important factors for safety increase of Gen III/III+ reactors, as well as for the development of small reactor size or the SMR (Small Modular Reactors). However, more detailed studies reveal how such an advantage deriving from the use of passive safety systems than the active ones is not so obvious: thus the assessment of the benefits and the challenges that the adoption of the two types of systems in the various reactors pose. The study is aimed at developing the methodical approach in order to identify the criteria suitable to drive the assessment process at the system level, regardless, in any case, of economic factors. For this reason both active and passive systems designed to accomplish the required safety functions, as the decay heat removal, have been deeply investigated mainly in terms of their safety performance and reliability shaping factors. Through a qualitatively conducted analysis, factors of both active and passive design are identified and compared on a reliability plane. The analysis points out the relevance of the reliability figure of merit as the most important criterion in the process of opting out of one system in favour of the other alternative. In particular any aspects like the functional failure probability and the large amount of uncertainties, are identified as most relevant factors affecting the system performance assessment in passive design. © 2017 by American Nuclear Society. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
