Passive systems, noticeably those systems which are capable of transferring thermal power from a heat source to a sink, without the use of pumps relying on electrical power, are in use in nuclear technology since the pioneering design of reactors. They received a step-wise, fashion-type, renewed interest following the three major nuclear accidents (or catastrophes) in 1979, 1986 and 2011. The words thermal-hydraulic passive systems, design and safety, open to a myriad of research and application activities, which, without surprise, may appear contradictory and, at least, not converging into a common understanding. The present Committee on the Safety of Nuclear Installations (CSNI) activity has been planned with the aim to achieve an international consensus in relation to the evaluation of the reliability of passive systems, and to set-up and/or confirm the availability of suitable techniques and databases for the analysis. The outcomes of the activity are expected to trace the way within a multi-topics space by contributing to the design and the safety assessment of those systems. The key conclusion is: support of suitable analyses providing specific demonstration of adequacy in the design and operation of thermal-hydraulic passive systems, namely those based on natural circulation, is required to guarantee the safety of nuclear reactors relying on such systems. Additional conclusions are: (a) there are several options for protecting the core of nuclear reactors and for the safety of nuclear installations among them the passive systems are not the panacea in each foreseeable accident condition; the importance of non-passive systems, e.g. implying the use of active components like pumps, should not be discarded as suitable engineering answer to protect and to mitigate accident conditions; (b) licensing rules specific for passive systems are strictly needed and not yet completely formulated and agreed; (c) passive systems functions can be affected by mechanical failures, e.g. originated by thermal stress at start-up, which are not considered in this report (rather, those mechanical failures are considered by designers).
SOAR on Reliability of Thermal-Hydraulic Passive Systems (SOAR-RPS)
Di Maio, F.;Zio, E.;
2019-01-01
Abstract
Passive systems, noticeably those systems which are capable of transferring thermal power from a heat source to a sink, without the use of pumps relying on electrical power, are in use in nuclear technology since the pioneering design of reactors. They received a step-wise, fashion-type, renewed interest following the three major nuclear accidents (or catastrophes) in 1979, 1986 and 2011. The words thermal-hydraulic passive systems, design and safety, open to a myriad of research and application activities, which, without surprise, may appear contradictory and, at least, not converging into a common understanding. The present Committee on the Safety of Nuclear Installations (CSNI) activity has been planned with the aim to achieve an international consensus in relation to the evaluation of the reliability of passive systems, and to set-up and/or confirm the availability of suitable techniques and databases for the analysis. The outcomes of the activity are expected to trace the way within a multi-topics space by contributing to the design and the safety assessment of those systems. The key conclusion is: support of suitable analyses providing specific demonstration of adequacy in the design and operation of thermal-hydraulic passive systems, namely those based on natural circulation, is required to guarantee the safety of nuclear reactors relying on such systems. Additional conclusions are: (a) there are several options for protecting the core of nuclear reactors and for the safety of nuclear installations among them the passive systems are not the panacea in each foreseeable accident condition; the importance of non-passive systems, e.g. implying the use of active components like pumps, should not be discarded as suitable engineering answer to protect and to mitigate accident conditions; (b) licensing rules specific for passive systems are strictly needed and not yet completely formulated and agreed; (c) passive systems functions can be affected by mechanical failures, e.g. originated by thermal stress at start-up, which are not considered in this report (rather, those mechanical failures are considered by designers).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
