Methods for Comparative Assessment of Active and Passive Safety Systems
Name
ANP-120.pdf
Description
ANP-120.pdf
Size
1.64 MB
Format
Adobe PDF
Checksum (MD5)
1eab28f8b040d1cfc3a3ae14a0555cec
Author(s)
Oh, Jiyong
Golay, Michael W.
Date Issued
February 2008
Publisher
Massachusetts Institute of Technology. Center for Advanced Nuclear Energy Systems. Advanced Nuclear Power Program
Series/Report no.
MIT-ANP;TR-120
Abstract
Passive cooling systems sometimes use natural circulation, and they are not dependent on
offsite or emergency AC power, which can simplify designs through the reduction of
emergency power supplying infrastructure. The passive system approach can lead to
substantial simplification of the system as well as overall economic benefits, and passive
systems are believed to be less vulnerable to accidents by component failures and human
errors compared to active systems. The viewpoint that passive system design is more
reliable and more economical than active system design has become generally accepted.
However, passive systems have characteristics of a high level of uncertainty and low
driving force for purposes of heat removal phenomena; these characteristics can result in
increasing system unreliability and may raise potential remedial costs during a system’s
lifetime.
This study presents a comprehensive comparison of reliability and cost taking into
account uncertainties and introduces the concept of flexibility using the example of active
and passive residual heat removal systems in a PWR. The results show that the active
system can have, for this particular application, greater reliability than the passive
system. Because the passive system is economically optimized, its heat removal capacity
is much smaller than that of the active system. Thus, functional failure probability of the
passive system has a greater impact on overall system reliability than the active system.
Moreover, considering the implications of flexibility upon remedial costs, the active
system may be more economical than the passive system because the active system has
flexible design features for purposes of increasing heat removal capacity.
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