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Title: Advanced Reactor Passive System Reliability Demonstration Analysis for an External Event

Abstract

We report that many advanced reactor designs rely on passive systems to fulfill safety functions during accident sequences. These systems depend heavily on boundary conditions to induce a motive force, meaning the system can fail to operate as intended because of deviations in boundary conditions, rather than as the result of physical failures. Furthermore, passive systems may operate in intermediate or degraded modes. These factors make passive system operation difficult to characterize within a traditional probabilistic framework that only recognizes discrete operating modes and does not allow for the explicit consideration of time-dependent boundary conditions. Argonne National Laboratory has been examining various methodologies for assessing passive system reliability within a probabilistic risk assessment for a station blackout event at an advanced small modular reactor. This paper provides an overview of a passive system reliability demonstration analysis for an external event. Considering an earthquake with the possibility of site flooding, the analysis focuses on the behavior of the passive Reactor Cavity Cooling System following potential physical damage and system flooding. The assessment approach seeks to combine mechanistic and simulation-based methods to leverage the benefits of the simulation-based approach without the need to substantially deviate from conventional probabilistic risk assessment techniques. Lastly,more » although this study is presented as only an example analysis, the results appear to demonstrate a high level of reliability of the Reactor Cavity Cooling System (and the reactor system in general) for the postulated transient event.« less

Authors:
 [1];  [1];  [1];  [1]
  1. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Nuclear Energy (NE)
OSTI Identifier:
1343460
Alternate Identifier(s):
OSTI ID: 1356579
Grant/Contract Number:
AC02-06CH11357
Resource Type:
Journal Article: Published Article
Journal Name:
Nuclear Engineering and Technology
Additional Journal Information:
Journal Volume: 49; Journal Issue: 2; Journal ID: ISSN 1738-5733
Publisher:
Korean Nuclear Society
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; 42 ENGINEERING; Advanced Reactor PSA; Passive System Reliability; Reactor Cavity Cooling System; Risk Assessment

Citation Formats

Bucknor, Matthew, Grabaskas, David, Brunett, Acacia J., and Grelle, Austin. Advanced Reactor Passive System Reliability Demonstration Analysis for an External Event. United States: N. p., 2017. Web. doi:10.1016/j.net.2017.01.005.
Bucknor, Matthew, Grabaskas, David, Brunett, Acacia J., & Grelle, Austin. Advanced Reactor Passive System Reliability Demonstration Analysis for an External Event. United States. doi:10.1016/j.net.2017.01.005.
Bucknor, Matthew, Grabaskas, David, Brunett, Acacia J., and Grelle, Austin. Tue . "Advanced Reactor Passive System Reliability Demonstration Analysis for an External Event". United States. doi:10.1016/j.net.2017.01.005.
@article{osti_1343460,
title = {Advanced Reactor Passive System Reliability Demonstration Analysis for an External Event},
author = {Bucknor, Matthew and Grabaskas, David and Brunett, Acacia J. and Grelle, Austin},
abstractNote = {We report that many advanced reactor designs rely on passive systems to fulfill safety functions during accident sequences. These systems depend heavily on boundary conditions to induce a motive force, meaning the system can fail to operate as intended because of deviations in boundary conditions, rather than as the result of physical failures. Furthermore, passive systems may operate in intermediate or degraded modes. These factors make passive system operation difficult to characterize within a traditional probabilistic framework that only recognizes discrete operating modes and does not allow for the explicit consideration of time-dependent boundary conditions. Argonne National Laboratory has been examining various methodologies for assessing passive system reliability within a probabilistic risk assessment for a station blackout event at an advanced small modular reactor. This paper provides an overview of a passive system reliability demonstration analysis for an external event. Considering an earthquake with the possibility of site flooding, the analysis focuses on the behavior of the passive Reactor Cavity Cooling System following potential physical damage and system flooding. The assessment approach seeks to combine mechanistic and simulation-based methods to leverage the benefits of the simulation-based approach without the need to substantially deviate from conventional probabilistic risk assessment techniques. Lastly, although this study is presented as only an example analysis, the results appear to demonstrate a high level of reliability of the Reactor Cavity Cooling System (and the reactor system in general) for the postulated transient event.},
doi = {10.1016/j.net.2017.01.005},
journal = {Nuclear Engineering and Technology},
number = 2,
volume = 49,
place = {United States},
year = {Tue Jan 24 00:00:00 EST 2017},
month = {Tue Jan 24 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.net.2017.01.005

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  • We report that many advanced reactor designs rely on passive systems to fulfill safety functions during accident sequences. These systems depend heavily on boundary conditions to induce a motive force, meaning the system can fail to operate as intended because of deviations in boundary conditions, rather than as the result of physical failures. Furthermore, passive systems may operate in intermediate or degraded modes. These factors make passive system operation difficult to characterize within a traditional probabilistic framework that only recognizes discrete operating modes and does not allow for the explicit consideration of time-dependent boundary conditions. Argonne National Laboratory has beenmore » examining various methodologies for assessing passive system reliability within a probabilistic risk assessment for a station blackout event at an advanced small modular reactor. This paper provides an overview of a passive system reliability demonstration analysis for an external event. Considering an earthquake with the possibility of site flooding, the analysis focuses on the behavior of the passive Reactor Cavity Cooling System following potential physical damage and system flooding. The assessment approach seeks to combine mechanistic and simulation-based methods to leverage the benefits of the simulation-based approach without the need to substantially deviate from conventional probabilistic risk assessment techniques. Lastly, although this study is presented as only an example analysis, the results appear to demonstrate a high level of reliability of the Reactor Cavity Cooling System (and the reactor system in general) for the postulated transient event.« less
  • Many advanced reactor designs rely on passive systems to fulfill safety functions during accident sequences. These systems depend heavily on boundary conditions to induce a motive force, meaning the system can fail to operate as intended due to deviations in boundary conditions, rather than as the result of physical failures. Furthermore, passive systems may operate in intermediate or degraded modes. These factors make passive system operation difficult to characterize within a traditional probabilistic framework that only recognizes discrete operating modes and does not allow for the explicit consideration of time-dependent boundary conditions. Argonne National Laboratory has been examining various methodologiesmore » for assessing passive system reliability within a probabilistic risk assessment for a station blackout event at an advanced small modular reactor. This paper provides an overview of a passive system reliability demonstration analysis for an external event. Centering on an earthquake with the possibility of site flooding, the analysis focuses on the behavior of the passive reactor cavity cooling system following potential physical damage and system flooding. The assessment approach seeks to combine mechanistic and simulation-based methods to leverage the benefits of the simulation-based approach without the need to substantially deviate from conventional probabilistic risk assessment techniques. While this study is presented as only an example analysis, the results appear to demonstrate a high level of reliability for the reactor cavity cooling system (and the reactor system in general) to the postulated transient event.« less
  • UHV dc transmission is receiving increasing attention as a means of bulk power transmission. From this standpoint, enhancement of UHV dc transmission reliability is important. This problem has not been discussed on a wide basis although the reliability of the ac-dc converter and dc line lightning fault prediction have been discussed. The reliability of a dc transmission system on a wide basis is analyzed. Basically, an application of ETA (Event Tree Analysis) method is used in the analysis.
  • This paper deals with the reliability assessment of passive systems that have been developed in recent years by suppliers, industries, utilities, and research organizations, aimed at plant safety improvement and substantial simplification in its implementation. The present study concerns the passive decay heat removal systems that use, for the most part, a condenser immersed in a cooling pool. The focus of the paper is a reliability study of the isolation condenser system foreseen for advanced boiling water reactors (BWRs) for the removal of the excess sensible and core decay heat from the BWR by natural circulation. Furthermore, an approach aimedmore » at the thermal-hydraulic performance assessment (i.e., the natural circulation failure evaluation) from the probability point of view is given. The study is not plant-specific-related but pertains to the conceptual design of the foregoing system.« less
  • The simplified boiling water reactor makes use of an isolation condenser (IC) submerged in a large water pool; following a postulated accident, the pool water boils off, releasing steam to the atmosphere and ensuring passive containment cooling for at least 3 days. A further improvement is the isolation condenser pool cooling system (ICPCS), proposed by ENEL/CISE. It makes use of reflux condensing heat exchangers directly connected to the pool gas space of the IC; noncondensable gases can be vented during the earlier phase of operation by means of a water seal mechanism operating in a passive way. The expected benefitsmore » from the ICPCS are the elimination of constraints on the ``grace period`` duration and the possibility of avoiding an extended release of a visible and potentially radioactive steam plume. To verify the performance both at component and system level, and instrumented ICPCS prototype, operating with a thermal power scaling factor of {approximately}1:615, has been built and tested at CISE laboratories, both in steady and dynamic conditions. The experimental results confirm the capability of the tested ICPCS module to operate in a safe and passive way.« less