- Link:
- http://hdl.handle.net/1721.1/33639
- Collection:
-
- Subject
- Nuclear Engineering.
- Creator:
- Zhu, Yingli, 1976-
- Contributors:
- Michael W. Golay. Massachusetts Institute of Technology. Dept. of Nuclear Engineering. Massachusetts Institute of Technology. Dept. of
Nuclear Engineering.
- Format
- 200 p.
- Format
- 9050776 bytes
- Format
- 9059212 bytes
- Format
- application/pdf
- Language
- eng
- Publisher
- Massachusetts Institute of Technology
- Rights
- M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See
provided URL for inquiries about permission.
- Rights
- http://dspace.mit.edu/handle/1721.1/7582
- Type
- Thesis
- Description
- The final outcome of a nuclear Probabilistic Risk
Assessment (PRA) is generally inaccurate and imprecise. This is
primarily because not all risk contributors are addressed in the
analysis, and there are state-of-knowledge uncertainties about
input parameters and how models should be constructed. In this
thesis, we formulate two measures, risk significance (RS) and risk
change significance (RCS) to examine these drawbacks and assess the
adequacy of PRA results used for risk-informed decision making. The
significance of an event within a PRA is defined as the impact of
its exclusion from the analysis on the final outcome of the PRA.
When the baseline risk is the final outcome of interest, we define
the significance of an event as risk significance, measured in
terms of the resulting percentage change in the baseline risk. When
there is a proposed change in plant design or activities and risk
change is the final outcome of interest, we define the significance
of an event as risk change significance, measured in terms of the
resulting percentage change in risk change. These measures allow us
to rank initiating events and basic events in terms of relative
importance to the accuracy of the baseline risk and risk
change.
- Description
- (cont.) This thesis presents general approaches to
computing the RS and RCS of any event within the PRA. Our
significance measures are compared to traditional importance
measures such as Fussell-Vesley (FV), Risk Achievement Worth (RAW),
and Risk Reduction Worth (RRW) to gauge their effectiveness. We
investigate the use of RS and RCS to identify events that are
important to meet the decision maker's desired degree of accuracy
of the baseline risk and risk change. We also examine the use of
95th confidence level acceptance guideline for assessing the
adequacy of the uncertainty treatment of a PRA. By comparing PRA
results with the desired accuracy and precision level of risk and
risk change, one can assess whether PRA results are adequate enough
to support risk-informed decisions. Several examples are presented
to illustrate the application and advantages of using RS and RCS
measures in risk-informed decision making. We apply our frame- work
to the analysis of the component cooling water (CCW) system in a
pressurized water nuclear reactor. This analysis is based upon the
fault tree for the CCW system presented in the plant's PRA
analysis.
- Description
- (cont.) One result of our analysis is an estimate
of the importance of common cause failures of the CCW pumps to the
accuracy of plant core damage frequency (CDF) and change in
CDF.
- Description
- by Yingli Zhu.
- Description
- Thesis (Ph. D.)--Massachusetts Institute of
Technology, Dept. of Nuclear Engineering, 2004.
- Description
- Includes bibliographical references (p.
194-200).
- Rights
- M.I.T. theses are protected by copyright. They may be
viewed from this source for any purpose, but reproduction or
distribution in any format is prohibited without written
permission. See provided URL for inquiries about
permission.
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