Risk analysis with dynamic safety measure for pressurized water reactors with advanced safety features
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Authors
Shah, Asad Ullah Amin
Issue Date
2023-08
Type
Electronic thesis
Thesis
Thesis
Language
en_US
Keywords
Nuclear engineering
Alternative Title
Abstract
After the Fukushima Daiichi Accident, the US Department of Energy initiated the LightWater Sustainability Program to investigate safety options for existing nuclear fleets, such as
accident-tolerant fuel and US diverse and flexible coping strategies. As these safety options are
relatively new, developing a framework that can assess their risk and benefits effectively is
essential. A dynamic probabilistic risk assessment framework is suggested to analyze the risk and
safety of these options during abnormal deviations or accidents. The framework can explicitly
highlight the risk and safety benefits of the existing and new safety systems, perform sensitivity
analysis of physical parameters and optimize the value of design variables of the system and
components.
The risk and sensitivity analysis has been demonstrated by leveraging the suggested
framework for analyzing two diverse accident scenarios: Station blackout and medium break loss
of coolant accident. A CDF- based benefit index and included in the framework can assess the risk
margin offered by the existing or the new safety options and provide a mathematical way of
comparing those. Additionally, a new concept design for forced safety injection tanks has been
suggested. The feasibility of this system has been demonstrated by modeling and integrating this
new system into the nuclear power plant model and analyzing the risk benefits. The presented
DPRA framework is further leveraged to optimize the FSIT's design parameters, such as actuation
set-point or the delays between the series operation of FSITs.
Since time is crucial during an accident evolution, a time-based dynamic event importance
index is introduced that supports the operator in deciding how much resources he should invest for
each component to recover the lost safety function. This measure provides reliability and timebased
component importance and ranks them for the operator to allocate resources to restore those
components. This measure is compared with the conventional measures. Then efforts are made to
estimate the cost savings from re-categorizing the safety components from RISC1 and RISC2
safety classification to RISC3 and RISC4, respectively.
Description
August2023
School of Engineering
School of Engineering
Full Citation
Publisher
Rensselaer Polytechnic Institute, Troy, NY