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Plant Protection System
Published in G. Vaidyanathan, Dynamic Simulation of Sodium Cooled Fast Reactors, 2023
The reactor protection system should be able to safely shut down the reactor before the consequences following the events exceed their respective category limits. All the events have been analyzed without considering any safety action to determine the time at which the process values of various SCRAM parameters reach their respective thresholds. Analysis has also been carried out by considering reactor SCRAM by insertion of rods by SDS-1 or SDS-2 at various instants following the events to estimate the maximum allowable SCRAM initiation time such that the DSL are not exceeded. While analyzing SCRAM by SDS-1, single failure of one CSR is considered, and the shutdown is effected by dropping eight CSRs. Similarly, while analyzing SCRAM by SDS-2, a single failure of one DSR is considered, and the shutdown is effected by dropping two DSRs.
Loss of Cooling
Published in Geoffrey F. Hewitt, John G. Collier, Introduction to Nuclear Power, 2018
Geoffrey F. Hewitt, John G. Collier
In some designs—for example, the British PWR, Sizewell B—the reactor protection system itself consists of two diverse systems: the primary protection system and the secondary protection system. The primary protection system is a microprocessor-based system that provides reactor trip and actuation of the engineered safety systems. The secondary protection system utilizes magnetic logic relays to initiate the reactor trip and engineered safety systems independent of the primary protection system.
Pressurized Water Reactors
Published in Kenneth D. Kok, Nuclear Engineering Handbook, 2016
The instrumentation and control systems can be viewed as the “central nervous system” of the plant and consist of the following major systems: Nuclear instrumentation system—Provides continuous indications of the reactor core power level from shutdown to full power.In-core instrumentation system—Senses the distribution of the nuclear flux within the core.Digital rod position indication system—Detects the position of the control rods in the reactor core.Process instrumentation system—Senses the state of the plant, when used together with the nuclear instrumentation, in-core instrumentation, and digital rod position indication system.Nuclear steam supply control system—Implements the operator’s control decisions and automatically changes the plant to and maintains it at selected operating states.Reactor protection system—Protects the reactor core and the NSSS by monitoring operating parameters and initiating safeguard actions on the detection of abnormal conditions.The control room—Provides information to the operator to enable him/her to comprehend the plant’s state and to make and implement operating decisions. Increasingly, ergonomic considerations have come to dominate the design of the layout: immediately in front of the operator are the controls and read-outs for normal operation. Up a little higher on the panel are instruments that show the effect of control manipulations, together with setpoint limits on key variables. Above that display are the alarms and signals of upset and accident conditions. All key instrumentation for each panel is within sight of the operator. Panels are arranged from the reactor and its auxiliaries, to the secondary systems, to the tertiary plant systems, and finally the electrical systems and their adjuncts. Arrangements are logical for normal power operation, shutdown and maintenance configurations, and emergency operations.Plant computer system—Provides computational, data processing, and data presentation services for the plant. Flow maps and instrumentation diagrams may be called-up and data-logged to allow sequence analysis after events. Computers are especially valuable in the training center to model the reactor and all other systems, and to simulate upset and accident conditions that could not be conducted on the actual plant. This tool is also important in the development of emergency procedures.
Scaling Methodology for Integral Effects Tests in Support of Fluoride Salt–Cooled High-Temperature Reactor Technology
Published in Nuclear Science and Engineering, 2020
Nicolas Zweibaum, Edward Blandford, Craig Gerardi, Per Peterson
The natural circulation class of scenarios assumes that from normal operation conditions (as described in Sec. III.B), the primary pumps trip because of some initiating event (e.g., pump motor failure, loss of heat sink, station blackout). The reactor protection system is actuated as off-normal conditions are detected, and the reactor scrams. Because the primary salt pumps shut down and no active auxiliary cooling is initiated, the simplified scenario involves a transition to natural circulation in the PHTS where only the density difference in the loop between the reactor core and heat removal system causes the primary salt to circulate. The systems and components credited for decay heat removal in the context of this paper are used for illustration of the scaling methodology only and do not reflect the actual KP-FHR system used for passive residual heat removal. This example is similar to the approaches taken in previous studies.4,13,14