Engineered Safety Features Research Articles

General design criteria for diesel-generator sets for nuclear power plants

This paper covers the design criteria for Diesel-Generators for Nuclear Power Plants. It deals with applicable standards, loading, design performance, and characteristics to be considered in the selection of diesel-generator set and its auxiliary system. This paper also discusses engineered safety features loads together with loss of power safe shutdown loads and their starting sequence, analysis of voltage and frequency response and the diesel-generator ability to start various load blocks successfully to meet the Reactor Emergency core cooling requirements.

Design Considerations for Meeting Separation Criteria for Class IE Systems within the Control Board

The logic diagram for an engineered safety features protection system is shown in Figure 1. The engineered safety feature system is similar for Babcock and Wilcox, Combustion Engineering, General Atomic, General Electric, and Westinghouse. As a result, the system will be used to illustrate the design considerations and techniques for meeting separation criteria for Class 1 systems. The engineered safety features system employs local coincidence logic. The system uses transmission logic, i.e., the transmission of electric power is required to initiate protective action. Transmission logic is used to prevent unwanted actuation of engineered safety features in the event of loss of electric power or safe channel failure. The system has three instrument channels for each variable. Bistable trip signals from the three instrument channels for each variable are fed to two two-of-three logic matrices; one for logic channel A and one for logic channel B. Two-of-three logic matrices are provided for each variable in both logic channels. The output of each two-of-three logic matrix is transmitted to a one-of-one logic matrix or actuator module which acts to transmit power to engineered safety feature equipment. Either output logic channel is capable of actuating the engineered safety features. In logic language, a one-of-three logic arrangement of three sets of three instrument trip signals and a one-of-one logic arrangement of two logic channels and electrical energizing signals initiate the engineered safety features actuation.1

The PWR Protection System - Present and Future

In a nuclear power generating station, the system used to protect the reactor and its containment is the plant protection sytem. The pressurized-water-reactor (PWR) protection systems encompass all electrical and mechanical devices and circuitry (from sensors to actuated device input terminals) involved in generating those signals associated with the protective function. These signals include actuation signals for the Reactor Protection System (RPS) and Engineered Safety Features System (ESFS) such as Safety Injection Actuation System, Containment Spray Actuation System, Main Steam Isolation System, Auxiliary Feedwater Actuation System, and Recirculation Actuation System. This paper deals with the present status and future development of the Plant Protection Systems utilized by Combustion Engineering, Inc. (C-E) and Kraftwerk Union (KWU) for their Pressurized Water Reactors. The latest techniques of signal processing, logic design, reactor trip and engineered safety features actuation circuitry, automatic testing, isolation and interfacing, are discussed. Current system design criteria, which as a result of the dynamic national and international licensing atmospheres influence system design philosophies, are highlighted.

Engineered Safety Features System by Solid State

One of the protection systems in the nuclear power plant is the engineered safety features system. The design of an engineered safety features system, utilizing solid state circuitry, is presented in the following. The solid state engineered safety features system provides a flexible, accurate, compact and reliable system. This is accomplished by selecting components with low failure rate, dividing actuation channels into multiple subchannels, including the diesel generator load sequencing and bus load shedding, and incorporating unique built-in test features. The solid state design facilitates periodic testing while the reactor is in operation. This paper describes these features and their correlation to published standards and guides for protection systems.

Air cleaning as an engineered safety feature in light-water-cooled power reactors. ORNL-NSIC-25.

Air cleaning as an engineered safety feature in light-water-cooled power reactors. ORNL-NSIC-25.