Albert William Crew

Multiprocessor shared-memory information exchange

In distributed microprocessor-based instrumentation and control systems, the inter- and intra-subsystem communication requirements ultimately form the basis for the overall system architecture. The authors describe a software protocol which addresses the intra-subsystem communications problem. Specifically, the protocol allows for multiple processors to exchange information via a shared-memory interface. Their primary goal is to provide a reliable means for information to be exchanged between central application processor boards (masters) and dedicated function processor boards (slaves) in a single computer chassis. The resultant Multiprocessor Shared-Memory Information Exchange (MSMIE) protocol, a standard master-slave shared-memory interface suitable for use in nuclear safety systems, is designed to pass unidirectional buffers of information between the processors while providing a minimum, deterministic cycle time for this data exchange. >

Diagnostic software and hardware for critical real-time systems

The authors describe a diagnostic software library which contains algorithms to test read-only memory, read/write memory, address lines, the main processor instruction set, the numeric data processor instruction set, and mutual exclusion hardware. The software library also contains algorithms to respond to unexpected software interrupts. A dedicated subsystem diagnostics board called the Multibus Diagnostic Monitor (MDM) is also described. >

Microprocessor-Based Architecture for a Modular Process Protection Upgrade System

The Westinghouse Process Protection Upgrade System (Eagle 21TM) is a functional replacement for the existing analog process protection equipment used to monitor nuclear generating stations and actuate the reactor trip and engineering safeguards systems as required. However, the Eagle 21TM system does more than merely replace the existing analog hardware; it exploits the power of a functionally decentralized architecture with multiple independent microprocessorbased subsystems to increase plant availablity, reduce test time, reduce reconfiguration time, and increase the amount of information available to the operator and to new diagnostic systems. The architecture of the system is described and the major benefits are highlighted.

Microprocessor-Based Testing Increases Power Plant Availability

Commercial nuclear power plants need equipment that increases plant availability, reduces test time and is both self-diagnostic and user-friendly. Westinghouses Process Protection Upgrade System, called Eagle 21¿, is a functional replacement for existing analog process protection equipment used to monitor nuclear power stations and to initiate the actuation of the reactor trip and engineering safeguards systems. Periodic testing of this protection equipment is required by industry regulations, and the advent of microprocessor systems has made it possible for plant test personnel to do this required testing in a short time, with great precision, and with few or no errors. The architecture of the testing system is described and the major benefits are highlighted.

Process Protection Software Structure and Design Philosophy

In the development of microprocessor-based systems that play a critical role in the operation of nuclear power plants, careful thought must be given to software design. To achieve the dual goals of system reliability and availability, the software must perform predictably at all times, be easily tested and verified, easily expanded to meet new customer or regulatory requirements, and easily adapted for each individual plant. The design criteria and development methods used in the development of the safety grade software for the Eagle 21TM Process Protection System are described.