HF Verification and Validation Activities: Simulator Based Operational Trials

Changes to shutdown system (SDS) software were made at the Darlington Nuclear Generating Station. This is a four unit CANDU (Canadian Deuterium Uranium) nuclear power station located on the north shore of Lake Ontario (each unit is approximately 900 MW). These changes were initiated through an agreement with the Canadian nuclear regulator to improve the maintainability of the safety critical software. In addition, a number of functional changes were made, based on operational experience, to improve the operability and maintainability of the shutdown systems as a whole. The integration of Human Factors Engineering (HFE) into the systems design process was achieved using a Human Factors Engineering Program Plan (see Beattie and Malcolm, 1991 for a discussion of this type of planning document). The HFE program steps were taken from NUREG 0711 - Human Factors Engineering Program Review Model (U.S. NRC, 1994). The program plan included formal HFE Verification and Validation, culminating with operational trials in the full-scale control room training simulator. Results indicated that all functional changes passed on all performance criteria, and that the measures showed a high degree of convergent validity.