There are many shift patterns employed in the conduct of operations, from four shift cycles to seven or eight. The important considerations are that they afford some continuity between shifts and provide ample opportunity for training. It is also recognised that alertness levels can vary throughout any given 24-hour period and so such factors should be taken into consid­eration when designing shift patterns.

In most cases shift ‘teams’ are kept together in the interest of promoting teamwork and effectiveness. The airline industry, however, is more con­cerned that familiarity between flight crews could have an adverse effect on performance, so they promote regular refreshment in their flight crews. There is considerable evidence to support the airline industry view. Shift teams that work together form group norms and habits, together with a reluctance to challenge each other’s standards.

It is also true that shift teams are not exposed to the same operational experience. Normally attempts are made to cross-fertilise experience across the shifts through training scenarios, but much experience is not covered in this way and one of the few ways where it can be promoted is through regular interchange of personnel between shifts.

5.9.2 Simulator training

When managing fault situations there is no substitute for the fundamental training that operators receive to qualify them for their roles. Such training enables them to make discerning decisions based on their knowledge and experience. Simulator training (see Appendix 4) can demonstrate to the operators the relevance of such knowledge and the effectiveness of deci­sions they make in transient and fault situations. Much more than that, it enables the operators to practise and perfect their actions and responses to both frequently and infrequently performed plant evolutions.

In addition to improving the man-machine interfaces, simulator training is an important platform for improving human performance at both the individual and group levels. Simulator scenarios that do not cover this are missing important opportunities to enhance performance.

Regular training on simulators can be clearly demonstrated to improve both safety and reliability. Most experience suggests that simulators are most effectively utilised when they are close to the nuclear power plant sites. Although practices differ in this respect, the trend is towards site — based simulators.