Plant operation total power failure

In some cases, the operation of a plant depends on the pumping of feed. In such a system, total power failure will result in loss of feed and, in turn, may stop any substantial relief from the plant. However, if the feed pump is partly turbine driven, feed will be available at a reduced rate, and the relief can be significantly higher. 

Over a total period of power plant operation 2 failures of the pumps have occurred both leading to the power reduction of the plant with a loop disconnection, i.e. in 1980 the motor and tachometer generator shaft coupling failed and in 1985 the electric motor brush unit failed. 

Totally 104 failures have occurred over a total operation period. The abnormal operation events due to equipment and system failures resulted in 28 plant shutdowns of which 18 shutdowns involved reactor scrams (5 events involved manual reactor emergency shutdowns). In the remainder the plant power reductions took place. 

The AFC-based power plants for Apollo and Orbiter spacecrafts described above have been used for numerous flights and attained a total operating time of tens of thousands of hours. Systematic long-term tests of simpler power plants for terrestrial applications have hardly been reported in the literature. It was said that, in a number of tests, the time to failure was 2000-3000 h. 

This process of event classification, in which initiators of all types, both internal and external to the plant, and all modes of operation, including normal operation, shutdown and refuelling, are considered, should lead to a list of different classes of plant specific events to be analysed. Different plant conditions, such as manual control or automatic control, should be investigated. Different site conditions, such as the availability of off-site power or the total loss of off-site power, should also be evaluated, with account taken of the possible interactions between plant manoeuvres and the grid and, where appropriate, possible interactions between different reactor units on the same site. Failures in other plant systems, such as the storage for irradiated fuel and storage tanks for radioactive gas, should also be considered. 

---