Worker health and safety in solar thermal power systems. V. Off-normal events

In addition to routine events, off-normal events can be expected to affect worker health and safety. Reflecting the distributed nature of solar energy, collector subsystem response to off-normal events may not be as controllable as, for example, the power in a fossil fueled power plant. The consequences are reflected within the receiver subsystem in the effect of mismatches in energy flows. For example, collectors are required to shut-down during an interruption of coolant flow (ICF) to the receiver, or in the event of a loss of energy sink (LES) in the coolant loop. The time allowed for this shut-down is dictated by the desire to maintain integrity in the coolant loop and other components, since their failure is both a potential hazard to workers and economically undesirable. Several methods of achieving shut-down exist, each with its own characteristic time and reliability. These times are compared to assessments of the interval before loss of integrity during an ICF and an LES in selected receivers and coolant loops.