Nuclear Production of Hydrogen, Fourth Information Exchange ...

USE OF PSA FOR DESIGN OF EMERGENCY MITIGATION SYSTEMS IN A HYDROGEN PRODUCTION PLANT
Emergency flushing system (EFS)
This system is similar to that of neutralisation, however the EFS pumps only pure water to the leak
area. It functions as a rinse, and due to the high volume it handles, it can dilute the acid spill to
innocuous concentrations. Because the EFS can produce violent reactions during the first moments of
its actuation, it should be employed only as a final measure.
System activation is given by the EAS-300 logic, when a low calcium carbonate concentration or
low flow is detected by AI302 and FI301 analysers, as shown in Figure 5.
EFS shares its electric back-up with the neutralisation system.
Figure 5: Emergency flushing system EAS-400
Event tree
The event tree of this study considers the three elements of mitigation system that are described in
the previous section. The sequence that conducts to the critical end state can be identified in Figure 6
as sequence 4, and corresponds to toxic cloud formation.
Figure 6: Event tree in Saphire® 6.0
Initiating event Mitigation systems Sequence End state
402 NUCLEAR PRODUCTION OF HYDROGEN – © OECD/NEA 2010