Very high temperature reactor safety

Ingersoll, D. T., et al. 2005, Status ofPhysics and Safety Analyses for the Liquid-Salt-Cooled Very High-Temperature Reactor (LS-VHTR), ORNL/TM-2005/218, Oak Ridge National Laboratory,... 

Very-high—temperature reactor (VHTR) safety (Class G) Restricted to 600 MW (thermal) huge thermal inertia of graphite structure and matrix fuel not damaged below 1600°C, single-phase inert coolant. 

Gas-cooled fast reactor (GFR) safety (Class G) Very-high—temperature fuel complex engineered safety systems. 

Research reactors themselves tend to have a very different set of safety-related parameters from power reactors. Some are helpful differences like simplicity, relatively low power, and low-temperature coolant. Other differences, especially the need for a high-power density core, pose challenges not faced in a power reactor. These challenges can be met through thoughtful design solutions. 

Since the number of LOR and scram during high power operations was very high, an exercise was carried out to optimize the trip parameters. As a first step, high winding temperature trips of sodium pump drive system motors (88 No) were deleted and control panels of these systems were housed in an air conditional atmosphere. These steps have vastly improved performance of the drive system. As second step the trip parameters of reactor protection system were reviewed and the following modifications were carried out to improve the reliability of the system without compromising the safety. 

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