Jan Leen Kloosterman, TU-Delft

Mission

My research is inspired by the facts that the world population and the corresponding energy consumption steadily increase. All these people striving for a better quality of life, will double the energy consumption rate in only several decades from now. Although science and technology have made it possible to extract energy from ever dense power sources, from wood to coal to oil to gas to nuclear, we need to fully exploit all the energy sources available to meet future energy demands. Therefore, the mission of my research and that of the PNR research group is to contribute to the development of safe and sustainable nuclear energy. My research focuses on the following reactor types:

Very High Temperature Reactor (VHTR)

This reactor uses so-called TRISO particles that contain the fuel nuclides and fission products. These particles can resist very high temperatures, up to 1600 ^oC. For a well-designed reactor, and that's our job, there is no scenario in which the temperature of the TRISO particles will exceed this limit. If the temperature would increase too much, the fission chain reaction will stop and the remaining decay heat of the radioactive fission products will safely be transfered to the environment. Two reactor designs exist: one with a pebble-bed core and one with a prismatic core. No big difference for a reactor physicist like me, but for the engineer each core design has its own pros and cons. Simply said: the pebble-bed reactor can be fueled on-line, which is an advantage for some applications, while the prismatic core can operate a long time without refuelling, which is advantageous for other applications. For both reactor designs, a test reactor is in operation either in China (pebble-bed) or Japan (prismatic core). Both of them are cooled with helium.

My research focuses on methods to safely increase the outlet temperature of the helium coolant. This may give to a better efficiency of the electricity generation process, and lead to possibly new applications like nuclear hydrogen production via thermo-chemical water-splitting processes. Furthermore, the High Temperature Reactor may be fueled with Thorium, which is abundantly present in the earth's crust and which produces less hazardous long-lived nuclear waste.

A very special version of the HTR is called the Advanced High Temperature Reactor (AHTR) or the Liquid Salt-cooled High Temperature Reactor (LS-HTR), which is actually an HTR with a molten fluoride salt as a coolant. This design has several advantages, like a low-pressure primary circuit and better heat transfer from the fuel to coolant.

Molten Salt Reactor (MSR)

In this reactor, the fuel is mixed with a molten lithium-berylium-fluroide salt. Only when this salt enters the graphite core, the neutrons released in a fission event can moderate to thermal energies and initiate new fission. Because the molten salt is used to remove the heat from the core and to circulate the fuel, a fraction of it can be diverged to extract the fission products and to add fresh fuel. Because of this on-line refuelling capability and the high neutron efficiency, the MSR is the only reactor with a thermal neutron spectrum in which breeding of new nuclear fuel can be achieved. Simply add thorium to the salt and you will get fissile uranium for free.

My research focuses on Molten Salt Reactors to exploit the enormous thorium resources available. This reactor is sometimes called the Liquid Fuel Thorium Reactor (LFTR). If we succeed, we will have energy sufficient for tens of thousands of years!