The Separation And Storage Of Tritium In Molten Salt Reactor Loop

Since the contradiction between energy supply and demand becomes worse andthe pressure of carbon emission increases, nuclear power has been chosen for thesolution of energy crisis and environment issue in China. Compared to traditionalfossil energy, nuclear energy shows some advantages such as higher in energyconversion rate, cleaner, and less cost. However, the current nuclear power technologyisn’t safe enough to eliminate people’s concern about it, especially the great fear fromthe Three Mile Island accident, Chernobyl disaster and Fukushima nuclear crisis.Therefore developing a new generation of nuclear power plant which has highersafety is a target for those countries with advanced technology pursues. As one of therecommended nuclear reactors of the fourth generation nuclear power, molten saltreactor has been studied recently.The fuel salt of molten salt reactor is comprised of LiF-BeF2-ThF4-UF4, whichcan produce more tritium than PWR. Since tritium is an important radioactive nuclide,and it would cause great damage to the reactor, the process to remove tritium fromfuel salt is a key point in the operation of molten salt reactor. In this article, theseparation and storage of gaseous tritium is mainly discussed.Palladium alloy membrane is typically used for the separation of gaseous tritium,it has an ability that could only let hydrogen permeate. The mechanism of hydrogenpermeation is as following. Hydrogen molecule is dissociated into atoms, then thehydrogen atoms dissolve in palladium and diffusion along the concentration gradient.After the atoms permeate the membrane, they would combine into molecule again andseparate from palladium membrane. While in the same condition, other moleculessuch as O2, N2, Ar, CH4, CO2, cannot permeate palladium membrane, due to their bigvolume and high dissociation energy. Based on this theory a palladium alloy membrane separation assembly is developed. The experiment of hydrogen permeationproves that air tightness of this assembly is good. It also demonstrates that thismethod is rational and feasible for hydrogen separation and purification. In order toseparate tritium from molten salt reactor, an experimental system for tritiumseparation and purification has been designed initially.La-Ni-Al alloy has been widely used for tritium storage, because it is steady andconvenient to transport. In this thesis, La-Ni-Al alloy is studied for itsthermodynamics and dynamics performance. The experimental results show thathydrogen pressure rises with the temperature increasing, while the amount ofhydrogen absorption reduces. As the amount of aluminum in alloy increases, both thehydrogen pressure and the amount of hydrogen absorption reduce. In the part ofthermodynamic performance, when the temperature increases, the rate of hydrogenabsorption increases. With the same condition of initial pressure and amount, the rateof hydrogen absorption increases as the amount of aluminum increases. In conclusion,LaNi5has the largest amount of hydrogen absorption among the three alloys. Thehydrogen pressure could be adjusted with the addition of Al, and the rate of hydrogenabsorption could also be raised.