Tianqi Zhang

Preliminary Study of Graphite Dust Resuspension in Steam Generator of HTR-10

The resuspension rate of graphite dust in steam generator of high temperature gas-cooled reactors (HTRs) is calculated both in theoretical Rock’n’Roll model and imperial model derived from precious experiments. Dust diameter, friction velocity, as well as roughness of wall is investigated in detail.Copyright

Modelling for Resuspension of Multilayer Particles

The resuspension of graphite dust in High Temperature Gas-cooled Reactors is not only an essential way to estimate the concentration of particles in the normal operating core, but also a key phenomenon related to the release of radioactive products in depressurization accidents and the safety evaluation of environment. Precise resuspension modelling is an important work in safety analysis of HTRs. Current models were based on a single particle sitting on the substrate, however, multilayers of graphite dust deposit in the core during decades of operation. This paper uses recursion to deduce Rock’n’Roll model on each layer, and finally get the resuspension fraction changing with time and flow velocity. The results showed a “lag effect” of resuspension compared with those of Biasi’s modified model. Compared with the results of multilayer resuspension, the original monolayer model overestimated the resuspension rate and fraction.Copyright

Chinese Innovative Patent Technologies for the Reactor Pressure Vessel

There is a huge and rapid growing demand for energy in China. The developing of new energy, including nuclear energy, is an important way to solve China’s energy and environment problems. Currently, Nuclear power is playing a more and more important role in China, especially in the coastal areas where the economy is developing rapidly. The main nuclear reactor equipment is the key guarantee to nuclear safety, such as the reactor pressure vessel. With the continuous development of science and technology, the reactor pressure vessel uses more and more of advanced design methods, high performance materials and industrial-proven technologies. As an airtight container who is directly exposed to the great operating pressure of reactor, the reactor pressure vessel plays a crucial role to the safety of reactor. In the paper, by retrieving Chinese Intellectual Property Office patent libraries, 12 Chinese innovative patents for the reactor pressure vessel are introduced, containing four kinds of main technologies: closure, body, nozzle safe end and other technologies. The patent results could lead the corresponding advice to the design of the equipment effectively, to the system arrangement reasonably, and further to the reference for designing a safe nuclear power plants. The paper is to exchange the latest technological progress of reactor pressure vessel, in order to promote technological innovation in the nuclear power field.Copyright

A Numerical Analysis on Graphite Dust Deposition and Resuspension in HTR-10 Steam Generator

The behavior of graphite dust is important to the safety analysis of High-Temperature Gas-cooled Reactor (HTGR). The fission products released by fuel elements would enter the primary loop and combine with dust, resulting in that the dust has a high load capacity of cesium, strontium, iodine and tritium. It would bring difficulty and inconvenience to the maintenance and repair of steam generator. Therefore, the behavior of graphite dust in the steam generator is essential to the safety of High Temperature Gas-cooled Reactors. The present study focused on the deposition and resuspension of graphite dust in steam generator of HTR by numerical method. The results show that the graphite dust in steam generator deposits on the surface of heat transfer tube through turbulent deposition, thermophoretic deposition, and other depositional mechanisms, of which thermophoretic deposition is the main mechanism for the particles with the diameter of 2.2μm in the present study. The preliminary calculation result shows that about 6760mg/m2 of graphite dust tends to load on the tube surface.Copyright