STAUB-II

Contributors:

Cooperation partner:

• Helmholtz-Zentrum Dresden-Rossendorf
• RWTH Aachen

In a Pebble Bed High Temperature Reactor (HTR), the reactor core consists of a large number of spherical graphite fuel elements. The pebbles are loaded into the reactor core as a packed bed with conical floor. During the operation the pebbles move through the core from top to the bottom size. Due to this overall movement in the pebble bed, relative movements between pebbles and reflector (graphite) as well as between pebbles among each other are unavoidable. This slow and continuous movement generates different types of graphite particles. Additionally, carbonaceous particles can be produced by chemical reactions. These particles are dispersed in the helium coolant and transported throughout the primary circuit. During severe accidents such as Depressurized Loss of Forced Coolant radioactive contaminated dust can be remobilized and released to the environment. In order to rule out radioactive contamination of the environment, retention systems such as filters need to be designed.
In this work, two high-temperature Helium test facilities are being designed and operated in order to analyze the transport of graphite and carbonaceous particles under conditions close to those in a HTR primary circuit. Separate effect studies are carried out focusing on deposition and resuspension of particles under stationary and transient flow conditions. Further, the long-term interaction between particles and materials such as metallic alloys and ceramics used in HTR primary circuit are investigated.
Goal is the creation of models for the transport behavior of graphite dust particles in primary circuit flows that can be implemented in codes such as computational fluid mechanics. On this basis, information on possible release conditions of contaminated particles can be derived as a basis for the design of suitable retention systems. 

Test Facility DRESDEN-TUBE
Test Facility DRESDEN-TANK

DRESEN-TUBE is a high temperature flow channel in closed design for the observation of transport and deposition of micro particles. The target of high temperature flow channel is to observe the transport, deposition and remobilizes effects of macro particles (Ø 0.3 – 10 µm) at high temperature condition. Experiments can be done with Helium, Argon, Oxygen or other gaseous fluids and there combination. Maximum temperature is 950 °C by normal condition 1 atm. The measurement quartz glass pipe is approximately 3 meters long with an inner diameter of 50 mm. With helium the maximal flow velocity can by 50 m/s.

High Temperature Autoclave DRESDEN-TANK

This test facility is a high pressure cylinder with 6 MPa at 950 °C of helium it is called TANK. The long-term test about 1.000 h allows to observe changing of materials and flow field at high temperature and pressure conditions. Especially design is an inert experiment space and an cooled bottom for the effects of heat sink.