Pebble-bed High Temperature Gas-cooled Reactor Research Articles

Steady-State Neutrbnic Investigations to the Accident of Water Ingress in Systems with Pebble-Bed High-Temperature Gas-Cooled Reactor Fuel

For light water reactors, loss of coolant is an important point in safety analysis, whereas for gas-cooled reactors the ingress of water into the core region is an incident of safety relevance. The applicability of the computer code system GAMTEREX to pebble beds of spherical high-temperature gas-cooled reactor fuel elements with simulated water ingress is verified by experiment. The measurements were performed at a Siemens-Argonaut reactor, using its ring core as a driver zone for a pebble-bed core in the center of the reactor.

Simulation Study of AVR-U Nuclear Process Heat Plant

A pebble-bed high temperature gas-cooled reactor AVR located at Jülich, West Germany has a modification plan to include a process heat loop. In the plan, half of the primary helium heated up to 950°C by the AVR core is supplied to the process heat loop. The helium flow of the process heat loop influences the flow of the AVR loop and vice versa. Consequently, flow instabilities and reverse flow in the modified plant may possibly happen. In the paper, a computer simulation is performed to investigate the dynamic behavior of the primary helium flow in the modified plant. At first, dynamic experiments conducted at the AVR plant are simulated in order to grasp the accuracy of the computer code. Then, the modified plant is simulated. As a result, the behavior of the primary flow is rather moderate against the disturbances which are expected under the normal plant operation. Further, the condition when the reverse flow appears is evaluated analytically by using a simplified flow network model.

Simulation study of AVR-U nuclear process heat plant.

A pebble-bed high temperature gas-cooled reactor AVR located at Jülich, West Germany has a modification plan to include a process heat loop. In the plan, half of the primary helium heated up to 950°C by the AVR core is supplied to the process heat loop. The helium flow of the process heat loop influences the flow of the AVR loop and vice versa. Consequently, flow instabilities and reverse flow in the modified plant may possibly happen. In the paper, a computer simulation is performed to investigate the dynamic behavior of the primary helium flow in the modified plant. At first, dynamic experiments conducted at the AVR plant are simulated in order to grasp the accuracy of the computer code. Then, the modified plant is simulated. As a result, the behavior of the primary flow is rather moderate against the disturbances which are expected under the normal plant operation. Further, the condition when the reverse flow appears is evaluated analytically by using a simplified flow network model.

Experimental and Theoretical Studies of Criticality Safety by Ingress of Water in Systems with Pebble-Bed High-Temperature Gas-Cooled Reactor Fuel

Experiments in a subcritical assembly with pebble-bed high-temperature gas-cooled reactor fuel and hydrogen ranging between 0 and 14.4 vol percent were carried out to study the effects of water ingress in reactivity and to test the accuracy of diffusion-code calculations for small subcritical systems. Special emphasis is given to an adequate description of the influence of the water ingress on the diffusion properties of the pebble-bed system. The agreement between experimental and theoretical results is in all cases better than +-0.01 in k/sub eff/.(auth)