HTGR Knowledge Base

Conference Article: Concept of Pebble Bed Based HTGR With Fast Pebble Discharge System

Jianling Dong, Suyuan Yu, INET, Beijing, CHINA

Abstract

The 10MW high temperature reactor (HTR-10) of China is an advanced pebble bed modular reactor, which is a high temperature, helium-cooled reactor using a steam generator. The system is passively safe against the accident of loss-of-forced-cooling. But to get such a safety feature, low mean core power density, such as 2MW/m3, had been adapted and decay heat has to be continuously removed from the core through the water wall surrounding the reactor pressure vessel during the reactor operation. Although the heat power of HTR-10 is only 10MW, the reactor core cavity has a diameter of 1.8m and mean height of 1.97m, which is surrounded by graphite reflectors with thickness of 1.0m. Therefore, much larger reactor pressure vessel and relevant surroundings had to be constructed. This results in higher construction and operation cost. One way to decrease the size of the pressure vessel and the relevant surroundings is to increase the core power density. But this may compromise its inherent safety performance. In this paper, concept of pebble bed based HTGR (high temperature gas cooled reactor) with fast pebble discharge system against loss-of-forced-cooling accident is put forward to try to make the reactor has passive safety feature by extracting decay heat of discharged pebbles into pebble catchers, which are designed and constructed in such a way that no secondary criticality could occur and the decay heat produced by discharged pebbles is removed by passively safe means, such as water wall, heat pipes etc.. The preliminary study shows that the concept is feasible in decreasing the size of reactor pressure vessel and relevant surroundings, and the decay heat continuously removed from the core.

view the full text of this article (7 pages, format: PDF, size= 53kB)

key words: high temperature gas cooled reactor (HTGR), fast pebble discharge system, core power density, passive safety.
Reference:
Proceedings of the Conference on High Temperature Reactors, Beijing, China, September, 22-24, 2004
International Atomic Energy Agency, Vienna (Austria)
HTR-2004, pp:1-7