[pjscott]

The German pebble-bed was built in 1983 and shut down in 1989. Pebble bed reactor designers have had 21 years to improve on that design, and they've not been idle. All real nuclear reactors have problems before you've had time to work out the bugs in the design. They're big, complicated machines, and they have to meet some pretty stringent engineering specs.

The German THTR-300 was the first attempt to build a full-scale pebble bed reactor, after they'd run just one smaller research reactor. Problems with the design are to be expected. That's not an indictment of pebble bed reactor designs; that's just how nuclear engineering works. I'm glad that the pebble bed guys are finally picking themselves off the floor and continuing on with the Chinese HTR-PM reactors, which were designed to avoid the problems which plagued the THTR-300.

[lispm]

This German study (2008) from Jülich (!) was quite critical about the whole concept:

http://juwel.fz-juelich.de:8080/dspace/bitstream/2128/3136/1...