Reason: fuel pebbles getting stuck in feed lines somehow causing small amounts of radioactive material to be leaked, if I'm reading and summarizing this right. Transporting pebbles seems like the least hard thing about nuclear energy, interesting.

Apt typo ;)

"As was determined in 1989, dismantling would begin after approximately 30 years in safe enclosure."

30 years waiting time before one can start to demolish the reactor. That shows how dangerous this technology really is.

the THTR-300 was a prototype system. It's a pitty that they didn't follow through with the next generation. I hope that the Chinese have studied the design of the THTR-300.