11.   The launch of space shuttle Columbia was scrubbed early Thursday because of a hydrogen leak in one of its three main engines, NASA said.

12.   The reactor was shut down Saturday because of hydrogen leaks, the state nuclear energy company Energoatom said.

13.   Workers apparently left a valve open while repairing a dangerous hydrogen fuel leak last weekend, allowing hydraulic fluid to drain out.

14.   Authorities shut down two turbines at the Chernobyl nuclear plant following a hydrogen leak in the cooling system of one of its reactors, state safety officials said Wednesday.

15.   The countdown had to be halted while technicians checked for a possible liquid hydrogen leak.