on twitter. we will see you back here at 8 p.m. >>> welcome to "newsline." i'm keiko kitagawa in tokyo. workers at japan's crippled nuclear plant are getting ready to dig deeper into a worrying mystery. radioactive water has leaked from at least one storage tank on the fukushima daiichi site. crews are preparing to investigate how it got out and how far it spread. officials with the tokyo electric power company said earlier this week that about 300 tons of highly radioactive water had leaked from a tank. they fear the water flowed through a ditch and into the ocean.