Reactor 1 of Tsuruga Nuclear Power Plant in Tsuruga City, Fukui Prefecture, operated by Japan Atomic Power Company, is the very first light-water reactor (by GE) built in Japan, and the 7th oldest commercial reactor in the world (as of January 2012).
(Fukushima I Nuke Plant's Reactor 1 is the second oldest, after Tsuruga's Reactor 1.)
Reactor 2 of Tsuruga Nuclear Power Plant (pressurized-water reactor by Mitsubishi Heavy Industries) may be sitting on top of an active fault.
Both reactors have been stopped due to scheduled maintenance.
From Yomiuri Shinbun (8/17/2012):
Metal covers of fuel assemblies have cracks, discoloration in Tsuruga Nuke Plant Reactor 1
Japan Atomic Power Company announced on August 17 that they found cracks and discoloration in 9 metal covers that cover fuel assemblies in Reactor 1 at Tsuruga Nuclear Power Plant (Tsuruga City, Fukui Prefecture) which has been stopped [for maintenance].
The [cracks and discoloration] are all minor, and there is no effect on the environment, according to the operator.
The metal covers are in the Spent Fuel Pool, and the cracks were found at the welded parts.
As damages were found in the metal covers at Tohoku Electric Power Company's Onagawa Nuclear Power Plant, the Nuclear and Industrial Safety Agency under the Ministry of Economy, Trade and Industry instructed Japan Atomic Power Company and other [nuclear power plant operators] to conduct investigation.
I think what Yomiuri is talking about ("metal covers") is a channel box that houses fuel assemblies. For Onagawa Nuke Plant's channel boxes, apparently damaged by the March 11, 2011 earthquake, read my post from July this year.
Japan Atomic Power Company has a lot to learn from TEPCO (believe it or not) when it comes to timely disclosure of information. At their website, the latest press release is from August 10. NISA or METI is no better; there is no press release on this incident on either of them.
Maybe this kind of news wasn't news at all in pre-Fukushima Japan.