Onagawa reactors, north of Fukushima, have had problems- they are typical of those on all of the reactors.
Pipes connecting reactor and spent fuel pool with water source seems to be a recurring problem.
Onagawa 1. Online 1984, shut down as result of a test in 2006. {Problem not specified. Returned online date?]

Onagawa 2. Online 1995.
Pipe leak in 2006 due to debris damage.
Difficulties with ressure control, July 2006
METI and NISA determined that performance not satisfactory.
[How and why? Corrective actions?]

Onagawa 3. Online 2002
Reactor shut down because of pipe integrity concerns, July 2006.
Reactor restarted after repairs, November 2006
Reactor shut down after fire and damage to turbines, March 2011 (Tohoku earthquake).

Backup diesel generators damaged in 2005 Miyagi earthquake.
Fire in turbine section following 2011 Tohoku quake.
Radiation levels 21microsieverts/hour and emergency declared, but returned to normal.
Water leaks reported from spent fuel pools after April 7 aftershock.
Two of three external power lines damaged by aftershock April 7, but cooling maintained with 3rd line. [Mainichi Press. Another newspaper said 3 of 4 lines knocked out- Yomiuri Press].

See Wikipedia entry on Onagawa plant for further details. I found little further information.
The three units remain in cold shutdown.