Apr. 12--All three reactors at the Palo Verde nuclear plant, which supplies energy to the Valley and four other states, were down Monday and Tuesday, each for a different cause, said Jim McDonald, spokesman for Arizona Public Service Co., which operates the plant.

Unit 2 was shut down Monday for problems with a water valve and is expected to be back up today if it passes overnight tests.

Unit 3 was shut down last week for scheduled refueling and is expected back in May.

Unit 1 has heavy vibration on a cooling line and has been shut down since late March with no expected return date.