The lights in the unit 3 main control room went on at 13:43 on 22 March, when external AC power reached it. TEPCO will start up reactor and suppression pool cooling systems after testing, according to a report from Japan Atomic Industrial Forum.

Reactor-by-reactor, system-by-system summary from JAIF on 23 March; yellow indicates abnormal/unstable; red means damaged/nonfunctional/unsafe

It is the first reactor in the four-reactor main block at Fukushima Daiichi. AC power has reached distribution panels for units 1, 2 and 4. Unit 1 and 2 cooling pumps will require maintenance because of damage from seawater, JAIF reported. Some power has been restored to units 5&6, which are slightly further up the coast.

Although most reactor monitoring functions have been lost since the earthquake and tsunami, Japan's Nuclear and Industrial Safety Agency reported on 23 March that unit 1 core temperature reached almost 400°C, exceeding design values of 302°C. As a result, the recovery team has increased the number of injection lines, according to JAIF. It also said that reactor vessel surface temperature gauges for units 2 and 3 have been restored.

In the meantime, Tokyo Fire Department is planning to continue to spray water into unit 3 today.

TEPCO announced that caesium and iodine radioisotopes were sampled in the air around the damaged plant on 20 and 21 March. The government has extended seawater sampling to 30km offshore after samples exceeding the legal limit were found in the outflow canal, JAIF reported.