A magnitude 9.0 earthquake hit northern Japan on March 11, triggering tsunamis that caused widespread devastation and crippled a nuclear power plant. Are you in an affected area? Send an iReport. Read the full report on the quake's aftermath and check out our interactive explainer on Japan's damaged nuclear reactors.

[5:30 a.m. ET Saturday, 6:41 p.m. Saturday in Tokyo] An official with the Tokyo Electric Power Company, which runs the Fukushima Daiichi nuclear power plant, apologized Saturday and said the exposure of three workers to highly radioactive water could have been avoided with better communication.

Hideyuki Koyama said tests of water found in the basement of the No. 1 reactor's turbine building on March 18 showed high levels of radiation.

That fact - and a general sense that water accumulating in turbine and others buildings around the plant may be dangerously radioactive - did not appear to resonate on March 24 during an operation in the No. 3 reactor's turbine building. On that date, three workers were exposed to between 173 and 181 millisieverts of radiation, including two with direct exposure on their skin, while laying cable.

Koyama said that radiation alarms went off while the men were working, but they continued with their mission for between 40 and 50 minutes assuming it was a false alarm.

[1:55 a.m. ET Saturday, 2:55 p.m. Saturday in Tokyo] Airborne radiation levels continue to fall outside the stricken Fukushima Daiichi nuclear plant, though concerns remain about potentially ominous breaches in reactor cores after water showed alarming radiation levels in tests at two locales.

An official with the Tokyo Electric Power Co. - which operates the facility - told reporters Saturday that water samples from the turbine buildings for the Nos. 1 and 2 reactors similarly found high levels of radiation.