Schematic of Reactor Design at Fukushima Daiichi

Schematic - from the Nuclear Energy Institute (NEI)

http://www.nei.org/howitworks/boiling-water-reactor-design/

Nuclear Regulatory Commission's (NRC) manual on Boiling Water Reactor (BWR) systems (18 pages)

http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf

Additional Information from MIT about the incident at the Fukushima Nuclear Plants in Japan

http://mitnse.com/