Tokyo's radiation levels remain very low but are still elevated versus levels prior to earthquake/tsunami of March 11. Levels are hovering around 0.12 uSv, which is a fraction of radiation received from dental x-ray.
Radiation readings from the perimeter area of the multiple nuclear plants have dropped to a 30 uSv level during the day of March 18.
Examples of daily life radiation exposures. (click on image to enlarge, source here.)
U.S. radiation levels have not measurably increased as feared by most MSM alarmists. (click on image to enlarge, source here)
Per the excellent daily update from this site, the plant officials are making headway in getting control of the situation. Based on preliminary reports, the actual reactor vessels at each plant have not been breached. Officials are making efforts to restore electrical power to the plants, which will allow the reactor's cooling systems to work (since the tsunami the cooling systems have been without power).
Based on helicopter observations, none of the spent fuel rod storage ponds have lost all their cooling water. At some of the ponds the water levels are down with water temperatures rising; they are attempting various methods (helicopters, fire engines, etc.) to fill the cooling ponds back to higher levels.
Summary by plant as of 4pm Japan time on March 18. (click on image to enlarge, source here)