Robots also entered unit 2, but the probe was hindered by fogging of the robot's camera lens from the high humidity, over 90%, inside the building. Test spraying of an "anti-scattering agent" on the ground to prevent further spread of radioactive materials from the site is carried out over an area of about 1200 m2. Tuesday, 19 April TEPCO begins transferring excess radioactive cooling water from the reactor 2's basement and maintenance tunnels to a waste processing facility. Operations to pump radioactive water in the basements of buildings of units 1, 2, 3 and their associated tunnels start with unit 2. Friday, 22 April Japanese Prime Minister Naoto Kan states additional towns might be asked to evacuate, which largely involves agricultural lands. The government also plans to build 30,000 temporary homes by the end of May, and an additional 70,000 will follow. The president of the Tokyo Electric Power Company (TEPCO), Masataka Shimizu, formally apologizes at the prefectural government office in Fukushima to the Fukushima Governor Yuhei Sato for the nuclear crisis following the 11 March 2011 earthquake and tsunamis. In response, the Governor requests better working conditions for the workers. Tuesday, 26 April To prevent the proliferation of dust, TEPCO initiates spraying a synthetic resin to contain contaminated dust. Wednesday, 27 April Junichi Matsumoto, a general manager at Tokyo Electric Power Co., reports that radiation readings taken by two iRobot PackBot robots inside the reactor 1 building are as high as 1120 mSv/h, the highest level disclosed to date. May 2011 Monday, 2 May T. Matsui of the University of Tokyo Institute of Physics releases a scientific paper analysing the ratio of iodine-131 to caesium-137 taken from water samples, which concludes that a recriticality may have occurred at least 10–15 days after the attempted shutdown. Thursday, 5 May Workers enter the reactor 1 building. This is the first time since the start of the crisis that a reactor building in the plant is visited by a human being. The workers will connect a ventilation system that should absorb radiation inside the building for the next 4–5 days, allowing them to start installation of the cooling system replacement. Because of protective gear, the workers are only exposed to a small amount of radiation (about 2 mSv). TEPCO expects to bring the plant into a cold shutdown within six to nine months. IAEA releases a briefing. Tuesday, 10 May In a