on 25 March. The exclusion zone was guarded by roadblocks to ensure that fewer people would be affected by the radiation. During the evacuation of hospitals and nursing homes, 51 patients and elderly people died. The earthquake and tsunami damaged or destroyed more than one million buildings leading to a total of 470,000 people needing evacuation. Of the 470,000, the nuclear accident was responsible for 154,000 being evacuated. Prior safety concerns 1967: Layout of the emergency-cooling system In 1967, when the plant was built, TEPCO levelled the sea coast to make it easier to bring in equipment. This put the new plant at above sea level, rather than the original . On 27 February 2012, the Nuclear and Industrial Safety Agency ordered TEPCO to report its reasoning for changing the piping layout for the emergency cooling system. The original plans separated the piping systems for two reactors in the isolation condenser from each other. However, the application for approval of the construction plan showed the two piping systems connected outside the reactor. The changes were not noted, in violation of regulations. After the tsunami, the isolation condenser should have taken over the function of the cooling pumps, by condensing the steam from the pressure vessel into water to be used for cooling the reactor. However, the condenser did not function properly and TEPCO could not confirm whether a valve was opened. 1991: Backup generator of Reactor 1 flooded On 30 October 1991, one of two backup generators of Reactor 1 failed, after flooding in the reactor's basement. Seawater used for cooling leaked into the turbine building from a corroded pipe at 20 cubic meters per hour, as reported by former employees in December 2011. An engineer was quoted as saying that he informed his superiors of the possibility that a tsunami could damage the generators. TEPCO installed doors to prevent water from leaking into the generator rooms. The Japanese Nuclear Safety Commission stated that it would revise its safety guidelines and would require the installation of additional power sources. On 29 December 2011, TEPCO admitted all these facts: its report mentioned that the room was flooded through a door and some holes for cables, but the power supply was not cut off by the flooding, and the reactor was stopped for one day. One of the two power sources was completely submerged, but its drive mechanism had remained unaffected. 2000