TEPCO： The bottom of the reactor pressure vessel of Unit 1 of Fukushima Daiichi Nuclear Power Plant may be perforated.

　　Recently, Tokyo Electric Power Company of Japan conducted an internal investigation on the reactor containment of Unit 1 of Fukushima Daiichi Nuclear Power Plant, and thought that the "control rod drive mechanism" at the bottom of the reactor pressure vessel might partially fall off and cause perforation at the bottom of the vessel.

　　Japan’s Kyodo News reported on the 16th that the investigation of TEPCO was carried out from March 28th to 31st, and the company put underwater robots into the containment of stagnant water. When the camera is used to photograph the surroundings, there is a space where no image is displayed, which is said to mean that the bottom of the pressure vessel is perforated. The attached blocks are considered as fuel fragments, which strongly interfere with the captured images and may have a high radiation around them. Blocks suspected of molten nuclear fuel (fuel fragments) are attached to the inner wall of the pressure vessel base. According to the analysis of TEPCO, "the heat of fuel fragments leads to the perforation of pressure vessels".

　　According to TEPCO, the control rod drive mechanism is a device that lifts the control rod from the lower side of the pressure vessel to adjust the output power of the reactor. At present, the tubular rod bundle about 4 meters long is lower than the normal position, and part of it falls to the bottom of the containment.