Decommissioning Plan of Fukushima Daiichi Nuclear Power > Plan & Action > Major Initiatives for Water Management > PCV
Over the period from April 10 to 20, 2015, a pre-investigation was conducted for the purpose of locating where melted fuels have been dropped in the PCV and identifying the condition of them including the form. In which, for the first time since the accident, robots were inserted into the damaged PCV to capture images of the internal conditions. The robot, which is a collective wisdom of Japan, worked so hard in this investigation to bring us vital information, i.e. images, radiation doses, and temperature inside the PCV. Inserting of robots into the PCV performed this time has been such an unprecedented challenge to the nuclear industry, and we believe that the fact that critical data was gained from the investigation have made a great step forward in the decommissioning operation to continue at the plant. At the same time, through piling up -one by one- each of the data obtained this time, we will get the most out of it for future decommissioning activities.
*This investigation is conducted within the site test “Investigation B1” on grating around the pedestal inside Unit 1 PCV in the “Development of a technology to investigate inside the Reactor Primary Containment Vessel (PCV)” by the International Research Institute for Nuclear Decommissioning (IRID).
No obstructions were found around the opening to access the bottom part of the PCV. That means the opening is available to use as part of an investigation route to find the fuel debris in the future. /a>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>
Data on temperature and radiation dose at each investigation point was obtained. The level of the measured radiation dose indicated lower values compared to the assumption. As a result, the investigation ended up being performed with a much longer time than originally planned./a>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>
No significant damages were found on the facilities inside the primary containment vessel.Air conditioning systems (HVH), piping systems of re-circulation pump (PLR pump), pedestal wall, recirculation pump (PLR pump), and inner surface of the containment vessel./a>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>>/>
The existence of a fallen object or obstacle, and the condition of the grating were checked by investing around inside the PCV.
Both robots used were determined to be left inside the PCV. Also it was confirmed that the remaining cable, which is extended from the robots will not cause trouble when conducting the upcoming investigation.
April 30, 2015
"Development of a technology to investigate inside the Reactor Primary Containment Vessel (PCV)" - Results of site test "Investigation B1" on grating around the pedestal inside Unit 1 PCV
April 20, 2015
"Development of a technology to investigate inside the Reactor Primary Containment Vessel (PCV)"- Results of follow up check after the site test "Investigation B1"on grating around the pedestal inside Unit 1 PCV - [Report for April 18 and April 19, 2015]
April 17, 2015
(4/20 video added) "Development of a technology to investigate inside the Reactor Primary Containment Vessel (PCV)" - Site test "Investigation B1" on grating around the pedestal inside Unit 1 PCV - [Prompt report for April 16, 2015]
April 16, 2015
(4/17 video added) "Development of a technology to investigate inside the Reactor Primary Containment Vessel (PCV)" - Site test "Investigation B1" on grating around the pedestal inside Unit 1 PCV -[Prompt report for April 15]
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