It is necessary to consider how to cope with a contingency, such as securing a maintenance work area, so that a quick action can be taken in the event of an accident or trouble. It is necessary to review the dose reduction work in the reactor building and the PCV internal investigation work that have been carried out so far, and utilize the review results in implementation of advance measures such as preparation, planning, and training for other work.

With regard to important safety assurance facilities such as the circulation system for cooling fuel debris, the nitrogen gas separator, and the PCV gas management system, TEPCO is conducting inspections and maintenance, remote monitoring and patrols based on its maintenance plan. It is important to continue to ensure that the functions of these facilities do not stop, not only in terms of facility maintenance, but also in terms of management and operation, including measures to maintain their functions.

When installing new equipment and facilities, it is important to prevent defects in them in the field, to the extent possible. Efforts should be made to ensure the implementation of quality assurance through design reviews, testing and inspection.

In terms of management and operation, for example, it is important to establish a remote maintenance and repair method as needed. On the other hand, it is necessary to improve the durability and the ease of maintenance of equipment and facilities.

For the PCV, the RPV and the piping, tests have been conducted to confirm the effectiveness of corrosion inhibitors for steel, considering the effects of the radiation environment and seawater input. Candidate effective corrosion inhibitors have been selected for overall and localized corrosion. On the other hand, in order to mitigate the effect of corrosion inhibitors on the existing circulating water cooling and purification system, it has been pointed out that the concentration of corrosion inhibitors should be reduced in the preliminary stage of purification. In the future investigation of the PCV circulating cooling system, it is necessary to comprehensively pursue measures for corrosion inhibition and measures for satisfying other requirement functions.