[en] Following the accident at TEPCO's Fukushima Daiichi Nuclear Power Station (NPS) on 11 March 2011, the ''Mid-and-Long-Term Roadmap towards the Decommissioning of TEPCO's Fukushima Daiichi Nuclear Power Station Units 1-4'' was adopted by the Government of Japan and TEPCO Council on Mid-to-Long-Term Response for Decommissioning in December 2011 and revised in July 2012. The Roadmap, which is scheduled for an additional update in June 2013, describes the main steps and activities to be implemented for the decommissioning of the Fukushima Daiichi NPS through the combined efforts of the Government of Japan and TEPCO. Within the framework of the IAEA Action Plan on Nuclear Safety, the Government of Japan invited the IAEA to conduct an independent peer review of the Roadmap with two main objectives: - To improve the decommissioning planning and the implementation of pre-decommissioning activities at TEPCO's Fukushima Daiichi NPS; and - To share with the international community the good practices and lessons learned by the review. The review has been organized in two steps, and the IAEA conducted the first part in Japan from 15 to 22 April 2013. The objective of the first mission was to undertake an initial review of the Roadmap, including assessments of decommissioning strategy, planning and timing of decommissioning phases and a review of several specific short-term issues and recent challenges. Specifically, it covered the assessment of current reactor conditions, assessment of management of radioactive releases and associated doses, control of radioactive exposure of employees and decontamination within the site for improvement of working environment, structural integrity of reactor buildings and other constructions. The incidents recently experienced at the site, related with failures of the power supply and leakages of water from the underground reservoirs, were also included in the review of the specific short-term issues. The Government of Japan and TEPCO have provided comprehensive information on the decommissioning plan. The mission was conducted through the assessment of the information provided to the team, professional and open discussions with the relevant institutions in Japan, and a visit to TEPCO's Fukushima Daiichi NPS, which provided an opportunity to observe how the Roadmap items were progressing and to discuss the generic and specific site issues with the plant operator.