Tokyo Electric Power Company (TEPCO) is conducting a comprehensive review to identify all the possible risks that might have an impact outside the site boundary of the Fukushima Daiichi Nuclear Power Plant, according to information recently submitted by Japan to the IAEA. The comprehensive review process follows the detection of a puddle of highly contaminated water at the large carry-in entrance rooftop of the Unit 2 Reactor Building on 24 February, which is a potential source of inlets to the drainage system.
In an an interim report released on 9 April, TEPCO also made available the details of the reviewing process, which aim to identify risks that might involve leakage of water or scattering of dust. After risks are identified, they will be classified into five categories: 1. Need further examination, 2. Countermeasures necessary to be taken, 3. Countermeasures in practice, 4. Follow-up observation (after implementing countermeasures) in practice, 5. No need for additional measures.
As for the risks classified as "Countermeasures necessary to be taken", suitable countermeasures will be considered and their implementation will start subsequently. In addition, risks will be regularly reviewed and the result of the review announced.
For further information about the detail of this reviewing process, please see this document.