The Japanese Red Cross Society (JRCS) has published this set of "Guidelines for Relief Activities under Nuclear Disasters". According to the guidelines, JRCS will conduct relief activities outside of the area restricted by the national/local authorities, as far as cumulative dose of radiation does not exceed 1 mSv during a activity. JRCS conformed the recommendation from International Commission on Radiological Protection (ICRP) which is applied for citizens. Since JRCS's relief activities are basically within a week per team, they can conduct activities even in most of the area called "difficult-to-return zones" in Fukushima if they follow this guidelines.Also in order to secure the safety of relief team members, JRCS defined the guideline for conducts during relief activities, and established training programmes on Radiological Protection for the members.
The Japanese version of the guidelines are available here.