[en] A number of potential nuclear reactor accidents that could result in a major release of radioactive material are described in terms of the in-plant events that lead to the release and the offsite conditions that could prevail as a result of the release. The consequences of the potential release are presented in terms of the projected radiation doses to whole body, thyroid and lung, and the projected land areas that might require interdiction of some type. These descriptions are intended as a data base which can be used by emergency service organizations to construct scenarios with which to exercise emergency plans and procedures