CLASSE Safety Handbook

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Technical Comment on Area Designations, Radiation Levels, & Exceptions to Policy

There are some semantic differences between Federal Nuclear Regulatory Commission area designations and those of Cornell EH&S (4.1.7, 5.1). In addition, CLASSE generally interprets the Cornell regulations in a conservative manner. Here we elaborate somewhat on these two issues.

What Cornell and CLASSE call "controlled" and "uncontrolled", the NRC calls "restricted" and "unrestricted", respectively. The NRC definition of "controlled area" does not have a direct counterpart for Cornell and CLASSE. Generally at CLASSE, a set of strategically-placed radiation monitors are interlocked to shut down radiation-producing equipment if the instantaneous radiation field rises above 2 mrem/hr outside of exclusion areas. Cornell and CLASSE designate an exclusion area as one where access is prohibited when a radioactive source or radiation-producing equipment is in use; at CLASSE, we also generally implement a light-beam interlock system to enforce the perimeter. Immediately before an exclusion area is opened for general access, a radiation survey for residual radioactivity is performed and any locations which exceed 2 mrem/hr at 30 cm are conspicuously marked with the reading; locations above 100 mrem/hr at 30 cm are marked and roped off at a perimeter where the level is below a 2 mrem/hr. (Within the positron converter cave in LS1 the radiation field adjacent to the converter is assumed to exceed 100 mrem/hr and may not be posted. Access to this area is always limited to specific need.)

CLASSE radiation safety policy will, at all times, conform with Cornell, NY State, and Federal standards and regulations. However, while the more conservative implementation at CLASSE, as described in this Handbook, will generally apply, exceptions may be granted in rare circumstances. For example, an individual might be allowed to remain inside the formal exclusion area perimeter when equipment is powered in order to accomplish something that cannot otherwise be done, such as surveying radiation fields (where it can be done safely). However, such exceptions may occur only with the express consent of the CLASSE Safety Director (or "acting" substitute) and one other knowledgeable person, typically, but not exclusively, the relevant radiation permit holder. Such exceptions will be recorded in the radiation log (including the dosimeter reading), and always remain in compliance with governmental and institutional rules and the spirit of ALARA.
Topic revision: r6 - 04 May 2012, bkh
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