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Page Title: Access Controls and Shielding from Radioactive Hazards - Continued
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Penetrations should generally be located as high up on a wall as possible. Penetrations
should not line up directly with the source or with any area or space that may be potentially
occupied (e.g., stairways and platforms). In particular, doors should be located or shielded so
that personnel standing in front of a closed door are not exposed to direct radiation from the
equipment within.
The number of penetrations should be minimized, particularly in shields serving as pri-
mary or secondary confinements; however, several smaller and dispersed penetrations are pre-
ferred to one large one. Penetrations should have the minimum diameter necessary. The radio-
logical effects of voids (partially penetrating openings or areas of lesser density) should be
The selection and design of penetrations should include consideration of the need for the
penetration to be sealed for radiation reduction, air flow or airborne radioactivity control, fire pro-
tection, or flooding. A radiation seal or shield should generally be provided for a penetration or
void under these conditions:
1. There is otherwise a direct shine from the source to a general access area through
the penetration.
2. It creates a hot spot in a frequently or continuously occupied area.
3. The dose rate exceeds an assumed hot spot criterion in an infrequently but regularly
occupied area (e.g., stairways, platforms, etc.).
4. It is into an area of varying but possibly high dose rate.
5. It is in a floor or roof slab.
6. It would create an area of unacceptably high dose rate after off-normal events in an
area where people or equipment must perform a mitigation or recovery function.
A radiation seal or shield should be considered for a penetration or void in these
1. Radioactivity buildup in a pipe passing through it might cause it to exceed an
assumed hot spot criterion.
2. The centerline is <8 ft above the floor and the penetration is >2 in. (except for
high-dose-rate cubicles).
3. The void is a glove port in a glovebox potentially containing, even when not in use,
radioactivity producing a high dose rate outside the box.
4. It is a gap between the top of a wall and the soffit of the floor above the wall, if offset-
ting is not adequate to satisfy applicable shielding requirements.

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