NUREG-1537, Part 2 - NRC

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The design features of the tank offer reasonable assurance of its reliability
and integrity for its anticipated life. The design of the tank is acceptable to
avoid undue risk to the health and safety of the public.
4.4 Biological Shield
Areas of ReWew
The radiation shields around non-power reactors are called biological shields and
are designed to protect personnel and reduce radiation exposures to reactor
components and other equipment. -The principal design objective is to protect the
staff and public., The second design objective is to make the shield as thin as
possible, consistent with acceptable protection factors. Non-power reactors are
sources of radiation used for a variety of reasons. Therefore, their shielding
.systems must allow access to the radiations internally near the reactor core and
externally in radiation beams. Traditional methods of improving protection factors
without increasing shield thickness are to use materials with higher density, higher
atomic numbers for gamma rays, and higher hydrogen concentration for neutrons.
The optimum shield design should consider all these.
Areas of review are discussed in this section of the format and content guide.
Acceptance Criteria
The acceptance criteria for the information on the biological shields include the
following:
* The principal objective of the shield design should beto ensure that the
projected radiation dose rates and accumulated doses in occupied areas do
not exceed the limits of 10 CFR Part 20 and the guidelines of the facility
ALARA (as low as is reasonably achievable) program discussed in
Chapter 11 of the SAR.
* The shield design should address potential damage from radiation heating
and induced radioactivity in reactor components and shields. The design
should limit heating and induced radioactivity to levels that could not cause
significant risk of failure.
* The tank or pool design, the coolant volume, and the solid shielding
materials should be apportioned to ensure protection from all applicable
radiation and all conditions of operation.
* Shielding materials should be based on demonstrated effectiveness at other
non-power reactors with similar operating characteristics, and the
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