Strontium-90 Is a Byproduct in Nuclear Reactors Fuelled by the Radioisotope

question 93

Multiple Choice

Strontium-90 is a byproduct in nuclear reactors fuelled by the radioisotope uranium-235.The $\text { half-life }$ of $\text { strontium-90 }$ is 28.8 y.What percentage of a strontium-90 sample remains after 85.0 y.?

• A)33.9%
• B)2.95%
• C)87.1%
• D)0.129%
• E)12.9%

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Definitions:

Secondary Datum

A reference point, axis, or plane used in addition to the primary datum to provide further geometric control on a manufactured part.

Three-Plane Datum System

A geometric referencing system in drafting and engineering that defines a part's orientation and location using three mutually perpendicular planes.

Secondary Plane

An auxiliary plane, usually oriented perpendicularly or at an angle to the primary plane, used in design and analysis for additional reference.