Which statement accurately describes shielding for the two reactor types?

• A. PWRs do not require shielding of the steam cycle because the primary fluid does not reach the turbine; BWRs require shielding of the steam cycle due to radiation in water and steam.
• B. Shielding is required only in PWRs.
• C. Shielding is not required in either design.
• D. Shielding in BWRs is handled by the turbine housing only.

Answer: (A)

Shielding decisions hinge on where radioactive materials can be carried in the plant. In a PWR, the primary coolant loop, which becomes radioactive, does not go to the turbine. The steam that drives the turbine comes from a separate secondary loop via the steam generator, so it remains essentially free of fission products. That separation means shielding the steam cycle itself is not typically required. In a BWR, the water that becomes steam goes directly through the reactor vessel and is in direct contact with the fuel; radioactive species can be carried into the steam and turbine, so shielding around the steam lines and turbine is needed to limit exposure. The idea that shielding is needed only in one design or that it would be confined to the turbine housing is not accurate, since the BWR’s steam cycle requires protection beyond just the turbine housing, and the PWR’s steam cycle does not require shielding for the primary radioactivity to reach the turbine.