The Nuclear Ship Savannah / First Atomic Merchant Ship, One of the World's Safest Ships

by United States. Department of Commerce; United States. Maritime Administration; U.S. Atomic Energy Commission

RADIATION SHIELDING

One of the most important features of the SAVANNAH is her radiation shielding. The main sources of radiation during operation of the SAVANNAH’s power plant are the reactor itself and the primary coolant loop lines. The primary coolant which passes through the reactor core is irradiated, and itself becomes a source of radiation. Both the reactor and the coolant emit neutrons and gamma rays. There are also radiation sources of lesser magnitude including process piping, hold-up tanks, pumps, and demineralizers.

The objective of radiation shielding on the SAVANNAH is twofold: First, it limits the radiation dose outside the containment to prescribed safe levels, and second, it reduces the activation of structure within the containment shell by reactor core neutrons. The latter consideration is necessary in order that the reactor plant be accessible for maintenance within 30 minutes after shutdown.

The shielding is divided into a primary shield, which surrounds the reactor itself, and a secondary shield, which surrounds the entire containment shell.