The Near Boiling Reactor: Design of a Small, Inherently Safe, Nuclear Reactor to Extend the Operational Envelope of the Victoria-Class Submarine

Abstract

The present work aims at initiating the conceptual design of a small nuclear reactor intended to provide sufficient electrical power (˜150 kW) to maintain the “hotel” load of the Victoria-class submarine and extend her operational envelope. The scope of the design is to provide the nuclear reactor system with sufficient inherent safety features as to permit the operation of the nuclear reactor by crews with minimal training for automatic operation. Several constraints provide the framework for carrying out the design work, such as, among others, maintaining the excess reactivity of the reactor at safe values at all times, providing enough fuel and reactivity for meeting operational requirements, and keeping the size of the reactor core and shielding such as to fit within the hull of the existing vessel.

The final reactor concept, named the Near Boiling reactor, employs TRISO fuel particles in zirconium-sheathed fuel rods. The reactor is light water moderated and cooled. The core life is specifically designed to coincide with the refit cycle of the Victoria-class submarine. The reactor employs a simple and reliable control and shutdown system that requires little intervention on the part of the submarine’s crew. Also, a kinetic model is developed that demonstrates the inherent safety features of the reactor during several accident scenarios. The low steady-state flux level of the reactor during normal operation results in very low negative reactivity after shutdown and eliminates any reactor dead time. The reactor is designed for automatic unattended control and does not require extensive training for its operators.