The Pressurized Heavy Water Reactor (PHWR) is based on natural uranium fuel and heavy water moderator. A unique feature of the PHWR is the horizontal fuel channel that allows for on-line re-fuelling and fuel management. A fuel channel consists of two concentric tubes, each approximately 6 meters long. The inner tube, known as the pressure tube, contains the uranium fuel bundles and the pressurized (∼10 MPa) primary coolant. The outer tube, known as the calandria tube, separates the heavy water moderator (∼70°C) from the pressure tube (∼300°C). A potential accident scenario is the bursting of a fuel channel. The escaping hot fluid generates a pressure wave in the moderator, which would interact with the adjacent pressure/calandria tube assemblies and the outer containment calandria vessel, potentially damaging components within the reactor core. To improve the understanding of channel bursts and associated fluid structure interaction, a 1:6 scale reactor vessel test facility (Small Scale Burst Facility) was constructed at the Atomic Energy of Canada Ltd, Chalk River Laboratories. The test facility allows for the measurement of transient pressures, the development and collapse of the steam bubble created by the burst tube, and resultant response of the neighboring tubes and scaled calandria vessel. A single bursting tube, or a single tube bursting within an array of neighboring tubes, can be tested. The results from recent tests are presented, which include a three-dimensional map of the pressure pulse from a single, bursting tube. Future work will include 3-D mapping of near wall bursts and modeling the experiments using Arbitary Lagrangian Eulerian methods in the finite element program, LS-DYNA. This work is part of the development of a next generation modeling tool for fuel channel phenomena.
Radiocarbon Dispersion around Canadian Nuclear Facilities
