| Popis: |
The objective of this research is to determine the thickness of a debris bed comprised of insulation material that would lead to a peak cladding temperature of 2200°F, which is a thermal limit specified in the Federal Code of Regulations for Nuclear Power Plants, following a loss of coolant accident. This study considers the case of a cold-leg break which leads to a loss of reactor coolant. In this accident, fiberglass debris is generated from the breakup of thermal insulation during the blowdown phase in the accident. The material is then transported to the sump where it may be pumped into the core where it is possible to build up a debris bed at spacer grid locations. The debris bed will restrict coolant flow and therefore lead to deteriorated heat transfer from the cladding to the coolant. A two-dimensional heat transfer analysis is performed to determine the critical length of blanketed region beyond which axial conduction in the pin is no longer adequate to prevent the peak cladding temperature from exceeding the regulatory limit. The feasibility of creating a debris bed thickness greater than the critical size is also evaluated. The amount of insulation debris potentially available to the core region is compared with the amount required to create a debris bed of the critical thickness. |
