![]() ![]() Breaks in the lines connected to the main RCL piping, these are called the auxiliary lines. ![]() Approximately 10 locations are typically selected in the main RCL piping to postulate breaks. For a pressurized water reactor (PWR) these breaks could be in the order of 30 inch in diameter. There are two groups of break locations that result in a LOCA: There are many good publications which address the loads caused by a postulated LOCA blowdown, in particular the US NRC’s NUREG-0609 (1981). In this article, we will limit ourselves to the first dynamic effect mentioned, the LOCA blowdown forces, which is listed as (3)(a) above. A rise of the pressure inside the compartment where the break occurs, causing pressure forces on the concrete walls.The whipping of the broken pipe, which could impact nearby SSCs, unless the pipe is restrained by special-purpose devices called whip restraints.For breaks inside the reactor shield wall, for example breaks at the RCL-to-RPV nozzles, the jet may impinge directly on the RPV. A strong jet of water and steam escaping from each side of the break.These loads are called the LOCA blowdown loads. A depressurization wave that will travel from the break, in both directions, causing unbalanced loads in the RCS and in particular on the RCL piping and the RPV and its internals and the fuel assemblies.The discharge of water from the break will cause dynamic effects on the RCL and the reactor pressure vessel (RPV).So, the ECCS is sized to make-up for the lost coolant water. This is why the RCS has redundant reactor coolant loops (RCL), and have the capability to inject additional coolant through the emergency core cooling system (ECCS). The LOCA would cause the water from the broken pipe to discharge into the building instead of reaching the reactor core.This would cause a harsh, hot, humid environment that will challenge the structures, systems, and components (SSCs) in the reactor building. The pressurized cooling water, as it discharges from the break, will flash to steam.Such a rupture would result in a loss of coolant accident (LOCA), which would challenge the plant in three ways: One of those accidents is the rupture of a pipe in the reactor coolant system (RCS). Nuclear power plants are designed with the capability to safely shut-down following a number of hypothetical accident scenarios. Design of a Nuclear Power Plant for a LOCA ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |