Abstract: Provided is a replacement basket configured to house a pellet bed through which fluid may pass. The flow direction of the fluid prevents the bed of pellets from fluidizing within the replacement basket. Provided also is a system using the replacement basket and a method of providing pellets in the replacement basket. According to example embodiments, a replacement basket may include a top surface portion, a bottom, and at least one vertical wall with a hole. The hole is configured to allow a flow of fluid to enter the replacement basket. A plenum, below the pellet bed, may allow a flow of fluid to proceed through the pellet bed in a downward direction. A central pipe may be provided in the replacement basket to allow the flow of fluid in the basket to exit the replacement basket.

Abstract: A method for operating a nuclear reactor may include adding one or more chemicals to water in the reactor prior to reactor shutdown, during reactor shutdown, or prior to and during reactor shutdown. The one or more chemicals may trigger release of one or more radioactive substances from at least one out-of-core surface of the reactor into the reactor water. A method for reducing post-shutdown radiation levels of a nuclear reactor may include adding one or more chemicals to water in the reactor prior to reactor shutdown, during reactor shutdown, or prior to and during reactor shutdown. The one or more chemicals may include, for example, one or more metals, metal ions, metal compounds, metals and metal ions, metals and metal compounds, metal ions and metal compounds, or metals, metal ions, and metal compounds.

Abstract: Provided is a replacement basket configured to house a pellet bed through which fluid may pass. The flow direction of the fluid prevents the bed of pellets from fluidizing within the replacement basket. Provided also is a system using the replacement basket and a method of providing pellets in the replacement basket. According to example embodiments, a replacement basket may include a top surface portion, a bottom, and at least one vertical wall with a hole. The hole is configured to allow a flow of fluid to enter the replacement basket. A plenum, below the pellet bed, may allow a flow of fluid to proceed through the pellet bed in a downward direction. A central pipe may be provided in the replacement basket to allow the flow of fluid in the basket to exit the replacement basket.