Burst shield containment for nuclear reactor and method of operating same

DETAILED DESCRIPTION We claim: 1.
A method of operating a nuclear reactor having a nuclear reactor core spacedly surrounded by a burst shield consisting of a multiplicity of stacked cast iron cylinder sections, comprising the step of: filling the space between said core and said burst shield with an incompressible fluent medium in the form of a flowable particulate solid to eliminate any free burst path between said core and said shield and to distribute burst forces uniformly to said shield; removing said fluent medium for inspection of said space, said space being filled with said flowable particulate solid by the steps of: forming a partition in said space set outwardly from said core by a distance at least sufficient to enable thermal expansion of said core as it is brought to operating temperature; introducing said particulate solid between said partition and said shield in a relatively cool state of said reactor core; bringing said reactor core to operating temperature; and thereafter displacing said partition into contact with said core and thereby eliminating any free burst path between said core and said shield.
2.
The method defined in claim 1 wherein said fluent medium is removed by draining it from the bottom of said space.
3.
The method defined in claim 1 wherein said fluent medium is removed by suction through a tube introduced into said space from the top thereof.
4.
In a nuclear reactor, in combination: a pressurized nuclear reactor core; a burst shield spacedly surrounding said core and defining therewith an inspection chamber; a body of a substantially incompressible fluent medium sealed in the form of a flowable particulate solid in said chamber and completely filling same to exclude any free burst path between said core and said shield; means for removing said fluent medium from said chamber to enable inspection thereof; a plurality of movable aprons disposed in said chamber and collectively forming a partition with adjustable spacing from said core, said particulate solid being disposed between said partition and said burst shield; and means operable externally of said burst shield for moving said aprons