A container to be received in a processing apparatus to subject the container to heat and/or pressure. The container is adapted to receive and contain a substance that includes nuclear material. The container includes a hollow body having an interior within which the substance is to be located. The body includes an opening through which the substance can be moved with respect to the interior. A lid is removably attached to the body to close the opening. At least one filter allows fluid flow into and from the interior. The body and lid hermetically seal the interior except for the at least one filter.