A method for manufacturing a long-term storage container for storage of radioactive material to inhibit radioactive radiation therefrom to the outside of the container, said container having a bottom and upright wall extending therefrom, the top of said container apt to be closed off by a lid, said container having an integral inner container part of a first material with a bottom and upright wall, an integral outer container part of a second material with a bottom and upright wall, and radioactive radiation inhibiting material in an inter-space between the walls and bottoms of said inner and outer container parts; characterised in: - integrally casting in a first mould (31, 31', 32; 61) through injection moulding a first container part (2; 34; 62) having a bottom and a wall (34"), the first container part then being removed from the first mould or being separated from a first part of the first mould which formed the exterior side wall and bottom face of the first integral container part, - integrally casting in a second and separately located mould (35, 36) through injection moulding or pressure moulding an inter-space container part (38; 68) of said radioactive radiation inhibiting material, said inter-space container part having a bottom and a wall (38") and forming a second container part, and removing said inter-space container part from the second mould, - c) placing the first container part in a third mould (39; 61), and placing said inter-space container (38; 68) in fitting engagement with the exterior face of the first container part (2; 34; 62) to form a first assembly of container parts, the inside of the removed first container part being fitted onto a core member of the third mould, or the separated first container part being in engagement with a portion of a second part (31, 31') of the first mould, the second part of the first mould having a portion inside the first container part to support it during moulding in the third mould, and a top of the second part (31, 31') of the first mould being configured to be used to close off an open end of a mould member of the third mould, - locating in the third mould (39; 61) the first assembly (34, 38; 62, 68) of container parts to cause said inter-space container part (38; 68) to be in spaced apart relationship to a mould member of the third mould (39; 61), so as to form a cavity between the mould member of the third mould and the outside of the inter-space container part (38; 68), - through injection moulding into said cavity, integrally casting the outer container part (43; 69) forming a third container part having a side wall and a bottom, said third container part engaging the exterior faces of the inter-space container part, and - removing from the third mould (31, 31', 40; 61) a second assembly (34, 38, 43; 62, 68, 69) of container parts formed by the first, second and third container parts to provide said storage container. - integrally casting in a first mould (31, 31', 32; 61) through injection moulding a first container part (2; 34; 62) having a bottom and a wall (34"), the first container part then being removed from the first mould or being separated from a first part of the first mould which formed the exterior side wall and bottom face of the first integral container part, - integrally casting in a second and separately located mould (35, 36) through injection moulding or pressure moulding an inter-space container part (38; 68) of said radioactive radiation inhibiting material, said inter-space container part having a bottom and a wall (38") and forming a second container part, and removing said inter-space container part from the second mould, - c) placing the first container part in a third mould (39; 61), and placing said inter-space container (38; 68) in fitting engagement with the exterior face of the first container part (2; 34; 62) to form a first assembly of container parts, the inside of the removed first container part being fitted onto a core member of the third mould, or the separated first container part being in engagement with a portion of a second part (31, 31') of the first mould, the second part of the first mould having a portion inside the first container part to support it during moulding in the third mould, and a top of the second part (31, 31') of the first mould being configured to be used to close off an open end of a mould member of the third mould, - locating in the third mould (39; 61) the first assembly (34, 38; 62, 68) of container parts to cause said inter-space container part (38; 68) to be in spaced apart relationship to a mould member of the third mould (39; 61), so as to form a cavity between the mould member of the third mould and the outside of the inter-space container part (38; 68), - through injection moulding into said cavity, integrally casting the outer container part (43; 69) forming a third container part having a side wall and a bottom, said third container part engaging the exterior faces of the inter-space container part, and - removing from the third mould (31, 31', 40; 61) a second assembly (34, 38, 43; 62, 68, 69) of container parts formed by the first, second and third container parts to provide said storage container.