A method and a moulding plant for manufacturing a storage container for storage of nuclear radiation material, the container having an inner container part of a first thermoplastic material, an intermediate container part of radiation inhibiting material on the outside of the inner container part, and an outer container part of a second thermoplastic material moulded onto the outside of intermediate container part. First, second, third and fourth locations are present along a circular path. First, second and third sets of outer mould means are provided at said second, third and fourth locations, respectively, for enabling injection moulding of said inner container part, said intermediate container part and said outer container part, respectively, thereat and at least one mould core or a plurality of mutually spaced mould cores being movable by means of a rotary turntable to successively move from the first location to the second location, then from the second location to the third location, then from the third location to the fourth location, and then from the fourth location back to the first location.