Radiation changes in hexagonal lattice shapes during materials research in the BOR-60 reactor assembly

Methods and results of research on radiation changes in the hexagonal lattices of the BOR-60 reactor research assembly induced by internal gas pressure are presented. The sample tested was a typical lattice element for materials research in the BOR-60 reactor made of stainless steel containing 1.6% nickel, 1.5% manganese, 0.3% boron, and no chromium. Stress was created in the lattice by internal helium pressure. The basic parameters under study--the dimensions of the keylike lattice and the main diagonal of the hexagon cross section--were remotely measured both before and after irradiation with a micrometer. No noticeable buckling or warping of the cladding tube was detected during a visual inspection of the hexahedron being investigated. Measurements also pointed to the absence of swelling. The maximum increase in the dimension of the keylike lattice element, from its nominal value of 44.00 mm, was approximately 1.4 mm. The modulus of radiation creep was calculated using the method of least squares for temperature intervals of 610-615, 640-660, 685-705, and 725-7500K and for 770K