Swelling and radiation creep of austenitic corrosion-resistant steel irradiated by neutrons in wide dose and temperature ranges

Abstract

The results of a study of the swelling and in-reactor creep of austenitic steel after irradiation in materials science assemblies in the range 330-700°C and damaging dose 20-96 dpa are presented. The temperature dependences of the volume change of steel were obtained from measurements of the diameter of unloaded ampuls. It is shown that the swelling of the steel increases linearly with increasing tangential stress. The modulus of in-reactor creep in the interval 410-630°C for the steel investigated in the cold-deformed state varies in the range (0.5-3)·10 -6 MPa -1 ·dpa -1 . For lower and higher temperatures, the creep modulus increases to (5-8)·10 -6 MPa -1 ·dpa -1 .Austenitic corrosion-resistant steel continues to remain the main material for making fuel-element cladding for fast reactors. The alternative variants, such as ferrite-martensite or high-nickel steels, have not yet found wide application. To calculate the stress-strain state of the fuel elements of a fast reactor and determine the maximum service life, it is necessary to know the initial properties of the fuel and construction materials and their variation under irradiation. Vacancy swelling and radiation creep of cladding steel are the most important factors determining the behavior of fuel elements under irradiation. Obtaining radiation-creep and swelling data from reactor experiments is fraught with difficulties. The most common and relatively inexpensive method is to irradiate tubes with internal gas pressure. Measuring the diameter of tubes after irradiation yields information about the deformation of swelling and radiation creep. Nine materials-science fuel assemblies with tubular samples under internal gas pressure and made of the steels EI-847 (0Kh16N15M3B), EP-172 (0Kh16N15M3BR), and ChS-68 (06Kh16N15M2G2TFR) in the austenitized and cold-deformed states were irradiated in a BN-350 reactor in Kazakhstan. After irradiation, the samples were investigated in a hot laboratory in the Physics and Power-Engineering Institute. Some results have been presented in conference proceedings [1][2][3].The present article presents the results of investigations of swelling and the characteristics of radiation creep of EI-847, EP-172, and ChS-68 steels after irradiation in the temperature range 330-700°C with damaging dose 20-96 dpa.Materials, Methods, and Irradiation Conditions. Vacancy swelling and radiation creep were investigated on thin-wall tubes made of austenitic steels EI-847, EP-172, and ChS-68 from different melts. All melts satisfied the technical

Swelling and Radiation Creep of Ferrite-Martensite Steel Irradiated in the Bn-350 Reactor in a Wide Range of Temperature and Damaging Dose

“…The origin of the high-temperature peak at 650°C is less well determined. It can only be noted that the identical maximum was observed at 630-680°C for irradiated tubular samples made from the austenitic steels EI-847, EP-172, and ChS-68 [29].…”

Irradiation Creep of Uranium-Plutonium Nitride Fuel and Serviceability of Fuel Element

“…To determine the characteristics of the radiation creep of the cladding material, the function = is usually used. For the cladding temperature interval of (500-550) o C in the centerline of the fast reactor core, the values of so called creep modulus B 0 for austenitic [15], ferritic-martensitic [16] and dispersion hardened by oxides steel [17] are close. For σ ~ 100 MPa the creep modulus is about of (1-2)•10 -6 MPa -1 dpa -1 , what corresponds to the value of (4-8)•10 -9 MPa -1 h -1 at a cladding damage rate of ~10 -6 dpa/s.…”