Vries, M.I. de; Schaaf, B. van der; Staal, H.U.; Elen, J.D.
Test specimens of stainless steel DIN 1.4948, which is similar to AISI type 304, have been irradiated at 723 K and 823 K up to fluences of 1.10 23 neutrons (n).m -2 and 5.10 24 n.m -2 (E > 0.1 MeV). These are representative conditions for the SNR-300 reactor vessel and inner components after 16 years of operation. High temperature (723 K to 1023 K) tensile tests at strain rates (depsilon/dt) from 10 -7 s -1 to 10 s -1 show a considerable decrease of tensile ductility. The extent depends on helium content, test temperature and strain rate. The atomic helium fractions of 3.10 -7 and 7.10 -6 result from the reactions of thermal neutrons with the 14 ppm boron, present in the steel. Helium embrittlement sets in at strain rates below 1 s -1 to 10 s -1 (the range of interest for Bethe-Tait accident analyses). A minimum total elongation value of 6% is shown at 923 K. The post-irradiation fatigue life is reduced by up to about 50% due to intergranular cracking. The combination of irradiation and fatigue causes a decrease of ductility after a smaller number of prior fatigue cycles than in the case of unirradiated material. (Auth.)
de Vries, M.I.; van der Schaaf, B.; Staal, H.U.; Elen, J.D.
Test specimens of stainless steel DIN 1.4948, which is similar to AISI Type 304, have been irradiated at 723 and 823 K up to fluences of 1*10$sup 23$ neutrons (n)*m$sup -2$ and 5*10$sup 24$ n*m$sup -2$ (E>0.1 MeV). These are representative conditions for the reactor vessel and inner components of the liquid metal fast breeder reactor SNR-300 after 16 years of operation. High-temperature (723 to 1023 K) tension tests at strain rates ($epsilon$) from 10$sup -7$ to 10 s$sup -1$ show a considerable decrease of tensile ductility. The extent depends on helium content, test temperature, and strain rate. The atomic helium fractions of 3*10$sup -7$ and 7*10$sup -6$ result from the reactions of thermal neutrons with the 14 ppm boron present in the steel. Helium embrittlement sets in at strain rates below 1 to 10 s$sup -1$ (the range of interest for Bethe-Tait accident analyses). A minimum total elongation value of 6 percent is shown at 923 K. The postirradiation fatigue life is reduced by up to about 50 percent due to intergranular cracking. The combination of irradiation and fatigue causes a decrease of ductility after a smaller number of prior fatigue cycles than in the case of unirradiated material. 8 refs
Vries, M.I. de; Schaaf, B. van der; Elen, J.D.
Test specimens of plate metal and welded joints of stainless steel DIN 1.4948, which is similar to AISI type 304, have been irradiated at 723 K and 823 K up to fluences of 1.10 23 n.m -2 and 5.10 24 n.m -2 (E > 0.1 MeV). These are representative conditions for the SNR-300 reactor vessel and inner components after 16 years of operation. High-rate (depsilon/dt = 1 s -1 ) tensile tests were performed after fatigue exposure up to various fractions of fatigue life (D) ranging from 5% to 95% at the same temperatures as the nominal temperatures of the irradiation series
Estimated reactivity effects of fission products in the SNR-300 fast breeder are given. Neutron cross sections of 127 I and 129 I are also given. Results of the in-pile canning failure experiments on fuel pins R54-F35 and F39 are discussed. Sinter experiments using mixed UC-UN powders are reported. Results of tensile tests on high-dose and low-dose irradiated specimens of 18Cr1 1Ni stainless steel (DIN 1.4948) used in the SNR-300 reactor vessel are given. It is shown that the aerosol behaviour in condensing sodium vapour can be described by the same MADCA model developed for the decay of aerosols in condensing water vapour. Results of heat transfer measurements in the electrically heated 28-rod bundle under liquid-phase and subsequently under two-phase conditions are commented on
This progress report summarizes the fast reactor research carried out by ECN during the period covering the year 1980. This research is mainly concerned with the cores of sodium-cooled breeders, in particular the SNR-300, and its related safety aspects. It comprises six items: A programme to determine relevant nuclear data of fission- and corrosion-products; A fuel performance programme comprising in-pile cladding failure experiments and a study of the consequences of loss-of-cooling and overpower; Basic research on fuel; Investigation of the changes in the mechanical properties of austenitic stainless steel DIN 1.4948 due to fast neutron doses, this material has been used in the manufacture of the reactor vessel and its internal components; Study of aerosols which could be formed at the time of a fast reactor accident and their progressive behaviour on leaking through cracks in the concrete containment; Studies on heat transfer in a sodium-cooled fast reactor core. As fast breeders operate at high power densities, an accurate knowledge of the heat transfer phenomena under single-phase and two-phase conditions is sought. (Auth.)
Results of capture cross section adjustments of the Nd isotopes and 147 Pm are reviewed. Results of the in-pile canning failure experiment R54-F37 are compared with those of R54-F26 and R54-F42; progress is reported on the preparations being made for the HFR-TOP transient overpower experiments on irradiated fuel pins. Recently commenced thermo-chemical investigations on the intermetallic compounds URu 3 , URh 3 and UPd 3 are discussed. The residual high-rate tensile ductility of stainless steel DIN 1.4948 measured after having applied various creep and fatigue damage fractions and results of tensile tests on post-low-cycle fatigue treated irradiated and non-irradiated DIN 1.4948 are given. Results of gas leak rate and aerosol penetration measurements on concrete specimens with artificially made cracks are reported on. Development of hydraulic computer codes, heat transfer measurements in the vicinity of grid-type spacers, planned Laser Doppler Anemometer measurements in a four-rod bundle and results of boiling experiments and temperature noise measurements behind a 34% blockage of a 28-rod bundle are discussed
Recently evaluated neutron capture cross section data of 142 143 144 145 146 150 Nd, natural Nd and Mo as well as adjustment of the capture cross sections of 152 154 Sm to fit integral data measured in STEK and CFRMF are discussed. The progress made with preparations for the HFR-TOP transient overpower experiments on fuel pins under irradiation in the pool-side facility of the HFR is reported on. Results are given of tensile tests on irradiated as well as on heat-treated stainless steel DIN 1.4948 specimens subjected to varying numbers of fatigue cycles. In the field of aerosol research, measured gas flow rates and pressure drops in stainless steel capillaries of various dimensions are compared with theory; the gas flow and aerosol penetration in cracks, artificially introduced in concrete test specimens, have been determined. Criteria in selecting the right light-scattering particles for use in Laser Doppler Anemometer measurements are given; the results of single and two-phase experiments with the second 28-rod bundle and the hydrodynamics during single-bubble boiling in the first bundle are discussed. (Auth.)