[en] The tensile stress which influence the corrosion behaviour of LMFBR's cladding materials in high temperature sodium is presented. A series of Cr13Ni17Mo3W austenitic steel which have been developed by China were used for studying and their corrosin resistence was compared with those of AISI 316SS under this experimental condition. A stress testing facility for high temperature sodium was used in this experiment. The specimens were exposed in sodium at temperature of 600 deg C under tensile stress of 0-176MPa for 500 hours. The experimental results show that when the stress applied to specimen is less than 117MPa there is not effect on the corrosion resistance and internal microstructure of materials, however, when the stress is increased to 176MPa there is a sufficient effect. The corrosion resistance of Cr13Ni17Wo3W3 is better than 316SS. On the othre hand, the corrosion resistance of Cr13Ni17Wo3W steel is related to the tungsten content in the material. The optimum tungsten content is about 1-2wt%

No abstract available

No abstract available

No abstract available

No abstract available

[en] The preliminary corrosion results of Ti-modified type 316 stainless steel exposed to 650 deg C sodium up to 10000 h are presented. These investigations are carried out in the thermal convective sodium loop with vacuum-inert glove box and prepared to gain basic information on corrosion behaviours of Ti-modified type 316 stainless steel and useful practical experience in sodium technology. Weight gain, microstructure changes due to sodium exposure are observed and the determinations of the concerned parameters are also carried out

[en] B₄C pellets with different B/C ratio and nuclear purity grade sodium were put into a stainless steel cladding tubes and the out-of-pile tests were carried out at 550, 650 and 750 degree C. The test period is 82 d. After compatibility test, the appearance of B₄C pellets is integral, and crack or break are not found. However, the surfaces become rough and original metal luster is lost. The chemical reaction product NaB₅O₈ deposits and adheres to the surface of B₄C pellets. This results in the volume increasing of B₄C pellets. No considerable change in microstructure and grain size of B₄C pellets are observed. There are B, Na and C penetrate into cladding inner surface. The amount of B and Na penetration increases with the temperature and B/C ratio increasing, but C penetration is opposite. The chemical reaction products among Na, impurities in sodium, B₄C and cladding are NaBO₂ , Cr₂B, Fe₂B and Ni₃B. The formation of the borides made increasing considerably in microhardness at the cladding inner surface

No abstract available

[en] Type of phases and feature on corrosion surface and changes of composition and microstructure on cross section of type 316Ti and 321 austenitic stainless steels exposed to sodium at 650degC for 4000, 5000, 8000, 10000 hrs are examined by optical microscope, scanning electromicroscope, Auger spectrum instrument and X-ray diffractometer. The effect of mass transfer on the steels is obvious in the flowing sodium, carbon diffuses from the flowing sodium to the steels and nickel and chromium diffuse from the steels to the flowing sodium, it causes the changes of composition, type of phases and microstructure and decreasing corrosion resistance of the steels. (author)

[en] The simulation specimens of the fast breeder reactor' control rod were put into the thermal convection sodium loop, and the out of pile tests for B₄C/Na/S.S. system chemical compatibility were performed at 550 degree C, and the effects of the test period and oxygen content in sodium on the compatibility characters were investigated. The appearance of B₄C pellets is integral, and crack or break are not found after compatible test. There is B penetration in cladding inner surface, the amount of B penetration is proportional to the square root of the test period. The depth of B penetration is not changed with the add of the test period. The microhardness at the cladding inner surface increases clearly, its increment is increasing slightly with the add of the test period. The depth of the hardening layers is about 40 μm for different test periods. The reaction products Cr₂B, Na₄B₁₀O₁₇, B₆Fe₂₃, CrB, Nib and NiB₁₂ are formed according to priority at the cladding inner surface for 80 to 400 d. The diffusion of B into the cladding relates to the temperature, test period and the oxygen content, and the oxygen promotes the B diffusion