The high pressure reactors are sometimes autofrettaged to have the life elongated which is based on the highly compressive residual stress near the bore surface. In this study, to evaluate the material degradation based on the autofrettaged strain, the effect of autofrettage on the fracture toughness behavior was investigated using the 3.5% Ni-Cr-Mo-V steels.
(1) When the prestrain increases, the fracture toughness decreases, especially in the higher yield strength steel. The decrease of the fracture toughness of the material was observed in the prestrain range larger than 5 percent for the about 1000MPa yield strength steel and than 2 percent for the about 1150 MPa yield strength steel.
(2) The material resistance to ductile fracture, that is, tearing modulus T_J decreases in the same prestrain ranges as those of the fracture toughness.
(3) However, the autofrettaged material taken out of the actual pressure reactor shows no decrease of the fracture toughness and the tearing modulus which is caused by the small amount of the prestrain, less than about 1 percent even in the 100 percent autofrettaged reactors.

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In flat-based liquid storge tanks such as oil storage tanks with no anchor, up lift that a part of the bottom plate separates from its base occurs during earthquake excitation. This phenomenon sometimes causes tank collapse, that is, crack at the bottm-shell corner or buckling at the lower part of the shell plate. To make this up lifting mechanism clear is very important for the seismic design of liquid storage tanks, and not less reports on this problem have been published. But the mechanism is so complex that any of them presents neither a sufficient solution nor a well established design practice. One of the reasons is that the tank models used hitherto in their experiments do not satisfy physical similarity to Buckingham's law, and that the results can not be used directly as the data for actual large-scaled tanks.
From this standpoint, we carried out a static tilt test with two tank models satisfying perfectly the similitude law. The models were made of polyethylene film, and to satisfy the similality they were reduced to 1/40 scale. One model (MODEL-A) had 488mm diameter, 488mm water depth, 0.36mm shell plate thickness and 0.28 annular plate thickness. Another one (MODEL-B) was 1220mm×488mm 0.54mm×0.36mm. Rigidity of the plates was too weak to measure strains, and we measured only displacements. Three 15mm thick rubber plates were used as the model of foundation, and in order to investigate the influence of foundation stiffness upon the tank up-lifting behavior we added experiments with various types of foundation. And the influence of the top roof was investigated, too.
Through the test we got the data corresponding to actual tanks, and found that up lifting mechanism was not only concerned with the lower part of the tank, but also with the whole of the tank.

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In the past several years, Hot Isostatic Processing (HIP) has grown as a production tool in a wide range of industries.
HIP is one of the most important process for powder compaction, defect healing, diffusion bonding, etc.
The following description explains the HIP equipment, emphasizing the major parts. In addition to this, some HIP process applications of metals and ceramics powder consolidation are outlined.

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Some aspects of synthesizing inorganic materials under pressure are given Discussions are made of high pressure apparatuses, the role of pressure, and high pressure processes.

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If leakage are found on the heat exchanger tube in a super heater and an evaporater by the in-service inspection, and they are found to be unsuitable for further service, we must apply the plug in that tube and keep effectiveness of the plant.
We have two methods to plug in the heat exchanger tube. One is a welding process, the other is a explosive bonding. These methods are performed in meny plants including atomic power plant. But it is questionable to plug in the heat exchanger tube in the steam generetor of fast breader reactor plant which is heated by liquid sodium. Quality of post plugging heat treatment is very important factor to the reservice of the steam generetor.
So we demand the plugging method without heat treatment. This desirable method is explosive plugging.
To apply this method to the“Monju”, we must reserch meny patents and meny experiences of other plants, and we must develop original techniques.

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