[en] Kobe Steel has more than 30 years of experience in manufacture of fuel channels. Kobe Steel manufactured fuel channels are used for a number of functions connected with BWR fuel assembly. In response to higher quality demand and greater cost savings, fuel channel fabrication has been greatly improved. In this paper, the functions, requirements and behavior of BWR fuel channels are described. A comparison between old and new fuel channel fabrication processes is also described. (author)

[en] Cold crucible induction melting (CCIM) technique which is used routinely to refine and melt active metals like titanium has excellent characteristics and has recently shown promise in the nuclear engineering field. To evaluate the applicability of CCIM in the electrolyzer portion of the oxide-electrowinning process and the melting decontamination process for low-level radioactive metal waste contaminated with uranium, several experiments were conducted. Experimental results showed that the CCIM technique could be adapted to the nuclear engineering field. (author)

[en] The principles and application examples for useful SR-XAFS for the structural analysis of molecular scale structural disordered system materials are introduced. Nickel-phosphorus alloy films, deposited on titanium by an electroless Ni-P plating process, were studied by SR-XFAS. Ni-P alloy film is widely used for industrial machine parts, etc. for the purpose of wear resistance and corrosion resistance improvement. Experimental results showed that small clusters of the inter-metallic compound Ni₃P were formed under as-deposited conditions before heat treatment in a phosphorus atomic environment. (author)

[en] In this paper, biofouling in condenser tubes and methods of prevention are described. Biofouling has a tendency to occur in tubes under lower velocity of sea water, and fouling organisms, if allowed to build up, cannot be removed by ordinary nylon brush cleaning. As the results of our investigation, it was concluded that sponge ball cleaning should be employed when the condenser is operated under lower velocity of sea water in the bacteria breeding season. (author)

[en] Grain refinement of austenitic stainless steel does not occur during heat treatment because of the lack of phase transformation. In order to establish a grain refining technique utilizing a hot working process, the effect of working conditions such as temperature, degree of deformation and elapsed time after working on the recrystallization and grain growth behavior, has been investigated by using SUS 304 austenitic stainless steel. Temperature-Deformation-Recrystallization (TDR) diagram is proposed in order to describe the abovementioned relation. (author)

[en] High level radioactive liquid waste from a reprocessing plant is vitrified for storage and disposal. In this process, molten glass is poured into a metal canister and this pockage is welded, leak-tested, decontaminated, heat-treated and inspected. A mechanical handling system for this process has been developed and the main equipment is now in mock-up test operation, as descrived here. (author)

[en] Various storage methods for krypton-85 recovered from a nuclear fuel reprocessing plant are under development in many countries. These methods include:(1) direct storage in pressurized cylinders, (2) storage of krypton adsorbed on charcoal or zeolite in pressurized cylinders and (3) immobilization (encapsulation) in zeolite. A krypton storage facility using pressurized cylinders has been constructed in the krypton recovery pilot plant in Tokaimura and other methods are now under development. These three methods are evaluated and the features of the constructed facility are also reported. (author)

[en] In underground nuclear waste disposal sites, bentonite clay is used as backfills or plugs to stop water leakage and ensure low permeability and nuclide adsorption. In this study, a new material (BENTBALL) developed by Kobe Steel to solve the problems which traditional bentonite has used in the execution is evaluated. (author)

[en] The increasing output of nuclear power generation calls for larger vessels for next-generation nuclear power plants. A vessel with an increased diameter requires increased load for its forging, which can make it difficult to use a conventional solid die. In order to reduce the forging load, a rotary incremental forging method has been applied to hot forging. This method includes pressing and rotating a material in an incremental manner such that a target shape is obtained. This study aimed at improving the accuracy of numerical simulation for the rotary incremental forging to reduce the load when forging large vessels. This has enabled the temperature of the material and flow stress to be precisely predicted; an example of this is reported in the paper. Specifically, the heat transfer coefficient to be used for the numerical simulation had been determined experimentally from a small-scale hot-forging. The reduction of the flow stress associated with incremental forging, had been deduced from a compression test, and the value was applied to the numerical simulation. A preform was designed on the basis of the above simulation to perform a 1/1 size scale experiment. A precision of better than 5% has been confirmed for the shape prediction. (author)

[en] In considering the application of ferritic stainless steels to heat exchanger tubing materials for moisture separator-reheaters in LWRs, the effects of environmental conditions (temperature, chloride, dissolved oxygen, pH), thermal history, and steel composition (content of C, N, Cr and Ti) on the Inter-Granular Stress Corrosion Cracking (IGSCC) in high temperature aqueous environments, were studied. The IGSCC was proved to depend on steel composition and thermal history rather than environment. From these results, a steel was designed to prevent IGSCC of the welding HAZ for 18Cr and 13Cr steels. (author)