Mitsubishi Heavy Industries Limited

Kanegafuchi Kagaku Kogyo Kabushiki Kaisha

Kaneka Corporation

Masahiko Yamada

Satomi Takahashi

Koichi Nunokawa

Junzo Hasegawa

Nobuo Nagashima

Hidenori Harada

A coupling structure of a fuel assembly includes a screw coupling means to provide a coupling structure of a fuel assembly which prevents foreign matters from mixing in the fuel and in which no vertical play is generated at a fitting portion between a latch sleeveand a lock key. The coupling structure of the fuel assembly includes: the latch sleevehaving a projecting portionformed at an upper end portion thereof; an upper nozzlehaving formed therein a latch sleeve installation holeinto which the upper end portion of the latch sleeveis inserted; and the lock keywhich is installed inside the latch sleeve installation hole, and which has an opening portionformed on a bottom surface thereof, the opening portionhaving a shape corresponding to the projecting portion. The screw coupling means screw couples the lock keyto the upper nozzlewith a male screw threadformed on a side surface of the lock key

Coupling structure of fuel assembly

A fuel assembly includes a bottom nozzle set on a lower core plate of a nuclear reactor, a top nozzle with a hold down spring to urge the bottom nozzle against the lower core plate, guide thimbles which guide control rods, having passed through the top nozzle, toward the lower core plate, a dashpot formed on each of the guide thimbles to reduce the fall velocity of a corresponding one of the control rods, a thimble screw which connects each of the guide thimbles to the bottom nozzle, and a drain hole formed to extend through each of the thimble screw. The dashpot has a large-diameter portion with substantially the same diameter as that of each of the guide thimbles. The diameter d of the drain hole falls within a range of 0.04 D&#x3c;d&#x3c;0.08 D where D is an inner diameter of the large-diameter portion.

Fuel assembly and thimble screw of the same

A fuel assembly includes a bottom nozzle set on a lower core plate of a nuclear reactor, a top nozzle with a hold down spring to urge the bottom nozzle against the lower core plate, guide thimbles which guide control rods, having passed through the top nozzle, toward the lower core plate, a dashpot formed on each of the guide thimbles to reduce the fall velocity of a corresponding one of the control rods, a thimble screw which connects each of the guide thimbles to the bottom nozzle, and a drain hole formed to extend through each of the thimble screw. The dashpot has a large-diameter portion with substantially the same diameter as that of each of the guide thimbles. The diameter d of the drain hole falls within a range of 0.04D<d<0.08D where D is an inner diameter of the large-diameter portion.

.gamma.-oxo-homophenylalanine derivatives and process for producing

A process for preparing a 5-arylhydantoin having the formula (II): ##STR1## which comprises: reacting methyl 2-hydroxy-2-methoxyacetate, urea and an aryl compound having the formula (I): ##STR2## in the presence of an acid. According to the process, the 5-arylhydantoin which is a very effective intermediate for preparing D-arylglycines can be easily prepared from inexpensive raw materials in a high purity.

Process for preparing 5-arylhydantoin

A process for preparing 5-hydroxyhydantoin which comprises oxidizing 4,5-dihydroxyimidazolin-2-one having formula (I): ##STR1## with hydrogen peroxide in an aqueous medium in the presence of a metal ion. According to the process, 5-hydroxyhydantoin is readily prepared from inexpensive starting materials.

Growing community of inventors

Kobe, Japan

Masahiko Yamada