Hitachi, Ltd.

The Tokyo Electric Power Company, Incorporated

Hitachi Engineering Co., Ltd.

Nippon Engelhard Ltd.

Masao Kitamura

Shunsuke Uchida

Eiichi Nishimura

Hideo Yusa

Hidefumi Ibe

Tatsuo Hayashi

Kunio Kamiya

Masaki Takeshima

Hiroji Mikawa

Eishi Ibe

Koichi Saito

Toshio Ishidate

Kanji Yamazaki

Ryoei Katsura

Norio Nakayama

Two dissolved gas components in sample water, for example, oxygen and hydrogen in core water, are readily quantitatively determined in one and same membrane-type oxygen meter by using a membrane producing an overlapped potential region where a potential region for an oxidation limiting current plateau is overlapped with that for a reduction limiting current plateau between two dissolved gas components, and applying to between a pair of an electrode and a counter-electrode a more positive potential than the equilibrium potential for oxidation-reduction reaction of one of the two dissolved gas components principally, thereby measuring a current generated between the electrodes, and a more negative potential than the equilibrium potential for oxidation-reduction reaction of the other dissolved gas component, when desired, thereby measuring a current generated between the electrodes, and quantitatively determining a concentration of the first dissolved gas component from the latter current quantity and quantitatively determining a concentration of the other dissolved gas component from a difference between the said two current quantities.

Method and apparatus for measuring dissolved gas concentrations

A control rod for a boiling-water reactor having blades arranged in the form of a cross in transverse cross section includes a plurality of poison tubes disposed therein. Boron carbide powder which is a neutron absorbing material causing an (n, .alpha.) reaction to take place is charged in the poison tubes. The control rod has plates of Hf-Zr alloy arranged in the blades in a position nearer to a forward end of the control rod at which the control rod is inserted in a reactor core than the poison tubes. The plates of Hf-Zr alloy are formed of an alloy of Hf having a large neutron absorption cross section and Zr having a small neutron absorption cross section. The concentration of Hf in the plates of Hf-Zr alloy is successively reduced in going from an end thereof adjacent the poison tubes toward and end thereof at the inserting end of the control rod. The plates of Hf-Zr alloy and the poison tubes have the same neutron absorbing capacity at the boundary therebetween at which they are in contact with each other.

Control rods and method of producing same

A radioactivity monitoring system capable of exactly detecting the concentration of .sup.131 I in a gas even in a low concentration is disclosed in which a sample gas is passed through a filter cartridge filled with an iodine absorbing material to accumulate iodine, radiation is counted on both entrance and exit sides of the filter cartridge, the absorption distribution of iodine absorbed in the filter cartridge is estimated from the ratio between respective counts obtained on the entrance and exit sides, and one of the counts is corrected by the estimated absorption distribution of iodine to calculate the radioactivity concentration of .sup.131 I in the gas.

Method of and apparatus for monitoring radioactivity concentration of gas

An iodine adsorbent comprises an alumina carrier having a large number of pores having a mean pore size of 200 to 2,000 A and silver supported on the alumina carrier. The alumina carrier has a pore volume of at least about 0.1 cc/g. High percent iodine removal is obtained in a highly humid atmosphere, and an amount of silver supported on the carrier is much reduced.

Iodine adsorbent

Growing community of inventors

Hitachiota, Japan

Masao Kitamura