Doryokuro Kakunenryo Kaihatsu Jigyodan

Yoshiyuki Kihara

Takashi Okada

Akio Todokoro

Yoshiharu Takashi

A method of separating and recovering Pu and Np from a Pu- and Np-containing nitric acid solution. The method comprises the steps of subjecting a nitric acid solution containing Pu and Np to valence adjustment by adding a reducing agent consisting of hydroxylamine nitrate and hydrazlne to said nitric acid solution so as to reduce Pu and Np in said nitric acid solution to Pu (III) and Np (IV), respectively; adjusting a nitric acid concentration of said nitric acid solution after said valence adjustment to 6 to 8 M; bringing said nitric acid solution after said nitric acid concentration adjustment into contact with a strong basic anion exchange resin so as to cause Np to be selectively adsorbed by said resin and to separate and recover Pu as a plutonium nitrate solution; and eluting said adsorbed Np (IV) by using diluted nitric acid of 1 M or below so as to recover Np as a neptunium nitrate solution. The valence adjustment step may be carried out by subjecting the Pu- and Np-containing nitric acid solution to electrolytic reduction instead of using the reducing agent.

Method of separating and recovering plutonium and neptunium from

A radiation shielding structure including a radiation shielding panel which comprises a lead transparent plate, for example, a transparent lead acrylic resin plate, lead glass plate, etc., and a thin nonlead transparent plate, for example, a transparent acrylate resin plate, glass plate, etc., which is laminated on at least one side of the lead transparent plate. Thus, lead that is contained in the lead transparent plate shields radioactive rays, while the nonlead transparent plate, which is laminated on at least one side of the lead transparent plate, prevents oxidation of the lead in the lead transparent plate by air or chemicals, which oxidation would otherwise form an oxide film on the panel surface and make the panel opaque.

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Ibaraki, Japan

Yoshiyuki Kihara