| Budget Amount *help |
¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1993: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1992: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Research Abstract |
Neutron measurements have been carried out at irradiation facilities of research reactors in Japan, namely JRR-2, JRR-4 and JRR-3M of JAERI, Toukai, and TRIGA II of Rikkyo University, Yokosuka. The purpose of this work is to contribute to the standardization of fission track ages from the basic arguments on reactor runs for fission track dating. The concluding remarks are as follows :
1) Characteristic values, thermal neutron flux, neutron temperature, cadmium ratio and fast neutron flux, of irradiation facilities of research reactors were determined by improved technique for inter-facility calibration.
2) Fission reaction rate of U-235, U-238 and Th-232 at these irradiation facilities were estimated from the data of neutron fluxes newly obtained and the cross-section data of nuclear data library of ENDF/B-VI and IRDF90.
3) Various irradiation facilities for common irradiation are desirable not only for basic reactor experiments but also for fission track studies.
4) The irradiation facilities entirely free from any problems of reactor neutron spectrum have to be used for fission track dating, because the reactor neutron dosimetry is very difficult at common irradiations for routine works.
5) The standardization of fission track ages have to be made by international cross-checking of various age standards using by restricted irradiation facilities of well thermalized reactors.
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