Japan Atomic Energy Research Institute (JAERI) has conducted irradiation experiments utilizing extensive fuel instrumentations at HBWR in Norway since 1967. The major effort has been given to the study of pellet cladding interaction. A special emphasis was placed on the studies of inpile fuel rod deformation including cladding diameter measurements. The experimental conditions cover steady state irradiation, power ramping and power cycling. The data obtained from the experiments were used for development and verification of the computer code FEMAXI. The present paper reviews and summarizes the major results of the experiments.

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A prototype annular electromagnetic flow coupler was tested with high temperature sodium and it worked successfully, verifying the operational principle. The pump head-flow characteristics of the coupler were first clarified from an analysis of its equivalent electric circuit. The pump head and the generator pressure drop decrease linearly with the pump flow rate under the conditions of constant generator flow rate and external magnetic flux density. The gradients of the linear changes are given by ratios of equivalent resistances in the electrical analog, and are independent of the generator flow rate, if the magnetic flux density is kept constant. Sodium tests of the prototype confirmed the above results when the Hartmann number of the test conditions is larger than 170. Both ratios of the differential pressures and the volumetric flow rate between pump and generator ducts exceed 50% while the wall loss of around 40% appears at peak efficiency due to the lack of electrical insulation and the relatively large wall thickness. The peak efficiency of the prototype coupler decreases with the sodium temperature at the rate of (2.33±0.21) X10-2 %/°C from 200 to 400°C and increases with the external magnetic flux density at 5.8±0.1 %/T from 0.36 to 0.60 T.

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Accurate solution of the group diffusion equations for PWR cores requires explicit treatment of the non-homogeneous macroscopic parameters within each fuel assembly. It is argued that the response matrix approach is a convenient method to handle this problem provided all matrix elements for the non-homogeneous assemblies can be computed. This so called local problem is solved in this paper by a perturbation algorithm which leads to sensitivity coefficients for the power series expansions of the response matrix elements. A numerical study for 2 representative assemblies of the Indian Point Unit No. 2 (IP2) reactor is carried out and response matrices obtained by the perturbative method are compared with values computed by a finite difference program.

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Separation of barium isotopes with a selective two-step photoionization process was accomplished using a continuous wave dye laser and ultra-high pressure mercury lamp. Narrow linewidth laser light was tuned to the 6s2 1S0-6s6p 1P1, resonance line (553.6 nm), and only a single isotopic component in an atomic beam was excited through the isotope shift. The excited atoms were successively ionized by uv radiation and deflected by a static electric field.
The spectrum of the ion current separated isotopically agreed well with spectroscopic data within the system resolution of 65 MHz. The isotopic enrichment of 138Ba was 97%, which corresponded to the selectivity of 1.36. The ionization rate defined as what portion of the incident atoms was ionized was approximately 4×10-5%. The photoionization cross section was estimated from the experimental results by using the least squares method. The resultant value was (4±1)×10-23m2.

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An analytical method of solving the convection-diffusion equation is presented for the centrifugal separation of a binary isotopic gas mixture under the condition that the pure axial flow velocity field is attained. In the present method, it is assumed that the radial concentration profile can be expressed in the form of multi-term expansion, and the two-dimensional partial differential equation is transformed into a set of ordinary differential equations through the multiple integration in the radial direction.
Computations are made on UF6 gas in various types of centrifuges which have the ports for feed, product, and waste on the end plates. The results of the present analysis are compared with the other results of existing theoretical analysis.
In spite of the approximate approach, the present method can provide a closer agreement with the two-dimensional finite difference method (FDM) proposed by Kai. Finally, it is shown that the results of the present analysis agree with the experimental data of Beams et al., using the internal flow pattern based on the boundary layer theory by Nakayama et al.

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Lead-iron phosphate glasses loaded with simulated high-level nuclear wastes at temperatures between 900 and 1, 100°C were studied on their soaking behavior in distilled water by means of leachate solution analysis.
The obtained results showed that the leach rates of the glass waste forms were at least 10 to 100 times lower than that of the currently investigated borosilicate glass, even though the selective release of Na ion from the forms was observed. Zirconium of the waste led the glass to partial crystallization at 900°C, but was able to be incorporated in the glass at near 1, 100°C.
The liquid chromatographic analysis of poly-phosphate ions in the leachate solution revealed that the low leachability of the glass forms was brought about by a certain degree of depolymerization of long poly-phosphate chains of lead metaphosphate caused by the addition of ferric oxide.

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