[en] In a fuel assembly in a reactor-loaded state, pellets to be loaded in a region higher than a predetermined height are made hollow. That is, the volume of the gap in the hollow portion of the pellet comprising fissible materials to be filled at a position higher by 1/2 to 1/3 height from the upper region (downstream of coolant flow) of at least a portion of fuel rods in a fuel assembly is reduced stepwise than that in the lower region (upstream of coolant flow). Alternatively, the volume of the gap is gradually reduced from the lower portion to the upper portion. The diameter of the hollow hole portion is thus varied and the volume of the gap of the fissible materials per pellet is controlled, to reduce the amount of the fissile materials per unit volume. With such a constitution, the power of fission energy in the reactor core upper portion can be lowered. Accordingly, the corrosion of a cladding tube upon high burnup degree can be suppressed, thereby enabling to ensure integrity. (T.M.)

[en] The present invention concerns a fuel assembly for PWR type reactors in which a great number of fuel rods are bundled in a fuel can. The concentration of fissible materials to be filled in a portion higher than the position by 1/2 to 1/3 height from the upper region (downstream of coolant flow) of at least a portion of fuel rods in the fuel assembly is decreased to lower than that in the lower region (upstream of coolant flow). Accordingly, since the power of nuclear fission energy in the reacctor core upper region can be lowered to decrease surface heat fluxes, the heat generation is reduced. As a result, the temperature at a metal-oxide layer boundary is lowered and the oxidation rate is lowered. Thus, the amount of corrosion of a fuel cladding tube upon high burnup degree can be suppressed, thereby enabling to ensure integrity. (I.N.)

[en] A leaf spring is manufactured by precision casting using corrosion resistant and heat resistant high strength steel material and, subsequently, the surface is treated with slight surface grinding or pickling. Further, for increasing resistance to stress corrosion cracks (SCC), shot blasting is applied to the surface. This reduces the surface roughness (Rmax) of the leaf spring to less than 0.005 mm, and the dimensional tolerance can be set to +0.005 mm, -0.0 mm. In this way, since the surface roughness is so small as not causing fabrication injury to the surface, the material has sufficient resistance to SCC. Further, since the accuracy for the plate thickness is high, stress distribution as designed can be attained to prevent stress concentration. Then, if a casting die is once prepared, the casting mass production is enabled to reduce the manufacturing cost for the leaf spring. (T.M.)

No abstract available

[en] The report outlines some results of a study carried out by the ISER (intrinsically safe and economical reactor) Investigation Group. In particular, nuclear design concepts are examined in relation to the fuel cycle. Discussion is also made on technical development efforts to be made for realizing an ISER. Calculation of some basic nuclear design parameters is performed and results are used to examine the reactor core and fuel for ISER. As a result, it is indicated that a high-burnup type reactor core should be used on a 4.5-batch replacement, 15 EFPM (effective full power month) scheme to optimize an ISER. For technical development, consideration is made on various tests to be performed with an experimental reactor, called ISER-E, as well as other tests to provide basic data required for demonstrating the inherent safety of ISER. The study also deals with the possibility of the application of currently available light water reactor techniques to experiments with a critical assembly, non-nuclear test loop, and the experimental reactor ISER-E. It is revealed that many of the required experiments can be carried out by using test facilities and light water reactor techniques which are currently, or will be readily, available. It is stressed that international cooperation is necessary to accomplish these tests. (Nogami, K.)

[en] A preliminary core design work on ISER (Intrinsically Safe and Economical Reactor) based on the concept of the PIUS reactor of ASEA-ATOM is performed in order to grasp the characteristics of the reactor core and the fuel management scheme. Certain relations between the fuel specifications and the cycle length are estimated. Items of improvement on the ISER core characteristics and problems to be considered on the nuclear design are presented. Experiments to be considered are also discussed in conjunction with the development of experimental reactor (ISER-E)

[en] 252 cases with primary lung cancer treated with supervoltage irradiation at Radiology Department of the Yamaguchi University Hospital during the period of 1963 to 1976 were investigated to evaluate the effectiveness of the present radiotherapy and remote results from the various standpoints, i.e., TNM classification, radiological classification, stage classification, histological classification and irradiation tumor doses. The results and findings were described with some comments and discussed. 1) Occurrence of lung cancer increased steadily year after year. The age distribution was from 20 to 80 years of age; the incidence was highest in the sixties, next in fifties and seventies and then forties in order. The ratio of male to female are 3.3 to 1. 2) Radiological classification of this series of lung cancer showed that 91 cases were classified as ''peripheral-nodular type'', 51 cases as ''Hilar nodular type'', 31 cases as ''peripheral-infiltrating type'' and 15 cases as ''hilar-infiltrating type''. 3) No significant relationship between the radiological findings and histopathological findings was noted. 4) Evaluation of the effects of this supervoltage irradiation in relation to the histopathological classification revealed that significant effect was obtained in cases of undifferentiated carcinoma and of squamous cell carcinoma. 5) The cases treated with 5,000 rads of tumor dose or more survived 4 times longer than the group received lesser dose. (author)

[en] On the 4 cases of operation for the late radiation effect, the process and notes for radiation colitis were described. Case 1; a female of 57 y with cervical carcinoma (IIIb) received 59.8 Gy of external irradiation and 24.0 Gy of intracervical irradiation. About 8 months after the radiotherapy, anemia due to gut bleeding was observed and hemorrhage was seen in the colon with the colon fiber. One year later, colostomy was performed. Case 2; a female of 79 y with cervical carcinoma (IIb) received 50.0 Gy of external irradiation and 18.0 Gy of intracervical irradiation. About 8 months after the therapy, gut bleeding and ileac symptom were observed and ulcer and stenosis in the sigmoid colon were seen. Sigmoidectomy was performed. Case 3; a female of 75 y with cervical carcinoma (IIIb) received external 49.8 Gy irradiation and intracervical 23.0 Gy irradiation. About 4 months after the therapy, anemia and ulcer with hemorrhage in the sigmoidal colon were recognized. Sigmoidectomy and colostomy were performed. Case 4; a female of 68 y with cervical carcinoma (IIb) and chronic renal failure received 50.4 Gy of external irradiation post hysterectomy. About 5 months later, iliac symptom was observed. She received ileectomy and then colostomy but died of MOF due to renal failure. (K.H.)

[en] This study was designed to evaluate the efficacy of CNS-prophylaxis with high-dose methotrexate (MTX). Seventy children with previously untreated acute lymphoblastic leukemia (ALL) entered to this study between July 1978 and December 1980. According to initial white blood count (WBC), they were stratified to induce remission with; vincristine and prednine in low initial WBC ( lt 25,000/mm³) group and these two agents plus adriamycin in high initial WBC ( gt 25,000/mm³) group. After inducing remission, 62 children who achieved CR, received different CNS-prophlaxis; using a regimen of three doses of weekly high-dose MTX (1,000 mg/m²) 6-hour infusion, which was repeated every 12 weeks-Group A (n = 14); high-dose MTX followed by 2400 rad cranial irradiation plus three doses of i.t. MT X-Group B (n = 15), 2400 rad cranial irradiation plus three doses of i.t. MTX-Group C (n = 16), and in 17 patients with high initial WBC, same as in Group A-Group D (n = 17). During an intravenous 6-h infusion of MTX at a dose of 1,000 mg/m², the CSF concentration of MTX rose to 2.3 +- 2.4 x 10^-6M after initiation of infusion and remained in 10^-7 M level for 48 hours. CNS-leukemia terminated complete remission in one of 14 children in Group A, two of 15 in Group B, two of 16 in Group C and two of 17 in Group D. The cumulative incidence of CNS-leukemia at 20 months calculated by the technique of Kaplan and Meier was 0% i n Group A, 18.1% in Group B, 7.1% in Group C and 50.8% in Group D. There was no statistical difference among Groups A, B and C. These data suggested that CNS-prophylaxis with high-dose intravenous MTX was effective as well as 2400 rad cranial irradiation plus three doses of i.t. MTX in childhood ALL with low initial WBC. (author)

[en] ²⁰¹Tl-chloride scintigraphy was performed for the purpose of distinguishing cold thyroid nodules by ¹²³I and/or sup(99m)Tc pertechnetate. Included in this study were 45 cases, consisting of 16 of thyroid cancer and 29 of benign lesions. Scans were performed 10 minutes (early scan) and 2 hours (delayed scan) after injection of ²⁰¹Tl. Early scintigrams showed warm or hot nodules in all cases except benign cystic lesions. Delayed scintigrams showed increased accumulations of radioactivities in a large number of malignant cases and a few cases of adenoma. Delayed scitigraphy might be clinically useful in differentiating malignant thyroid nodules from benign nodules. Positive images of metastatic lesions were visualized in three cases of thyroid cancer. (author)