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Nakashio, Nobuyuki*; Osugi, Takeshi; Kurosawa, Shigenobu; Ishikawa, Joji; Hemmi, Ko; Iketani, Shotaro; Yokobori, Tomohiko
JAEA-Technology 2022-016, 47 Pages, 2022/08
JAEA-Technology-2022-016.pdf:2.23MB
The Nuclear Science Research Institute (NSRI) of the Japan Atomic Energy Agency (JAEA) started operation of the Advanced Volume Reduction Facilities (AVWF) for production of waste packages for disposal of low-level radioactive solid wastes (LLW). To clarify the operating conditions for homogenization of non-metallic LLW, preliminary tests were carried out using the plasma melting furnace of the non-metal melting unit. The fluidity of molten waste influences homogenization conditions of solidified products. It was clarified that the viscosity, which is determined by the chemical composition and the melting temperature, influence the fluidity of molten waste greatly through previous literature review and the small-scale melting tests. In the preliminary tests, the simulated waste with a cold tracer loaded in 200 L drums were melted. Using the waste chemical components (basicity, iron oxide concentration) as an experimental parameter, the homogeneity of the chemical components of the solidified product was investigated and the homogenization conditions of melting tests were examined. The retention ratio of the tracer in the molten bath was also confirmed. The viscosity of the molten wastes was measured and the correlation with homogeneity was examined. In addition, the technical requirements that should be concerned in advance for future actual operation were discussed.
Hanus, G.*; Sato, Ikken; Iwama, Tatsuya*
Proceedings of International Waste Management Symposia 2016 (WM2016) (Internet), 12 Pages, 2016/03
JAEA plans a large-scale test to evaluate damage and relocation behavior of BWR core materials consisting of fuel rods, channel boxes, control blade and lower support structures. Its purpose is to contribute to understanding of core material relocation behavior in the event of severe accidents with the BWR design conditions for which existing experimental database is quite limited. Prior to large-scale testing, JAEA desires preliminary investigations to examine melting test pieces. The purpose of such tests is to verify the materials and test piece will be heated by plasma to the target temperature (ca.2900K) and to collect data about the material relocation behavior. Results from preliminary computational simulations are presented illustrating the effectiveness of a 150 kW non-transferred plasma jet. An experimental test program using the computational analyses as a basis and a plasma torch is described.
Haraga, Tomoko; Kameo, Yutaka; Nakashima, Mikio
Bunseki Kagaku, 55(1), p.51 - 54, 2006/01
Times Cited Count：4 Percentile：14.43(Chemistry, Analytical)A relatively large quantity of sample solutions have to be prepared for radiochemical analysis of solidified products yielded by plasma melting treatment of non-metallic radioactive wastes. In order to dissolve the solidified products sample rapidly, dissolution method with microwave heating devices was applied. In a conventional method only by external heating with various mixtures of acids (HNO
, HF, HClO
and H
SO), a 0.1 g amount of the sample was dissolved with difficulty. However, applying the microwave assisted dissolution method, a 1 g amount of the sample was completely dissolved in a shorter time. Thereby the time for dissolution procedures was shortened less than a one-tenth. The present dissolution method was successfully applied to the blast furnace slag as a reference material to determine main elements with good precision.
-ray spectrometry for the rapid radioactivity evaluation of solidified products prepared from radioactive wastesHaraga, Tomoko; Kameo, Yutaka; Hoshi, Akiko; Yonezawa, Chushiro*; Nakashima, Mikio
JAERI-Tech 2005-050, 35 Pages, 2005/09
JAERI-Tech-2005-050.pdf:1.35MB
Non-destructive -ray spectrometry has been examined as a simple and rapid radioactivity measurement technique for the solidified products prepared by plasma melting for low level radioactive miscellaneous wastes generated from nuclear facilities. The Compton background resulting from the coexisting radionuclides pose a problem in the usual -ray spectrometry which uses only a Ge detector. In order to reduce the background count and to measure the interested nuclide selectively, the coincidence and the anti-coincidence -ray spectrometry using the Ge-BGO detector system were examined. As a result of applying the anti-coincidence -ray spectrometry to a single -ray emitter 
Cs and the coincidence -ray spectrometry to multiple -ray emitter 
Eu under existence of 
Co, the detection limits of Cs and Eu in the sample, which contained Co, were reduced by a factor of about 6 and 1.5, respectively. It was confirmed that the present methods are useful for the -activity measurement of solidified products.
*; Sasaki, Akira; Kunugi, Tomoaki*; *; *
Inst. Phys. Conf. Ser., (159), p.451 - 454, 1999/00
no abstracts in English
Kunugi, Tomoaki
SAND-92-0222, p.3-6 - 3-13, 1991/00
no abstracts in English
