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JAEA Reports

Review and evaluation on the surface area of vitrified products of high-level waste; Surface area increase factors due to fracturing and their bases for the performance assessment of geological disposal

Igarashi, Hiroshi

JAEA-Review 2020-006, 261 Pages, 2020/09

JAEA-Review-2020-006.pdf:4.42MB

A literature review was conducted on the increase in surface area of vitrified products of HLW due to the fracturing caused by cooling during glass pouring process and by mechanical impact, from the perspective of a parameter of the radionuclide release model in the performance assessment of geological disposal system studied overseas. The review was focused on the value of surface area increase factor set as a parameter in the model, the experimental work to evaluate an increase in surface area, and how the parameters on surface area were determined based on the experimental results. The surface area obtained from the experiments executed in Japan was also discussed in comparison with the overseas studies. On the basis of the investigation, the effects of various conditions on the surface area were studied, such as a diameter of vitrified product, cooling condition during and after the glass pouring, impact on vitrified products during their handling, environment after the closure of disposal facility, and others. The causes of fracturing are associated with the phenomena or events in the waste management process such as production, transport, storage, and disposal. The surface area increase factors set in the nuclide release model of the glass and their bases were reviewed. In addition, the measured values and the experimental methods for surface increase factors published so far were compared. Accordingly, the methods for measuring surface area as the bases were identified for these factors set in the models. The causes of fracturing and features of these factors were studied with respect to the relation with the waste management process. The results from the review and assessment can contribute to the expanding the knowledge for the conservative and realistic application of these factors to performance assessment, and to the developing and upgrading of safety case as a consequence.

Journal Articles

Development of stress intensity factors for subsurface flaws in plates subjected to polynomial stress distributions

Lu, K.; Mano, Akihiro; Katsuyama, Jinya; Li, Y.; Iwamatsu, Fuminori*

Journal of Pressure Vessel Technology, 140(3), p.031201_1 - 031201_11, 2018/06

https://doi.org/10.1115/1.4039125

Times Cited Count：11 Percentile：43.60(Engineering, Mechanical)

Journal Articles

Development of Stress intensity factor coefficients database for a surface crack of an RPV considering the stress discontinuity between cladding and base metal

Onizawa, Kunio; Shibata, Katsuyuki*; Suzuki, Masahide

Proceedings of 2005 ASME/JSME Pressure Vessels and Piping Division Conference (PVP 2005), 12 Pages, 2005/07

Under a transient loading like pressurized thermal shock (PTS), the stress discontinuity near the interface between cladding and base metal of a reactor pressure vessel (RPV) is caused by the difference in their thermal expansion factors. So the stress intensity factor (SIF) of a surface crack which the deepest point exceeds the interface should be calculated by taking account of the stress discontinuity. Many SIF calculations are performed in Monte Carlo simulation of the probabilistic fracture mechanics (PFM) analysis. To avoid the time consuming process from the SIF calculation in the PFM analysis, the non-dimensional SIF coefficients corresponding to the stress distributions in the cladding and base metal were developed. The non-dimensional SIF coefficients database were obtained from 3D FEM analyses. The SIF value at the surface was determined by linear extrapolation of SIF value near the surface. Using the SIF coefficients database, the SIF values at both surface and deepest points of a surface crack can be evaluated precisely and in a reasonable time.

Journal Articles