Verification methodology and results of probabilistic fracture mechanics code PASCAL

Masaki, Koichi; Miyamoto, Yuhei*; Osakabe, Kazuya*; Uno, Shumpei*; Katsuyama, Jinya; Li, Y.

Proceedings of 2017 ASME Pressure Vessels and Piping Conference (PVP 2017) (CD-ROM), 7 Pages, 2017/07

A probabilistic fracture mechanics (PFM) analysis code PASCAL has been developed by Japan Atomic Energy Agency (JAEA). PASCAL can evaluate failure frequencies of Japanese reactor pressure vessels (RPVs) during pressurized thermal shock (PTS) events based on domestic structural integrity assessment models and data of influence factors. In order to improve the engineering applicability of PFM to Japanese RPVs, we have performed verification of the PASCAL. In general, PFM code consists of many functions such as fracture mechanics evaluation functions, probabilistic evaluation functions including random variables sampling modules and probabilistic evaluation models, and so on. The verification of PFM code is basically difficult because it is impossible to confirm such functions through the comparison with experiments. When a PFM code is applied for evaluating failure frequencies of RPVs, verification methodology of the code should be clarified and it is important that verification results including the region and process of the verification of the code are indicated. In this paper, our activities of verification for PASCAL are presented. We firstly represent the overview and methodology of verification of PFM code, and then, some verification examples are provided. Through the verification activities, the applicability of PASCAL in structural integrity assessments for Japanese RPVs was confirmed with great confidence.

Collapse evaluation of double notched stainless pipes subjected to combined tension and bending

Suzuki, Ryosuke*; Matsubara, Masaaki*; Yanagihara, Seiji*; Morijiri, Mitsugu*; Omori, Atsushi*; Wakai, Takashi

Procedia Materials Science, 12, p.24 - 29, 2016/00

https://doi.org/10.1016/j.mspro.2016.03.005

In this study, the plastic collapse strength of asymmetry multiple circumferential notched stainless steel pipes subjected to combined axial tension and bending is investigated experimentally and is compared with the theoretical plastic collapse strength. In addition, the potential is discussed for the simplification of structural integrity evaluation of multiple cracked piping. The integrity of the asymmetry multiple circumferential notched stainless steel pipes subjected to combined axial tension and bending can be evaluated conservatively using the theoretical plastic collapse strength for the pipe with multiple notches calculated based on the elastic-perfectly plastic model.

Design optimization of ADS plant proposed by JAERI

Saito, Shigeru; Tsujimoto, Kazufumi; Kikuchi, Kenji; Kurata, Yuji; Sasa, Toshinobu; Umeno, Makoto*; Nishihara, Kenji; Mizumoto, Motoharu; Ouchi, Nobuo; Takei, Hayanori; et al.

Nuclear Instruments and Methods in Physics Research A, 562(2), p.646 - 649, 2006/06

https://doi.org/10.1016/j.nima.2006.02.078

JAERI is conducting R&D on the Accelerator Driven System (ADS) to transmute minor actinides (MAs) contained in the high-level radioactive waste under the OMEGA (Options Making Extra Gains from Actinides and fission products) program. The present study discusses the design of the ADS plant and various R&D on the ADS. The reference design of ADS plant in JAERI is the 800 MWth, Pb-Bi eutectic (LBE) cooled, tank-type subcritical reactor loaded with (MA+Pu) nitride fuel. LBE is selected as a spallation target material. In our results of the optimization study on the neutronics of the ADS, we have adopted the maximum multiplication factor (k) of 0.97. From the results of the thermal-hydraulic analysis around the LBE spallation target, partition wall and flow control nozzle are required to keep the structural integrity around the core and the beam window. Feasibility of beam window was also discussed for transient conditions of proton beam.

System evaluation for the volume change of the engineered barrier

Aoyagi, Takayoshi*; Mihara, Morihiro; Tanaka, M.*; Okutsu, Kazuo*

JNC TN8400 99-058, 55 Pages, 1999/11

JNC-TN8400-99-058.pdf:6.84MB

For the emplaced waste in TRU waste disposal facility, it may have the void for waste bodies it. And, generating void which accompanies those component elution in concrete pit and filler in which the cement material becomes the candidate material is assumed. It is considered that the security of the diffusion control in the bentonite is not done when these voids collapsed, and when it generated the volume change inside the buffer material (bentonite). The imperfect blockage of the void by not obtaining, the sufficient swelling pameability swelling bentonite is a cause on this. Then, volume change of the bentonite inside is analyzed in this study under the conservative estimation. And the following are tested: Self-sealing, maximum swelling rate, density distribution change of the batonite. Evaluation of the engineered barrier system for volume change from the result was carried out. Prior to the evaluation, generating void was calculated based on the conservative estimation. The density of the buffer material as it assumed the blocking by buffer material uniformly awelling using this calculated data, was obtained. By the permeability got from existing research result which shows the relationship between density and permeability of the bentonite, it was confirmed to become diffusion control in the buffer material inside, in existing engineered barrier specification. Next, it was tested, when the conservative void of the superscription was assumed, in order to confirm whether it does the security, as permeability necessaly for maintaining diffusion control, puts it for the swelling of actual bentonite. As the result, it was possible to confirm sufficient swelling performance in order to do the security of the diffusion control in Na-bentonite. However, the swelling performance greatly lowered by comparing Na-bentonite in Ca-bentonite with under 1/6. The increase of the permeability not do the security of the diffusion control, when it was based on void quantity ...

Investigation on fracture toughness evaluation method for reactor pressure vessel surveillance

Onizawa, Kunio; Tobita, Toru; Suzuki, Masahide

Proc. of 2nd Int. Workshop on the Integrity of Nuclear Components, p.273 - 289, 1998/00

no abstracts in English

Integrity evaluations for the 2nd Fugen pressure tube surveillance test

; ; ; ; ; Shibahara, Itaru

PNC TN9410 92-321, 30 Pages, 1992/10

PNC-TN9410-92-321.pdf:0.67MB

Integrity evaluations have been performed for the 2nd Fugen pressure tube test (8 years irradiation, 5.6 10n/cm (E1Mev)). Test items mainly consist of tensile test, bending test, corrosion test and hydrogen analysis. It has become clear using these data that the pressure tube material has maintained its integrity during the irradiation by the integrity assessment on both tensile and fracture toughness properties. Besides, both thickness loss by corrosion and absorbed hydrogen content were lower than those of design values.

A New modelling approach for containment event tree construction; Accident progression stage evaent tree method

Watanabe, Norio; *; Muramatsu, Ken

2nd Int. Conf. on Containment Design and Operation,Conf. Proc., Vol. l, 14 Pages, 1990/00

no abstracts in English

EMAT-guided wave approach for detecting and quality evaluation of the laser beam butt welding line on the inner surface of the steel pipe

Furusawa, Akinori; Nishimura, Akihiko; Torimoto, Kazuhiro; Takenaka, Yusuke*; Saijo, Shingo*; Toyama, Ryoji*

no journal, , 

The aim of this work presented here is to investigate the applicability of the guided wave testing to detect and evaluate the quality of laser beam butt welding line. First, four test pipes were prepared. All of the pipes were laser beam butt welded from inside of the pipe using laser torch. Two pipes of them were high-quality welded, the others were low-quality. Two different pipe-wall-thicknesses were in each quality. Secondly, Laser beam butt welding line detection and the quality evaluation experiments were performed. T(0,1) mode guided wave was excited and received by electromagnetic acoustic transducer array. Finally, the experimental results were analyzed and issues concerning with the applicability of the guided wave testing to detection and quality evaluation of the laser butt welding line were discussed.

Development status of drying simulation code for waste storage

Terada, Atsuhiko; Yamagishi, Isao; Hino, Ryutaro

no journal, , 

Toward the establishment of a long-term soundness evaluation method of storage vessels, such as zeolite wastes generated by the treatment of radioactive saline water at the Fukushima Daiichi Nuclear Power Station, the analysis code to predict the drying process behavior by the decay heat of the waste. In this paper, as an example the spent zeolite vessel, we report the development status of this code.

Laser ultrasonic approach for detecting a deteriorated rebar in concrete

Furusawa, Akinori; Nishimura, Akihiko; Takenaka, Yusuke*

no journal, , 

Large number of concrete structures built in the era of rapid economic growth will exceed fifteen years old in next 10 to 20 years. Developing maintenance and health monitoring techniques for these existing concrete structures is inevitable problem to be resolved. JAEA have tackled to that problem on collaborative research, having achieved to crack detection technique for surface on the concrete of railroad tunnel (1). The technique reported in ref. (1), however, is focusing on the surface cracks, not taking into account the condition of the deep region, including a steel reinforcing bar (rebar) in a reinforced concrete structure. This work supposes a new approach for detecting deteriorated rebar in concrete structure based on laser-ultrasonic. Irradiating the one end of a rebar by nanosecond laser pulses repetitively generates ultrasonic wave propagating along it. The waveform of the ultrasonic received the other end is analyzed to extract the information about its condition.