• Proceedings of the Korean Nuclear Society Conference
• /
• 1999.10a
• /
• pp.369.2-369
• /
• 1999

• Proceedings of the Korean Nuclear Society Conference
• /
• 1999.10a
• /
• pp.372.2-372
• /
• 1999

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2016.10a
• /
• pp.405-406
• /
• 2016

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.21 no.6
• /
• pp.83-90
• /
• 2017

Concrete structure for nuclear power plant is mass concrete structure with large wall depth and easily permits cracking in early age due to hydration heat and drying shrinkage. It always needs cooling water so that usually located near to sea shore. The crack on concrete surface permits rapid chloride intrusion and also causes more rapid corrosion in the steel. In the study, the effect of age and crack width on chloride diffusion is evaluated for the concrete for nuclear power plant with 6000 psi strength. For the work, various crack widths with 0.0~1.4 mm are induced and accelerated diffusion test is performed for concrete with 56 days, 180days, and 365 days. With increasing crack width over 1.0mm, diffusion coefficient is enlarged to 2.7~3.1 times and significant reduction of diffusion is evaluated due to age effect. Furthermore, apparent diffusion coefficient and surface chloride content are evaluated for the concrete with various crack width exposed to atmospheric zone with salt spraying at the age of 180 days. The results are also analyzed with those from accelerated diffusion test.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.10b
• /
• pp.637-642
• /
• 1998

This study was performed to develop effective management system of concrete structures in Nuclear Power Plants. This D/B system includes three kinds of data : 1)visual inspection data(cracking, spalling, etc.) 2) durability data carbonation, chloride attack, etc. 3) in-service inspection data(prestressing force. material properties, etc. ) By using the life management D/B System, the field engineers can easily acquire the information about the various inspection data. repair and accidental histories of structures. This system, will contribute to the efficient life management of concrete structures.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1996.10a
• /
• pp.546-550
• /
• 1996

The personal-computer software program named SAMS(Structural Aging Management System) was developed for the concrete structure of NPP(Nuclear Power Plant). SAMS is constituted of three part, detabase system containing various inspection data, operation program for standard input/output of the inspection data, and application program for efficient operation of database system. Using the SAMS, the field engineers can easily acquire the information about the various inspection data, repair and accidental histories of NPP structures. SAMS will contribute to the effcient maintenance of NPP structures.

• Journal of the Korea Concrete Institute
• /
• v.24 no.6
• /
• pp.695-703
• /
• 2012

Recently, major infrastructure such as bridges, tunnels, PCCVs (Prestressed Concrete Containment Vessel), and gas tanks are Prestressed Concrete (PSC) structure types, which improve their safety by using confining effect from prestressing. Generally, concrete is known to be an outstanding fire resistant construction material. Because of this reason, researches related to extreme fire loaded PSC member behaviors are not often conducted even though PSC behavior under extreme fire loading is significantly different than that of ordinary reinforced concrete (RC) behavior. Therefore, in this study, RABT fire loading tests were performed on bi-directionally prestressed concrete panels with $1000{\times}1400{\times}300mm$ dimensions. The prestressed specimens were applied with 430 kN prestressing (PS) force using unbonded PS thread bars. Also, residual strength structural tests of fire tested PSC and ordinary RC structures were performed for comparison. The study results showed that PSC behavior under fire loading is significantly different than that of RC behavior.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.5 no.3
• /
• pp.223-229
• /
• 2017

When concrete is exposed to neutron rays for a long time, the concrete tends to become activated. If activated, it is classified as middle or low level radioactive waste. However, the great amount of the activated concrete is hard to dispose. In this study, low-activation cement was developed for decreasing the activated waste from shielding concrete around nuclear reactor. Furthermore, the manufactured low-activation was analyzed with activation nuclide Eu, Co. The low-activation cement showed great advantage for low-activation with detecting none of Eu and 3.75ppm of Co while ordinary portland cement showed 0.4~0.9ppm of Eu, 5.5~19.8ppm of Co content. As the results of physical properties of the low-activation cement, it is similar to type 1 ordinary portland cement and accords with type 4 low heat portland cement. Meanwhile, as for the chemical properties of the cement, it accords wite type 1 and 4 at the same time.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.22 no.3
• /
• pp.38-45
• /
• 2018

The purpose of this study is to deduct the structural damage / work process risks factors which can be occurred during the decommissioning in the NPP containment concrete structure. To achieve these purpose, risk profile specified in the construction industry is analyzed, and the work process of NPP decommissioning and the construction project were matched based on the similarity of each works. Accordingly, human and physical risk factors are classified. Finally, the risk associated with the building structure and work process was classified as per their process activities, and risk typology explaining the disaster which put the structure, equipments, machine and workers in serious danger was developed.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.18 no.1
• /
• pp.103-111
• /
• 2020

Pulling-type cutting devices, which use a diamond wire saw, have been used generally for cutting concrete structures. In this study, a pushing-type cutting device with a collection cover was developed by overcoming the disadvantages of pulling-type devices. In this device, dry or liquid methods can be selected to cool frictional heat. Operation and leakage tests of the dust generated during the dismantling of a concrete structure were carried out, confirming the suitable operation of the fabricated cutting device; the leakage rate was approximately 1.7%. For a conservative evaluation, the internal dose of workers was estimated in dismantling the core center part of biological shield concrete with a specific activity of 99.5 Bq·g^-1. The committed effective dose per worker was 0.25 mSv. The developed cutting device contributed to reducing radioactive concrete waste and minimizing worker exposure due to its easy installation. Therefore, it can be utilized as a cutting apparatus for dismantling not only reinforced concrete structures but also radioactive biological shield concrete in nuclear power plant decommissioning efforts.