• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.15-20
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• 1996

The nonlinear dynamic analyses were performed by newly developing an appropriate impact modelling for the evaluation of the CANFLEX fuel bundle structural integrity during the refuelling period. The initial load under the refuelling condition is considered as initial velocity at impact incident, and the impact of one bundle contacted another bundle for at short time is studied by performing several dynamic analysis method. The impact analysis shows to predict an appropriate velocity and acceleration profile according to load time history for two bundles impact.

• Nuclear Engineering and Technology
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• v.48 no.2
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• pp.482-494
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• 2016

The Feshbache-Kermane-Koonin (FKK) multi-step direct (MSD) theory of pre-equilibrium reactions has been used to compute the single-step cross-sections for some (p,${\alpha}$) reactions using the knock-on and pick-up reaction mechanisms at two incident proton energies. For the knock-on mechanism, the reaction was assumed to have taken place by the direct ejection of a preformed alpha cluster in a shell-model state of the target. But the reaction was assumed to have taken place by the pick-up of a preformed triton cluster (also bound in a shell-model state of the target core) by the incident proton for the pick-up mechanism. The Yukawa forms of potential were used for the proton-alpha (for the knock-on process) and proton-triton (for the pick-up process) interaction and several parameter sets for the proton and alpha-particle optical potentials. The calculated cross-sections for both mechanisms gave satisfactory fits to the experimental data. Furthermore, it has been shown that some combinations of the calculated distorted wave Born approximation cross-sections for the two reaction mechanisms in the FKK MSD theory are able to give better fits to the experimental data, especially in terms of range of agreement. In addition, the theory has been observed to be valid over a wider range of energy.

• Strategy21
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• s.34
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• pp.93-127
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• 2014

During the four years following the sinking of the Cheonan frigate in 2010, the South Korean public opinion has seen changes in four basic ways. First, public polls with respect to the cause of the sinking show that 70% of the people consider North Korea as the culprit, while 20% maintain that it was not an act carried out by North Korea. Second, the opinions relative to the cause of the incident seem to vary according to age difference, generational difference, and educational difference. From 2011, people in their 20s showed 10% increase in regarding North Korea as the responsible party. People in their 30s and 40s still have a tendency not to believe the result of the investigation carried out by the combined military and civilian group. Third, the most prominent issue that arose aftermath of the Cheonan incident is the fact that political inclination and policy preference are influencing the scientific determination of the cause. In other words, scientific and logical approach is lacking in the process of determining the factual basis for the cause. This process is compromised by the inability of the parties concerned in sorting out what is objective and what is personal opinion. This confused state of affairs makes it difficult to carry on a healthy, productive debate. Fourth, rumors, propaganda, and disinformation generated by pro-North Korea Labor Party groups in the internet and SNS are causing considerable impact in forming the public opinion. Proposed Strategy 1. The administration can ascertain public trust by accurately determining the nature of the provocation based on accurate information in the early stages of the incident. 2. Education in scientific, logical, rational methodologyis needed at home, school, and workplace in order toenhance the people's ability to seek factual truths. 3. In secondary education, the values of freedom, human rights, democracy, and market economy must be reinforced. 4. It is necessary for the educational system to teach the facts of North Korea just as they are. 5. Fundamental strength of free democratic system must be reinforced. The conservative, mainstream powers must recognize the importance of self-sacrifice and societal duties. The progressive political parties must sever themselves from those groups that take instructions from North Korea's Labor Party. The progressives must pursue values that are based on fundamental human rights for all. 6. Korean unification led by South Korea is the genuine means to achieve peace in a nuclear-free Korean peninsula. The administration must recognize that this unification initiative is the beginning of the common peace and prosperity in the Far East Asia, and must actively pursue international cooperation in this regard.

• Journal of Radiation Protection and Research
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• v.1 no.1
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• pp.10-14
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• 1976

Influence of the cavity size on the response of LiF TLD was theoretically investigated for a presumed system of spherical TLD cavity imbedded in a medium of polyethylene. Calculation of the response for different radii of the spherical cavity was carried out as a function of incident photon energy, applying recent cavity theory. The range of the radii covers 1.578 to 6.528 mm, while that of the incident photon energies extends from 0.02 to 3.0 MeV. As a results, the response of the LiF TLD imbedded in a medium as a cavity was found to be functions of its own size as wall as the incident photon energy.

• Journal of the Korean Society of Safety
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• v.36 no.5
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• pp.43-51
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• 2021

Incident investigation is one of the most important processes among various other safety management methods to prevent industrial accidents. Finding the root causes of accidents, eliminating hazards, and improving safety are the most important purposes of investigating accidents. During the investigation process, root cause analysis (RCA) techniques are used to effectively identify RCA. Over the past few decades, over 30 RCA methods have been developed. These techniques are being widely used in some industries, such as the nuclear and aircraft industries; however, most of the RCA techniques require professional knowledge and special training, making it difficult for safety managers in their respective fields to understand and apply them. Therefore, managers of general industrial sites are rarely present at the scene of actual accident investigations, and they cannot contribute much to the purpose and effectiveness of these investigations. In this study, to address these issues, we developed an RCA technique to facilitate root cause investigation of accidents in real-world industrial sites. To develop new techniques, Systematic Cause Analysis Technique (SCAT), one of the RCA techniques, was used to investigate incidents in the enterprise over three years. We also utilized feature analysis and other papers from existing RCA techniques. To verify its effectiveness, the technique proposed was also applied to the accident case. The technique developed can easily identify and analyze the root cause of an accident and help industrial managers. It can also identify the root cause category where accidents are concentrated and use this data to establish guidelines for preventing future accidents and, thus, focus on prioritizing improvement initiatives.

• Korean Journal of Optics and Photonics
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• v.6 no.1
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• pp.26-32
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• 1995

A Kerr cell was utilized as an optical shutter to generate a shortened pulse and as an isolator between amplifiers in an iodine laser system. By rotating the polarization of incident laser pulse only during the timing window of high voltage applied to the Kerr cell, shortened pulses of 5 ns and 1 ns, corresponding to the difference in propagation time of two coaxial cables, were obtained. It was also noticed that more than one timing window of Kerr cell was produced with a long incident laser pulse from the oscillator. The measured transmittance of Kerr cell with respect to applied voltage was compared with the theoretical estimation using the electro-optic Kerr effect theory. Through the amplification of the shortened pulse in iodine amplifiers. a pulse of 0.5 GW(2 J in 4 ns) was obtained. ained.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.547-553
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• 1989

Last several stages of high capacity fossil power steam turbine and most stages of nuclear power steam turbine operate on wet steam. As a consequence, the flows in those cascades are accompanied by condensation, and the latent heat caused by condensation affects an oblique shock wave being generated at the vicinity of trailing of the blade. In the case of expanding of moist air through a suction type indraft wind tunnel, the effect of condensation affection the oblique shock wave generated by placing the small wedge into the supersonic part of the nozzle was investigated experimentally. In these connections, the relationship between condensation zone and reflection point of the incident oblique shock wave, angle between wedge bottom wall and oblique shock wave, and the variations of angles of incident and reflected shock waves due to the variation of initial stagnation relative humidity are discussed. Furthermore, the relationship between initial stagnation relative humidity and load working on the nozzle wall, obtained by measuring static pressure at the nozzle centerline, is discussed.

• Corrosion Science and Technology
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• v.12 no.2
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• pp.85-92
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• 2013

This work is concerned with an evaluation of dynamic boric acid corrosion (BAC) of low alloy steel for reactor pressure vessel of a pressurized water reactor (PWR). Mockup test method was newly established to investigate dynamic BAC of the low alloy steel under various conditions simulating a primary water leakage incident. The average corrosion rate was measured from the weight loss of the low alloy steel specimen, and the maximum corrosion rate was obtained by the surface profilometry after the mockup test. The corrosion rates increased with the rise of the leakage rate of the primary water containing boric acid, and the presence of oxygen dissolved in the primary water also accelerated the corrosion. From the specimen surface analysis, it was found that typical flow-accelerated corrosion and jet-impingement occurred under two-phase fluid of water droplet and steam environment. The maximum corrosion rate was determined as 5.97 mm/year at the leakage rate of 20 cc/min of the primary water with a saturated content of oxygen within the range of experimental condition of this work.

• Nuclear Engineering and Technology
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• v.49 no.4
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• pp.881-885
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• 2017

This work presents a new technique for discriminating between alpha particles of different energy levels. In a first study, two groups of alpha particles emitted from radium-226 and americium-241 sources were successfully separated using a CR-39 microfilm of appropriate thickness. This thickness was adjusted by chemical etching before and after irradiation so that lower-energy particles were stopped within the detector, while higher-energy particles were revealed on the back side of the detector. The number of tracks on the front side of the microfilm represented all alpha particles incident on that side from the two sources. However, the number of tracks on the back side of the microfilm represented only the long-range alpha particles of higher energy that arrived at that side. Therefore, by subtracting the number of tracks on the back side from the number of tracks on the front side, one could easily determine the number of tracks for the short-range alpha particles of lower energy that remained embedded in the microfilm. Discrimination of the two energy levels is thus achieved in a simple, fast, and reliable process.

• Nuclear Engineering and Technology
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• v.53 no.4
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• pp.1127-1133
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• 2021

A Spent Fuel Pool (SFP) is designed to store spent fuel assemblies in the pool. And, a SFP cooling and cleanup system cools the SFP coolant through a heat exchanger which exchanges heat with component cooling water. If the cooling system fails or interfacing pipe (e.g., suction or discharge pipe) breaks, the cooling function may be lost, probably leading to fuel damage. In order to prevent such an incident, it is required to properly cool the spent fuel assemblies in the SFP by either recovering the cooling system or injecting water into the SFP. Probabilistic safety assessment (PSA) is a good tool to assess the SFP risk when an initiating event for the SFP occurs. Since PSA has been focused on reactor-side so far, it is required to study on the framework of PSA approach for SFP and identify the key factors in terms of fuel damage frequency (FDF) through a case study. In this study, therefore, a case study of SFP-PSA on the basis of design information of APR-1400 has been conducted quantitatively, and several sensitivity analyses have been conducted to understand the impact of the key factors on FDF.