• Nuclear Engineering and Technology
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• 제50권1호
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• pp.80-87
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• 2018

Consideration is given to the possibility to use changes in buoyancy as a negative reactivity feedback mechanism during temperature transients in heavy liquid metal fast reactors. It is shown that by the proper use of heavy pellets in the fuel elements, fuel rods could be endowed with a passive self-ejection mechanism and then with a negative feedback. A first estimate of the feasibility of the mechanism is calculated by using a simplified geometry and model. If in addition, a neutron poison pellet is introduced at the bottom of the fuel, then when the fuel element is displaced upward by buoyancy force, the reactivity will be reduced not only by disassembly of the core but also by introducing the neutron poison from the bottom. The use of induced buoyancy opens up the possibility of introducing greater amounts of actinides into the core, as well as providing a palliative solution to the problem of positive coolant temperature reactivity coefficients that could be featured by the heavy liquid metal fast reactors.

• Environmental Analysis Health and Toxicology
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• 제12권3_4호
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• pp.15-22
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• 1997

This experiment was performed to examine the immuno-reactive characteristics of fish metal-binding protein, metallothionein (MT), and gain the practical understandings for the proposed use of fish MT as a biomarker. Liver MT induced by Cd in the silver carp was seperated and purified by gel filtration chromatography and ion exchange chromatography. The immuno-reactivity of fish MT was examined with 3 rabbit antisera. Fish MT showed little reactivity with rabbit anti-rat MT antiserum and a weak reactivity with anti-MT peptide antiserum while showed a strong reactivity with rabbit anti-fish MT antiserum. The time-course change of liver MT in the silver carp, after waterborne exposure to 1 ppm of Cd, was checked by Cd-hem method and established competitive ELISA. In both cases, the induction of liver MT showed a good increasing relationship with the exposure days. The results indicate that the fish MT can be developed as a useful biomonitoring means in the toxicological study and for the evaluation of water pollution.

• Bulletin of the Korean Chemical Society
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• 제32권1호
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• pp.219-224
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• 2011

The new MPV type reagent, Al-trifluoromethanesulfonyldiisobutylalane ($DIBAO_3SCF_3$), has been prepared and its reducing characteristics in the reduction of selected organic compounds containing representative functional groups have been examined, and compared its reactivity with that of Al-methanesulfonyldiisobutylalane ($DIBAO_3SCH_3$) in order to understand the fluorine-substituent effect on its reactivity. In general, the reactivity of $DIBAO_3SCF_3$ appears to be much higher than that of $DIBAO_3SCH_3$, apparently due to the acidity increase by the electron-withdrawing fluorine-substituent. The reagent reduced aldehydes and ketones readily, but showed a perfect selectivity in the reduction of $\alpha,\beta$-unsaturated aldehydes and ketones to produce the corresponding allylic alcohols in an absolutely 100% purity. In addition, the reagent achieved the regioselective cleavage of phenyl- or/and alkyl-substituted epoxides to the less substituted alcohols in a perfect regioselectivity. Moreover, the reagent also showed an high stereoselectivity in the reduction of substituted cycloalkanones to produce the thermodynamically more stable alcohol epimers exclusively.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 추계 학술논문 발표대회
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• pp.165-170
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• 2009

Since artificial building materials and environmental contamination are getting worse recently, people has been interested in eco-friendly construction. In addition, the problems like Sick Building Syndrome are issued these days. In order to solve these problems, the reuse of building materials and the development of environment-friendly materials are urgently in demand. In this sense, Hwangtoh is in the limelight as the environment-friendly material, and broad studies on it have been in progress. However the reactivity of Hwangtoh is low, and without activation process it is very hard to use it as a building material. This study examined the usability of Hwangtoh as an environmental building material by experimenting the reactivity of inactivated Hwangtoh with Reaction Induction Material.

• 대한전자공학회논문지
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• 제4권3호
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• pp.19-27
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• 1967

원자로에서 급격한 부하변동은 출력의 편차를 크게 만드는 요소가 되므로 원자로 안전제어상 그 한도를 정확히 알 필요가 있는 것이나 실제 원자로가 가동되고 있을 때는 매우 측정하기 곤란한 것이다. 고로 실제로 측정할 수 있는 장치를 아나로그 계산기로 모의하여 이 값을 정밀히 측정하고 그것이 이론치와 일치됨을 논하였다.

• Nuclear Engineering and Technology
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• 제51권4호
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• pp.963-967
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• 2019

Accurate measurement of the reactivity worth of safety rods is very important for the safe reactor operation, in normal and emergency conditions. In this paper, the reactivity worth of safety rods in Heavy Water Zero Power Reactor (HWZPR) in the new lattice pitch is measured by advanced source jerk method. The average of the results related to two different detectors is equal to 29.88 mk. In order to verify the result, this parameter was compared to the previously measured value by subcritical to critical approach. Different experiment results are finally compared with corresponding calculated result. Difference between the average experimental and calculated results is equal to 2.2%.

• Nuclear Engineering and Technology
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• 제53권2호
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• pp.414-422
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• 2021

The aim of this work considers a second order point reactor kinetics model based on the P1 approximation of transport theory, called in this work as P1 point reactor model. The P1 point reactor model implicitly considers the time derivative of the neutron source which has not been thus considered previously. The inverse method to calculate the reactivity in nuclear reactors -chosen because its high accuracy- Matrix Formulation. The numerical results shown that the Matrix Formulation for the reactivity estimation constitutes a method with insignificant calculation errors.

• Bulletin of the Korean Chemical Society
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• 제10권3호
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• pp.223-226
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• 1989

The chemical reactivity of 5,7-dimethoxycoumarine with adenosine has been calculated by the frontier electron and PPP-Cl MO methods. Results suggest that the major reactivity of the 5,7-dimethoxycoumarin is highest at the carbon-4 (position 4), whereas the electrophilic reactivity is generally spread all over the 5,7-dimethoxycoumarin molecule. These results are consistent with the experimental photoaddition reaction products. The small change of bond orders on excitation does not give enough reactivity to triplet states or the efficient intersystem crossing from $T_1\;to\;S_0$ inhibits photoaddition of 5,7-dimethoxycoumarine to adenosine. Although the relative intensity of the singlet band appears to be considerably higher than the triplet band intensity, its integrated intensity, i.e. oscillator strength, is comparable to that of the 5,7-dimethoxycoumarin and adenosine bands.

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.3106-3116
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• 2022

The present work presents analysis results of the core design optimizations for an annular, prismatic High Temperature Gas-cooled Reactor (HTGR) with passive decay-heat removal features. Its thermal power is 100 MW_t and the operating temperature is 850 ℃ (1123 K). The neutronic calculations are done for the core with heterogeneous distribution of fuel and burnable poison particles (BPPs) to flatten the reactivity swing and power peaking factor (PPF) during the reactor operation as well as for control rod (CR) insertion into the core to restrain a small excess reactivity less than 1$. The next step of the study is done for evaluation of core reactivity coefficient of temperature.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.433-434
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• 2007