Simulation of the hybrid and steady state advanced operating modes in ITER

Kessel, C.E.,Giruzzi, G.,Sips, A.C.C.,Budny, R.V.,Artaud, J.F.,Basiuk, V.,Imbeaux, F.,Joffrin, E.,Schneider, M.,Murakami, M.,Luce, T.,St John, Holger,Oikawa, T.,Hayashi, N.,Takizuka, T.,Ozeki, T.,Na, International Atomic Energy Agency 2007 Nuclear fusion Vol.47 No.9

<P>Integrated simulations are performed to establish a physics basis, in conjunction with present tokamak experiments, for the operating modes in the International Thermonuclear Experimental Reactor (ITER). Simulations of the hybrid mode are done using both fixed and free-boundary 1.5D transport evolution codes including CRONOS, ONETWO, TSC/TRANSP, TOPICS and ASTRA. The hybrid operating mode is simulated using the GLF23 and CDBM05 energy transport models. The injected powers are limited to the negative ion neutral beam, ion cyclotron and electron cyclotron heating systems. Several plasma parameters and source parameters are specified for the hybrid cases to provide a comparison of 1.5D core transport modelling assumptions, source physics modelling assumptions, as well as numerous peripheral physics modelling. Initial results indicate that very strict guidelines will need to be imposed on the application of GLF23, for example, to make useful comparisons. Some of the variations among the simulations are due to source models which vary widely among the codes used. In addition, there are a number of peripheral physics models that should be examined, some of which include fusion power production, bootstrap current, treatment of fast particles and treatment of impurities. The hybrid simulations project to fusion gains of 5.6–8.3, β<SUB>N</SUB> values of 2.1–2.6 and fusion powers ranging from 350 to 500 MW, under the assumptions outlined in section 3. Simulations of the steady state operating mode are done with the same 1.5D transport evolution codes cited above, except the ASTRA code. In these cases the energy transport model is more difficult to prescribe, so that energy confinement models will range from theory based to empirically based. The injected powers include the same sources as used for the hybrid with the possible addition of lower hybrid. The simulations of the steady state mode project to fusion gains of 3.5–7, β<SUB>N</SUB> values of 2.3–3.0 and fusion powers of 290 to 415 MW, under the assumptions described in section 4. These simulations will be presented and compared with particular focus on the resulting temperature profiles, source profiles and peripheral physics profiles. The steady state simulations are at an early stage and are focused on developing a range of safety factor profiles with 100% non-inductive current.</P>

TRADE LIBERALIZATION AND ECONOMIC GROWTH IN MEXICO

Kessel, Georgina 서울大學校 스페인中南美硏究所 1994 이베로아메리카硏究 Vol.5 No.-

The success of NAFTA in promoting a larger flow of goods and services within the area will certainly improve Mexico's economic prospects, contributing to higher standards of living for our population and with them, greater opportunities to import from the rest of the world.

Simulation Modeling for Planning a Soil Remediation Process

David Kessel,Chang-Lak Kim,Jihan Jeon,Eui-taek Lee 한국방사성폐기물학회 2019 한국방사성폐기물학회 학술논문요약집 Vol.2019 No.05

U.S. Policy and Current Practices for Blending Low-Level Radioactive Waste for Disposal

David S. Kessel,Chang-Lak Kim 한국방사성폐기물학회 2016 방사성폐기물학회지 Vol.14 No.3

우리나라를 포함한 많은 국가들에서 향후 원전 해체로 저준위폐기물이 대량으로 발생할 전망이다. 본 논문에서는 미국의저준위방사성폐기물 처분 관련 규제 기준을 분석하고, 특히 원자력발전소의 운영 및 해체를 포함하는 전주기에서 발생하는 폐기물의 처분 옵션을 확장하는 방안으로 사용되고 있는 저준위방사성폐기물의 블랜딩에 대해 검토하였다. 2007년 미국 NRC는 미국 저준위폐기물 관리 프로그램에 대한 전략분석 결과, 방사선위험도와 성능평가에 기반한 새로운 저준위폐기물 관리 규제의 필요성을 제기하였는데, 특히 방사성핵종 농도가 다른 폐기물의 블랜딩을 처분에 대한 옵션을 다양화할 수있는 안전한 방안으로 제시하였다. NRC는 블랜딩을 처분에 적합하도록 방사성핵종의 농도가 다른 저준위폐기물을 비교적균일하게 혼합(mixing)하는 것으로 정의하였다. 2015년 2월 농도 평균과 포장에 대한 NRC BTP의 개정판으로 공표된 블랜딩에 대한 구체적인 기술요건을 분석하였고 국내 해체폐기물에 대한 적용 방안도 예시하였다. 대량으로 발생할 해체폐기물에 대해 블랜딩과 농도평균을 적용하면 처분 효율성을 향상시킬 수 있다. 바이오쉴드 콘크리트에 대한 농도평균 적용에 대해 예시하였다. In the near future, many countries, including the Republic of Korea, will face a significant increase in low level radioactive waste (LLW) from nuclear power plant decommissioning. The purpose of this paper is to look at blending as a method for enhancing disposal options for low-level radioactive waste from the decommissioning of nuclear reactors. The 2007 U.S. Nuclear Regulatory Commission strategic assessment of the status of the U.S. LLW program identified the need to move to a risk-informed and performance-based regulatory approach for managing LLW. The strategic assessment identified blending waste of varying radionuclide concentrations as a potential means of enhancing options for LLW disposal. The NRC’s position is that concentration averaging or blending can be performed in a way that does not diminish the overall safety of LLW disposal. The revised regulatory requirements for blending LLW are presented in the revised NRC Branch Technical Position for Concentration Averaging and Encapsulation (CA BTP 2015). The changes to the CA BTP that are the most significant for NPP operation, maintenance and decommissioning are reviewed in this paper and a potential application is identified for decommissioning waste in Korea. By far the largest volume of LLW from NPPs will come from decommissioning rather than operation. The large volumes in decommissioning present an opportunity for significant gains in disposal efficiency from blending and concentration averaging. The application of concentration averaging waste from a reactor bio-shield is also presented.

고리1호기 해체시 발생할 방사성금속폐기물 관리 옵션 연구

David S. Kessel,Chang-Lak Kim 한국방사성폐기물학회 2017 방사성폐기물학회지 Vol.15 No.2

방사성금속폐기물의 관리 옵션들을 안전성, 경제성, 작업자 피폭, 부피 감용 등의 선별 기준을 적용하여 비교 평가하였다. 원전 해체로부터 발생하는 금속폐기물의 관리 옵션에는 무구속 방출, 제한적 재사용, 그리고 직접 처분이 있다. 고려된 각 각의 옵션들은 금속폐기물의 절단과 용융에 의한 부피감용을 수반한다. AHP기법을 적용하여 각 옵션들의 순위를 부여하였 다. 방사성금속폐기물을 용융하여 금속 잉곳을 제조한 후 제한적 재이용 또는 무구속 방출하는 방안이 가장 효율적인 옵션 으로 도출되었다. The purpose of this paper is to evaluate several leading options for the management of radioactive metallic waste against a set of general criteria including safety, cost effectiveness, radiological dose to workers and volume reduction. Several options for managing metallic waste generated from decommissioning are evaluated in this paper. These options include free release, controlled reuse, and direct disposal of radioactive metallic waste. Each of these options may involve treatment of the metal waste for volume reduction by physical cutting or melting. A multi-criteria decision analysis was performed using the Analytic Hierarchy Process (AHP) to rank the options. Melting radioactive metallic waste to produce metal ingots with controlled reuse or free release is found to be the most effective option.

Simulations of KSTAR high performance steady state operation scenarios

Na, Yong-Su,Kessel, C.E.,Park, J.M.,Yi, Sumin,Becoulet, A.,Sips, A.C.C.,Kim, J.Y. International Atomic Energy Agency 2009 Nuclear fusion Vol.49 No.11

<P>We report the results of predictive modelling of high performance steady state operation scenarios in KSTAR. Firstly, the capabilities of steady state operation are investigated with time-dependent simulations using a free-boundary plasma equilibrium evolution code coupled with transport calculations. Secondly, the reproducibility of high performance steady state operation scenarios developed in the DIII-D tokamak, of similar size to that of KSTAR, is investigated using the experimental data taken from DIII-D. Finally, the capability of ITER-relevant steady state operation is investigated in KSTAR. It is found that KSTAR is able to establish high performance steady state operation scenarios; β<SUB>N</SUB> above 3, <I>H</I><SUB>98</SUB>(<I>y</I>, 2) up to 2.0, <I>f</I><SUB>BS</SUB> up to 0.76 and <I>f</I><SUB>NI</SUB> equals 1.0. In this work, a realistic density profile is newly introduced for predictive simulations by employing the scaling law of a density peaking factor. The influence of the current ramp-up scenario and the transport model is discussed with respect to the fusion performance and non-inductive current drive fraction in the transport simulations. As observed in the experiments, both the heating and the plasma current waveforms in the current ramp-up phase produce a strong effect on the <I>q</I>-profile, the fusion performance and also on the non-inductive current drive fraction in the current flattop phase. A criterion in terms of <I>q</I><SUB>min</SUB> is found to establish ITER-relevant steady state operation scenarios. This will provide a guideline for designing the current ramp-up phase in KSTAR. It is observed that the transport model also affects the predictive values of fusion performance as well as the non-inductive current drive fraction. The Weiland transport model predicts the highest fusion performance as well as non-inductive current drive fraction in KSTAR. In contrast, the GLF23 model exhibits the lowest ones. ITER-relevant advanced scenarios cannot be obtained with the GLF23 model in the conditions given in this work. Finally, ideal MHD stability is investigated for the ITER-relevant advanced scenarios in KSTAR. The methods and results presented in this paper are expected to contribute to improving the ITER and beyond ITER predictive simulations.</P>

The Development and Its Validation of Knowledge Productivity and Value Creation

강석진,Joseph, W. M. Kessels,이은수,조영삼 한국전문경영인학회 2014 專門經營人硏究 Vol.17 No.3

Knowledge productivity and value creation have changed and progressed significantly in our fast-changing knowledge economy during recent decades, presenting important challenges for managing businesses. Especially, knowledge productivity became the main factor for value creation, which is a priority objective of managing businesses. The purpose of this study is to develop and validate scales for the measurement of knowledge productivity and value creation. First, as a preliminary investigation, we conducted in-depth interviews with 39 executives and senior managers to develop the items for a questionnaire. Second, we conducted formal in-depth group interviews with 72 interviewees and collected completed questionnaires from 387 study participants. To test the convergent validity of the questionnaire items, we conducted an exploratory factor analysis using this sample. The results for the scale measuring knowledge productivity showed that 28 items could be categorized into two factors (KP1: improvement and innovation of products, services, and work processes, and KP2: sustainable development of the future growth engine). The results for the scale measuring value creation also indicated that all 28 items could be categorized into four factors (VC1: corporate reputation, image, and corporate social responsibility, VC2: employee satisfaction with work environment, VC3: employee satisfaction with financial benefits, and VC4: sustainability). The reliability of the measurement instruments, containing two factors related to knowledge productivity and four factors related to value creation, was acceptable. Results of a confirmatory factor analysis to verify the discriminant validity of the instrument items indicated that the two-factor model for knowledge productivity and the four-factor model for knowledge productivity fitted the data significantly better than other alternative models for both measures. Finally, as an additional test, the results of the correlation analysis for both knowledge productivity and value creation proved the validity of our study variables for measurement purposes. The results of these validation tests support the usefulness and practicality of these variables for future research.

Management of Spent Ion-Exchange Resins From Nuclear Power Plant by Blending Method

Kamaruzaman, Nursaidatul Syafadillah,Kessel, David S.,Kim, Chang-Lak Korean Radioactive Waste Society 2018 방사성폐기물학회지 Vol.16 No.1

With the significant increase in spent ion-exchange resin generation, to meet the requirements of Waste Acceptance Criteria (WAC) of the Wolsong disposal facility in Korea, blending is considered as a method for enhancing disposal options for intermediate level waste from nuclear reactors. A mass balance formula approach was used to enable blending process with an appropriate mixing ratio. As a result, it is estimated around 44.3% of high activity spent resins can be blended with the overall volume of low activity spent resins at a 1:7.18 conservative blending ratio. In contrast, the reduction of high activity spent resins is considered a positive solution in reducing the amount of spent resins stored. In an economic study, the blending process has been proven to lower the disposal cost by 10% compared to current APR1400 treatment. Prior to commencing use of this blending method in Korea, coordinated discussion, and safety and health assessment should be undertaken to investigate the feasibility of fitting this blending method to national policy as a means of waste predisposal processing and management in the future.

Logistical Simulation for On-site Concrete Waste Management in Decommissioning

Lee, Eui-Taek,Kessel, David S.,Kim, Chang-Lak Korean Radioactive Waste Society 2019 방사성폐기물학회지 Vol.17 No.4

Large amounts of concrete waste are likely to arise from the decommissioning of a Kori-1 nuclear power plant. Several studies have been conducted on decommissioning concrete waste in recent decades, however, they have been limited to contaminated concrete issues or were small pilot-scale experiments. This study constructed two industrial-scale models of on-site concrete waste management for clean as well as contaminated concrete. To evaluate the performance of both the models, simulations were conducted using the Flexsim software. The concrete particle size distribution of Kori-1 and concrete processor properties based on widely used construction equipment were used as sources of input data for the simulations. It was observed that it may take over two years to complete the on-site concrete management processes owing to the performance of existing processors. In addition, it was demonstrated that it is essential to identify bottlenecks in the system and enhance the performance of the relevant processors to avoid delays of the decommissioning schedule. Our results suggest that this novel approach can contribute to developing schedules or expediting delayed activities in the Kori-1 decommissioning project.

Choosing a Knowledge Management Strategy for Decommissioning of NPP

So-Yoon Kim,David Kessel,Chang-Lak Kim 한국방사성폐기물학회 2020 한국방사성폐기물학회 학술논문요약집 Vol.2020 No.12