• Nuclear Engineering and Technology
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• 제37권1호
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• pp.91-100
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• 2005

Kyung-hee Thorium Fuel (KTF), a heterogeneous thorium-based seed and blanket design concept for pressurized light water reactors, is being studied as an alternative to enhance proliferation resistance and fuel cycle economics of PWRs. The proliferation resistance characteristics of the KTF assembly design were evaluated through parametric studies using neutronic performance indices such as Bare Critical Mass (BCM), Spontaneous Neutron Source rate (SNS), Thermal Generation rate (TG), and Radio-Toxicity. Also, Fissile Economic Index (FEI), a new index for gauging fuel cycle economy, was suggested and applied to optimize the KTF design. A core loaded with optimized KTF assemblies with a seed-to-blanket ratio of 1: 1 was tested at the Korea Next Generation Reactor (KNGR), ARP-1400. Core design characteristics for cycle length, power distribution, and power peaking were evaluated by HELIOS and MASTER code systems for nine reload cycles. The core calculation results show that the KTF assembly design has nearly the same neutronic performance as those of a conventional $UO_2$ fuel assembly. However, the power peaking factor is relatively higher than that of conventional PWRs as the maximum Fq is 2.69 at the M$9^{th}$ equilibrium cycle while the design limit is 2.58. In order to assess the economic potential of a heterogeneous thorium fuel core, the front-end fuel cycle costs as well as the spent fuel disposal costs were compared with those of a reference PWR fueled with $UO_2$. In the case of comprising back-end fuel cycle cost, the fuel cycle cost of APR-1400 with a KTF assembly is 4.99 mills/KWe-yr, which is lower than that (5.23 mills/KWe-yr) of a conventional PWR. Proliferation resistance potential, BCM, SNS, and TG of a heterogeneous thorium-fueled core are much higher than those of the $UO_2$ core. The once-through fuel cycle application of heterogeneous thorium fuel assemblies demonstrated good competitiveness relative to $UO_2$ in terms of economics.

• Nuclear Engineering and Technology
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• 제56권7호
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• pp.2641-2649
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• 2024

Effective management of slightly used nuclear fuel (SUNF) is crucial for both technical and public acceptance reasons. SUNF management, radiotoxicity risk, and associated financial investment and technological capabilities are major concerns in nuclear power production. Reducing the volume of SUNF can simplify its management, and one possible solution is utilizing small modular reactors (SMR) and advanced fuel designs like those with thorium. This research focuses on studying the neutronic performance and radionuclide inventory of three different thorium fuel configurations. The mass of fissile material in thorium-based fuel significantly impacts Kinf, burn-up, and neutron energy spectrum. Compared to uranium, thorium as a fuel produces far fewer transuranic elements and less long-lived fission products (LLFPs) at the end of the core cycle (EOC). However, certain fission product elements produced from thorium-based fuel exhibit higher radioactivity at the beginning of the core cycle (BOC). Physical separation of thorium and uranium in the fuel block, like seed-and-blanket units (SBU) and duplex fuel designs, generate less radioactive waste with lower radioactivity and longer cycle lengths than homogeneous or mixed thorium-uranium fuel. Furthermore, the SBU and duplex feel designs exhibit comparable neutron spectra, leading to negligible differences in SUNF production between the two.

• 에너지공학
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• 제25권2호
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• pp.52-64
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• 2016

토륨은 우라늄에 비해 풍부한 자원으로서의 가치와 핵분열 물질인 U233을 증식하고, 장주기 액티나이드 핵종 발생이 감소하는 특성으로 인해 원자력 연구개발 초기부터 우라늄 주기와 함께 주요 연구대상이었다. 하지만 토륨은 자체적으로 핵분열이 불가능하므로 에너지원으로 활용하기 위해서는 별도의 외부 중성자원이 필요하고, 토륨 주기 과정에서 고방사성 물질이 발생하며, 효과적인 증식을 위해서는 긴 시간의 중성자 조사가 필요했다. 이에 따른 기술적 어려움과 연구개발 필요성의 감소로 1970년대 중반 이후 토륨 관련 연구가 거의 중단되었다. 하지만 1990-2000년대에 에너지 자원에 대한 사회적 시각 변화와 외부 중성자 공급원으로 이용하는 가속기 구동 원자로의 출현으로 과거 토륨주기의 단점으로 지목되었던 성질들이 오히려 핵확산 저항성과 감시성을 높이고, 가속기 구동 원자로의 미임계 운전 특성에 의한 원자력 안전성 증대라는 장점으로 부각되어 토륨에 관한 연구가 세계적으로 활발히 추진되고 있다. 본 연구에서는 토륨주기의 장단점을 우라늄주기와 비교, 분석하고 가속기 구동형 원자로를 이용한 토륨 연구의 기술 현황을 분석한다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 춘계학술발표회논문집(1)
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• pp.52-57
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• 1998

In this paper, we performed a design study of a thorium fueled reactor according to the design concept of the Radkowsky Thorium Reactor (RTR) and evaluated its overall performance. To enhance its performance and alleviate its problems, we introduced a new metallic uranium fuel, uranium-zirconium hydride (U-Zr $H_{1.6}$), as a seed fuel. For comparison, typical ABB/CE-type PWR based on SYSTBM 80+ and standard RTR-type thorium reactor were also studied. From the results of performance analysis, we could ascertain advantages of RTR-type thorium fueled reactor in proliferation resistance, fuel cycle economics, and back-end fuel cycle. Also, we found that enhancement of proliferation resistance and safer operating conditions may be achieved by using the U-Zr $H_{l.6}$ fuel in the seed region without additional penalties in comparison with the standard RTR's U-Zr fuelr fuelel

• Nuclear Engineering and Technology
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• 제37권4호
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• pp.363-374
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• 2005

A heterogeneous thorium-based Kyung Hee Thorium Fuel (KTF) assembly design was assessed for application in the APR-1400 to study the feasibility of using thorium fuel in a conventional pressurized water reactor (PWR). Thermal hydraulic safety was examined for the thorium-based APR-1400 core, focusing on the Departure from Nucleate Boiling Ratio (DNBR) and Large Break Loss of Coolant Accident (LBLOCA) analysis. To satisfy the minimum DNBR (MDNBR) safety limit condition, MDNBR>1.3, a new grid design was adopted, that enabled grids in the seed and blanket assemblies to have different loss coefficients to the coolant flow. The fuel radius of the blanket was enlarged to increase the mass flow rate in the seed channel. Under transient conditions, the MDNBR values for the Beginning of Cycle (BOC), Middle of Cycle (MOC), and End of Cycle (EOC) were 1.367, 1.465, and 1.554, respectively, despite the high power tilt across the seed and blanket. Anticipated transient for the DNBR analysis were simulated at conditions of $112\%$ over-power, $95\%$ flow rate, and $2^{\circ}C$ higher inlet temperature. The maximum peak cladding temperature (PCT) was 1,173K for the severe accident condition of the LBLOCA, while the limit condition was 1,477K. The proliferation resistance potential of the thorium-based core was found to be much higher than that of the conventional $UO_2$ fuel core, $25\%$ larger in Bare Critical Mass (BCM), $60\%$ larger in Spontaneous Neutron Source (SNS), and $155\%$ larger in Thermal Generation (TG) rate; however, the radio-toxicity of the spent fuel was higher than that of $UO_2$ fuel, making it more environmentally unfriendly due to its high burnup rate.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 춘계학술발표회논문집(1)
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• pp.21-26
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• 1997

Recently, thorium is receiving increasing attention as an important fertile material for the expanding nuclear power programs around the world. The superior nuclear and physical properties of thorium-based fuels could lead to very low fuel cycle cost and make thorium reactors economically attractive. In addition, the use of thorium in reactors would permit more efficient utilization of low cost uranium reserves and reduction nuclear wastes. In this work, the nuclear characteristics of a new type thorium fueled reactor (Radkowsky Thorium Reactor) consisting seed-blanket assemblies are addressed and compared with those typical assemblies of a PWR (CE type). Also, an assessment on several advantages of thorium fueled reactors is provided. All these results are based on the HELIOS code calculation.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2002년도 춘계 학술발표회 논문집
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• pp.135-141
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• 2002

PWR에의 토륨 핵연료 운용방안의 하나로 제안되었던 KTF 설계안을 바탕으로, APR-1400 노심에 맞게 설계변수에 빠른 최적화를 수행하였다. 최적화 방향은 핵확산 저항성 증대와 경제성 제고를 목표로 하였으며 최적화의 설계 기준은 핵확산 저항성의 경우 SNS, TG, BCM, Toxicity를 기준으로 하고 경제성은 FEI라는 새로운 지수를 사용하여 두 가지 모두 최대가 되는 방향으로 최적화하였다. 최적 설계안을 이용하여 APR-1400의 노심을 설계하는 과정을 여러 측면에서 검토하였으며, 비균질 노심에 토륨핵연료집합체를 사용한 설계안이 안전성 및 경제적 타당성을 갖음을 확인하였다.

• Nuclear Engineering and Technology
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• 제47권3호
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• pp.315-322
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• 2015

The research carried out on thorium-based fuels indicates that these fuels can be considered as economic alternatives with improved physical properties and proliferation resistance issues. In the current study, neutronic assessment of $UO_2$ in comparison with two $(Th-^{233}U)O_2$, and $(Th-^{235}U)O_2$ thorium-based fuel loads in a heavy water research reactor has been proposed. The obtained computational data showed both thorium-based fuels caused less negative temperature reactivity coefficients for the modeled research reactor in comparison with $UO_2$ fuel loading. By contrast, $^{235}U$-containing thorium-based fuel and $^{235}U$-containing thorium-based fuel loadings in the thermal core did not drastically reduce the effective delayed neutron fractions and delayed neutron fractions compared to $UO_2$ fuel. A provided higher conversion factor and lower transuranic production in the research core fed by the thorium-based fuels make the fuel favorable in achieving higher cycle length and less dangerous and costly nuclear disposals.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1999년도 춘계학술발표회요약집
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• pp.8-8
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• 1999

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2002년도 춘계공동학술발표회요약집
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• pp.44-44
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• 2002