• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(1)
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• pp.191-196
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• 1996

이 논문에서는 Gadolinia, Erbia, IFBA를 비교평가 대상 독물질로 선정하여, 영광 3/4호기 노심을 대상으로 주기길이별 독봉장전노심을 구성하여 노심핵특성인자들을 비교평가하였다. 주기길이측면에서 Gd 장전노심과 IFBA 장전노심이 비슷하게 예측되었으며 Erbia 장전노심이 약 10∼13일 정도 작게 예측되었다. 냉각재 온도계수 측면에서는 Erbia 장전노심의 타 독물질 장전노심에 비해 우수하게 평가되었다. 최대 Fr 인자 측면에서는 Erbia 장전노심과 IFBA 장전노심이 거의 비슷한 수준에서 우수하게 평가되었으며 Gd 장전노심은 이 측면에서 취약한 것으로 평가되었다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 추계학술발표회논문집(1)
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• pp.15-20
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• 1996

We present the result of physical studies for three integral-type burnable absorbers of gadolinia, erbia and IFBA, in the hexagonal fuel assembly. The analysis of nuclear characteristics for gadolinia and IFBA cases shows that the spectrum hardening of hexagonal fuel assembly compared to rectangular one leads to smaller reactivity hold-down worth(RHW) and less change of MTC in the negative direction per insertion of one burnable absorber rod. Erbia case, on the other hand, exhibits reversed trend in RHW and MTC due to the enhanced absorption of large resonance of Erbium at 0.5 eV It turns out to be that Erbia performs best in terms of minimizing the peak pin power and maintaining as more negative MTC as practically attainable during the entire operational phase, and IFBA provides the least residual reactivity penalty at EOC. Therefore, we take Erbium as the suitable burnable absorber and provide optimal designs of 60, 120, 180, 240 and 300 erbia-shimmed hexagonal fuel assemblies with regard to minimizing the peak pin power.

• 한국세라믹학회지
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• 제54권5호
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• pp.413-421
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• 2017

In this work, we studied a fluorite structure oxides: Yttria stabilized zirconia, (YSZ); Gd doped $CeO_2$ (GDC); erbia stabilized $Bi_2O_3$ (ESB); Zr doped erbia stabilized $Bi_2O_3$ (ZESB); Ca doped erbia stabilized $Bi_2O_3$ (CESB) in the temperature range of 250 to $600^{\circ}C$ using electrochemical impedance spectroscopy (EIS). As is well known, grain boundary blocking effect was observed in YSZ and GDC. However, there is no grain boundary effect on ESB, ZESB, and CESB. The Nyquist plots of these materials exhibit a single arc at low temperature. This means that there is no space charge effect on ${\delta}-Bi_2O_3$. In addition, impedance data were analyzed by using the brick layer model. We indirectly demonstrate that grain boundary ionic conductivity is similar to or even higher than bulk ionic conductivity on cubic bismuth oxide.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2002년도 추계 학술발표회 논문집
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• pp.71-79
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• 2002

이중구조 가연성독봉(Duplex BP)의 성능을 평가하기 위해 한국표준형발전소 24개월 주기를 기준으로 16개 Gadolinia 독봉이 장전된 핵연료집합체에 대해 핵적 평가를 수행하였다. 16개 Gd 독봉이 장전된 핵연료집합체와 동일한 반응도 억제가를 갖는 Duplex 독봉집합체를 설계하기 위해 내심에 Natural U-12wt%Gd$_2$O$_3$, 외심에는 4.95wt%$UO_2$-2w/oEr$_2$O$_3$을 넣어 이중 성형한 24개의 이중구조 가연성독봉이 장전된 핵연료집합체를 설계하였다. 또한 같은 방법으로 140개의 Erbia 독봉이 장전된 등가핵연료집합체를 설계하였다. 핵설계 특성평가를 위해 연소도에 따른 무한증배계수, 반응도억제가, 첨두봉출력 그리고 냉각재 온도재수에 대한 변화에 대해서 비교하였다. Duplex 독봉은 Gadolinia 독봉에 비해 k-inf의 2차 첨두현상을 완화시켜 반응도 제어면에서 유리한 것으로 나타났다. 그러나, 다량의 Erbia 독봉을 전체적으로 골고루 장전한 핵연료집합체보다는 Duplex BP를 장전한 핵연료집합체가 노심내 반응도 제어면에서 유리하지 못한 것으로 나타났다.

• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2578-2590
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• 2023

In this work, a 24-month two-batch fuel management strategy for the APR1400 using LEU + has been investigated, where enrichments of 5.9 and 5.2 w/o are utilized in lieu of the conventional 4-5 w/o UO₂ fuel. In addition, an Accident Tolerant Fuel (ATF) clad based on the swaging technology is applied to APR1400 fuel assemblies. In this special ATF clad design, both outer and inner SS316 layers protect the conventional zircaloy clad. Erbia (Er₂O₃) is introduced as a burnable absorber with two-fold goals to lower the critical boron concentration in the long-cycle LEU + loaded core as well as to handle the LEU + fuel in the existing front-end fuel facilities without renewing the license. Two types of fuel assemblies with different loading of gadolinia (Gd₂O₃) are considered to control both the reactivity and the core radial power distribution. The erbia burnable absorber is uniformly admixed with UO₂ in all fuel pins except for the gadolinia-bearing ones. In this study, two core designs were devised with different erbia loading, and core performance and safety parameters were evaluated for each case in comparison with a core design without any burnable absorbers. The core analysis was done using the two-step method. First, cross-sections are generated by the SERPENT 2 Monte Carlo code, and the 3-D neutronic analysis is performed with an in-house multi-physics nodal code KANT.

• 에너지공학
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• 제13권4호
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• pp.242-258
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• 2004

한국원자력연구소에서는 기존의 일체형 가연성 독봉과 다른 이중구조로 된 가연성독봉 개념을 제시하였다. 이중구조 가연성독봉(Erbia Duplex BP)은 내부에 Natural U+Gd$_2$O$_3$, 외부에는 Enriched $UO_2$+Er$_2$O$_3$를 배열시킨 구조이다. 이러한 독봉은 장주기 노심에서 기존의 Gadolinia BP과 동일한 반응도제어를 할 수 있을 것이라 예상된다. 이중구조 가연성독봉의 핵적 타당성을 확인하기 위해 24개월 주기용 한국표준형원자로를 비교대상으로 선정하였으며, 기존 연구된 여러 가지 독봉설계안들과 4가지 핵특성에 대하여 비교 분석하였다. 핵특성 평가 결과, 이중구조가연성 독봉은 비교대상보다 무한증배계수, 첨두봉출력인자, 반응도억제가, 감속재온도계수측면에서 모두 유리한 경향을 보였다. 설계변수에 따른 민감도분석을 통해 도출한 최적화된 핵연료집합체를 이용하여 노심적용 타당성을 확인하였다. 주기길이, 첨두출력 및 감속재온도 계수를 비교하였으며 전 노심해석결과 주기길이가 비고대상보다 4-7일 길게 나타났다. 이러한 결과는 등가의 독봉집합체를 설계했음에도 불구하고 노심에 장전되는 우라늄의 양이 서로 달라서 생기는 현상으로 판단된다. 하지만 전체적인 핵특성을 비교해보면 이중구조 가연성독봉을 장전한 노심이 비교대상노심보다 다소 유리하면서도 거의 비슷함을 알 수 있었다. 마지막으로 경제성 평가를 통해 장주기 노심에서의 이중구조 가연성독봉의 제조 가능성 및 적용 타당성이 충분히 확인되었다.

• 한국세라믹학회지
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• 제24권2호
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• pp.123-132
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• 1987

Yttria-stabilized zirconia with erbia-lanthana were investigated with respect to the amount of Ln2O3 (Ln; Er, La) addition in the range of 0.5∼5 mol% to the base composition of 8 mol% yttriazirconia. Following analysis and measurement were adopted for the characterization of synthesizes of solid electrolyte; phase transformation, lattice parameter, crystallite size, relative density, chemical composition and SEM/EDS. Electrical conductivity by two-probe method versus temperature from 350$^{\circ}C$ to 800$^{\circ}C$ and frequency in the range of 5Hz∼13MHz by complex impedance method was also conducted together with the determination of oxygen ion transference number by EMF method for the evaluation of their electrical properties. The results were as followsing; Electrical conductivity were decreased with increase in Ln2O3 content, but their activation energies increased. In the case of La2O3 addition, espicially, its electrical conductivity was decreased owing to the segregation of second phases at the grain-boundary. Grain-boundary conductivity of the specimen contained 0.5 mol% Er2O3 exhibited a maximum conductivity among thecompositions experimented. However, their bulk conductivities decreased in both case. Oxygen ion transference number was also reduced with decrease in oxygen partial pressure. For example, in the case of Er2O3 addition it retained value in the range of 0.97∼0.94 abvove 4.74${\times}$10-2in oxygen partial pressure. With the increase in the quantities of the evaporation of additive components, the crystallite size of stabilized zirconia decreased, and their relative density also reduced owing to the formation of porosity in their matrices. In the case of La2O3 the sinterbility was improved in the limited amount of addition up to 0.5 mol%, in the same range of addition the strength of sintered bodies were improved perhaps owing to the precipitation of metastable tetragonal phase in the fully stabilized zirconia.

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.3095-3105
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• 2022

Solid Microencapsulated Fuel (SMF) is a type of solid fuel rod design that disperses TRISO coated fuel particles directly into a kind of matrix. SMF is expected to provide improved performance because of the elimination of cladding tube and associated failure mechanisms. This study focused on the neutronics and some of the fuel cycle characteristics of SMF by using OpenMC. Two kinds of SMFs have been designed and evaluated - fuel particles dispersed into a silicon carbide matrix and fuel particles dispersed into a zirconium matrix. A 7×7 fuel assembly with increased rod diameter transformed from the standard NHR200-II 9×9 array was also introduced to increase the heavy metal inventory. A preliminary study of two kinds of burnable poisons (Erbia & Gadolinia) in two forms (BISO and QUADRISO particles) was also included. This study found that SMF requires about 12% enriched UN TRISO particles to match the cycle length of standard fuel when loaded in NHR200-II, which is about 7% for SMF with increased rod diameter. Feedback coefficients are less negative through the life of SMF than the reference. And it is estimated that the average center temperature of fuel kernel at fuel rod centerline is about 60 K below that of reference in this paper.