• Nuclear Engineering and Technology
• /
• v.49 no.6
• /
• pp.1240-1249
• /
• 2017

An essential component of the neutron transport solver is the resonance self-shielding calculation used to determine equivalence cross sections. The neutron transport code, MPACT, is currently using the subgroup self-shielding method, in which the method of characteristics (MOC) is used to solve purely absorbing fixed-source problems. Recent efforts incorporating multigroup kernels to the MOC solvers in MPACT have reduced runtime by roughly $2{\times}$. Applying the same concepts for self-shielding and developing a novel lumped parameter approach to MOC, substantial improvements have also been made to the self-shielding computational efficiency without sacrificing any accuracy. These new multigroup and lumped parameter capabilities have been demonstrated on two test cases: (1) a single lattice with quarter symmetry known as VERA (Virtual Environment for Reactor Applications) Progression Problem 2a and (2) a two-dimensional quarter-core slice known as Problem 5a-2D. From these cases, self-shielding computational time was reduced by roughly $3-4{\times}$, with a corresponding 15-20% increase in overall memory burden. An azimuthal angle sensitivity study also shows that only half as many angles are needed, yielding an additional speedup of $2{\times}$. In total, the improvements yield roughly a $7-8{\times}$ speedup. Given these performance benefits, these approaches have been adopted as the default in MPACT.

• Nuclear Engineering and Technology
• /
• v.55 no.2
• /
• pp.749-755
• /
• 2023

A new approximation method was proposed for treating the non-resonant spatial self-shielding effects of double heterogeneous region such as the double heterogeneous effect of VHTR fuel compact in the thermal energy range and that of BP compact with BISO. The method was developed based on the effective homogenization method and a spherical unit cell model with explicit coated layers and a matrix layer. The self-shielding factor was derived from the relation between the collision probabilities for a double heterogeneous compact and the effective cross section for the homogenized compact. First, the collision probabilities and transmission probabilities for all layers of the spherical model were calculated using conventional collision probability solver. Then, the effective cross section for the homogenized sphere cell representing the homogenized compact was obtained from the transmission probability calculated using the probability density function of a chord length. The verification calculations revealed that the proposed method can predict the self-shielding factor with a maximum error of 2.3% and the double heterogeneous effect with a maximum error of 200 pcm in the typical VHTR problems with various packing fractions and BP compact sizes.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• v.5B no.1
• /
• pp.13-19
• /
• 2005

The performance of two designs of permanent magnet brushless motor, by having self-shielding magnetized magnets or sinusoidally shaped parallel-magnetized magnets with essentially sinusoidal airgap flux distributions, are compared. It is shown that the parallel-magnetized motor with shaped sintered NdFeB magnets can result in a higher airgap flux density and torque density than that of a self-shielding magnetized motor equipped with an anisotropic injection moulded NdFeB ring magnet.

• Proceedings of the IEEK Conference
• /
• 1998.10a
• /
• pp.1145-1148
• /
• 1998

New capacitance modeling and transient analysis for multi-layer interconnects with shielding effect are presented. The upper layer capacitances with under-layer shielding lines are represented by introducing a filling factor η which can be defined as the ratio of upper-layer line length to the total under-layer line width. The upper-layer effective self capacitances considering two extreme cases which the underlayer metals are assumed as a ground or as a Vdd are modeled. The signal transient analysis with shielding effect model is performed.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1996.05a
• /
• pp.197-201
• /
• 1996

In the detail reaction-rate measurements in a critical assembly using the foil activation method, the measured activations of detector foils have inevitably errors caused by detector foil self-shielding effect. If neutron flux could be approximated to Westcott flux: i.e. well thermalized Maxwellian distribution, these activations of detector foil could be corrected to represent the unperturbated flux at any detected position in the cell with using Westcott option and reaction-rate option of the lattice code, WIMS-AECL. These calculated detector material self-shielding correction factors of the tested fuel, CANFLEX provided much information about neutron spectrum of test lattice cell as well as the correction factors themselves. The results could be verified by another lattice calculations.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1995.10a
• /
• pp.73-78
• /
• 1995

이중 또는 삼중으로 탄소 피막된 핵연료 입자를 Graphite 소결체에 채워넣은 핵연료를 설계하고, 이에 대한 핵적 타당성을 검토하고자 하였다. 핵계산 체계로서 CASMO-3가 갖는 Spatial Self-shielding 효과의 문제, 코드의 계산 방식 문제, 핵자료 결손 문제를 검토한 후 보정 계수를 산출하려 하였다. CASMO-3의 정확도는 MCNP-4A를 통해 검증하였는데, 비균질한 소결체 내부를 균질화 함으로서 야기되는 Spatial Self-Shielding 효과는 임계도의 차이가 거의 없는 것으로 확인되어졌고, 계산 코드의 차이로 인한 효과 또한 무시할 수 있었다. 그러나 CASMO-3의 핵자료에서 탄소와 실리콘의 자료 부족은 임계도 차이가 0.06184정도로 다소 차이가 나기 때문에 보정이 필요함을 확인하였으나 CASMO-3 자체의 유용성에는 문제가 없었다.

• Elastomers and Composites
• /
• v.49 no.4
• /
• pp.336-340
• /
• 2014

The functionality such as deodorant, antibacterial, ultraviolet shielding of titanium dioxide self-actuated photocatalyst $Weltouch^{TM}$ treated polyester fiber was characterized in conditions without light. The deodorizing capacity was maintained more than 97% reduction irrespective of before washing and after 20 times repeated washing, and antimicrobial capacity was also retained more than 99.9% reduction. Titanium dioxide self-actuated photocatalyst was still maintained to the surface of polyester fiber without separation even after 20 times repeated washing. According to washing durability of polyester fiber, the reduction effect for ammonia was still retained even after 20 times repeated washing as much as before washing. The ultraviolet shielding capacity was still maintained at least 83% irrespective of before washing and 20 times repeated washing.

• Nuclear Engineering and Technology
• /
• v.54 no.4
• /
• pp.1464-1470
• /
• 2022

This paper presents a high performance burnable absorber named as CIMBA (Cylindrically Inserted and Mechanically Separated Burnable Absorber) for the soluble-boron-free SMR. The CIMBA is the cylindrical gadolinia inserted into the annular fuel pellets. Although the CIMBA utilizes the spatial self-shielding effect of the fuel material, a large reactivity upswing occurs when the gadolinia is depleted. To minimize the reactivity swing of the CIMBA-loaded FA, two approaches were investigated. One is controlling the spatial self-shielding effect of the CIMBA as burnup proceeds by a multi-layered structure of the CIMBA (ML-CIMBA) and the other is the mixed-loading of two different types of CIMBA (MIX-CIMBA). Both approaches show promising performances to minimize the reactivity swing, where the MIX-CIMBA is more preferable due to its simpler fabrication process. In conclusion, the MIX-CIMBA is expected to accelerate the commercialization of the CIMBA and can be used to achieve an optimal soluble-boron-free SMR core design.

• Macromolecular Research
• /
• v.10 no.6
• /
• pp.345-358
• /
• 2002

The electrical conductivity during vulcanization process was measured as a function of time for the system of TiC loaded styrene-butadiene rubber (SBR) composites. The phenomenon of negative and positive temperature coefficients of conductivity and its conduction mechanism were also studied for the SBR polymeric composites. The current-voltage characteristics of the polymeric composites were non-linear in high voltage and showed a switching effect. The effects of temperature on the thermal conductivity and effective dielectric constant were measured. The measured parameters were found to be dependent on TiC concentration. The electromagnetic wave shielding (EMS) of the SBR-TiC polymeric composite was also examined. The SBR filled with TiC could be expected to be promising novel smart polymeric composites for self-electrical heating, temperature sensor, time delay switching, and electro-magnetic wave shielding effectiveness.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.10 no.4
• /
• pp.121-126
• /
• 2010

Regarding HEMP has been studied as few thousand of paper by major nuclear bomb holding countries with USA for the self protection against nuclear bomb attract. Major HEMP protection facilities are consist of the shielding, filtering, grounding and high voltage protection circuits. Shielding room construction required a highest cost among the key protective facilities. Most of a theoretical formulas listed on the paper and related books has a little correlations in the certain frequency band between the theoretical formulas and field measuring results. For the reasons we proposed the advanced new theoretical formulas and developed the computer simulation S/W as enough as apply to the cost effective shielding room design for HEMP considering the various structural constants.