Empirical estimation of beach-face slope and its use for warning of berm erosion

Typical berm erosion and accretion are closely related to the beach-face slope. Empirical equation for prediction of the beach-face slope is proposed. The beach-face slope is expressed as a function of the wave period and the bed sediment grain size. Coefficients in the equation are obtained from three sets of carefully chosen laboratory data through a multiple linear regression with two independent variables using SPSS version 22. The computed correlation coefficient is as high as 0.983, which is believed to justify the validity of the present formulation. A shore profile is split into beach-face and underwater bed profile in the surf zone, and described with two straight lines. Possibility of using the beach-face slope strategically for warning of future berm erosion at the site is proposed

Empirical estimation of beach-face slope and its use for warning of berm erosion

Typical berm erosion and accretion are closely related to the beach-face slope. Empirical equation for prediction of the beach-face slope is proposed. The beach-face slope is expressed as a function of the wave period and the bed sediment grain size. Coefficients in the equation are obtained from three sets of carefully chosen laboratory data through a multiple linear regression with two independent variables using SPSS version 22. The computed correlation coefficient is as high as 0.983, which is believed to justify the validity of the present formulation. A shore profile is split into beach-face and underwater bed profile in the surf zone, and described with two straight lines. Possibility of using the beach-face slope strategically for warning of future berm erosion at the site is proposed

Empirical estimation of beach-face slope and its use for warning of berm erosion

Typical berm erosion and accretion are closely related to the beach-face slope. Empirical equation for prediction of the beach-face slope is proposed. The beach-face slope is expressed as a function of the wave period and the bed sediment grain size. Coefficients in the equation are obtained from three sets of carefully chosen laboratory data through a multiple linear regression with two independent variables using SPSS version 22. The computed correlation coefficient is as high as 0.983, which is believed to justify the validity of the present formulation. A shore profile is split into beach-face and underwater bed profile in the surf zone, and described with two straight lines. Possibility of using the beach-face slope strategically for warning of future berm erosion at the site is proposed

FINAL ICONE17-75008 DEVELOPMENT OF A NEW SPACER GRID FORM TO ENHANCE THE INTEGRITY OF FUEL ROD SUPPORT AND THE CRUSH STRENGTH OF A SPACER GRID ASSEMBLY

ABSTRACT A spacer grid is one of the most important structural components in a LWR fuel assembly. The spacer grid, which supports nuclear fuel rods laterally and vertically with a friction grip, is an interconnected array of slotted grid straps welded at the intersections to form an egg-crate structure. Dimples and springs are stamped into each grid strap to support the fuel rods. The form of grid straps and spring form is known to be closely related with the crush strength of spacer grid assembly and the integrity of fuel rod support, respectively. Zircaloy is prevailing as the material of the spacer grid because of its low neutron absorption characteristic and its successful extensive in-reactor use. The primary considerations are to provide a Zircaloy spacer grid with crush strength sufficient to resist design basis loads especially due to seismic accidents, without significantly increasing pressure drop across the reactor core. Generally, the thickness and height of the Zircaloy grid strap have been the main design variables in order to meet the above considerations. Recently, it was reported that a dimple location is also a design variable that affects the crush strength of a spacer grid assembly. In this study, a new spacer grid form was developed in order to enhance the integrity of the fuel rod support and the crush strength of the spacer grid assembly by using a systematic optimization technique. Finite element analysis and crush strength tests on the developed new spacer grid form were carried out to check the performance enhancement compared to commercial spacer grids. The enhancement of fuel rod support was confirmed by comparisons of contact area, peak stresses, plastic deformation and etc. According to the results, it is estimated that the actual critical load enhancement of the spacer grid assembly is approximately up to 30 % and the actual contact area, when a fuel rod inserted into a spacer grid cell, is more than double for the developed new spacer grid form. And also, some design variables that effect the crush strength of a PWR spacer grid assembly were classified and their effects on the crush strength were investigated by a finite element analysis and a crush strength test

Improvement of Lifetime Using Transition Metal-Incorporated SAPO-34 Catalysts in Conversion of Dimethyl Ether to Light Olefins

Transition metal (Mn, Fe, or Ni) incorporated SAPO-34 (MeAPSO-34) nanocatalysts were synthesized using a hydrothermal method to improve the catalytic lifetime in the conversion of dimethyl ether to light olefins (DTO). The structures of the synthesized catalysts were characterized using several methods including XRD, SEM, BET, 29Si-MAS NMR, and NH3-TPD techniques. Although the structure of the MeAPSO-34 catalysts was similar to that of the SAPO-34 catalyst, the amount of weak acid sites in all MeAPSO-34 catalysts was markedly increased and accompanied by differences in crystallinity and structural arrangement. The amount of weak acid sites decreased in the following order: NiAPSO-34 > FeAPSO-34 > MnAPSO-34 > SAPO-34 catalyst. The MeAPSO-34 catalysts, when used in the DTO reaction, maintained DME conversion above 90% for a longer time than the SAPO-34 catalyst, while also maintaining the total selectivity above 95% for light olefins. In addition, the NiAPSO-34 catalyst showed the longest catalytic lifetime; the lifetime was extended approximately 2-fold relative to the SAPO-34 catalyst. Therefore, the increase in the catalytic lifetime is related to the amount of weak acidic sites, and these sites are increased in number by incorporating transition metals into the SAPO-34 catalyst