• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.2
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• pp.143-150
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• 2010

Vitrification technology has been gradually recognized as one of effective solidification methods for concentrated boric acid wastes generated in PWR. Vitrification for low- and intermediate-level radioactive wastes has a large volume reduction and good durability for the final products. A feasibility study for the vitrification of concentrated boric acid wastes has been performed with developing the pre-treatment methods of powdered wastes, glass compositions using glass formulation and demonstration test. The pre-treatment method is pelletizing the powder type for stable feeding within cold crucible melter. The glass compositions should be developed considering molten glass are related with wastes reduction. High contents of sodium and boron within borate wastes give influence to waste loading. A variety of factors obtained from the demonstration test are reviewed, which is wastes feeding rate, off-gas characteristics on stack and glass characteristics of final products such as durability for implementing the wastes disposal requirement. The aim of this paper is to present the feasibility of vitrification and review the solidification method for concentrated boric acid wastes and obtain the physicochemical characteristics of solidified glass.

• Membrane Journal
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• v.7 no.4
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• pp.167-174
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• 1997

The concentration of silica is required to meet a certain level because silica affects fuel and materials integrity by forming a zeolite layer on fuel cladding surfaces. When the established Feed and Bleed method is employed, nuclear waste increase and the corresponding amount of boric acid is constantly consumed. This study concentrates on minimizing the amount of nuclear waste and consumption of boric acid. Using five different membranes, operating conditions such as temperatur, feed water flow rate, boric acid recovery and silica removal rate were examined. A silica-selective removal system was designed based on the above optimization procedures. Three-stage system was designed with two characteristically different membranes so that it could correspond with the different situation easily. Compared to the pevious results of the Feed and Bleed method, the current method showed that the amount of nuclear waste was reduced to 7%, and the consumption of boric acid to 15.7%.

• Journal of the Korean institute of surface engineering
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• v.37 no.1
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• pp.13-21
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• 2004

The deposition rate, the current efficiency and surface morphology of trivalent Cr deposits were investigated according to additives in sulfate bath and current density. The deposition rate of the Cr deposits plated from the formic acid complexed bath was noticeably higher than that of the glycine complexed bath. The current efficiency of the deposition from formic acid bath was higher than that of the glycine bath and increased with current density in the range of 20-50 A/d$\m^2$. The current efficiency of the deposition from the formic acid bath with boric acid buffer was higher than that of the bath with aluminum sulfate or boric acid-aluminum sulfate buffers. The nodular crystallite size of the Cr deposits increased with current density and the uniform and crack-free growth of the deposits for the aluminum sulfate was observed compared to the other buffers.

• Journal of the Korean institute of surface engineering
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• v.36 no.4
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• pp.317-323
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• 2003

The effect of additives such as complexing agents, stabilzers and boric acid on the bath stability and the deposition rate of electroless black Ni-Zn plating has been examined. The deposits obtained became black and showed an amorphous structure. The significant increasing in the deposition rate was not found when only glycine and citric acid were used as complexing agents. The deposition rate increased up to 3 and 4 times by adding malic acid and glycolic acid as an additional complexing agent, respectively. The stabilizers and the boric acid, however, had little influence on the deposition rate.

• Journal of the Korean Wood Science and Technology
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• v.35 no.5
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• pp.46-57
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• 2007

The leachability of boron in zinc borate (ZB)-modified oriented strandboard (OSB) from southern wood species was investigated in this study. The leaching experiments were conducted by exposing edge-sealed OSB samples under running water at $31^{\circ}C$ for 8, 24, 72, and 216 h. The results from leached samples were compared with those from the unleached controls. Boron leaching of the modified OSB occurred upon the initial water exposure, and the leaching rate decreased as the leaching time increased. Initial boric acid equivalent (BAE) level, wood species, and sample thickness swelling significantly influenced the leachability. There was no consistent effect of polyethylene glycol (PEG) on zinc borate leaching. The glue-line washing within OSB due to thickness swelling of the test samples under water and decomposition of the borate to form water-soluble boric acid were thought to be two possible causes for the observed leaching. The relationship between assayed BAE and leaching time followed a decaying exponential function for zinc borate treated OSB. From the boron/zinc ratio after each leaching period, boron element in ZB was more or less leachable. The material constant of the regression models allowed comparing the leachability of the modified OSB for various wood species. An unified leaching method for treated wood composite materials is needed.

• Nuclear Engineering and Technology
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• v.52 no.3
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• pp.538-543
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• 2020

Boric acid is used as a coolant for pressurized-water reactors, and the degree of burnup is controlled by the concentration of boric acid. Therefore, accurate measurement of the concentration of boric acid is an important factor in reactor safety. An improved system was proposed for the accurate determination of boron concentration. A new boron-concentration measurement technique, called multisensitive detection, was developed to improve the measurement accuracy of boron meters. In previous studies, laboratory-scale experiments were performed based on different sensitivity detectors, confirming a 65% better accuracy than conventional single-detector boron meters. Based on these experimental results, an experimental system simulating the coolant-circulation environment in the reactor was constructed; accuracy analysis of the boron meter with a multisensitivity detector was performed at the actual coolant pressure and temperature. In this study, the boron concentration conversion equation was derived from the calibration test, and the accuracy of the boron concentration conversion equation was examined through a repeatability test. Through the experiment, it was confirmed that the accuracy was up to 87.5% higher than the conventional single-detector boron meter.

• Journal of the Korean Wood Science and Technology
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• v.49 no.6
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• pp.602-615
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• 2021

Red jabon wood is a potential fast-growing species for veneer, furniture, and many other wood products, but its durability is very low. The purpose of this study was to investigate the effects of castor bean oil and heating on boron leaching, dimensional stability, and resistance to decay fungi in treated jabon wood. Red jabon wood was preserved with boron solutions containing 5% boron (boric acid, borax, or borax-boric acid). Following that, castor bean oil impregnation and heating were used as posttreatments. Furthermore, all the wood samples were tested in terms of leaching, dimensional stability, and resistance against Schizophyllum commune and Fomitopsis palustris fungi. This study discovered that boron compounds, castor bean oil, and heating treatments influenced the leaching, dimensional stability, and resistance of red jabon wood to decay fungi. The double impregnation of boric acid or borax and castor bean oil, followed by heating at 160℃, significantly reduced water absorption and leaching while increasing the dimensional stability and resistance of red jabon wood against the two tested decay fungi.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3215-3224
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• 2022

Latest studies found that for 316LN austenitic stainless steel (ASS), its LCF life decreased noticeably in high temperature water containing a great amount of dissolved oxygen (DO) (2 ppm DO), compared with that in the water containing 50 or 100 ppb DO. This finding is different from previous studies about ASSs. This study confirmed that the 316L had similar behavior to 316LN. The LCF life of 316L in water containing 1000 ppb DO water was considerably shorter than that in the water containing 50 ppb DO. Addition of boric acid & lithium hydroxide and pre-soaking did not display noticeable effects on the LCF life of this material in the water with 1000 ppb DO, indicating the discrepancy between the latest studies and previous studies was not caused by the boric acid & lithium hydroxide and pre-soaking. This study also confirmed that similar to 316LN, when a certain amount of DO was added into the water, the amount of hydrogen absorbed into the material decreased significantly compared with that when the DO was less than 5 ppb.

• Korean Journal of Materials Research
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• v.17 no.5
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• pp.244-249
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• 2007

The properties of anodized films on aluminum 6061 alloy in single electrolyte of sulfuric acid and mixed electrolyte of sulfuric-boric acid and sulfuric-boric-nitric acid have been studied. Polarization tests in NaC solution were used to investigate the corrosion performance. Characteristics of film formation and surface morphology were examined by optical microscopy, FE-SEM and EDS. The results obtained have indicated that oxide films growth have been promoted by nitric acid and anodized films in mixed electrolyte have superior corrosion resistance. In case of anodic films formed in mixed electrolyte, some grooves and numerous crazings were also observed at the surface.

• Journal of the Korean Ceramic Society
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• v.41 no.10 s.269
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• pp.756-765
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• 2004

We present extraction process and reaction mechanism of boric acid from one of calcium borate ores, colemanite by reaction with sulfuric acid. Colemanite has been fully decomposed under pH 5 with sufficiency amount of sulfuric acid, more than the amount stoichiometrically required. Calcium sulfate was separated out, leaving boron in the liquid phase after sulfuric acid addition. The extraction process of boric acid was affected by dissolution temperature and time, amount of sulfuric acid and ammonium sulfate, pH and a degree of concentration before recrystallization. The $SiO_2$ of the impurities which colemanite contains was insoluble so that it was separated out with calcium sulfate from liquid phase. The species of $CaO,\;Al_2O_3,\;Fe_2O_3,\;MgO$ were remained in a liquid phase after reaction with sulfuric acid. These impurities were separated out by addition of ammonia to the liquid phase, funhermore, boric acid was produced by process of pH adjustments and acidification, concentration, and recrystallization.