In order to develop the neutron absorbing and shield materials, a hot-rolled 0.02%-Gd duplex stainless steel was prepared with 55 vol. % of ferrite and 45 vol. % of austenite. The σ phase with an average grain size of 9–11 μm in austenitic (γ) grains tended to be elongated parallel to the rolling direction, with (100) poles concentrated towards the normal direction, and (110) poles located between the normal and radial directions (ND and RD, respectively). Most of the gadolinium existed as sub-micro-meter-sized Gd2O3 and GdCrO3 precipitates. The yield strength, ultimate tensile strength, elongation, and microhardness of the 0.02%-Gd duplex stainless steel were 522.8 MPa, 700.2 MPa, 38.1%, and 258.5–314.7 HV, respectively. The friction coefficient and wear resistance were 3.11 and 0.004 mg/kg/cycle, respectively. The corrosion potential and corrosion rate of the 0.02%-Gd duplex stainless steel were–0.448 VSHE and 1.263 × 10–3 A/cm2 for 1M-HCl,–0.544 VSHE and 2.619 × 10–3 A/cm2 for 1M-NaCl,–0.299 VSHE and 1.469 × 10–3 A/cm2 for 1M-H2SO4, and–0.607 VSHE and 2.295 × 10–3 A/cm2 for synthetic water, respectively. The coefficient of neutron transmission for the 0.02%-Gd duplex stainless steel sheet of 2 mm thickness at neutron beam wavelength of 0.48 nm was 0.6. © 2015, Pleiades Publishing, Ltdclose0

The effects of pre-charged hydrogen inside steel and the hydrogen ions on its surface on the sulfide stress corrosion cracking (SSCC) behavior was studied by slow strain rate tests. The specimen had an ASTM grain size number of about 11. Most of precipitates were 30–50 nm in size, and their distribution density was about 10⁶ mm⁻². The crystallographic texture consisted of major α-fiber (〈110〉//RD) components with a maximum peak at {115}〈110〉 relatively close to {001}〈110〉, and minor γ-fiber (〈111〉//ND) components with a peak slightly shifted from {111}〈112〉 to {332}〈113〉. Hydrogen was pre-charged inside the steel by a high-temperature cathodic hydrogen charging (HTCHC) method. SSCC and corrosion tests were carried out in an electrolytic solution (NaCl: CH₃COOH: H₂O: FeCl₂ = 50: 5: 944: 1, pH = 2.7). The corrosion potentials and the corrosion rates of the specimen without hydrogen charging for 24 hours were −490 mVSHE and 1.2 × 10⁻⁴ A cm⁻², and those with charging were −520 mVSHE and 2.8 × 10⁻⁴ A cm⁻², respectively. The corrosion resistance in the solution with 1000 ppm iron chloride added was decreased significantly, such that the corrosion potential and corrosion rate were −575 mV_SHE and 3.5 × 10⁻⁴ A cm⁻², respectively. Lower SSCC resistance of the pin-hole pre-notched specimen was observed at the open circuit potential than at the 100 mV cathodically polarized condition. Pre-charged hydrogen inside of the specimen had a greater influence on the SSCC behavior than hydrogen ions on the surface of the specimen during the slow strain rate test.

The effect of thiourea on the nano-mechanical and chemical properties of NiP foil was studied to develop a high performance NiP deposit for automobile and machinery parts. The NiP deposit was prepared by electroforming in a modified sulphate bath with different amounts of thiourea. Chemical analysis of the electrodeposited NiP foils by energy dispersive spectroscopy showed that phosphorous in the foil was reduced with thiourea. Structural analysis by X-ray diffractometry revealed that the (111) plane of the NiP deposits grew preferentially with increasing crystallinity. Surface analysis by atomic force microscopy and fieldemission scanning electron microscopy showed that the surfaces of the NiP electrodeposited with 0 and 0.01 g/L thiourea were relatively smooth and clean showing no nodules, whereas, the cauliflower-like nodules were observed on the surfaces of the deposits prepared with 0.03, 0.05, 0.07 and 0.1 g/L thiourea. The surface roughness (R RMS) of the deposits increased by addition of 0.1 ppm of thiourea from 6 to 54 nm. Nanomechanical properties of the NiP foil such as elastic modulus, hardness and stiffness determined by tribonano-indenter were tended to increase by addition of 0.1 ppm of thiourea from 77 to 156 GPa, 6.6 to 8.9 GPa and 109.6 to 186.6 µN/nm, respectively.

Layer-by-layer depositions of nickel and copper with nano-sized thickness were well formed by two-step pulsation at pH 4.5. The multi-layers were composed of a copper-rich nickel phase of 8: 2 with 14-nm thickness and a nickel-rich copper phase of 9: 1 with 16-nm thickness, respectively. The Ni²⁺-citrate solution controls the optical and chemical properties of the Cu²⁺Ni²⁺-citrate solution. The absorbance change with pH was related to complex formation. The relative contents of nickel and copper of an electroplated layer depended on electroplating conditions like the current density and pH. The electromagnetic shielding efficiency of the copper-nickel composite mesh/PI film showed more effective electromagnetic interference (EMI) shielding properties than a pure copper mesh/PI film in the GHz frequency range.

Technology for the direct usage of a spent PWR fuel in CANDU reactors (DUPIC) was developed in KAERI to reduce the amount of spent fuel. DUPIC fuel pellets were fabricated using a dry processing method to re-fabricate CANDU fuel from spent PWR fuel without any intentional separation of fissile materials or fission products. The DUPIC fuel element fabrication process satisfied a quality assurance program in accordance with the Canadian standard. For the DUPIC fuels with various fuel burn-ups between 27,300 and 65,000 MWd/tU, the sintered pellet density decreased with increasing fuel burn-ups. Fission gas releases and powder properties of the spent fuel also influenced the DUPIC fuel characteristics. Measurement of cesium content released from green pellets revealed that their sintered density significantly depended on sintering temperature history. It was useful to establish a DUPIC fuel fabrication technology in which a high-burn-up fuel with 65,000 MWd/tU was treated.