[en] -In order to evaluate actinide isotope assay in a spent fuel, comparison of calculation results will be done with experimental values. This work is designed to be performed many-years project including uncertainty evaluation, but it was stopped after one year period of 2007. - 1-Group Cross Sections for ORIGEN was produced and was the same regardless of energy group structures in flux and total reaction rates. - By the tally evaluation in MCNP, one-group cross section was produced by a systematic procedure. - It was known that one-group cross sections of TRU isotopes under 0-20MeV range was different depending on the flux weighting methods

[en] The concept of Common-Cause Failure (CCF) first appeared in the aerospace industry several decades ago, and nuclear power industry actively adopted the concept to the nuclear power plant (NPP) system analysis after the TMI accident. Since digital Instrumentation and Control (I and C) systems were applied to the NPP design, the CCF issues once again drew attention from the nuclear power industry in 90's. Identification of CCF has not been considered as a challenging issue because of its simplicity. However, as the systems become more complex and interconnected, demands are increasing to analyze CCF in more detail, for example, CCF with multiple initiating events or supporting situation awareness of the operation crew. The newly suggested CCF propagation paths identification method, CCF-SIREn, is expected to resolve path identification issue more practically and efficiently. CCF-SIREn uses general diagrams so that the compatibility and usability can be hugely increased. It also offers up-to-date CCF information with a least analysis effort whenever the ordinary NPP design change processes are made. A back-propagation technique is still under development to find out root-causes from the suspiciously responding signals, alarms and components. The probabilistic approach is also under consideration to prioritize defined CCF.

[en] The control of the ratio of hydrogen to the deuterium is one of the very important issues for ion cyclotron range of frequency (ICRF) minority heating as well as the plasma wall interaction in the tokamak. The ratio of hydrogen to deuterium during the tokamak shot was deduced from the emission spectroscopy measurements during the KSTAR 2009 experimental campaign. Graphite tiles were used for the plasma facing components (PFCs) at KSTAR and its surface area exposed to the plasma was about 11 m². The data showed that it remained as high as around 50% during the campaign period because graphite tiles were exposed to the air for about two months and the hydrogen contents at the tiles are not fully pumped out due to the lack of baking on the PFC in the 2009 campaign. The validation of the spectroscopy method was checked by using the Zeeman effects and the ratio of hydrogen to the deuterium is compared with results from the residual gas analysis. During the tokamak shot, the ratio is low below 10% initially and saturated after around 1 s. When there is a hydrogen injection to the vessel via ion cyclotron wall conditioning and the boronization process where the carbone is used, the ratio of the hydrogen to the deuterium is increased by up to 100% and it recovers to around 50% after one day of operation. However it does not decrease below 50% at the end of the experimental campaign. It was found that the full baking on the PFC (with a high temperature and sufficient vacuum pumping) is required for the ratio control which guarantees the efficient ICRF heating at the KSTAR 2010 experimental campaign.

[en] The first comprehensive particle balance study is carried out in the KSTAR 2010 campaign with a full graphite first wall and diverted plasmas. The dominant retention is observed during the gas puffing into the plasmas. Statistical analysis shows that deuterium retention is increased with the number of injected particles. Particle balance analysis in the whole campaign shows that the long-term retention ratio is ∼21%, and the retention via implantation can be partially recovered by He-glow discharge cleaning (GDC), while long-term retention via co-deposition. The wall pumping capability is decreased with the D₂ plasma due to fuel accumulation in the first wall, and He-GDC is effective in recovering the wall pumping. Boronization assisted by the D₂ glow discharge using C₂B₁₀H₁₂ strongly enhances the wall puffing and leads to negative retentions, but the wall pumping capability is recovered in 2–3 days by He-GDCs. Electron cyclotron resonance heating enhances wall outgassing during the discharge. During a diverted H-mode discharge, the retention rate decreases to a very low value, and a high divertor particle flux of ∼1.5 × 10²³ D s⁻¹ is observed indicating the strong recycling divertor. The amount of recovered deuterium after discharges mainly depends on the plasma–wall interaction when the plasma is terminated, and disruptive discharges release more particles from the first wall. (paper)

[en] Highlights: • We studied the surface reaction of different silicon chlorides during ALD process. • NH/SiNH₂*-terminated silicon nitride surface was constructed to model ALD using NH₃. • Total energy was calculated for physisorption, chemisorption, or transition state. • The order of precursors in energy barrier is Si₃Cl₈, Si₂Cl₆, SiH₂Cl₂ and SiCl₄. • Precursor with lower barrier in DFT showed lower saturation dose in literature. The reaction of precursor with surface active site is the critical step in atomic layer deposition (ALD) process. We performed the density functional theory calculation with DFT-D correction to study the surface reaction of different silicon chloride precursors during the first half cycle of ALD process. SiCl₄, SiH₂Cl₂, Si₂Cl₆ and Si₃Cl₈ were considered as the silicon precursors, and an NH/SiNH₂*-terminated silicon nitride surface was constructed to model the thermal ALD processes using NH₃ as well as the PEALD processes using NH₃ plasma. The total energies of the system were calculated for the geometry-optimized structures of physisorption, chemisorption, and transition state. The order of silicon precursors in energy barrier, from lowest to highest, is Si₃Cl₈ (0.92 eV), Si₂Cl₆ (3.22 eV), SiH₂Cl₂ (3.93 eV) and SiCl₄ (4.49 eV). Silicon precursor with lower energy barrier in DFT calculation showed lower saturation dose in literature for both thermal and plasma-enhanced ALD of silicon nitride. Therefore, DFT calculation is a promising tool in predicting the reactivity of precursor during ALD process.

[en] We report the deposition of cobalt oxide films at 120–300 °C using alternating injections of a novel liquid cobalt precursor, bis(1,4-di-iso-propyl-1,4-diazabutadiene)cobalt [C_1_6H_3_2N_4Co, Co(dpdab)_2], and ozone. The saturation doses of Co(dpdab)_2 and O_3/O_2 were 4 × 10"6 and 1 × 10"8 L, respectively. The atomic layer deposition (ALD) temperature window was between 120 °C and 250 °C with a maximum growth per cycle of 0.12 nm/cycle. The deposited films showed excellent step coverage. Cobalt oxide films deposited at 250 °C consisted of stoichiometric and crystalline Co_3O_4. - Highlights: • Cobalt oxide films were grown by ALD using a novel cobalt precursor and O_3. • The ALD temperature window was 120–250 °C with a growth per cycle of 0.12 nm/cycle. • Cobalt oxide thin films showed excellent step coverage. • Cobalt oxide films deposited at 250 °C were stoichiometric and crystalline Co_3O_4

[en] We report the formation of smooth and conformal copper seed layer for electrodeposition by atomic layer deposition (ALD) and reducing anneal of a copper nitride film. The ALD copper nitride film was prepared at 100–140 °C using bis(1-dimethylamino-2-methyl-2-butoxy)copper(II) and NH_3, and reduced to metallic copper film by annealing at 200 °C or higher temperatures. The growth rate of ALD copper nitride was 0.1 nm/cycle at 120–140 °C on both ruthenium and silicon oxide substrates, and the thickness of film was reduced approximately 20% by annealing. The resistivity of the 4.2 nm-thick copper film was 30 μΩ·cm. Both the ALD copper nitride and the reduced copper films exhibited extremely smooth surface and excellent step coverage, whereas the copper film deposited using alternating exposures to the copper precursor and H_2 showed a rough surface. The copper film electrodeposited on the copper seed of this study exhibited lower resistivity and smoother surface as compared to the copper film electrodeposited on the ALD ruthenium seed. - Highlights: • Copper nitride thin film was grown by atomic layer deposition (ALD) at 100–140 °C. • Copper nitride was reduced to metallic copper by annealing in H_2 at ≥ 200 °C. • Copper nitride and copper films showed smooth surface and excellent step coverage. • The copper film was better than ALD Ru as the seed layer for electrodeposition

[en] The initial phase wall conditioning in KSTAR is depicted. The KSTAR wall conditioning procedure consists of vessel baking, glow discharge cleaning (GDC), ICRH wall conditioning (ICWC) and boronization (Bz). Vessel baking is performed for the initial vacuum conditioning in order to remove various kinds of impurities including H₂O, carbon and oxygen and for the plasma operation. The total outgassing rates after vessel baking in three successive KSTAR campaigns are compared. GDC is regularly performed as a standard wall cleaning procedure. Another cleaning technique is ICWC, which is useful for inter-shot wall conditioning under a strong magnetic field. In order to optimize the operation time and removal efficiency of ICWC, a parameter scan is performed. Bz is a standard technique to remove oxygen impurity from a vacuum vessel. KSTAR has used carborane powder which is a non-toxic boron-containing material. The KSTAR Bz has been successfully performed through two campaigns: water and oxygen levels in the vacuum vessel are reduced significantly. As a result, KSTAR has achieved its first L-H mode transition, although the input power was marginal for the L-H transition threshold. The characteristics of boron-containing thin films deposited for boronization are investigated.

[en] First boronization was performed in KSTAR tokamak during 2009 campaign in order to reduce oxygen impurities and to lower the power loss due to radiation. We report the results from the experiences on carborane during the first boronization in KSTAR. After the boronization, H₂O and O₂ level in the vacuum vessel are reduced significantly. The characteristics of the deposited thin films were analyzed by variable angle spectroscopic ellipsometry, XPS, and AES. ∼1.78 x 10¹⁶ cm^-2 s^-1 of carbon flux on the wall is estimated by using cavity technique.