Since cementitious materials used in repositories will be in contact with water, one of the most important tasks is to assess their long-term performance while they are being degraded very slowly by leaching. The authors have proposed an electrochemical acceleration test method and clarified its applicability. In this method, a specimen is placed between two glass vessels containing water. An anode and a cathode connected to a DC power source provide a potential gradient across the specimen. Ca2+ ions in the pore solution move rapidly to the cathode side, and thus hasten cement hydrate dissolution.In this study, we obtained two types of almost homogeneously degraded specimens by controlling cumulative quantity of dissolved Ca2+ ions. In the first type, there was no Ca(OH)2and the C-S-H phases underwent insignificant alteration, whereas in the second type, degradation of the C-S-H phases occurred.As a preliminary evaluation of cementitious materials, diffusion coefficients of tritiated water were measured for nondegraded and degraded specimens. Diffusion coefficients were increased by degradation and closely corresponded to changes in porosity.
Low-level radioactive waste (LLRW) is disposed of by shallow land burial. Reinforced concrete is used as the radioactive waste repository. However, the concrete structure is in contact with water and will gradually degrade over an extended period of time due to leaching.It is important to investigate the interaction between radionuclides and degraded concrete in the safety assessment of nuclear waste disposal. The authors measured the distribution coefficients (Kd) of various radionuclides for calcium-leached mortars. The calcium-leached mortars were prepared by an accelerated leaching test for mortar based on the electrical potential gradient. These degraded conditions are similar to that of degraded concrete in contact with water for a long period of time. The degradation degree of calcium-leached mortar is evaluated by the CaO/SiO2 molarratio (Ca/Si ratio) of calcium silicate hydrate (C-S-H).As a result, the relationship between Kd and the Ca/Si ratio in C-S-H can be roughly grouped into the following three types:1.137Cs and 85Sr – Kd decreases with an increase in the Ca/Si ratio.2. 95mTc and 110mAg – There is no correlation between Kd and the Ca/Si ratio.3. 14C, 241Am and 125I – Kd increases with an increase in the Ca/Si ratio.
In the field of communications, specifically real time data management and interface tools, the landscape has changed a lot in the last ten years. This article highlights the development and implementation of the Production Operations Support Center (POSC) in Kazakhstan and details the application of several new technological advances, improving the way we operate to produce hydrocarbons safely and effectively.
The POSC has been built in Atyrau based on the industry leading guidelines on Collaborative Work Environment, which is a forum created to integrate people, processes, technology and facility for improved cross-functional and virtual collaboration, learning and high quality decision-making. This setup allows the company to maximize the available knowledge and operational knowhow between locations, minimizes the duplication of work streams by providing each team with the same "data" information stream at the same time and encourages collaboration in order to analyze process, rotating, corrosion and flow assurance issues as an integrated team. In this way the company can make more effective use of resources which ultimately results in a safe and stable production asset. POSC has already justified its value during Kashagan Start-Up Operations on 24/7stand-by duty with engineering support from the office.
Kashagan is a large green field development in the Northern Caspian Sea covering an area of 75 km in length, 45 km in width at about 5km in depth. The geographical, logistical and environmental challenges make Kashagan one of the most complex projects in the world, requiring state of the art technologies in most of its aspects in order to maximize value for the Republic of Kazakhstan.
In order to provide this important center, POSC project team has delivered an integrated solution of functional communications hardware, across our different locations, supporting software including Real Time surveillance, lean process flow mapping, together with the development of local staff capabilities to ensure value creation and maximization.
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