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Assessment of London underground tube tunnels - investigation, monitoring and analysis
Wright, Peter Techno-Press 2010 Smart Structures and Systems, An International Jou Vol.6 No.3
Tube Lines has carried out a "knowledge and investigation programme" on the deep tube tunnels comprising the Jubilee, Northern and Piccadilly lines, as required by the PPP contract with London Underground. Many of the tunnels have been in use for over 100 years, so this assessment was considered essential to the future safe functioning of the system. This programme has involved a number of generic investigations which guide the assessment methodology and the analysis of some 5,000 individual structures. A significant amount of investigation has been carried out, including ultrasonic thickness measurement, detection of brickwork laminations using radar, stress measurement using magnetic techniques, determination of soil parameters using CPT, pressuremeter and laboratory testing, installation of piezometers, material and tunnel segment testing, and trialling of remote photographic techniques for inspection of large tunnels and shafts. Vibrating wire, potentiometer, electro level, optical and fibre-optic monitoring has been used, and laser measurement and laser scanning has been employed to measure tunnel circularity. It is considered that there is scope for considerable improvements in non-destructive testing technology for structural assessment in particular, and some ideas are offered as a "wish-list". Assessment reports have now been produced for all assets forming Tube Lines' deep tube tunnel network. For assets which are non-compliant with London Underground standards, the risk to the operating railway has to be maintained as low as reasonably practicable (ALARP) using enhanced inspection and monitoring, or repair where required. Monitoring techniques have developed greatly during recent years and further advances will continue to support the economic whole life asset management of infrastructure networks.
SIMULATED AP1000 RESPONSE TO DESIGN BASIS SMALL-BREAK LOCA EVENTS IN APEX-1000 TEST FACILITY
Wright, R.F. Korean Nuclear Society 2007 Nuclear Engineering and Technology Vol.39 No.4
As part of the $AP1000^{TM}$ pressurized water reactor design certification program, a series of integral systems tests of the nuclear steam supply system was performed at the APEX-1000 test facility at Oregon State University. These tests provided data necessary to validate Westinghouse safety analysis computer codes for AP1000 applications. In addition, the tests provided the opportunity to investigate the thermal-hydraulic phenomena expected to be important in AP1000 small-break loss of coolant accidents (SBLOCAs). The APEX-1000 facility is a 1/4-scale pressure and 1/4-scale height simulation of the AP1000 nuclear steam supply system and passive safety features. A series of eleven tests was performed in the APEX-1000 facility as part of a U.S. Department of Energy contract. In all, four SBLOCA tests representing a spectrum of break sizes and locations were simulated along with tests to study specific phenomena of interest. The focus of this paper is the SBLOCA tests. The key thermal-hydraulic phenomena simulated in the APEX-1000 tests, and the performance and interactions of the passive safety-related systems that can be investigated through the APEX-1000 facility, are emphasized. The APEX-1000 tests demonstrate that the AP1000 passive safety-related systems successfully combine to provide a continuous removal of core decay heat and the reactor core remains covered with considerable margin for all small-break LOCA events.
Wright, N.G.,Easom, G.J. Techno-Press 1999 Wind and Structures, An International Journal (WAS Vol.2 No.4
Accurate turbulence modeling is an essential prerequisite for the use of Computational Fluid Dynamics (CFD) in Wind Engineering. At present the most popular turbulence model for general engineering flow problems is the ${\kappa}-{\varepsilon}$ model. Models such as this are based on the isotropic eddy viscosity concept and have well documented shortcomings (Murakami et al. 1993) for flows encountered in Wind Engineering. This paper presents an objective assessment of several available alternative models. The CFD results for the flow around a full-scale (6 m) three-dimensional surface mounted cube in an atmospheric boundary layer are compared with recently obtained data. Cube orientations normal and skewed at $45^{\circ}$ to the incident wind have been analysed at Reynolds at Reynolds number of greater than $10^6$. In addition to turbulence modeling other aspects of the CFD procedure are analysed and their effects are discussed.
Creep and creep-rupture of Alloy 617
Wright, J.K.,Lillo, T.M.,Wright, R.N.,Kim, Woo-Gon,Sah, In-Jin,Kim, Eung-Seon,Park, Ji-Yeon,Kim, Min-Hwan Elsevier 2018 Nuclear engineering and design Vol.329 No.-
<P><B>Abstract</B></P> <P>The Ni-Cr-Mo-Co material Alloy 617 is the leading candidate for VHTR intermediate heat exchangers operating above 750°C. Time-dependent properties are an important consideration in qualifying the alloy for construction of nuclear components. Creep behavior of several different heats of Alloy 617 has been evaluated in the temperature range of 800–1000°C. Power law creep behavior was observed for the minimum creep rate, with a stress exponent of 5.6 and activation energy of approximately 400kcal/Mol. The Monkman-Grant approach relating minimum creep rate to time to rupture gave a reasonable representation of the data for all of the testing with a slope of −0.84. Similarly, a modified Monkman-Grant fit the strain to failure data reasonably well. A Larson-Miller analysis was carried out to compare rupture behavior determined in the current experiments and historical data with well-known provenance over a wide range of conditions. It appears that the properties of modern heats of material are near the lower bound of rupture behavior when all of the data are considered in the same analysis.</P>