Three-dimensional thermal and structural analysis of the first wall in the SIRIUS-P reactor
The thermal-structural behavior and performance of the SIRIUS-P power reactor first wall concept is analyzed. The SIRIUS-P conceptual design study is of a 1.0 GWe laser driven inertial confinement fusion power reactor utilizing near symmetric illumination of direct drive targets. Sixty laser beams providing a total of 3.4 MJ of energy are used at a repetition rate of 6.7 Hz with a nominal target gain of 118. The spherical chamber has an internal radius of 6.5 m and consists of a first wall assembly made from carbon-carbon composite material, and a blanket assembly made of SiC composite material. The chamber is cooled by a flowing granular bed of solid ceramic materials, non-breeding TiO{sub 2} for the first wall assembly and breeding Li{sub 2}O for the blanket assembly. Helium gas (P = 0.15 MPa) is used in a fluidized bed outside the reactor to return the particles to the top of the reactor. A moving bed is chosen over a fluidized bed because of its superior heat transfer capability. The heat transfer in a moving bed depends on the level of agitation and on the effective thermal conductivity of the solid material and the interstitial gas, whereas in a fluidized bed,more » it is entirely dominated by the thermal conductivity of the carrier gas. This work describes the three-dimensional thermo-structural steady state analysis of the first wall coolant tubes. The performance of the first wall depends, under normal operating conditions, on the thermal loading conditions and internal coolant pressure loading conditions. The analysis utilizes a commercial finite element analysis code with complete 3-D modeling. The analysis shows that the stresses are dominated by bending due to the internal pressure of the He gas; modifying the shape of the tube from purely elliptical at the midplane, while keeping the flow area constant, reduces the stresses. A comparison between the results of this 3-D model with a previous 2-D study shows a pronounced effect on the temperature distribution.« less
Temperature dependence of the thermal conductivity of carbon-carbon composites
High temperature thermal conductivity data of several commercial and developmental 1-D, 2-D, 3-D and 4-D composites are discussed in terms of temperature dependence and composite structure. The samples chosen for this study include a Pseudo-monocrystal graphite and a 2-D composite manufactured by Le Carbone-Lorraine, 1-D and 2-D composites from Mitsubishi Kasei America, Inc., and a 3-D and 4-D composite manufactured by Fiber Materials Incorporated. The Mitsubishi specimens where measured as processed, heat treated by the manufacturer at some undisclosed high temperature and heat treated by ORNL at 3000{degrees}C. All specimens were machined into 12.5 mm disks with thicknesses in the range 0.4 to 0.8 cm. 4 refs., 1 fig.
Contractor Failure: Analysis
The possibility exists for any construction contractor to fail to filfill the contract requirements associated with a facility. Contractor failure occurs when a contractor is unable to perform his/her contractual duties, thus requiring the facility owner to invoke the contract's nonperformance clause. This paper provides aggregate contractor business failure statistics and outlines potential causes for failure. A framework to identify and quantify the associated costs is also introduced. Several case studies are presented to examine the cause and cost of failure and the means by which the facilities were completed. Alternatives available for project completion when contractor failure occurs are discussed. Recommendations to identify and monitor contractors at high risk for failure are outlined as well. This paper provides facility owners with a greater awareness of the possibility of contractor failure, how to quantify costs of contractor failure, and avoidance techniques.