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Latest News
Vogtle-3 shuts down for valve issue
One of the new Vogtle units in Georgia was shut down unexpectedly on Monday last week for a valve issue that has since been investigated and repaired. According to multiple local news outlets, Georgia Power reported on July 17 that Unit 3 was back in service.
Southern Company spokesperson Jacob Hawkins confirmed that Vogtle-3 went off line at 9:25 p.m. local time on July 8 “due to lowering water levels in the steam generators caused by a valve issue on one of the three main feedwater pumps.”
Mohammad Z. Hasan
Fusion Science and Technology | Volume 16 | Number 1 | August 1989 | Pages 44-52
Technical Paper | Blanket Engineering | doi.org/10.13182/FST89-A29095
Articles are hosted by Taylor and Francis Online.
An analytical solution for the temperature profile and film temperature drop for fully developed laminar flow in a circular tube is provided. The surface heat flux varies circumferentially but is constant along the axis of the tube. The volumetric heat generation is uniform in the fluid. The fully developed laminar velocity profile is approximated by a power velocity profile to represent the flattening effect of a perpendicular magnetic field when the coolant is electrically conducting. The presence of volumetric heat generation in the fluid adds another component of the film temperature drop to that due to the surface heat flux. The reduction of the boundary layer thickness by a perpendicular magnetic field reduces both of these film temperature drops. The Nusselt number for constant surface heat flux increases from 4.36 for the parabolic velocity profile to 8 for the nearly flat velocity profile or slug flow. The corresponding increase in the Nusselt number for uniform volumetric heat generation is from 2.46 to 5.33. A strong perpendicular magnetic field can reduce the film temperature drop by a factor of 2 if the fluid is electrically conducting. The effect of nonuniformity of the surface heat flux, however, is to reduce the Nusselt number or increase the film temperature drop at the location of the maximum heat flux compared to the case of uniform surface heat flux. At the point of maximum surface heat flux with a cosine variation, which is very close to the case of a coolant tube in the first wall and limiter/divertor plate of a fusion reactor, the Nusselt number can be reduced from 4.36 to 2.7 and from 8 to 3 f or parabolic and flat velocity profiles, respectively. The effect of perpendicular magnetic field (or the flatness of the velocity profile) on the film temperature drop due to nonuniform surface heat flux is less pronounced than on that due to uniform surface heat flux. An example is provided to show the relative effects of these two film temperature drops in the thermal design of fusion reactors.