Meteorological Measurements towards Reconstruction of Common Exhaust Stacks for Hamaoka Nuclear Power Station Units 1 and 2
March 14, 2013
Chubu Electric Power Co.,Inc.
In December 2004, cracks caused by wind vortex excitation* were discovered in the junction of the common exhaust stacks for Hamaoka Nuclear Power Station Units 1 and 2 (hereafter, exhaust stacks.) As a permanent measure to respond to this issue, it was decided that exhaust stacks incorporating measures to respond to wind vortex excitation would be reconstructed in a different position. (Previously announced on June 08, 2005.)
Following this, Units 1 and 2 were shut down in 2009, and, because the design parameters for the exhaust stacks had changed (for example, the amount of radioactive substances projected as being released from them was reduced), future guidelines in relation to the stacks were reexamined.
As a result, it has been decided that planning will proceed, following an evaluation of the potential for exposure of the general public in the surrounding area, towards the rebuilding of the stacks at a height that will ensure sufficient dispersion of the gases that are vented and will minimize the effect of wind vortex excitation.
Because the evaluation of the potential for exposure of the public in the surrounding area depends upon meteorological data obtained within the grounds of the facility, a new meteorological measurement device (a Doppler SODAR) was set up in order to measure wind direction and speed above the facility in March, and will be used from June this year to conduct meteorological observations including wind direction and speed for the scheduled period of one year.
* Wind vortex excitation is a type of vibration generated in long and narrow structures such as towers, beams and electrical cables by the action of wind. This type of vibration occurs within a specific range of wind speeds, determined by the shape of the cross-section of the structure and its natural frequency. An eddy of wind generated behind the structure (on the lee side) causes it to vibrate (resonate) in the direction perpendicular to the wind.