Study on the siltation in the intake of nuclear power plant using longterm water depth monitoring and coupled modeling

摘要

Since 'waste heat' is generated as a result of plant operation, sea water is needed for cooling purposes and therefore plants are situated near coastal areas. However, the effect on the coastal area such as erosion, deposition, and siltation from the construction of the plant itself is subject of continuing controversy and another being the effects on the coastal environment from warm water that is produced after the cooling process. Generally, topographic change is maintained in equilibrium by the tidal currents reciprocating motion in the coastal areas where there are dominant tidal currents. However, artificial action on the current flow for operating a nuclear plant operation at the intake and the outlet breaks the equilibrium of the tides and this in the end results in disturbing the equilibrium condition of bottom topography. This research used the results of long term investigation data of water depth and data of flow discharge conducted inside the intake to investigate erosion and the change in siltation at the intake of the nuclear power plant. After having analyzed the changes in water depth of the intake area, the results confirmed that there are 100～140cm/year and 80～300 cm/year of excess siltation at the middle area and both sides, respectively. After artificial dredging which is conducted every two years, siltation had proceeded at a substantial pace, and after some time, the pace has slowed down to its normal rate, going towards equilibrium condition. This research used the siltation pace change acquired from monitoring results to formulate coupled model in order to predict the change of water depth which will take place due to artificial construction of the intake in the future more precisely.