4.2　High Astronomic Tide

4.2.1　The compiled and reviewed tidal data for over a full year obtained from the observation station close to the site shall be used to determine the high astronomic tide.

4.2.2　The observed tidal data shall be used to determine the partial tidal harmonic constants for the sea area neighboring the plant site and astronomic tide process for no less than 19 years shall be forecasted.

4.2.3　The high astronomic tide used to determine the design basis flood level may be the highest astronomic tide for 19 consecutive years.Astronomic tides with an exceedance probability of 10% obtained from the monthly maximum astronomic tides series for 19 consecutive years can also be deemed as high astronomic tide.