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Hourly Data Usage

Why is hourly data not used in PAVAN, because NRC requires it for licensee applications?

As you noted, hourly data is required in license applications. The hourly data is then used to create the joint frequency distribution (JFD) for PAVAN. The NRC is currently reviewing a “newer” version of PAVAN that uses hourly data. However, we do not have a projected date of completion at this time. Nevertheless, we have compared the JFD and hourly meteorological data versions for multiple U.S. sites and have found there is very little difference in the results. So, even though a JFD “loses” some meteorological information, it does not appear to meaningfully impact the results.