Data retention in Cassandra

We are trying to estimate the Cassandra capacity required to run Temporal. What is the data retention policy for the tables in temporal or temporal_visibility keyspaces? Is there any TTL set while writing the data? I did not find any TTL in the table definitions. If yes, what is the value of TTL and is it configurable?

Each namespace has workflow_execution_retention_period setting. A closed workflow after this period is removed from DB. It includes visibility records as well.