Database does not follow simple recovery model behaviour in SQL Server 2012

Assume that you set the recovery model of the model database to Simple in Microsoft SQL Server 2012. When you create a new database, it is displayed as using the simple recovery model. However, the new database does not behave as if the simple recovery model is being used. Specifically, you can back up the transaction log, which should not occur under the simple recovery model.

Cumulative update package 4 for SQL Server 2012 SP1

Workaround

ALTER DATABASE <Name> SET RECOVERY FULL;

ALTER DATABASE <Name> SET RECOVERY SIMPLE;