SSRS report expression FormatDateTime changes Nulls to '1/1/0001'
Below will work : 

=IIf(IsNothing(Fields!Temperature_Control_Inspection_Date.Value), "", FormatDateTime(Fields!Temperature_Control_Inspection_Date.Value, DateFormat.ShortDate))


Above will have null dates as blank. Also, it will remove the time and just get you the date portion.