Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
When did the construction of the unit Chinon B1 with net power of 905 MW start?

### Inputs:
table_name: table, columns: ['Unit', 'Type', 'Net power', 'Total power', 'Construction start', 'Construction finish', 'Commercial operation', 'Shut down']

### Response:
SELECT Construction start FROM table WHERE Net power = 905 MW AND Unit = Chinon B1