Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_15564 ( "Unit" text, "Type" text, "Net Power" text, "Total Power" text, "Finish construction" text )

### Question ###
What was the net power, when the type was wwer-440/230, and when construction was finished on 24.10.1977?

### Accurate SQL ###

SELECT "Net Power" FROM table_15564 WHERE "Type" = 'wwer-440/230' AND "Finish construction" = '24.10.1977'