Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Unit | Type | Net power | Total power | Construction start | Construction finish | Commercial operation | Shut down |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Chinon A1 | Magnox-Reactor | 70 MW | 80 MW | 01.02.1957 | 14.06.1963 | 01.02.1964 | 16.04.1973 |
| Chinon A2 | Magnox-Reactor | 210 MW | 230 MW | 01.08.1959 | 24.02.1965 | 24.02.1965 | 14.06.1985 |
| Chinon A3 | Magnox-Reactor | 480 MW | 480 MW | 01.03.1961 | 04.08.1966 | 04.08.1966 | 15.06.1990 |
| Chinon B1 | PWR | 905 MW | 954 MW | 01.03.1977 | 30.11.1982 | 01.02.1984 | Qualified to operate until 2024 |
| Chinon B2 | PWR | 905 MW | 954 MW | 01.03.1977 | 29.11.1983 | 01.08.1984 | Qualified to operate until 2024 |
| Chinon B3 | PWR | 905 MW | 954 MW | 01.10.1980 | 20.10.1986 | 04.03.1987 | Qualified to operate until 2027 |
Question:
When did the construction of the unit Chinon B1 with net power of 905 MW start?
Answer:
1031977.0