To estimate the FFO (Funds From Operations) to Net Debt ratio according to S&P methodology, we must adjust both the standard FFO and Net Debt based on S&P’s Global Ratings criteria.

**1. Calculate S&P Adjusted FFO**
S&P defines FFO as Cash Flow from Operations (CFO) excluding changes in working capital, minus cash interest paid (if classified as financing) and cash taxes paid (usually already captured in CFO). 
* Cash Flows From Used In Operating Activities (Total CFO): 8,586 million EUR
* Increase Decrease In Working Capital: The cash effect was a 2,424 million EUR outflow (derived from Operations before WC of 12,415 minus Taxes Paid of 1,504 minus CFO of 8,487 = ~2,424 outflow). We add this back to CFO.
* Interest Paid Classified As Financing Activities: 822 million EUR (S&P deducts this to arrive at an after-interest operating cash flow).

Adjusted FFO = 8,586 (CFO) + 2,424 (WC Changes) - 822 (Interest Paid) = 10,188 million EUR.

**2. Calculate S&P Adjusted Net Debt**
S&P adjusts reported financial debt by capitalizing Asset Retirement Obligations (AROs) and Pension obligations (which fall under provisions), while deducting accessible cash and liquid investments (including dedicated assets earmarked for nuclear provisions).
* Long-term Borrowings: 28,083 million EUR
* Current Borrowings: 12,508 million EUR
* Plus Total Provisions (AROs, Pensions, etc.): Noncurrent (24,663) + Current (2,365) = 27,028 million EUR
* Less Cash and Cash Equivalents: 15,570 million EUR
* Less Other Financial Assets (Liquid investments & dedicated nuclear assets): Noncurrent (10,599) + Current (2,394) = 12,993 million EUR

Adjusted Net Debt = (28,083 + 12,508) + 27,028 - 15,570 - 12,993 = 39,056 million EUR.

**3. FFO / Net Debt Ratio**
FFO / Net Debt = 10,188 / 39,056 = 0.26085 (or ~26.1%)

<answer>0.26</answer>