Section 18

It shall be the duty of the Authority to conserve the Fund by so exercising and performing its powers, functions and duties under this Act as to secure that the total revenues of the Authority are, subject to any directions given by the Minister under section 8, sufficient to meet all sums properly chargeable to its revenue account, including, without prejudice to the generality of that expression provisions in respect of its obligations under sections 17 and 19 and depreciation and interest on capital, taking one year with another.