Section 611 - Disclaimer by appointee, permissible appointee, or taker in default of exercise of power of appointment(a) A disclaimer of an interest in property by an appointee of such interest in property as a result of an exercise of a power of appointment by a holder takes effect as of the time the instrument by which the holder exercised the power becomes irrevocable.(b) A disclaimer of an interest in property by a permissible appointee of an interest in property or by a taker of an interest in property as a result of a holder's failure to effectively exercise a power of appointment granted to such holder (a taker in default) takes effect as of the time the instrument creating the power of appointment becomes irrevocable. 63 Del. Laws, c. 448, §1; 75 Del. Laws, c. 302, § 1.;