Practical application of the chain reaction theory for the interpretation of data on thermal and radiation cracking of hydrocarbons and calculations of the basic cracking parameters faces certain difficulties associated with the following problems of the theory:

The kinetic description of the chain cracking reactions often comes into contradiction with the process of thermodynamics. In the case of thermal cracking (TC), it does not allow a distinct determination of the cracking start temperature, while in the case of radiation-thermal cracking (RTC), it does not allow the determination of the dependence of the cracking start temperature on the irradiation dose rate.

The methods for the calculation of the reaction chain length on the base of the process kinetic characteristics are not sufficiently developed. In the case of radiation cracking, dependence of the chain length on temperature and dose rate remains practically unknown.

A correct description of the dependence of the cracking rate on temperature and dose rate (in the case of radiation cracking) requires a special theoretical consideration.

The nature of the reactions and molecular states, as well as mechanisms of chain propagation in low-temperature radiation cracking (LTRC), still remains unclear.