Values of delayed neutron parameters

10 Values of delayed neutron parameters and the problem of stiffness 

Tabto 21.2 Delayed neutron parametera for fast fission  

It may be seen from the tables that the spread of time constants defining the production of delayed neutrons, r, = 1 /ki, corresponds to a factor of over 200, and hence the neutronics equations are stiff according to the criteria of Chapter 2, Section 2.7. It is therefore common for control engineers interested in modelling the interaction of the reactor with the steam plant to 

This method of weighting has been used to combine all six groups into one in the Overall rows in Tables 21.1 and 21.2. 

To give another example, the number of delayed neutron groups for thermal fission of uranium-235 could be reduced from six to three by combining groups 3, 4, 5 and 6 = 0.005247 and X3 = 0.2463, 

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Table 21.1 gives values of delayed neutron parameters, Pi, ki, for thermal fission, while Table 21.2 gives... 

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