Accounting for the reference data correlation when determining the calculation error using the maximum likelihood method

Given the assumption of normal distribution, the determination of the calculation error for the correlation of the initial reference data is considered. In this case, it is proposed to use the maximum likelihood method with a non-diagonal covariance matrix. The relationship of calculation deviations from the reference data is assumed to be described by known correlation coefficients. Techniques for constructing the average value, error variance, and distribution of its probability are described. The determination of the correlation coefficient for k_eff is considered using two consecutive campaigns of the PIK reactor. Possible directions for future modification of the methodology are discussed.