Estimation and interpretation of k{sub eff} confidence intervals in MCNP

Journal Article · Tue Aug 01 04:00:00 EDT 1995 · Nuclear Technology

OSTI ID:89661

Urbatsch, T J ^[1]; Forster, R A; Prael, R E; Beckman, R J ^[2]

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1. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering
2. Los Alamos National Lab., NM (United States)

The Monte Carlo code MCNP has three different, but correlated, estimators for calculating k{sub eff} in nuclear criticality calculations: collision, absorption, and track length estimators. The combination of these three estimators, the three-combined k{sub eff} estimator, is shown to be the best k{sub eff} estimator available in MCNP for estimating k{sub eff} confidence intervals. Theoretically, the Gauss-Markov theorem provides a solid foundation for MCNP`s three-combined estimator. Analytically, a statistical study, where the estimates are drawn using a known covariance matrix, shows that the three-combined estimator is superior to the estimator with the smallest variance. Empirically, MCNP examples for several physical systems demonstrate the three-combined estimator`s superiority over each of the three individual estimators and its correct coverage rates. Additionally, the importance of MCNP`s statistical checks is demonstrated.

• OSTI ID: 89661
• Journal Information: Nuclear Technology, Journal Name: Nuclear Technology Journal Issue: 2 Vol. 111; ISSN 0029-5450; ISSN NUTYBB
• Country of Publication: United States
• Language: English

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