MOCUS-BACFIRE user's manual.

This report is the user's manual for MOCUS-BACFIRE, a computer programme for qualitative common cause analysis. The MOCUSBACFIRE package code was developed by coupling the MOCUS code and BACFIRE code. The MOCUS code is a computer programme to generate cut sets of a fault tree. BACFIRE is a computer programme to search among the basic events of a minimal cut set for potential common casuse failures. Both codes are written in FORTRAN IV for the IBM 360/370 computer series. The input data to MOCUS-BACFIRE are the fault tree and common cause susceptibilities. The input and output of the programme are described in detail in this handbook

Common cause analysis : a review and extension of existing methods

The quantitative common cause analysis code, MOBB, is extended to include uncertainties arising from modelling uncertainties and data uncertainties. Two methods, Monte Carlo simulation and the Method-of-Moments are used to propagate uncertainties through the analysis. The two different capabilities of the code are then compared. When component failure rates are assumed lognormallv distributed, bounded lognormal (Sb) distributions are used to evaluate higher moment terms, as required by the Method-of-Moments, in order to minimize the effect of the tail of the lognormal. A code using the discrete probability distribution (DPD) method is developed for analyzing system unavailability due to common initiating events (internal and external). Sample problems demonstrating each approach are also presented

Generic nuclear safety issues : methods of analysis

"Prepared for: Nuclear Safety Analysis Center."Includes bibliographical references (leaves 223-231

Analyzing the safety impact of containment inerting at Vermont Yankee

Includes bibliographical referencesFinal Report; July 1980Post-accident hydrogen generation in BWR containments is analyzed as a function of engineered hydrogen control system, assumed either nitrogen inerting or air dilution. Fault tree analysis was applied to assess the failure probability per demand of each system. These failure rates were then combined with the probability of accidents producing various hydrogen generation rates to calculate the overall system hydrogen control probability. Results indicate that both systems render approximately the same overall hydrogen control probability (air dilution: .917 - .989; nitrogen inerting: .987 - .998). Drywell entries and unscheduled shutdowns were also analyzed to determine the impact on the total BWR accident risk as it relates to the decay heat removal system. Results indicate that inerting may increase the overall risk due to a possible increase in the number of unscheduled shutdowns due to a lessened operator ability to correct and identify "unidentified" leakage from the primary coolant system. Further, possible benefits of inerting due to reduced torus corrosion and fire risk in containment appear to be dominated by the possible operations related disbenefits

A survey of methodology for the global minimization of concave functions subject to convex constraints

Methodology is described for the global solution to problems of the form minimize f(x) subject to x[set membership, variant]G, ui [greater-or-equal, slanted] xi [greater-or-equal, slanted] li where f(x) is a concave function of the vector x in Rn space and G is a convex polytope. This paper investigates recent work accomplished to solve this problem. Basically, solution algorithms can be categorized into three distinct areas: (1) branch-and-bound methods, (2) cutting plane methods, and (3) build-up of polyhedra methods. Computational experience with these methods is also examined. Particular attention is paid to the possibility for extension of these algorithms to problems of large scale, specifically to those evidencing separable objective functions which are subject to linear sets of constraints.

Assessing nuclear fuel cycle diversion resistance, Quantitative methods for

"Prepared for Department of Energy, Nuclear Alternatives System Assessment Program, Washington, D.C."Includes bibliographical referencesFinal report; October 197