Portions of this document may be illegible AbstractThe BLOCKAGE 2.5 code described in t h i s User's Manual was developed by the United States Nuclear Regulatory Commission (NRC) as a tool to evaluate licensee compliance with NRC Bulletin 96-03, "Potential Plugging of Emergency Core Cooling Suction Strainers by Debris in Boiling Water Reactors". As such, BLOCKAGE 2.5 provides a generalized framework into which a user can input plant-specific and insulationspecific data for performing analyses in accordance with Regulatory Guide 1.82, Rev. 2. This user's manual describes the capabilities of BLOCKAGE 2.5 along with a description of the graphics user's interface provided for data entry. Each input/output dialog is described in detail along with special considerations related to developing and executing BLOCKAGE. Also, several sample problems are provided such that user can easily modlfy them to suit a particular plant of interest. The models used in BLOCKAGE 2.5 and their validation are presented in the accompanying NUREG/CR-6371.The BLOCKAGE models were designed to be parametric in nature, allowing the user flexibility to examine the impact of several modeling assumptions and to conduct sensitivity analyses. As a result, BLOCKAGE 2.5 results are known to be very sensitive to the user provided input. It is therefore strongly recommended that users become thoroughly familiar with BLOCKAGE models and their limitations as described in NUREG/CR-6224.iii
NRC ABSTRACTA central question for resolution of GSI-24 is whether or not PWRs that currently rely on a manual system for ECCS switchover to recirculation should be required to install an automatic system. Risk estimates are obtained by reevaluating the contributions to core damage frequencies (CDFs) associated with failures of manual and semiautomatic switchover at a representative PWR. This study considers each separate instruction of the corresponding emergency operating procedures (EOPs), the mechanism for each control, and the relationship of each control to its neighbors. Important contributions to CDF include human errors that result in completely coupled failure of both trains and failure to enter the required EOP.This detailed study finds that changeover to a semiautomatic system is not justified on the basis of cost-benefit analysis: going from a manual to a semiautomatic system reduces the CDF by 1.7~10-~ per reactor-year, but the probability that the net cost associated with the modification being less than $1,000 per person-rem is about 20% without license renewal. Scoping analyses, using optimistic assumptions, were performed for a changeover to a semiautomatic system with automatic actuation and to a fully automatic system; in these cases the probability of having a net cost being less than $l,OOO/person-rem is about 50% without license renewal and over 95% with license renewal.
The Reference Manual contains additional information that supports the use of BLOCKAGE 2.5. It contains descriptions of the analytical models contained in the code, programmer guides illustrating the structure of the code, and summaries of coding verification and model validation exercises that were performed to ensure that the analytical models were correctly coded and applicable to the evaluation of BWR pump suction strainers.The BLOCKAGE code was developed by SEA and programmed in FORTRAN as a code that can be executed from the DOS level on a PC. A graphical users interface (GUI) was then developed by SEA to make BLOCKAGE easier to use and to provide graphical output capability. The GUI was programmed in the C language. The user has the option of executing BLOCKAGE 2.5 with the GUI or from the DOS level and the Users Manual provides instruction for both methods of execution.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.