Reactor Loose Part Damage Assessments on Steam Generator Tube Sheets

debris;monte carlo;loose part;nuclear;steam generator;steam generator tube sheet;tube sheet;tubesheet;damage assessment;pressurized water reactor;pwr

Proctor, William Cyrus ; Moody T. Chu, Committee Member,Mohamed A. Bourham, Committee Member,J. Michael Doster, Committee Chair,Proctor, William Cyrus ; Moody T. Chu ; Committee Member ; Mohamed A. Bourham ; Committee Member ; J. Michael Doster ; Committee Chair

University:North Carolina State University

关键词: debris;    monte carlo;    loose part;    nuclear;    steam generator;    steam generator tube sheet;    tube sheet;    tubesheet;    damage assessment;    pressurized water reactor;    pwr;   

Others  :  https://repository.lib.ncsu.edu/bitstream/handle/1840.16/2383/etd.pdf?sequence=1&isAllowed=y

美国|英语

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【 摘 要 】

PROCTOR, WILLIAM CYRUS. Reactor Loose Part Damage Assessments on SteamGenerator Tube Sheets. (Under the direction of Joseph Michael Doster).Damage from loose parts inside reactor systems can potentially cause integrity issues thatjeopardize the operations of these facilities. Parts such as nuts, bolts, pins, sections of tubing andeven hand tools are found inside the primary circuits of PWRs [Michel]. These parts carried bythe coolant flow impact structures including the steam generator tube sheets and can causesignificant damage leading to the unscheduled shut down of a facility. In this work we assess thebehaviors of typical loose parts that may reside in the primary coolant system. Validations ofscaled simulations are linked to previous experiments conducted by Shi [Shi]. Monte Carlosimulations of typical impact and energy distributions on a representative steam generator areanalyzed and discussed.To obtain a more complete understanding of loose part damage caused to the tube sheet ofPWR steam generators, CFD using the ANSYS CFX software package is used to computedetailed three dimensional flow fields within the steam generator inlet plenum. The flow fieldinformation is then input into a Monte Carlo program developed as part of this work to predictthe trajectory of the loose part. Existing software packages lack the ability to track finite volume,finite mass particles. Additionally, there were no packages available that allowed for detailedmanipulation of the collision physics necessary to accurately model impacts. The particletracking program developed here then allows for the calculation of loose part impact locationsand the energy imparted from loose part impacts with the tube sheet surface. Ultimately giventhis information along with the previous models developed by Shi, damage rates can beestimated aiding in the development of guidelines to improve the decision making process whenloose parts are detected in the primary coolant system.As part of previous research, a 1:8 scaled model of the McGuire steam generator inletplenum and tube sheet was constructed by Shi. This scaled steam generator tube sheet impactpattern experiment was run with two different types of hexagonal nuts and varied fluid inletvelocities. These experiments serve as a benchmark reference for development of thecomputational models in this work.Simulations of a full scale system similar to that of a Westinghouse Model D steamgenerator have also been performed. Detailed impact analysis is conducted as a function ofcoolant temperature, coolant inlet velocity, loose part type, shape, mass, density, initial startinglocation and initial kinetic energy. No a priori knowledge is assumed for the initial startinglocation and initial kinetic energy of the parts. Full scale results are compared to the scaledexperiment to assess the validity of making predictions using only a scaled simulation.