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Incorporating flow-accelerated corrosion effects into probabilistic risk assessment

IP.com Disclosure Number: IPCOM000128095D
Original Publication Date: 1998-Dec-31
Included in the Prior Art Database: 2005-Sep-14
Document File: 7 page(s) / 24K

Publishing Venue

Software Patent Institute

Related People

Kao, Tsu-Mu: AUTHOR [+3]

Related Documents

http://theses.mit.edu:80/Dienst/UI/2.0/Describe/0018.mit.theses/1998-260: URL

Abstract

Traditional probabilistic risk assessments (PRAs), in general, do not include passive SSCs (systems, structures, and components), since they are much more reliable than the active components modeled in PRAs routinely. Aging phenomena, however, may make passive SSCs less reliable than assumed. This thesis investigates the impact of flow-accelerated corrosion (PAC) on carbon steel piping on the secondary cooling system of a PWR.

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 This record is the front matter from a document that appears on a server at MIT and is used through permission from MIT. See http://theses.mit.edu:80/Dienst/UI/2.0/Describe/0018.mit.theses/1998-260 for copyright details and for the full document in image form.

Incorporating Flow-Accelerated Corrosion Effects into Probabilistic Risk Assessment

by

Tsu-Mu Kao
B.S., Nuclear Engineering (1980), National Tsing-Hua University, Taiwan, R.O.C. M.S., Nuclear Engineering (1982), National Tsing-Hua University, Taiwan, R.O.C.

Submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY at the Massachusetts Institute of Technology September 1998
SIGNATURE OF author: [[signature omitted]]

Department of Nuclear Engineering

July 9, 1998
CERTIFIED BY: [[SIGNATURE OMITTED]] George E. Apostolakis
Professor of Nuclear Engineering Thesis Supervisor Ronald G. Ballinger

Associate Professor of Nuclear Engineering Thesis Reader

ACCEPTED BY: [[SIGNATURE OMITTED]]

Lawrence M. Lidsky

Chairman, Departmental Committee on Graduate Students

ARCHIVES MASSACHUSETTS INSTITUTE OF TECHNOLOGY LIBRARIES JUL 20 1999

Massachusetts Institute of Technology Page 1 Dec 31, 1998

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Incorporating flow-accelerated corrosion effects into probabilistic risk assessment

Incorporating Flow-Accelerated Corrosion Effects into Probabilistic Frisk Assessment

By Tsu-Mu Kao

Submitted to the Department of Nuclear Engineering on July 9,1998 in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY

Abstract

Traditional probabilistic risk assessments (PRAs), in general, do not include passive SSCs (systems, structures, and components), since they are much more reliable than the active components modeled in PRAs routinely. Aging phenomena, however, may make passive SSCs less reliable than assumed. This thesis investigates the impact of flow-accelerated corrosion (PAC) on carbon steel piping on the secondary cooling system of a PWR.

A stress-strength interference (or reliability physics) model based on physical FAC phenomena (rather than estimating distribution parameters from expert opinions) is proposed. We determined the capacity probability distribution using the KWUKastner-Riedle (KWUKR) FAC model. The uncertainties associated with the KWU-KR model itself are assessed.

The Surry IPE (Individual Plant Examination) has been used as a case study. We calculate the core damage probability (CDP) due to FAC for a 10-year period of time.

The failure probability due to the steady-state pressure is dominated by epistemic uncertainties. Since the hazard function is meaningful for aleatory failures only, it cannot be calculated in this case. However, the failure rate due to transients can be calculated, because they involve aleatory uncertainties. Our calculations show that the failure rate due to transients can be approximated by a straight line, as the linear aging model postulates. We point out that this is not the total impact of FA(;,...