I= SIMULATION OF CORROSION PRODUCT ACTIVITY IN PRIMARY COOLANT OF A TYPICAL PWR UNDR LINEARLY AND NON-LINEARLY RISING CORROSION RATE AND FLOW RATE TRANSIENTS.
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Title of Thesis
SIMULATION OF CORROSION PRODUCT ACTIVITY IN PRIMARY COOLANT OF A TYPICAL PWR UNDR LINEARLY AND NON-LINEARLY RISING CORROSION RATE AND FLOW RATE TRANSIENTS.

Author(s)
Muhammad Rafique.
Institute/University/Department Details
Pakistan Institute Of Engineering And Applied Sciences (PIEAS)/ Department Of Physics And Applied Mathematics
Session
2005
Subject
Applied Mathematics
Number of Pages
171
Keywords (Extracted from title, table of contents and abstract of thesis)
pressurized water reactors (pwrs), corrosion product activity, corrosion rates, coolant

Abstract
In comparison with emerging nuclear power systems, the Pressurized Water Reactors (PWRs) have many times higher post shutdown radiation levels, mainly due to the corrosion product activity (CPA), prolonging the maintenance resulting in substantial economic penalties. The advent of high-power fuel with higher potential for crud deposition has aggravated this problem further. Recent studies have also identified corrosion cracking, corrosion fatigue, stress corrosion, and erosion-corrosion as major safety concerns in these systems requiring reliable estimates of corrosion products in both normal as well as transient conditions.

In this work, a detailed methodology has been developed for modeling and simulation of corrosion product activity in primary loops of typical PWRs. This is based on system of differential equations governing the kinetics of dominant CPAs throughout the primary loop. In view of experimentally observed variation of corrosion rates with plant aging, temperature and pressure, models have been developed for both linearly and non-linearly rising corrosion rates. Also flow rate perturbation has been added in order to take in to account various transients. This methodology has been implemented in a fortran-77 based computer program CPAIR-RC has been found in good agreement with the corresponding experimental data. Similarly, the value of the activity ratios for 58Co to 60Co calculated by CPAIR-RC program compare well with the corresponding results found by using CRUDSIM/MIT code. The linearly rising corrosion rates tend to smear-out the effect of flow rate perturbations on the specific activity of the primary coolant. Also considerable changes have been observed on specific activity in reactor transients when linearly rising corrosion rate model is replaced with non-linearly rising model. The saturation values of specific activities due to 24Na, 59Mn, 59Fe, 58Co, 60Co and 99Mo have been found to depend on changes in flow rate as well as on the corrosion rate. The time required to reach saturation level has been found to depend strongly on flow rates and efficiencies of filters, dematerializing units etc. to remove CPAs.

Download Full Thesis
1937.55 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
146.39 KB
2 1 Introduction 1
332.34 KB
  1.1 Background 1
  1.2 Nature of Problem 12
  1.3 Review of Some Existing Computer Models 14
  1.4 Objectives 29
  1.5 Layout of Thesis 31
3 2 Mathematical Modeling 32
188.7 KB
  2.1 Corrosion Products PWRs 32
  2.2 Reactor Transients Effects 33
  2.3 Mathematical Derivation of The Problem 35
  2.4 Modeling of Flow Rate Perturbations 44
  2.5 Modeling of Power Perturbations 46
  2.6 Chapter Summary 49
4 3 Cpari-Rc and its Comparison With Various Numerical Techniques 50
165.47 KB
  3.1 Cpari-Rc Program Description 50
  3.2 Numerical Solution Techniques 51
  3.3 Numerical Solutions of ODEs by Using One step Methods 53
  3.4 Multistep Methods 60
  3.5 Chapter Summary 68
5 4 Results and Discussion 69
380.19 KB
  4.1 Corrosion Product Activity In Primary Coolant of A Typical PWR under Linearly Rising Corrosion and Flow Rate perturbations 69
  4.2 Kinetic Study of CPA in Primary Coolant Pipes of A Typical PWR under Flow rate Transients and Flow Rate and Linearly Rising Corrosion Rates 83
  4.3 Nonlinearly Rising Corrosion and Flow Rate Transients 94
  4.4 Comparison of CPAIR-RC with CVRUDSIM/MIT 109
  4.5 Chapter Summary 109
6 5 Summary, Conclusions and Recommendations for Future Work. 113
51.68 KB
  5.1 Summary 113
  5.2 Conclusions 114
  5.3 Recommendations for Futrue Work 116
7 6 References 118
57.08 KB
8 7 Appendix 123
830.83 KB
  7.1 Reprints of Published Papers 123
  7.2 Vita 124