증기 폭발에 의한 원자로 하부 헤드의 건정성에 관한 연구 = Structural Analysis for the Lower Head of Nuclear Reactor under In-Vessel Vapor Explosion Loads

다국어 초록 (Multilingual Abstract)

The objective of this paper is to assess the lower head of nuclear reactor under the in-vessel vapor explosion load. Firstly, the calculated explosion pressure loads are applied on the lower head inner wall for 2-D model and 3-D model, respectively, to calculate the equivalent strain and membrane stress intensity; secondly, both calculated explosion pressure loads and thermal loads are imposed on the 2-D model of the lower head to calculate the equivalent stain, membrane stress intensity, and total mechanical and thermal strain. Then, the calculated strain and stress results are compared with the reference standard values of failure criteria to determine the failure probability of the lower head. All the stain and stress calculations are performed by ANSYS 11.0 Program.
The structure analysis results show that the lower head failure does not exist under the pressure value up to 118.5 MPa in vessel explosion.
The thermo-mechanical results show that the lower head failure under the pressure value up to 118.5 MPa and temperature value up to 700℃ in-vessel explosion also does
not exist. During this analysis process, the nucleate boiling crisis will not occur when the

outside wall of lower head is cooled by the saturation water at 100℃ and 0.1 MPa.

목차 (Table of Contents)

• Abstract i
• List of Tables iii
• List of Figures iv
• 1. Introduction 1
• 1.1 The reason to cause failure of reactor vessel 1
• 1.2 Two kinds of failures of reactor vessel 1
• 1.2.1 Alpha-mode containment failure 1
• 1.2.2 Lower head failure 1
• 2. Analysis procedure of lower head failure 3
• 2.1 Introduction 3
• 2.2 Safety assessment process 3
• 2.3 Analysis of in-vessel explosion 4
• 2.4 Analysis method using ANSYS program 5
• 2.4.1 Static analysis of ANSYS 6
• 2.4.2 Transient analysis of ANSYS 7
• 2.5 Failure criteria 17
• 2.5.1 Design criteria 17
• 2.5.2 Structural failure criteria 17
• 2.5.3 Boiling failure criteria 18
• 2.5.4 Thermal failure criteria 19
• 3. Structural analysis procedure and results 20
• 3.1 Structural analysis of 2-D modeling lower head 20
• 3.1.1 Stress analysis under design condition 20
• 3.1.2 Transient dynamic analysis of explosion load 22
• 3.1.3 Results of simplified 2-D model structural analysis 22
• 3.1.3.1 Stress analysis results under design condition 22
• 3.1.3.2 Transient dynamic analysis of explosion load results 23
• 3.2 Structural analysis of 3-D model lower head 41
• 3.2.1 Stress analysis under design condition 41
• 3.2.2 Transient dynamic analysis of explosion load 41
• 3.2.3 Results of 3-D modeling structural analysis 41
• 3.2.3.1 Stress analysis results under design condition 41
• 3.2.3.2 Transient dynamic analysis of explosion load results 42
• 3.3 Thermal Analysis 55
• 3.3.1 Introduction 55
• 3.3.2 Thermal analysis results 56
• 3.4 Thermo-mechanical analysis for 2-D modeling 58
• 3.4.1 Thermo-mechanical analysis under design condition 58
• 3.4.2 Thermo-mechanical analysis under transient dynamic of explosion load 58
• 3.4.3 Results of thermo-mechanical analysis 59
• 3.4.3.1 Thermo-mechanical analysis results under design condition 59
• 3.4.3.2 Thermo-mechanical analysis results under transient dynamic of explosion load 59
• 4. Conclusion and Future Work 73
• References 75