0
Research Papers: Fluid-Structure Interaction

Safety Assessment of Reactor Pressure Vessel Integrity for Loss of Coolant Accident Conditions

[+] Author and Article Information
Dieter Beukelmann

 TÜV SÜD Industrie Service GmbH, Westendstr. 199, 80686 Munich, Germanydieter.beukelmann@tuev-sued.de

Wenfeng Guo

 TÜV SÜD Industrie Service GmbH, Westendstr. 199, 80686 Munich, Germanywenfeng.guo@tuev-sued.de

Wieland Holzer

 TÜV SÜD Industrie Service GmbH, Westendstr. 199, 80686 Munich, Germanywieland.holzer@tuev-sued.de

Robert Kauer

 TÜV SÜD Industrie Service GmbH, Westendstr. 199, 80686 Munich, Germanyrobert.kauer@tuev-sued.de

Wolfgang Münch

 TÜV SÜD Industrie Service GmbH, Westendstr. 199, 80686 Munich, Germanywolfgang.muench@tuev-sued.de

Christoph Reichel

 TÜV SÜD Industrie Service GmbH, Westendstr. 199, 80686 Munich, Germanychristoph.reichel@tuev-sued.de

Peter Schöner

 TÜV SÜD Industrie Service GmbH, Westendstr. 199, 80686 Munich, Germanypeter.schoener@tuev-sued.de

J. Pressure Vessel Technol 134(1), 011302 (Dec 08, 2011) (10 pages) doi:10.1115/1.4004799 History: Received January 12, 2011; Revised July 01, 2011; Published December 08, 2011; Online December 08, 2011

One of the critical issues for reactor pressure vessel (RPV) structural integrity is related to the pressurized thermal shock (PTS) event. Therefore, within the framework of safety assessments special emphasis is given to the effect of PTS-loadings caused by the nonuniform azimuthal temperature distribution due to cold water plumes or stripes during emergency coolant injection. This paper describes the method used to predict the thermal mechanic boundary conditions (system pressure and wall temperature). Using a system code the pressure and global temperature distributions were calculated, systematically varying the leak size and the location of the coolant water injection. Spatial and temporal temperature distributions in the main circulation pipes and at the RPV wall were predicted by mixing analyses with a computational fluid dynamics (CFD) code. The model used for these calculations was validated by post-test calculations of a UPTF (upper plenum test facility) experiment simulating cold leg injection during a small break loss of coolant accident (LOCA). Comparison with measured temperatures showed that the modeling used is suitable to obtain enveloping results. Fracture mechanics analyses were carried out for circumferential flaw sizes in the weld joint near the core region and between the RPV shell and the flange, as well as for axial flaws in the nozzle corner. Stress intensity factors KI were calculated numerically using the finite element program ansys and analytically on the basis of weight and polynomial influence functions using stresses obtained from elastic finite element analyses. Benchmark tests revealed good agreement between the results from numerical and analytical calculations. For all regions of the RPV investigated and the most severe transients it was demonstrated that a large safety margin against brittle crack initiation exists and brittle fracture of the RPV can be excluded.

Copyright © 2012 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Cooling system with ECC water injection and relevant phenomena

Grahic Jump Location
Figure 2

Geometric model and numerical grid

Grahic Jump Location
Figure 4

RPV wall temperature distribution at 470 s

Grahic Jump Location
Figure 5

Model and calculated temperature distribution after 1695 s (UPTF TRAM C1 Run2a1)

Grahic Jump Location
Figure 6

Attached ECC water plume (t = 1695 s)

Grahic Jump Location
Figure 7

UPTF TRAM C1 Run2a1: cfx calculation (bold lines) versus UPTF experiment (thin lines)

Grahic Jump Location
Figure 8

UPTF TRAM C1 Run2a1: cfx calculation using SAS (bold lines), cfx calculation using SST (dashed lines) versus UPTF experiment (thin lines)

Grahic Jump Location
Figure 9

UPTF TRAM C1 Run21a2: two-phase cfx calculation of the cold water plume at lowered water level

Grahic Jump Location
Figure 10

Temperature distribution for a leak size of 100 cm2 after 1800 s

Grahic Jump Location
Figure 11

Temperature distribution (left side) and distribution of Von Mises’ equivalent stresses (right side)

Grahic Jump Location
Figure 12

FE-models: (a) 180 deg section global model, (b) submodel with axial crack in the nozzle corner, and (c) submodel with circumferential crack in the flange joint

Grahic Jump Location
Figure 14

Axial stress profiles due to thermal loading and internal pressure in the flange joint after 2000 s

Grahic Jump Location
Figure 15

FE calculations of load paths KIm and KIth for a completely circumferential crack with crack depth a = t/40 in flange joint

Grahic Jump Location
Figure 16

FE and analytical calculations of load paths KIm and KIth for an axial crack with crack depth a = t/4 in nozzle corner

Grahic Jump Location
Figure 17

Analytical load path results for core region, KIc -curve for RTNDTj  = 29°C and KIc -curve for load path maximum a = 4 mm

Grahic Jump Location
Figure 18

Analytical load path results for flange joint, KIc -curve for RTNDT  = 0°C and KIc -curve for load path maximum a = 4 mm

Grahic Jump Location
Figure 19

Analytical and numerical load path results for flange joint, KIc -curves for RTNDT  =− 55 °C and RTT0  =− 44.5 °C

Grahic Jump Location
Figure 20

Analytical load path results for nozzle corner, KIc -curve for RTNDT  = 0°C and constraint representative KIc -curves

Grahic Jump Location
Figure 21

Analytical and numerical load path results for nozzle corner, KIc -curves for RTNDT  =− 5°C and RTT0  =− 63.2°C and constraint representative KIc -curve

Grahic Jump Location
Figure 3

Cold water isovolume (T < 510 K) at 450 s

Grahic Jump Location
Figure 13

Analysis of LOCA: Example with intact and broken cladding (schematic diagram), according to KTA 3201.2 [9]

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In