Probability of Burst in Steam Generator Tubes Using Monte Carlo Method

2006 ◽  
Author(s):  
Jae Bong Lee ◽  
Jai Hak Park ◽  
Hong-Deok Kim ◽  
Han-Sub Chung ◽  
Tae Ryong Kim
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Steam Generator ◽  
Flaw Size ◽  
Assessment Model ◽  
Statistical Approaches ◽  
Inspection Data ◽  
Steam Generator Tubes ◽  
Non Destructive ◽  
Service Inspection

A statistical assessment model for structural integrity of steam generator tubes was proposed using Monte Carlo method. The growth of flaws in steam generator tubes was predicted using statistical approaches. The statistical parameters that represent the characteristics of flaw growth and initiation were derived from in-service inspection (ISI) non-destructive evaluation (NDE) data. Based on the statistical approaches, flaw growth models were proposed and applied to predict distribution of flaw size at the end of cycle (EOC). Because NDE measurement results differ from that of real ones in steam generator tubes, a simple method for predicting the physical number of flaws from periodic in-service inspection data was proposed. The probabilistic flaw growth rate was calculated from the in-service non-destructive inspection data. And the statistical growth of flaw was simulated using the Monte Carlo method. Probabilistic distributions of the flaw size and the probability of burst were obtained from numerously repeated simulations using the proposed assessment model.

Statistical Assessment of Integrity in Steam Generator Tubes Considering Uncertainty of NDE

2006 ◽  
Vol 326-328 ◽  
pp. 545-548
Author(s):  
Jae Bong Lee ◽  
Jai Hak Park ◽  
Hong Deok Kim ◽  
Han Sub Chung ◽  
Tae Ryong Kim
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Steam Generator ◽  
Structural Integrity ◽  
Assessment Model ◽  
Statistical Assessment ◽  
The Monte Carlo Method ◽  
Proposed Model ◽  
Inspection Data ◽  
Steam Generator Tubes

A statistical assessment model for structural integrity of steam generator tubes with axial cracks at the top of the tubesheet was proposed using Monte Carlo method. In the model, a method for estimating the number of "real cracks" from in-situ inspection (ISI) data was used. Based on the estimated "real cracks", the number of newly detected cracks and growth of cracks during arbitrary operating period were simulated using the Monte Carlo method. The flaw growth rate used in the simulation was statistically calculated from the periodic in-service non-destructive inspection data. The number of cracks, the probabilistic distribution of crack sizes at the end of next operating interval and the probability of burst during operation were calculated from numerously repeated simulations using the proposed model.

The Geometry of Steam Generator Tube and Its Relevance to the Occurrence of Stress Corrosion Cracking in Operating Nuclear Power Plants

2010 ◽  
Author(s):  
Deok Hyun Lee ◽  
Do Haeng Hur ◽  
Myung Sik Choi ◽  
Kyung Mo Kim ◽  
Jung Ho Han ◽  
...  
Keyword(s):  
Stress Corrosion ◽  
Steam Generator ◽  
Stress Corrosion Cracking ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Corrosion Cracking ◽  
Location Type ◽  
Steam Generator Tubes ◽  
Non Destructive

Occurrences of a stress corrosion cracking in the steam generator tubes of operating nuclear power plants are closely related to the residual stress existing in the local region of a geometric change, that is, expansion transition, u-bend, ding, dent, bulge, etc. Therefore, information on the location, type and quantitative size of a geometric anomaly existing in a tube is a prerequisite to the activity of a non destructive inspection for an alert detection of an earlier crack and the prediction of a further crack evolution [1].

RELAP5 Code Analysis of LSTF Small Break LOCA Tests With Steam Generator Intentional Depressurization and its Uncertainty Quantification by Monte Carlo Method and Wilks Formula Approach

2016 ◽  
Author(s):  
Ikuo Kinoshita ◽  
Michio Murase
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Steam Generator ◽  
Tolerance Limit ◽  
Injection System ◽  
Test Facility ◽  
Statistical Fluctuation ◽  
Limit Values ◽  
Upper Limit ◽  
Secondary Side

The Best Estimate Plus Uncertainty (BEPU) method has been applied by the authors to analysis of the “intentional depressurization of steam generator secondary side” which is an accident management procedure in a small break loss-of-coolant accident with high pressure injection system failure. In the present study, experimental analyses using the RELAP5/MOD3.2 code were carried out for the ROSA/Large Scale Test Facility (LSTF) secondary-side depressurization tests. The two test cases were selected with different break sizes and different depressurization conditions to ensure the reliability for the accident scenario analyses. The uncertainty propagation analyses were performed through the random variations of input parameters whose uncertainty ranges and distributions were determined previously by the PIRT and the separate effects tests. One thousand random calculations were conducted to get the 95% upper limit values of the peak cladding temperature (PCT) by the Monte Carlo method. Furthermore, the 95%/95% tolerance limits for the PCT were obtained according to Wilks formula. It was confirmed that the code predicted well the major event progressions such as rod surface temperature and the 95% uncertainty bands included the measured values. Furthermore, the 95% upper limit values of the PCT are below the 95%/95% tolerance limit values. However, the statistical fluctuation of the tolerance limit values by Wilks first order formula is as large as the uncertainty value itself. The statistical fluctuation decreases with increasing order of Wilk formula. It is desirable to increase the order of Wilks formula to more than the second order to get the reliable safety margin.

Ten Years Experience on Inconel Alloys Since the Bugey Leak in 1991

2002 ◽  
Author(s):  
Franc¸ois Champigny ◽  
Claude Pages ◽  
Claude Amzallag ◽  
Franc¸ois Billy
Keyword(s):  
Stress Corrosion ◽  
Steam Generator ◽  
Stress Corrosion Cracking ◽  
Nickel Alloys ◽  
Inconel 600 ◽  
Inconel Alloys ◽  
The Sixties ◽  
Steam Generator Tubes ◽  
Non Destructive ◽  
Destructive Methods

Base nickel alloys like Inconel 600 or 182 are particularly sensitive to stress corrosion cracking. This fact is well known since Corriou’works at the beginning of the sixties and its applications to the steam generator tubes in the seventies. For the RP vessel heads, the major fact of the nineties was the leak that occurred on one penetration in 1991 in the French NPP unit of Bugey. Several important decisions were taken after discover of this leak. First of them was to understand why it appeared so quickly, then test repairs for the Bugey case, then decide to replace all vessel heads considering that the repair solutions was to high cost. In parallel many developments were launched to establish laws for PWSCC and develop non-destructive methods to inspect the head penetrations. The conclusions obtained show the decision was good and no new leak happened on the VH penetrations.

Optimisation of helical geometry of inspection probe for steam generator tubes of the PFBR

2021 ◽  
Vol 63 (10) ◽  
pp. 585-591
Author(s):  
G Perumalsamy ◽  
P Visweswaran ◽  
D Jagadishan ◽  
S Joseph Winston ◽  
S Murugan
Keyword(s):  
Steam Generator ◽  
Structural Design ◽  
Smooth Transition ◽  
Fast Breeder Reactor ◽  
Groove Design ◽  
Helical Groove ◽  
Helical Geometry ◽  
Steam Generator Tubes ◽  
Helical Grooves ◽  
Service Inspection

The steam generator (SG) tubes of the prototype fast breeder reactor (PFBR) located in Kalpakkam, India, need to be periodically inspected using the remote field eddy current (RFEC) technique. During the pre-service inspection of the SG tubes, it was found that the RFEC probes experienced frequent mechanical breakages. To avoid these failures, changes in the existing structural design of the RFEC probe were required. A helical groove design was proposed to obtain a smooth transition in the variation of stress across the probe during the inspection. It was difficult to calculate the flexural stiffness of the proposed helical geometry probe due to the varying cross-section along its length. In this paper, the smearing approach adopted to calculate the stiffness of the RFEC probe and the sensitivity analysis carried out to determine the optimal design of the probe are discussed. A probe was fabricated based on the helical groove design and tested to qualify its suitability for the SG inspection. The RFEC probe with helical grooves was employed for the pre-service inspection of the SG tubes of the PFBR. More than 200 tubes have been inspected using the proposed design and no mechanical failure of the probe has been observed.

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