Advanced

Evaluation of prestress losses in nuclear reactor containments

Lundqvist, Peter LU and Nilsson, Lars-Olof LU (2011) In Nuclear Engineering and Design 241(1). p.168-176
Abstract
The most critical safety barrier in a nuclear power plant, the concrete containment, is prestressed by hundreds of tendons, both horizontally and vertically. The main purpose of the containment is to prevent radioactive discharge to the environment in the case of a serious internal accident. Due to creep and shrinkage of concrete and relaxation of the prestressing steel, tendon forces decrease with time. These forces are thus measured in Swedish containments with unbonded tendons at regular in-service inspections. In this paper, the prestress losses obtained from these in-service inspections are compared to losses estimated using several prediction models for creep, shrinkage and relaxation. In an attempt to increase the accuracy of these... (More)
The most critical safety barrier in a nuclear power plant, the concrete containment, is prestressed by hundreds of tendons, both horizontally and vertically. The main purpose of the containment is to prevent radioactive discharge to the environment in the case of a serious internal accident. Due to creep and shrinkage of concrete and relaxation of the prestressing steel, tendon forces decrease with time. These forces are thus measured in Swedish containments with unbonded tendons at regular in-service inspections. In this paper, the prestress losses obtained from these in-service inspections are compared to losses estimated using several prediction models for creep, shrinkage and relaxation. In an attempt to increase the accuracy of these models, existing expressions for the development of shrinkage were modified using previous findings on the humidity and temperature inside two Swedish containments. The models which were used and modified for predicting creep and shrinkage were CEB-FIP Model Codes 1990 and 1999, ACI 209, Model B3 and GL2000. Eurocode 2 was used for the prediction of relaxation. The results show that the most accurate of the models were CEB/FIP MC 99 and ACI 209. Depending on the model, the accuracy of the prediction models was increased by 0.5-1.2 percentage points of prestress losses when using the modified development of shrinkage. Furthermore, it was found that the differences between the different models depend mainly on the prediction of creep. Possible explanations for the deviation between the calculated and measured models can be the influence of reinforcement on creep and shrinkage of concrete and the influence of friction on horizontal tendons. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Creep, Prediction models, Prestress losses, KstrConcrete, Reactor containment, Shrinkage, Relaxation
in
Nuclear Engineering and Design
volume
241
issue
1
pages
168 - 176
publisher
Elsevier
external identifiers
  • wos:000287049900020
  • scopus:78650690281
ISSN
1872-759X
DOI
10.1016/j.nucengdes.2010.11.007
language
English
LU publication?
yes
id
23a536d0-4de1-4215-8adf-fbfa575f815e (old id 1768895)
date added to LUP
2011-01-24 15:01:36
date last changed
2017-11-12 03:15:53
@article{23a536d0-4de1-4215-8adf-fbfa575f815e,
  abstract     = {The most critical safety barrier in a nuclear power plant, the concrete containment, is prestressed by hundreds of tendons, both horizontally and vertically. The main purpose of the containment is to prevent radioactive discharge to the environment in the case of a serious internal accident. Due to creep and shrinkage of concrete and relaxation of the prestressing steel, tendon forces decrease with time. These forces are thus measured in Swedish containments with unbonded tendons at regular in-service inspections. In this paper, the prestress losses obtained from these in-service inspections are compared to losses estimated using several prediction models for creep, shrinkage and relaxation. In an attempt to increase the accuracy of these models, existing expressions for the development of shrinkage were modified using previous findings on the humidity and temperature inside two Swedish containments. The models which were used and modified for predicting creep and shrinkage were CEB-FIP Model Codes 1990 and 1999, ACI 209, Model B3 and GL2000. Eurocode 2 was used for the prediction of relaxation. The results show that the most accurate of the models were CEB/FIP MC 99 and ACI 209. Depending on the model, the accuracy of the prediction models was increased by 0.5-1.2 percentage points of prestress losses when using the modified development of shrinkage. Furthermore, it was found that the differences between the different models depend mainly on the prediction of creep. Possible explanations for the deviation between the calculated and measured models can be the influence of reinforcement on creep and shrinkage of concrete and the influence of friction on horizontal tendons.},
  author       = {Lundqvist, Peter and Nilsson, Lars-Olof},
  issn         = {1872-759X},
  keyword      = {Creep,Prediction models,Prestress losses,KstrConcrete,Reactor containment,Shrinkage,Relaxation},
  language     = {eng},
  number       = {1},
  pages        = {168--176},
  publisher    = {Elsevier},
  series       = {Nuclear Engineering and Design},
  title        = {Evaluation of prestress losses in nuclear reactor containments},
  url          = {http://dx.doi.org/10.1016/j.nucengdes.2010.11.007},
  volume       = {241},
  year         = {2011},
}