Concrete Containment Building Research Articles

Analysis of impact of large commercial aircraft on a prestressed containment building

In this paper, the results of nonlinear dynamic analyses of a concrete containment building under extreme loads are presented. The impact of a large commercial B747 airliner is investigated as the extreme load, and a rigid wall impact test is performed using commercial nonlinear finite element codes. The impact forces exerted by the aircraft are verified compared with the time-dependent impact force provided by OECD/NEA (2002), which was calculated based on the so-called Riera method. The rigid wall impact analysis shows that the finite element model of a B747 is appropriate for the purpose of the aircraft crash analysis exposed to the external hazard of “Beyond Design-Basis Events” defined by U.S. Nuclear Regulatory Commission. Finally, the applicability of this methodology is further studied and verified by conducting parametric studies on the critical infrastructures of nuclear power plant containment structures.

Evaluation of protective quality of prestressed concrete containment buildings of nuclear power plants

The permeability and sorptivity properties of the two prestressed concrete containment buildings (PCCBs) of a nuclear power plant in South China, which had been under operation for 5 years, were measured by using the autoclam permeability system. The air permeability, sorptivity and water permeability indexes of No.1 PCCB are smaller than or equal to 0.11 ln(102 Pa)/min, 0.98×10−7 m3/min1/2 and 1.93×10−7 m3/min1/2, respectively, and the air permeability, sorptivity and water permeability indexes of No.2 PCCB are smaller than or equal to 0.17 ln(102 Pa)/min, 1.6×10−7 m3/min1/2 and 4.43×10−7 m3/min1/2, respectively. Based on the criteria for evaluating the protective quality of concrete structures in terms of their permeability and sorptivity properties, proposed by the research organization of the autoclam permeability system, the protective quality of No.1 PCCB is still in very good grade and that of No.2 PCCB is not in very good grade but in good grade, and the in-service inspection of the protective quality of No.2 PCCB should be strengthened in the future.

Updating the long-term creep strains in concrete containment vessels by using Markov chain Monte Carlo simulation and polynomial chaos expansions

The time-dependent loss of prestress of cables in Nuclear Power Plant concrete inner containment buildings may affect the vessel leak-tightness and reduce its life extension. Thus, the assessment of the structural integrity of the containment vessel requires a correct estimation of the long-term creep strains. The article aims at computing and updating the evolution in time of a confidence interval on the creep strains by updating the prior density of input parameters that is specified in a Bayesian framework.

Softening response properties of plain concrete by large-scale direct tension tests

The softening response properties of plain concrete, which directly affect the structural capacity of the concrete containment building of nuclear power plants, were studied via direct tension tests using large-size concrete specimens with two notches. A variation of two and three levels of the concrete strength and the maximum size of coarse aggregate, respectively, was considered. Two independently controlled actuators were used to ensure a homogeneous increase of crack mouth opening displacement (CMOD) on the top and bottom notches of the specimen and to avoid secondary flexural stresses. From the tests, the complete load–CMOD responses with stable post-peak descending curves were obtained for each specimen. The fracture energy data obtained using the complete load–CMOD responses and one evaluated using a classical prediction equation were compared. The results, owing to size effect, indicated that the fracture energy obtained in the current investigation is larger on average than that obtained using a classical prediction equation. The direct tensile strength of the large-size specimens was, however, about half the splitting tensile strength of the cylindrical specimens.

Seismic fragility analysis of a CANDU type NPP containment building for near-fault ground motions

In this study, the seismic fragility of a CANDU (CANada Deuterium Uranium) containment building is estimated by performing the nonlinear seismic analysis for the near-fault earthquakes. The lumped mass model of the containment building was used for a nonlinear dynamic time history analysis. The tri-linear skeleton curve was used for the nonlinear behavior of the prestressed concrete containment building. In order to estimate the inelastic nonlinear response of the containment, the maximum point oriented model was used for the hysteretic rule of the shear deformation. For the nonlinear seismic analyses, 30 set of real near-fault earthquake records were used as the input motion. The seismic responses and seismic fragility of the containment for the near-fault ground motions are compared with the responses and fragility for the design ground motion generally used in Korea.

비선형 지진해석에 의한 PSC 격납건물의 지진취약도 분석

원전 구조물 및 주요기기의 지진 안전성 평가에서는 내진성능을 정량화하는 방법으로 취약도 분석이 사용되고 있다. 지진취약도 분석은 격납건물의 설계 시 반영된 보수성을 배제한 실질적인 내진성능을 평가하는 것으로 이러한 보수성을 성능 및 응답에 관련된 확률론적 변수로 고려하여 평가하게 된다. 본 연구에서는 비선형 지진 해석으로부터 얻은 구조물의 변위응답을 기초로 한 지진취약도 분석 방법을 제시하였다. 또한 원전부지에서 선정된 발생가능한 근거리지진, 원거리지진, 설계지진 및 확률론적 시나리오지진을 시나리오지진으로 선정하고 이들 지진동에 대한 비선형 지진해석을 통하여 한국 표준형 원전 격납건물의 지진취약도를 평가하였다. The seismic fragility analysis method has been used as a quantitative seismic safety evaluation method for the NPP(Nuclear Power Plant) structures and equipments. The seismic fragility analysis gives a realistic seismic capacity excluding the convertism included in the design stage. The conservatism is considered as the probabilistic parameters related to the response and capacity in the seismic fragility analysis. In this study, the displacement based seismic fragility analysis method was proposed based on the nonlinear dynamic analysis results. In this study, the seismic safety of the prestressed concrete containment building of KSNP(Korean Standard Nuclear Power Plant) was evaluated for the scenario earthquakes, neat-fault, far-fault, design earthquake and probability based scenario earthquake, which can be occurred in the NPP sites.

ReliabIlity analysis of containment building subjected to earthquake load using response surface method

The seismic safety of reinforced concrete containment building can be evaluated by probabilistic analysis considering randomness of earthquake, which is more rational than deterministic analysis. In the safety assessment of earthquake-resistant structures by the deterministic theory, it is not easy to consider the effects of random variables but the reliability theory and random vibration theory are useful to assess the seismic safety with considering random effects. The reliability assessment of reinforced concrete containment building subjected to earthquake load includes the structural analysis considering random variables such as load, resistance and analysis method, the definition of limit states and the reliability analysis. The reliability analysis procedure requires much time and labor and also needs to get the high confidence in results. In this study, random vibration analysis of containment building is performed with random variables as earthquake load, concrete compressive strength, modal damping ratio. The seismic responses of critical elements of structure are approximated at the most probable failure point by the response surface method. The response surface method helps to figure out the quantitative characteristics of structural response variability. And the limit state is defined as the failure surface of concrete under multi-axial stress, finally the limit state probability of failure can be obtained simply by first-order second moment method. The reliability analysis for the multiaxial strength limit state and the uniaxial strength limit state is performed and the results are compared with each other. This study concludes that the multiaxial failure criterion is a likely limit state to predict concrete failure strength under combined state of stresses and the reliability analysis results are compatible with the fact that the maximum compressive strength of concrete under biaxial compression state increases.

원자력 발전소 격납건물 벽체의 균열거동

Tension tests of six half-thickness concrete containment wall elements were conducted as a part of Korea Atomic Energy Research Institute (KAERI) program. The aim of the KAERI test program is to provide a test-verified analytical method for estimating capacities of concrete reactor containment buildings under internal overpressurization from postulated degraded core accidents. The data from the tests reported herein should be useful for benchmarking analytical method that require modeling of material behavior including concrete cracking behavior and reinforcement/concrete interaction exhibited by the test. Major test variable is compressive strength of concrete, and its effect on the behavior of prestressed concrete panel subjected to biaxial tension is investigated.

The effects of thermal load and frost cycles on the water transport in two high-performance concretes

Abstract Moisture diffusivity of two high-performance concretes used in concrete containment buildings of nuclear power plants is measured as a function of temperature up to 80°C, and the effects of high-temperature exposure up to 800°C and freeze/thaw cycles on its value are analyzed. The temperatures in the range of 0–80°C are found to have a moderate effect on the moisture diffusivities of both concretes, the typical increase being about 100–200% over the whole region. The high temperature exposure results in a much more significant increase of moisture diffusivity, up to three orders of magnitude, and the freeze/thaw exposure of 400 cycles to an increase up to one order of magnitude. As the main reason for the mentioned moisture diffusivity increase, the crack formation is identified. Both thermal decomposition accompanied by release of substantial amount of gaseous substances and water freezing in the porous system can damage the internal microstructure of the matrix due to the significant pressure increase in the porous body. The magnitude of changes of moisture diffusivity is found to be affected by the quality of aggregates rather than by the quality of cement. High quality quartzitic aggregates with very low porosity and very good mechanical properties perform much better than other more porous siliceous aggregates such as opal, and than the calcareous aggregates such as chalk.

The Business of Professional History

I CAUGHT THE DISEASE at Three Mile Island. Perhaps it was the day that I scampered over the roof of the concrete containment building that housed the crippled reactor. My memory isn't as clear as I would like it to be, or maybe the affliction didn't seem so important at the time. I do remember that it happened sometime in June or July 1979. I was thinner and beardless then, did not have to adjust my glasses to read, had never used a personal computer, and did more scampering than I do now. And although I was a historian, I generally defined change as something that happened in the past to other people. Three Mile Island changed all that.

Current state of knowledge on the behavior of steel liners in concrete containments subjected to overpressurization loads

In the US, concrete containment buildings for commercial nuclear power plants have steel liners that act as the internal pressure boundary. The liner abuts the concrete, acting as the interior concrete form. The liner is attached to the concrete by either studs or by a continuous structural shape (such as a T-section or channel) that is either continuously or intermittently welded to the liner. Studs are commonly used in reinforced concrete containments, while prestressed containments utilize a structural element as the anchorage. The practice in some countries follows the US practice, while in other countries the containment does not have a steel liner. In this latter case, there is a true double containment, and the annular region between the two containments is vented. This paper will review the practice of design of the liner system prior to the consideration of severe accident loads (overpressurization loads beyond the design conditions). An overpressurization test of a 1:6 scale reinforced concrete containment at Sandia National Laboratories resulted in a failure mechanism in the liner that was not fully anticipated. Post-test analyses and experiments have been conducted to understand the failure better. This work and the activities that followed the test are reviewed. Areas in which additional research should be conducted are given.

Testing and analyses to investigate liner tearing of the [formula omitted] reinforced concrete containment building

The overpressurization of a 1:6- scale reinforced concrete containment building demonstrated that liner tearing is an important failure mode. A combined experimental and analytical program was developed to determine the important parameters that contribute to liner tearing. Three sets of test specimens were designed to investigate the mechanisms important in causing failure. The tests investigated effects produced by the anchorage system, loading conditions, and transition in thickness from the liner to insert plate. Before testing, the specimens were analyzed using two- and three-dimensional finite element models. Based on the analysis, the failure mode and load conditions were predicted. Test data and posttest examination show mixed agreement with the analytical predictions. Many similarities were observed between the response of the liner in the 1:6- scale reinforced concrete containment model and the response of the test specimens. This work illustrates that the failure mechanism can be greatly influenced by details of liner and anchorage system design. Furthermore, it significantly increases the understanding of containment building response under severe conditions.

Post-test analysis of a piping penetration in a 1:6-Scale model of a reinforced concrete containment building

In a scale-model overpressurization test of a reinforced concrete containment building, the steel liner proved to be the weak-link for preventing the escape of gas from the containment. During the experiment, a tear propagated through the liner along the edge of a thickened section that surrounded a piping penetration. The rate of leakage through this tear was so great that it made further pressurization of the model impossible. A post-test finite element analysis of the region where the tear developed indicates that the tear was initiated by high strains that developed locally near a stud anchor which attached the liner to the reinforced concrete. This conclusion is also supported by visual observations of the failed area and measurements of local thinning of the liner. The elevated strains near the stud anchor were caused by a shear force that was introduced to the liner through the stud. This shear force developed as the result of circumferential slippage between the liner and concrete caused by the presence of the thickness discontinuity in the reinforced area.

Implications of results from full-scale tests of reinforced and prestressed concrete containments

Test results from full-scale tests of elements of concrete containments indicate that small liner plate cracks may form. A possible consequence of these small cracks could be depressurization without global failure and with much reduced release of contaminants. The tests of response of reinforced and prestressed concrete containment buildings are being performed at Construction Technology Laboratories, Inc. (CTL) in Skokie, Illinois, under the sponsorship of the Electric Power Research Institute (EPRI). Three specimens are discussed. Two large square elements of a containment wall were tested in biaxial tension while a central pipe penetration was axially loaded. A large L-shaped wall/basemat junction specimen was tested with a combination of axial tension, bending, and shear. The loading on each specimen represented the forces developed from severe over-pressurization in the containment. The specimens were tested at full-scale to avoid modifications that could be required to produce a scale model. Full-size details were used for the liner and anchorage. The overall intent of the EPRI sponsored program is to establish a data base that can be used for verification of analytical models being developed by Anatech International, La Jolla, California. Testing is continuing at CTL.

Soil-structure interaction effects on the reliability evaluation of reactor containments : Pires, J; Hwang, H; Reich, M Proc Third US National Conference on Earthquake Engineering, Charleston, 24–28 August, 1986V1, P529–539. Publ El Cerrito: Earthquake Engineering Research Institute, 1986

The probability-based method for the seismic reliability assessment of nuclear structures, which has been developed at Brookhaven National Laboratory (BNL), is extended to include the effects of soil-structure interaction. A reinforced concrete containment building is analyzed in order to examine soil-structure interaction effects on: (1) structural fragilities; (2) floor response spectra statistics; and (3) correlation coefficients for total acceleration responses at specified structural locations.

Results of large-scale test of discontinuity region in a prestressed concrete containment

The test described in this paper is part of an Electric Power Research Institute (EPRI) program (Research Program RP2172-2) to provide a test-verified analytical method of estimating capacities of concrete reactor containment buildings under internal overpressurization from postulated degraded core accidents. Phase 2 of the EPRI program, on which this paper is based, includes tests of five large-scale specimens with steel liner plates. The specimens represent structural elements of prestressed concrete containment buildings. Four full-scale square wall element specimens and one specimen representing the wall/basemat junction region were tested. This paper describes results of the wall/basemat junction region test. Results of this experimental work indicate that highly localized strains in the steel liner plate caused by internal overpressurization or other accident conditions can result in liner tearing and subsequent containment leakage. It appears that this liner tearing occurs in a controller manner. Extrapolating from these test results, leakage and depressurization is more likely to occur than global failure.

Testing of large-scale concrete containment structural elements

The tests described in this paper are part of an Electric Power Research Institute (EPRI) program (Research Project 2172-2) to provide a test-verified analytical method of estimating capacities of concrete reactor containment buildings under internal overpressurization from postulated degraded core accidents. Experimental study in Phase 2 of the investigation, on which this paper is based, includes tests of five large-scale specimens with steel liner plates representing structural elements of prestressed concrete containment buildings. Four square wall element specimens and one specimen representing the wall/basemat junction region were tested. This experimental work indicates that under internal overpressurization or other accident conditions, highly localized strains in the steel liner plate can result in liner tearing and subsequent containment leakage. These results support the theory of leak before break where liner tearing occurs in a controlled manner and leakage and depressurization occur rather than global failure.

Construction of the containment building for the gentilly nuclear power reactor

A brief description is given of the techniques and methods used for the construction of the prestressed concrete containment building for the Gentilly Nuclear Power Station. The containment building consists of a base slab, a circular wall, a ring beam and a dome. It has the shape of a cylinder measuring 120 feet interior diameter, topped by a spherical dome. The total height is 175 feet measured from the basement floor to the top of the dome. Leaktightness is achieved by the use of an epoxy-vinyl lining applied on the interior surface of the containment.

Prestressed Concrete Containment Building for the Gentilly Nuclear Power Station

Prestressed Concrete Containment Building for the Gentilly Nuclear Power Station