Experimental and analytical studies of the thermal stratification phenomenon in the outlet plenum of fast breeder reactors

Ieda, Y.; Maekawa, Isamu; Muramatsu, Toshiharu; Nakanishi, S.

doi:10.1016/0029-5493(90)90390-j

Cited by 53 publications

(24 citation statements)

References 4 publications

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“…Figure shows the position of the turning point of axial temperature distribution corresponding to different Ri numbers as a function of time. The accuracy of the interfacial level is approximately ±10 mm due to the difficulty in defining the interface. In these experiments, a typical test run was selected whose operational conditions are summarized in Table .…”

Section: Validation Of the Program With Experimentsmentioning

confidence: 99%

“…Extensive experiments and numerical studies have been done to understand and provide tools to explore thermal stratification phenomena. Representative in‐pile and out‐of‐pile experimental studies have been reported . These efforts indicated that thermal stratification phenomena were affected by a number of factors, including non‐dimensional thermal‐hydraulic parameters (Re, Pe, and Ri), geometrical features, and operation conditions.…”

Section: Introductionmentioning

confidence: 99%

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Validation of a methodology for thermal stratification analysis in sodium-cooled fast reactors

et al. 2018

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Summary Thermal stratification phenomena usually occur in the upper plenum after a scram of sodium‐cooled fast reactors, which should be closed concerned in the fields of structural integrity assessment and residual heat removal capacity. A 2‐dimensional analysis program under cylindrical coordinate was developed for predicting the in‐vessel thermal hydraulics. Non‐orthogonal block‐structured grids were generated to resolve the problems with complex structures. A second‐order discrete scheme based on midpoint rule was applied to the spatial discretization of convection and diffusion terms. Two sets of experiments characterized by distinct shapes of their apparatuses were used for the validation, mainly from the viewpoints of vertical temperature distribution and rising behaviors of the stratification interface. Results show that RANS‐type turbulent models make the significant impacts on different flow regimes. In the calculation of a scaled model with plenty of stagnant sodium in the upper region, the realizable k − ε model (RKE) considering the mean deformation rate gives better outcomes than the standard k − ε model (SKE). For the plant‐type upper plenum with considerable flow rate along the entire height, buoyancy modeling is the crucial issue to follow the upward movement of the interface and the relaxation process of the temperature gradient. In this case, employment of the turbulent Prandtl number reflecting the damping effect by incorporating the local Richardson number well reproduced the experimental results.

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Section: Validation Of the Program With Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Validation of a methodology for thermal stratification analysis in sodium-cooled fast reactors

et al. 2018

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“…Ieda et al 6) and Moriya et al 9) showed that the Reynolds number did not affect the thermal stratification phenomena under Re > 10 4 conditions. Furthermore, Ieda et al 6) and Vidil et al 5) investigated the effect of the Peclet number.…”

Section: Experimental Conditionmentioning

confidence: 99%

“…Furthermore, Ieda et al 6) and Vidil et al 5) investigated the effect of the Peclet number. In these studies, the Pe number also did not influence the behavior of the thermal stratification interface under Pe $ 4 Â 10 3 to 2 Â 10 4 conditions.…”

Section: Experimental Conditionmentioning

confidence: 99%

“…Water experiments and also sodium experiments [5][6][7][8] were carried out for the thermal stratification phenomena in conventional sodium-cooled reactors, where a homogeneous flow velocity in azimuthal angle arose in R/V. The effects of Reynolds number (Re) and Richardson number (Ri) on the thermal stratification were investigated through a water experiment, 9) and temperature fluctuation due to the sloshing phenomena of stratification interface was recognized.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Study on Thermal Stratification in a Reactor Vessel of Innovative Sodium-Cooled Fast Reactor—Mitigation Approach of Temperature Gradient across Stratification Interface—

Kimura

Miyakoshi

Kamide

2010

Journal of Nuclear Science and Technology

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An innovative sodium-cooled fast reactor has been investigated as part of the fast reactor cycle technology development project (FaCT). Thermal stratification after a scram is one of the main thermal loads of a reactor vessel (R/V). R/V has an upper inner structure (UIS), which consists of perforated horizontal plates and control rod guide tubes, and has a slit in the radial direction for fuel handling. The UIS slit causes an asymmetric flow pattern in R/V. A water experiment using a 1/10-scale model was carried out. A steep temperature gradient across the stratification interface was observed at the neighborhood of the UIS slit in the experiment. This means that the jet through the UIS slit entrains the bottom of the stratification interface. In order to mitigate the temperature gradient across the stratification interface, the height of a plug, which was installed in the upper plenum to infill a hole at the dipped plates where a fuel handling machine was inserted during a fuel exchange operation, was changed as the parameter in the experiment. The experimental result shows that the temperature gradient near the R/V wall in the case of the lower plug position was 21% smaller than that in the case of the higher plug position. This reduction of the temperature gradient was sufficient to maintain the structural integrity of the R/V wall against the thermal stratification.

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Direct numerical simulation of homogeneous stratified rotating turbulence

Iida

Tsujimura

Nagano

2005

Theor. Comput. Fluid Dyn.

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Experimental and analytical studies of the thermal stratification phenomenon in the outlet plenum of fast breeder reactors

Cited by 53 publications

References 4 publications

Validation of a methodology for thermal stratification analysis in sodium-cooled fast reactors

Validation of a methodology for thermal stratification analysis in sodium-cooled fast reactors

Experimental Study on Thermal Stratification in a Reactor Vessel of Innovative Sodium-Cooled Fast Reactor—Mitigation Approach of Temperature Gradient across Stratification Interface—

Direct numerical simulation of homogeneous stratified rotating turbulence

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