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Research Papers

# Numerical Simulation of Temperature Distribution in a Containment Vessel of an Operating PWR Plant

[+] Author and Article Information
Yoichi Utanohara

Institute of Nuclear Safety System, Inc., 64 Sata, Mihama-cho, Mikata-gun, Fukui 919-1205, Japan
e-mail: utanohara@inss.co.jp

Michio Murase

Mem. ASME,
Institute of Nuclear Safety System, Inc.,
64 Sata, Mihama-cho, Mikata-gun, Fukui 919-1205, Japan
e-mail: murase@inss.co.jp

Akihiro Masui, Ryo Inomata, Yuji Kamiya

MHI Nuclear Engineering Company, Ltd.,
3-1, Minatomirai 3-chome, Nishi-ku, Yokohama 220-8401, Japan

1Corresponding author.

Manuscript received April 29, 2014; final manuscript received September 14, 2014; published online February 9, 2015. Assoc. Editor: Mark Anderson.

ASME J of Nuclear Rad Sci 1(1), 011002 (Feb 09, 2015) (12 pages) Paper No: NERS-14-1004; doi: 10.1115/1.4026389 History: Received April 29, 2014; Accepted November 14, 2014; Online February 09, 2015

## Abstract

The structural integrity of the containment vessel (CV) for a pressurized water reactor (PWR) plant under a loss-of-coolant accident is evaluated by a safety analysis code that uses the average temperature of gas phase in the CV during reactor operation as an initial condition. Since the estimation of the average temperature by measurement is difficult, this paper addressed the numerical simulation for the temperature distribution in the CV of an operating PWR plant. The simulation considered heat generation of the equipment, the ventilation and air conditioning systems (VAC), heat transfer to the structure, and heat release to the CV exterior based on the design values of the PWR plant. The temperature increased with a rise in height within the CV and the flow field transformed from forced convection to natural convection. Compared with the measured temperature data in the actual PWR plant, predicted temperatures in the lower regions agreed well with the measured values. The temperature differences became larger above the fourth floor, and the temperature inside the steam generator (SG) loop chamber on the fourth floor was most strongly underestimated, $−16.2 K$ due to the large temperature gradient around the heat release equipment. Nevertheless, the predicted temperature distribution represented a qualitative tendency, low at the bottom of the CV and increases with a rise in height within the CV. The total volume-averaged temperature was nearly equal to the average gas phase temperature. To improve the predictive performance, parameter studies regarding heat from the equipment and the reconsideration of the numerical model that can be applicable to large temperature gradient around the equipment are needed.

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## References

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## Figures

Fig. 1

Schematic drawings of the CV. (a) Outer view of the CV. (b) Inside the CV

Fig. 2

Ventilation and air conditioning systems

Fig. 3

Structure of 2F (pressure header room and reactor cavity), arrows denote inlet and outlet flow directions

Fig. 4

Structure of the ring duct, arrows denote inlet and outlet flow directions

Fig. 5

Structure of 3F, arrows denote inlet and outlet flow directions

Fig. 6

Structure of 4F, arrows denote inlet and outlet flow directions

Fig. 7

Computational grids. (a) 2F, (b) 3F, (c) 4F, (d) 5F, (e) x = 0 m cross section, lower, and (f) x = 0 m cross section, upper

Fig. 8

Heat release model to the CV exterior

Fig. 9

Grid convergence of predicted volume averaged temperature on each floor

Fig. 10

Volume-averaged temperature profiles, extrapolated value, and fine-grid solution with discretization error bars computed using Eq. (19)

Fig. 11

Velocity and temperature distributions on cross sections of x = 0 m and y = 0 m. (a) velocity distribution, and (b) temperature distribution

Fig. 12

Velocity vector distributions on vertical cross sections (A, B, C: SG loop chambers), (a) x = 8.59m, and (b) x = 0 m

Fig. 13

Velocity vector and temperature distributions on each floor. (a) Elevation of 14 m. (b) Elevation of 20 m. (c) Elevation of 26.9 m. (d) Elevation of 35 m. (Points denote temperature measurement points and the corresponding values are the differences between measurement and simulation values. White regions in the temperature distributions are components where temperature was not calculated.)

Fig. 14

Flow field and temperature distribution around the pressurizer, (a) velocity vector distribution, (b) temperature distribution (x denotes measurement points), and (c) pressure distribution (gauge pressure)

Fig. 15

Downward flow through openings in the floor and its influence on the temperature distribution, (a) velocity vector distribution, (b) temperature distribution, and (c) pressure distribution (gauge pressure)

Fig. 16

Flow field and temperature distribution when the door of the pressurizer chamber was open, (a) velocity vector distribution (4F, elevation 26.9 m), (b) temperature distribution (4F, elevation 26.9 m), and (c) temperature distribution around the pressurizer

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