Numerical Analysis of Thermal Stratification and Turbulence Penetration into Leaking Flow in a Circular Branch Piping

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Key Words: Thermal Stratification(㡊㎇䂋), Turbulence Penetration(⋲⮮䂾䒂), Safety Injection System(㞞㩚㭒㧛Ἒ䐋), Branch piping(⿚₆⺆ὖ)

Abstract

In the nuclear power plant, emergency core coolant system(ECCS) is furnished at reactor coolant

system(RCS) in order to cool down high temperature water in case of emergency. However, in this coolant

system, thermal stratification phenomenon can be occurred due to coolant leaking in the check valve. The

thermal stratification produces excessive thermal stresses at the pipe wall so as to yield thermal fatigue

crack(TFC) accident. In the present study, when the turbulence penetration occurs in the branch piping, the

maximum temperature differences of fluid at the pipe cross-sections of the T-branch with thermal

stratification are examine

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Y Z

X

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X Y Z

Temperature 363.15 359.466 355.782 352.097 348.413 344.729 341.045 337.361 333.676 329.992 326.308 322.624 318.939 315.255 311.571 307.887 304.203 300.518 296.834 293.15

X Y Z

Temperature 363.15 359.466 355.782 352.097 348.413 344.729 341.045 337.361 333.676 329.992 326.308 322.624 318.939 315.255 311.571 307.887 304.203 300.518 296.834 293.15

X Y Z

Temperature 363.15 359.466 355.782 352.097 348.413 344.729 341.045 337.361 333.676 329.992 326.308 322.624 318.939 315.255 311.571 307.887 304.203 300.518 296.834 293.15

Z X

Y

Temperature 363.15 359.466 355.782 352.097 348.413 344.729 341.045 337.361 333.676 329.992 326.308 322.624 318.939 315.255 311.571 307.887 304.203 300.518 296.834 293.15

X Z

Y

Temperature 363.15 359.466 355.782 352.097 348.413 344.729 341.045 337.361 333.676 329.992 326.308 322.624 318.939 315.255 311.571 307.887 304.203 300.518 296.834 293.15

X Y Z

Temperature 363.15 359.466 355.782 352.097 348.413 344.729 341.045 337.361 333.676 329.992 326.308 322.624 318.939 315.255 311.571 307.887 304.203 300.518 296.834 293.15

X Y Z

Temperature 363.15 359.466 355.782 352.097 348.413 344.729 341.045 337.361 333.676 329.992 326.308 322.624 318.939 315.255 311.571 307.887 304.203 300.518 296.834 293.15

X

Y Z

Temperature 363.15 359.466 355.782 352.097 348.413 344.729 341.045 337.361 333.676 329.992 326.308 322.624 318.939 315.255 311.571 307.887 304.203 300.518 296.834 293.15

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X Y

Temperature 363.15 359.466 355.782 352.097 348.413 344.729 341.045 337.361 333.676 329.992 326.308 322.624 318.939 315.255 311.571 307.887 304.203 300.518 296.834 293.15

X

Y Z

Temperature 363.15 359.466 355.782 352.097 348.413 344.729 341.045 337.361 333.676 329.992 326.308 322.624 318.939 315.255 311.571 307.887 304.203 300.518 296.834 293.15

0.00 0.05 0.10 0.15 0.20

0 10 20 30 40 50 60 70

Temperature difference[K]

Distance[m]

0 deg 30 deg 60 deg 90 deg

0.000 0.005 0.010 0.015 0.020 0.025

Distance(mm)

0.000 0.005 0.010 0.015 0.020 0.025

290 300 310 320 330 340 350 360

370 30⁰ pipe

Temperature(K)

Distance(mm) After inleakage

37.5mm away from in-liakage 75mm away from in-liakage

0.000 0.005 0.010 0.015 0.020 0.025

290 300 310 320 330 340 350 360 370

Distance(mm)

Temperature(K)

60⁰ pipe

After inleakage

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0.000 0.005 0.010 0.015 0.020 0.025 290

300 310 320 330 340 350 360 370

Distance(mm)

Temperature(K)

90⁰ pipe

After inleakage

-200 -150 -100 -50 0 50 100 150 200

290 300 310 320 330 340 350 360 370

Temperature(K)

Distance(m)

Re=34,000(A1) Re=57,000(Ref) Re=114,430(A2) Re=228,860(A3)

-200 -150 -100 -50 0 50 100 150 200

290 300 310 320 330 340 350 360 370

Temperature(K)

Distance(m)

Re=34,000(A1) Re=57,000(Ref) Re=114,430(A2) Re=228,860(A3)

-200 -150 -100 -50 0 50 100 150 200

290 300 310 320 330 340 350 360 370

Temperature(K)

Distance(m)

Re=34,000(A1) Re=57,000(Ref) Re=114,430(A2) Re=228,860(A3)

0.00 0.05 0.10 0.15 0.20

0 10 20 30 40 50 60 70

Re=34,000(A1) Re=57,000(Ref) Re=114,430(A2) Re=228,860(A3)

Temperature difference(K)

Distance(m)

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