RBMK SP-2 Validation Results RBMK SP-2 Validation Results (KS PH - - PowerPoint PPT Presentation

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RBMK SP-2 Validation Results (KS PH Rupture Simulation) RBMK SP-2 Validation Results (KS PH Rupture Simulation)

Bruce Schmitt

Battelle, PNNL

April, 2002 Bruce Schmitt

Battelle, PNNL

April, 2002

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RINSC/INSC Code Validation Support

RINSC/INSC Code Validation Support

Joint Project 6 established to assist with code validation, primarily with the application of western codes like RELAP5 Standard problems were defined to investigate important phenomena for VVER and RBMK designs PNNL provided analysis support to ANL for RBMK problems PNNL and KI jointly analyzed SP-2

RBMK Standard Problem 2 (SP-2)

RBMK SP-2 was defined from a series of stop flow experiments that were performed with the KS facility SP-2 was to simulate a pressure header rupture

– although it was performed at system pressure

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RBMK SP-2 phenomena investigated

water release (ejection) from the fuel channel (FC) model and fuel simulator surface drying, dryout under sharp flow deceleration at the inlet of the RBMK-1000 and RBMK-1500 fuel assembly (FA) models, post dryout heat transfer and fuel simulator temperature conditions in the FA model under channel drying, steam and water counter current flows in the steam-water piping, and in the FC with the FA model, propagation of the reflood and quench front in the FA model under flow resumption at the channel inlet.

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3 0 10 9 8 IX V I II V II X X V I I V V I 40 X X I II II X X X I 2 7 X X I V X V X X X II 4 5 I X X X X X V II I X I V X X X V X X V I IV I I I 2 э 1 р 1 б 1 э X X X V II X I I X II I 53 5 3' X X X V II I X X I X

XX X I X

12 6 X I 1 3 1 4 2 9 1 8 1 9 2 0 21 2 2 1 c 2c 3 c 4т 5 т 6т 7 т 8т 1к 2 к 3к 9т 11 24 23 7 1 0т V = 2 м 3 1 8т 35 38 3 9 60 7 6 08 К О 4 6 3 7 32 47 Д Д Д Д 3 5 6 4 1 28 12 9 С оле ме р _ V = 4 м 3 12 1 1 19 12 0 1 39 1 22 26 16 15 1 7 1 38 Д 1 42 54 7Н ( Х Т Р 4/32 0) 3Н ( Т4 А ) 5 Н (1 ,5 X -6 Л ) 5 1 Э П Д Д 2 Н 1Н 44 Д 2 25 2 8 X X II X V I 3 6A 36 X X 1 X X X V I II X V I I X I X 4 6 4 5 3 p 3б 3э 5 0 X 41 3 3 A B C Д X X V 1 37 Д 7 61 2б 2р ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Э П Д Д п 22 6 п 2 24 п 22 7 п 27 2 п 2 80 п 1 17 п 2 09 п 10 8 U p pe r he a d er In ta ke h e a de r L ow e r he a d er

T e st s ec tio n 1 T e st se ct ion 2 T e st se c tion 3 Ф Ф Ф

S e p er a tor s H e a t e x c ha ng e rs P um ps

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SWC model Upper Header From the circulation pumps 2r LWC model G TIN Lower header FC model PIN DP16-4 Sampling 16 Sampling 15 Sampling 4 TW1 TW2 TW3 TW4

1044 3814 6854 6894 7000 186 1586 6836

To separators To hear echangers Bypass

Отбор 16 475 289 1400 475 311 222 490 19х360=6840 Отбор 15 Отбор 4 8468 3х120=360 R267 756 7000 89х8 Начало зоны тепловыделения Конец зоны тепловыделения (обогреваемая длина) Обозначения:

• решетка-интенсификатор

с полным набором ячеек

• решетка-интенсификатор

с неполным набором ячеек

• штатная решетка ТВС

реактора РБМК-1000 5250 Вход теплоносителя Выход теплоносителя 75х5

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80 109 121 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 32 61.8 1

Термопара из провода КТМС ∅1.5 Припой ПСР-72 Имитатор твэла

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234 240 300-02 300-01 300-40 300-41 250 305-00 315-00 160-08 160-09 210-02 210-03 200-01 210-01 320-07 Upper Drum Seperator Pressure Tube 320-01 320-02 SWC (0.72o slope) 110-07 110-06 110-05 110-03 110-03 110-02 110-01 410-01 410-06 410-07 410-05 420-02 420-03 420-04 420-01 410-08 430-02 445-00 440 (01-06) 331-01 332-01 330-01 335-01 500-02 500-03 500-04 500-01 500-06 500-07 500-05 515-00 510 (01-05) 600-01 600-02 600-07 615-00 610 (01-06) 100-01

100-01

430-01

• 02
• 03
• 01
• 07
• 01
• 1

415-01 610-01 620-02 620-03 620-05 620-06 62-04 620-07 Condenser Bypass Hx After Cooler 620-08 620-09 630-01 700-01 710-01

• 02
• 06
• 05
• 04
• 03

810-00 820-01 820-02 820-03 820-04 820-05 820-05 820-06 850-01 850-02 850-03 850-04 850-05 850-06 850-07 850-08 850-09 850-10 853-01

• 01
• 09

N2 Receiver Accumulator Bypass 160-01 160-02 150-01 150-02 150-04 Lift Path

• 01
• 02
• 02
• 16
• 17
• 18
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520- 450- 310-

• 01
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720- 725-01

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785-

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775-

710-02 725-02

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735-01 745-01 740- 730-02 730-01

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750-

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705- 755-01 760-01 770-01

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770- 01 7 5 5

• 3

765-

760-01

Figure 6) KS Model Node Diagram

852-

700-01

• 01
• 01

710-01

150-03 210-58 210-57 220-01 230-01

105-00 155-00 700-02 700-04

630-02 700-03 Lower Header Intake Header

331-01

Circulation Pumps Pump Bypass 780-00 605-00 505-00 435-00 Upper SWC 400-00 165-00

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Table 2) KS Facility Initial Conditions No. Experiment Electrical power

• f fuel assembly

model, MWth Pressure at inlet of fuel assembly, P16, MPa Water temperature at inlet of fuel channel, TF1, ºK Water flow rate at inlet GL, kg/s 1 Test-4 1.691 7.68 516.1 3.90 2 Test-5 2.486 8.40 527.4 4.70 3 Test-5? 2.532 7.95 533.1 4.17 4 Test-6 2.926 8.23 527.3 4.28 5 Test-7 3.488 8.23 529.3 4.13 6 Test-8 4.566 8.74 531.1 6.27

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Table 1) RELAP5 Model Equivalent Data Locations Data RELAP5 Model Thermocouples HS Volume TW-1 2102-59 mesh 8 210-58 TW-2 2102-58 mesh 8 210-57 TW-3 2101-33 mesh 8 210-32 TW-4 2102-10 mesh 8 210-09 Pressure Taps Volume P4 210-57 P16 210-02

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Table 3) Calculation Matrix Case Options Test ID e s m t h vp b 4

X O X O O O

5

X X O

5?

X O X O O O

6

X X O

7

X X O

8

X O X O O X O

Case Option Definitions (x –results presented here, o –results not presented) e - EPRI bundle friction correlation (this is the ‘basecase’ model setup) s - the SWC piping junction diameter is reduced by 1/8, based on SP-1 results [5] for liquid drainback m - improved CHF multiplier coefficient, based on SP-1 results [5] for dryout prediction v - valve leakage allowed p - early power shutdown t - time step size reduction h - heat structure radial mesh reduction b - Bestion bundle friction correlation

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Conclusions Conclusions

Overall Performance considered minimal or poor

The predicted steady state pressure drop in the heater bundle is not well correlated by RELAP5, and is considered to be minimally acceptable. This suggests that the RBMK bundle requires a more specific correlation than the Lockart-Martinelli correlation used in RELAP5 or that the mass-flux dependent coefficients be defined specific to the RBMK bundle. Time to dryout is reasonably predicted for each case. However, this would be expected for even significant errors in the predicted CHF for this evaluation.

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Conclusions Conclusions

RELAP5 consistently under-predicts rewet for the cases where power is maintained constant and the overall prediction is considered poor. In general this is in the conservative direction. However, for the case of power reduction, Test 5′, early rewet is predicted. Sensitivity studies performed do indicate that an improved CHF correlation (specific to the RBMK fuel assemblies) would likely provide significant improvement. It should also be noted that for RELAP5/MOD3.2, the reflood model is disabled because of incompatibilities. Updated versions of RELAP5 with a reflood model may provide additional improvement as well.

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Conclusions Conclusions

Post-dryout heat transfer is reasonably predicted (except during rewet), as indicated by the rate of heatup in the cladding after dryout, and the peak cladding temperature is reasonably predicted. However, this is limited to conditions prior to reflood. The progression of the quench front is not correctly predicted for all cases. the sequencing of temperature turn-over shows an inversion where the lower elevation cladding remains in post-dryout while the upper cladding is in partial rewet.

• updated versions of RELAP5 with a reflood model may

provide additional improvement.