NUREG/IA-0188

International 

Agreement Report

RELAP5/MOD3 .2 Validation

Using BETHSY Test 6.9a 

Prepared by 

S. Bouabdallah 

NNC Ltd. 

Booths Hall 

Chelford Road 

Knutsford, Cheshire 

GB-WA16 8QZ 

UNITED KINGDOM 

Office of Nuclear Regulatory Research 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001 

August 2000 

Prepared as part of 

The Agreement on Research Participation and Technical Exchange 

under the International Code Application and Maintenance Program (CAMP) 

Published by 

U.S. Nuclear Regulatory Commission
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NUREG/IA-0188

International 

Agreement Report

RELAP5/MOD3.2 Validation 

Using BETHSY Test 6.9a 

Prepared by 

S. Bouabdallah 

NNC Ltd. 

Booths Hall 

Chelford Road 

Knutsford, Cheshire 

GB-WA16 8QZ 

UNITED KINGDOM 

Office of Nuclear Regulatory Research 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001 

August 2000 

Prepared as part of 

The Agreement on Research Participation and Technical Exchange 

under the International Code Application and Maintenance Program (CAMP)

Published by 

U.S. Nuclear Regulatory Commission
Abstract

This report provides the results of a RELAP5/MOD3.2 calculation of Test 6.9a which was carried out on 

the BETHSY facility. The purpose of the calculation is to provide validation evidence for the use of 

RELAP5/MOD3.2 for application to faults at Sizewell B which can occur when the plant is in Modes 5 

and 6 (and including the use of nozzle dams).

iii
CONTENTS

1. Introduction ................... 

2. The BETHSY facility ........... 

3. Test 6.9a ..................... 

3.1 Test 6.9a description ......... 

3.2 Relevance of test ............ 

4. The RELAP5/MOD3.2 model ..... 

5. Calculation results .............. 

6. Summary of calculation .......... 

7. Conclusions ................... 

8. References .................... 

9. List of calculations .............. 

10. List of Figures ................ 

Figures ......................

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

.. F1-F22

V
NNC C5166TNW/001 -NNC Issue 01 

Introduction 

This report provides the results of a RELAP5/MOD3.2 (Ref 1) calculation of 

Test 6.9a (Ref 2) which was carried out on the BETHSY facility (Ref 3). The 

purpose of the calculation is to provide validation evidence for the use of 

RELAP5/MOD3.2 for application to faults at Sizewell B which can occur when 

the plant is in Modes 5 and 6 (and including the use of nozzle dams). 

2 The BETHSY facility 

The BETHSY facility is a three loop, full elevation, 1/100 volume scale model of a 

Framatome three loop PWR of 2775 MWth core power (Ref 3). The BETHSY 

facility simulates: 

(i) the entire primary circuit - pressure vessel, primary piping for three loops including SG primary sides, coolant pumps and pressuriser connected to the 

hot leg of loop 1 via a surge line (the surge line is connected to the top of 

the hot leg) 

(ii) the secondary system consisting of three SG secondary sides, main 

feedwater lines and main steam lines 

(iii) the emergency auxiliary systems including a High Pressure Injection 

System, Low Pressure Injection System, accumulators, Auxiliary 

Feedwater System etc. 

The vessel contains a core simulator consisting of 428 fuill length electrically heated 

rods and 29 guide thimbles of a design (pitch, diameter and length) typical of a 

17 x 17 fuel bundle. The downcomer consists of an external tube connecting the 

cold legs to the lower plenum of the vessel. The bypass from upper plenum to 

downcomer top is simulated by pipework with calibrated orifices. Figures 1 to 4 

show schematic layouts of the BETHSY facility. 

3 Test 6.9a 

Test 6.9a (Ref 2) consists of the simulation of a loss of RHR with the plant at 

mid-loop, decay heat corresponding to 0.5% nominal full power and with the 

pressuriser manway open. The SGs were filled with air and isolated. Both gravity 

and forced Safety Injection were used to recover from the fault. The systems were 

activated dependent on core rod temperatures. 

3.1 Test 6.9a description 

Test 6.9a (Ref 2) was initiated with the primary system pressure (upper plenum) at 

1.15 bar, the water level at mid-loop elevation as described above and with the 

fluid within most of the primary system stagnant and close to saturation. The 

space above the liquid was filled with saturated steam.

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C5166n/TN/01 

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The start of the test consisted of the core power being ramped from zero to 141 kW (0.5% power) in 15 s and the opening of the valve simulating the 

pressuriser manway. Boiling occurred very rapidly in the core and this resulted in 

increasing primary pressure, steam discharge from the manway and level swell in the core and upper plenum. Some steam passed up the guide tube, through the 

upper head and into the downcomer (henceforth termed the upper head bypass) where it condensed on the water which was slightly subcooled (both initially and due to the rising pressure). Two-phase mixture flowed from the upper plenum into the guide tube, the hot legs, the surge line and the pressuriser. Liquid continued to be entrained with the vapour into the surge line and pressuriser and the level in the pressuriser continued to rise causing the system pressure to increase. The boil-off 

of liquid led to draining of the cold legs so that condensation in the downcomer ceased, the upper head bypass flow fell and at about 2000 s the guide tube drained. By 2400 s the two-phase mixture in the pressuriser had risen to the top so that 

between 2400 s and 2600 s some liquid was entrained with the vapour out of the 

manway. Further discussion of liquid discharge through the manway is provided in 

section 5. 

By about 2900 s the upper plenum level fell below the hot leg elevation so that only steam flowed into the pressuriser. As the boil-off continued, the level in the 

upper plenum continued to fall and at about 5000 s the top of the core became uncovered. The uncovered core started to heat up, the rate of steam generation 

fell and the system pressure fell. 

At 6045 s gravity injection to cold leg 1 was initiated in response to the hottest rod 

temperature reaching 250°C. The mixture level in the core rose slowly but the 

upper part of the core continued to heat up. Vapour flow from the core via the 

upper head bypass increased and the vapour condensed on the cold injection water in cold leg 1 and the downcomer. The resulting fall in system pressure aided the gravity injection since the flow was proportional to the differential pressure between the injection source at 1.5 bar and cold leg 1. The injection flow was not of sufficient magnitude to remove all the decay heat and so the mixture level in the 

core continued to fall, whilst the core continued to heat up. 

At 7060 s the rod temperature had reached 400'C, gravity injection was terminated 

and pumped injection to cold leg I was initiated. The pumped injection rapidly refilled the core, with total core quench being complete by 8040 s. By 9500 s the mixture level in the upper plenum had reached the elevation of the hot legs, resulting in the further entrainment of liquid into the hot legs, surge line and pressuriser, with further liquid discharge from the manway. The upper head bypass steam flow increased because of the increased condensation potential of the 

injection flow. The bypass steam flow then fell as the cold legs became water-filled, with condensation then only occurring in the top of the downcomer. 

The test was effectively terminated at 12410 s when the core power was turned 

off. 

2 

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C5166/TNIO01 

Issue 01 

3.2 Relevance of test 

The phenomena occurring in the test which are judged to be of most importance 

for the validation of RELAP5/MOD3.2 for application during Modes 5 and 6 (and 

including use of nozzle dams) are the following: 

(i) level swell in the core and upper plenum 

(ii) liquid carry-over into the hot legs 

(iii) counter-current flow and pressuriser surge line flooding 

(iv) RCS pressurisation and gravity drain 

(v) upper head bypass flow and condensation. 

4 The RELAP/5MOD3.2 model 

The RELAP5/MOD3.2 model of the BETHSY facility is based upon that 

developed originally by INEL for the RELAPS/MOD3 (development version 7 vq) 

analysis of ISP-27 (BETHSY Test 9.1.b). The model has subsequently been 

revised for application with more recent versions of RELAP5/MOD3 and for 

application to BETHSY Test 6.9a. The noding scheme is shown in Fig 5 to 8. 

5 Calculation results 

The most significant results of the calculation are compared with the experimental 

results in Fig 9 to 22. Experimental results are shown with a solid line and the 

results of the RELAP5IMOD3.2 calculations are shown with a dashed line. 

Figure 9 shows the pressuriser pressure. There was an initial fall in pressure due to 

the manway opening, but this was halted as liquid began flashing to steam. The 

pressure subsequently rose due to boiling as the core heat reached its steady value 

at 15 s. As the pressure rose, steam was discharged from the manway (Fig 10). 

The measured pressure reached a peak of about 1.06 bar at about 2000 s when the 

steam relief at the manway approximately balanced the steam generation in the 

core. In the calculation the initial pressure fall was greater and the subsequent 

pressure rise was greater, but was delayed compared to the test. Figure 11 shows 

the pressure in the loop I cold leg. The entrainment of a two-phase mixture from 

the vessel into the surge line and pressuriser led to a higher pressure in the cold leg 

than at the top of the pressuriser. The pressure differentials across the pressuriser 

and surge line are shown in Fig 12 and 13 respectively. After about 2500 s, 

RELAP5/MOD3.2 is calculating a pressure differential in the pressuriser greater 

than measured by about 0.1 bar. Since the velocities and thus dynamic pressure 

across the pressuriser are small, this suggests that the calculation is entraining too 

much liquid into the pressuriser. This is believed to be due to the interfacial drag 

model in RELAP5/MOD3.2 which overpredicts the drag between the liquid and 

vapour phases. This causes an overprediction of the level swell within the core and

WP5917 3
C5166n/TNOO1 

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upper plenum and thus in the hot legs resulting in too much liquid being entrained 

with the steam into the surge line and pressuriser. The differential pressure across 

the surge line was reasonably well calculated. There was an initial peak in 

differential pressure (reasonably well calculated), presumably due to the initial 

surge of low quality fluid driven through the surge line by the initial level swell in the vessel. Because the cross-sectional area of the pressuriser is about 24 times 

that of the surge line, this increase in differential pressure is not observed in the pressuriser as the low quality fluid enters the pressuriser. In both the pressuriser and surge line, a peak in the differential pressure occurred in the test at about 

2000 s, whereas the peak was calculated to occur at about 2750 s. The effect of these differential pressure peaks is reflected in the cold leg pressure which peaked at the same time (Fig 11). The pressure differential across the pressuriser is, because of the relatively low fluid velocities in the pressuriser, effectively a 

measure of the mass of liquid in the pressuriser. This mass initially increased as the pressuriser filled up with a two-phase mixture, and then fell to a stable value 

following the discharge of liquid out of the manway. Liquid discharge is claimed 

to occur in the test at either 2400 s to 2600 s (page 17 of Ref 2) or 2900 s to 

3000 s (page 20 of Ref 2). Note that the experimental data shown in Fig 10 does 

not record liquid discharge. It can be deduced from the integrated manway discharge shown in Fig 4.14 of Ref 2 (reproduced as Fig 14), that liquid discharge through the manway occurred between about 1900 s and 2300 s. This is consistent with the fall in differential pressures in the surge line (Fig 13) and pressuriser (Fig 12) and the fall in cold leg pressure, which occurred between about 2000 s and 3000 s (Fig 11). Figure 19 also confirms increased discharge from the manway during the period from 1900 s to 2300 s. All of these pressures and differential 

pressures are reduced to steady values by 3000 s, reflecting the steady static heads 

in the surge line and pressuriser, since the liquid masses in the two regions remain 

constant, with steam discharge out of the manway and steam inflow from the loop I hot leg. Liquid discharge was calculated to occur between about 2200 s 

and 3100 s (Fig 10). The total quantity of liquid discharged through the manway 

was calculated to be considerably more than occurred in the test (Fig 14). In the 

calculation, the peaks in pressures and differential pressures were delayed compared to the test due to condensation effects described below and due to liquid discharge from the manway. 

The system pressure is affected by steam discharge from the manway and by condensation of steam on the slightly subcooled water in the downcomer and in the cold legs after the cold legs have drained sufficiently to form a mixture level. The 

calculated pressures in the loop I cold leg (Fig 11) and in the pressuriser (Fig 9) were initially below those in the test due to overprediction of condensation, since 

the steam discharge from the manway is well predicted (Fig 10 and 14). The steam 

condensing in the downcomer and cold legs was drawn through the guide tube and 

upper head bypass. Figure 15 shows the flowrate, whilst Fig 16 shows the 

pressure drop across the guide tube. The calculation exhibits considerable 

two-phase flow, whereas only steam flow occurred in the test. Note that the single BETHSY guide tube extends from the upper head down to an elevation 

approximately halfway between the upper core plate and the bottom of the hot leg. It is open at the bottom and has three slots near the bottom. In contrast, the 

4 

WP5917
NNC C5166/TN/001 NNCIssue 01 

Sizewell B guide tubes extend down to the upper core plate and have slots at 

approximately the same elevation as the slots in the BETHSY guide tube. The fact 

that the Sizewell B guide tubes extend down to the upper core plate and thus draw 

flow directly from the core may have a significant effect on the flow behaviour in 

the upper plenum and bypass. 

When the condensation ceased (1900 s in the test and 2600 s in the calculation 

(Fig 16 and 17)), the cold leg pressure continued to rise. However, in both test 

and calculation, shortly after condensation ceased the liquid discharge from the 

manway ceased and the cold leg pressure fell (Fig 11) due to the greater steam 

relief The calculated cold leg pressure remained above that of the test due to the 

greater liquid hold-up in the pressuriser (Fig 12). 

The void fractions in the cold and hot legs of loop 1 are shown in Fig 17 and 18 

respectively. The cold leg started to void at about 100 s in both test and 

calculation and was empty by 2000 s in the test and 2600 s in the calculation. Note 

that it is believed that the maximum void fraction of 0.87 observed in the data 

corresponds to complete voidage and is the result of a calibration error. 

The total mass inventory in the primary circuit is shown in Fig 19. The inventory 

reflects the manway discharge (Figs 10 and 14), with the higher discharge in the 

calculation during the first 6000 s (Fig 10) resulting in a lower inventory. The 

liquid discharge from the manway, calculated to occur between 2200 s and 3100 s, 

was considerably higher than measured and resulted in the significant 

underprediction of mass inventory until after injection refilled the system. The 

underprediction of mass inventory was contributed to by the mass loss error 

inherent in RELAP5IMOD3.2 calculations. The maximum mass error (a loss) was 

only about 2% at the time of minimum inventory (Fig 22). 

After the hot leg had emptied, the vessel level fell due to the continuing boil-off 

and the top of the core started to uncover at about 5000 s in the test and about 

5500 s in the calculation. This can be seen in Fig 20, which shows the core heat-up 

of the hottest rod. It is evident that the heat-up rate is greater in the calculation 

than in the test. The uncovering of the top of the core reduced the rate of steam 

production and hence reduced the discharge from the manway (Fig 10). The 

primary system pressure started to fall (Fig 9 and 11). The fall in pressuriser 

pressure was much more severe in the calculation than in the test, this reflecting the 

fact that at the elevation of the pressuriser pressure tap (cell 5308 in the RELAP 

deck), the mixture level in the pressuriser fell through cell 5308 and thus reduced 

the static pressure at that elevation. This did not occur in the test. This supports 

the belief that RELAP5/MOD3.2 overcalculates the interfacial drag and this caused 

excessive liquid to be drawn into the pressuriser earlier in the calculation. The 

pressure differential across the pressuriser did not change significantly in the test or 

calculation during this period (Fig 12), suggesting that the liquid content within the 

pressuriser was not affected by the falling steam flow and that the pressure 

differential was caused by the liquid content in the pressuriser, this dominating the 

pressure differential due to the steam flow. However, the pressure differential 

across the surge line fell in both test and calculation, this being due to the reduced 

5 

WP5917
C5166/TN/001 

Issue 01 NNC 

frictional pressure loss due to the reduced steam flow, there being little liquid held in the surge line. Since the fall in surge line differential pressure results from the fall in steam generation in the core due to the uncovery, and since the fall in differential pressure in the calculation is greater than that in the test, this suggests a 

more severe uncovery in the calculation than occurred in the test. 

When the maximum rod temperature reached 250 TC, the gravity injection was initiated. The injected flows began at 6045 s in the test and at about 6090 s in the calculation, as shown in Fig 21. In the test the gravity injection flow was slightly greater than the manway flow (Fig 10) and this caused a slight increase in the primary system mass inventory (Fig 19). Because of the higher cold leg pressure in the calculation (Fig 11), the injection flow was less than the manway flow (Fig 21 compared to Fig 10) and so the inventory continued to fall (Fig 19). The injection flow caused an increase of bypass steam flow (Fig 15) due to increased 

condensation in the downcomer and loop I cold leg. Because of the lower injection flow in the calculation, the bypass flow was much lower than in the test until pumped injection began. The condensation contributed to the reduction in the 

pressure in the cold leg (Fig 11) and the pressuriser (Fig 9) and thus reduced the 

manway flow (Fig 10). The effect of the condensation can be seen in the loop 1 cold leg with a reduction of the void fraction in both the test and the calculation (Fig 17). However the effect of the injection on the core was such as to increase the rate of heat-up because the subcooling of the injection flow reduced the boiling in the covered part of the core and therefore the steam cooling of the uncovered 

part of the core was reduced. Because of the faster heat-up rate in the calculation, the maximum core temperature reached 400'C at 6450 s and pumped injection was 

initiated (Fig 21). The pumped injection started at 7100 s in the test. 

In both test and calculation the initial injection flow was much greater than the 

manway flow and refilling of the primary system occurred. The injection flow was subsequently increased in a step-wise manner as shown in Fig 21. The peak core 

temperatures occurred at 7480 s in the test and 6940 s in the calculation and complete core quench occurred at 8040 s and 7940 s respectively. The increase in 

steam generation during the rapid core quench caused an increase in the system pressure in both test and calculation (Fig 9 and 11), the increase in pressure in the calculation being much more than in the test. In the calculation the increased 

steam flow into the pressuriser increased the surge line differential pressure (Fig 13) and entrained liquid out of the manway between 7000 s and 8000 s (Fig 10). In the test there was no liquid discharge from the manway during the 

core quench period (Fig 14). This provides further confirmation of the effect of the over-calculation of interfacial drag in RELAP5IMOD3.2 and its effect on entraining too much liquid with the steam into the upper plenum, hot legs and 

pressuriser. 

The relatively higher injection flowrates after 8000 s resulted in more significant condensation on the pumped injection water in the loop 1 cold leg (Fig, 1-7) This resulted in a fall in pressure in the system (Fig 9 and 11). 

6

WP5917
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By 9000 s in the calculation, the vessel had filled up to the hot legs and liquid 

began to be entrained into the loop 1 hot leg (Fig 18) and the surge line and then 

into the pressuriser, increasing the differential pressures across the surge line and 

pressuriser (Fig 13 and 12) and thus the cold leg pressure (Fig 11). Flow into the 

hot leg did not occur in the test until about 9500 s (Fig 18) and into the pressuriser 

until after 10000 s (Fig 12). The calculated differential pressure across the 

pressuriser (a measure of the liquid mass in the pressuriser) remained above that 

measured (Fig 12) and resulted in considerable liquid discharge through the 

manway after 10400 s in the calculation and after 11000 s in the test (Fig 10 

and 14). The loop 1 cold leg became nearly-filled in both the test and the 

calculation at about 10000 s and remained full (Fig 17). 

The rising level in the upper plenum resulted in the calculation of two-phase flow 

through the upper head bypass after 10500 s (Fig 15), in contrast to the test which 

only exhibited vapour flow. In the test the vapour flow gradually fell as the cold 

leg filled until the condensation was only occurring at the top of the downcomer 

and the flow became negligible. In the calculation, the two-phase flow continued 

until the end of the calculation (Fig 15). 

6 Summary of calculation 

The calculation exhibited the following compared to the test: 

(i) Excessive two-phase flow into hot legs, surge line, pressuriser and out of 

the manway. This is believed to be the result of the interfacial drag model 

in RELAP5/MOD3.2. 

(ii) Too much condensation in the downcomer and cold legs. The effect of 

over-calculating the condensation rate on a fault such as this is complex. 

For example it reduces pressure which increases the condensation rate 

further by increasing injection flow and drawing more fluid through the 

bypass (a positive feedback process). The fall in pressure may also increase 

flashing and level swell in the core. From the results of the calculation it 

can be concluded that the conservatively low mass inventory resulting from 

the interfacial drag model more than outweighs any benefits resulting from 

the effects of over-calculating condensation. 

(iii) A more rapid core heat-up during the core uncovery. It is believed that this 

is caused by the calculation of too deep a core uncovery as a result of 

underpredicting the primary system mass inventory. The deeper uncovery 

results in reduced steam generation in the covered part of the core and 

hence reduced steam cooling of the uncovered part of the core. 

(iv) A delay in the time at which core uncovery begins. This is believed to be 

caused by the interfacial drag model resulting in excessive level swell. 

7 

WP5917
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There was also a mass loss from the system during the calculation. This amounted 

to approximately 18 kg by the end of the calculation. At the time of minimum 

mass in the system the mass loss was only about 2%. 

7 Conclusions 

A RELAP5/MOD3.2 calculation of BETHSY Test 6.9a has been performed to provide validation evidence for the application of RELAP5/MOD3.2 to faults in 

Modes 5 and 6 (including the use of nozzle dams). 

The results show that all the major phenomena of the test were calculated. The major concerns with regards to RELAP5/MOD3.2 resulting from this validation 

relate to the over-prediction of interfacial drag between the liquid and vapour phases and the over-prediction of condensation. The over-prediction of interfacial 

drag can have effects on level prediction, break and other flows and condensation. 

Care will have to be taken when applying RELAP5/MOD3.2 to reactor 

calculations to ensure that uncertainties due to the errors introduced by the interfacial drag model are accounted for in a conservative fashion. For example, the delay in core uncovery shown by the calculation, resulted from the interfacial drag model causing an over-prediction of level swell. This calculational effect may, under other circumstances, result in the calculation of no core uncovery whereas a 

shallow core uncovery could in practice occur. 

The calculation also exhibited the mass loss error inherent in RELAP5IMOD3.2 

calculations; although the maximum mass loss was only about 2% and did not 

seriously affect the calculation. 

8 References 

Ref Title 

1 NUREG/CR-5535. RELAP5/MOD3 Code Manual. The RELAP5 Code 

Development Team. June 1995. 

2 STR/LES/92-1 11. BETHSY Test 6.9a. Loss of Residual Heat Removal 

System during Mid-loop Operation. Pressuriser Manway Open. Test 

report. G Lavialle. December 1992. 

3 SETh/LES/90-97. BETHSY General Description. April 1990. 

9 List of calculations 

Calc note number Issue Status 

C5166/CAL/371 01 P 

8 

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10 List of figures 

Fig Title 

1 Schematic diagram of rig circuits 

2 Primary cooling system - top view 

3 Primary cooling system - elevations 

4 Pressure vessel - general view 

5 RELAP5/MOD3.2 BETHSY overall noding scheme 

6 RELAP5/MOD3.2 BETHSY vessel noding scheme 

7 RELAP5IMOD3.2 BETHSY loop 1 noding scheme 

8 RELAP5/MOD3.2 BETHSY loops 2 and 3 noding scheme 

9 Pressuriser pressure 

10 Manway flowrate 

11 Cold leg 1 pressure 

12 AP across the pressuriser 

13 AP across the surge line 

14 Integrated manway discharge 

15 Upper head bypass flowrate 

16 AP across the guide tube 

17 Cold leg 1 void fraction 

18 Hot leg 1 void fraction 

19 Primary system mass inventory 

20 Hottest rod maximum temperature 

21 Gravity and pumped injection flowrate 

22 RELAP5/MOD3.2 mass error 

9

WP5917
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Figure I - Schematic diagram of rig circuits

C5166/TN/001 

Issue 01

WP5917

oil

Page Fl
ump Broken loop "CL break I 

surge line location 

, SGI ACC : ccumulator 

SI nozzle cSI : safety injection , 

nozzle 

location NS : normal spray 0 

nozzle 

spool pieces TA 

pressure vessel 

Sl'p ISIS spool I pi..ecest 

%%,,,./ SG2 

ACC • 

SI o Intact loops_ N NS
C5166/TN/001 

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Figure 3 - Primary cooling system - elevations 

Steam generator 

Pressurizer 

20655 

20371 -, 

relief nozzle 

- 1, 

Pressure vessel 24 

87 -7 

54 3Pump 

oldeg hot legaxs 

leg , -- 3656 

intermediate I 

- 2164 

Pape F3

8335 

6870 

748

2595 (axis) 

leg

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NNC C5166/TN/001 

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Figure 4 - Pressure vessel - general view

cold le 

nozzle

BB View

thimbles

,upper core 

support plate

hot leg nozzle 

,upper core and 

tie plates 

"428 full length HR 

cosine axial power 

17 x 17 design 

29 guides thimbles 

uniform

core by-pass

WP5917

I

Page R4
time dependent -LI -ýý Junction SAFETY INJECFON SYSTMS

*uI

C

0ný 

ON

o0 

W, 

M 

0=
NNC C5166/TN/O01 

Issue 01

Figure 6 - RELAP5/MOD3.2 BETHSY vessel noding scheme 

/•'•upper head 

18801 t 1802 

-29 -guide tube 

bypass o! I ' odfice plate 

2400 • ' ' 1 / - - tube 

ur hadto 2102I 806 17 -upper plen-r 

downcomer 8050 

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NRC FORM 335 U.S. NUCLEAR REGULATORY COMMISSION 1. REPORT NUMBER 

(2-89) (Assigned by NRC, Add Vol., Supp., Rev., NRCM 1102. and Addendum Numbers, if any.) 

3201• 3202 BIBLIOGRAPHIC DATA SHEET 

(See instructions on the reverse) 

2. TITLE AND SUBTITLE NUREG/IA-0188 

RELAP5/MOD3 Validation Using BETHSY Test 6.9a 3. DATE REPORT PUBLISHED 

MONTH YEAR 

August 2000 

4. FIN OR GRANT NUMBER 

5. AUTHOR(S) 6. TYPE OF REPORT 

S. Bouabdallah Technical 

7. PERIOD COVERED (Inclusive Dates) 

8. PERFORMING ORGANIZATION -NAME AND ADDRESS (If NRC, provide Division, Office or Region, U.S. Nuclear Regulatory Commission, and mailing address; if contractor, 

provide name and mailing address.) 

NNV LTD Booths Hall 

Chelford Road 

Knutsford, Cheshire GB-WA16 8QZ 

UNITED KINGDOM

9. SPONSORING ORGANIZATION - NAME AND ADDRESS (If NRC, type "Same as above", if contractor, provide NRC Division, Office or Region, U.S. Nuclear Regulatory Commission, 

and mailing address.)

Division of Systems Analysis and Regulatory Effectiveness. 

Office of Nuclear Regulatory Research 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001

10. SUPPLEMENTARY NOTES

11. ABSTRACT (200 words or less) 

This report provides the results of a RELAP5/MOD3.2 calculation of Test 6.9a which was carried out on the BETHSY facility. 

The purpose of the calculation is to provide validation evidence for the use of RELAP5/MOD3.2 for application to faults at 

Sizewell B which can occur when the plant is in Modes 5 and 6 (and including the use of nozzle dams).

12. KEY WORDS/DESCRIPTORS (List words or phrases that will assist researchers in locating the report.) 13. AVAILABILITY STATEMENT 

RELAP5/MOD3 unlimited 

BETHSY Test 6.9a 14. SECURITY CLASSIFICATION 

(This Page) 

unclassified 

(This Report) 

unclassified 

15. NUMBER OF PAGES 

16. PRICE

NRC FORM 335 (2-89)
Federal Recycling Program
NUREG/IA- 0188 RELAP5/MOD3.2 VALIDATION USING BETHSY TEST 6.9A AUGUST 2000

UNITED STATES 

NUCLEAR REGULATORY COMMISSION 

WASHINGTON, D.C. 20555-0001

years