ML19350A511

Nonproprietary Version of Hydraulic Flow Test of Model C Prototype Fuel Assembly.

ML19350A511
Person / Time
Site:	Millstone
Issue date:	03/31/1981
From:	WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:
Shared Package
ML19260G747	List: ML19350A508 ML19350A511
References
TAC-43380, TAC-47355, TAC-47389, TAC-47473, NUDOCS 8103160364
Download: ML19350A511 (16)

Text

,

Docket No. 50-336 Attachment 2 Millstone Nuclear Power Station, Unit No. 2 Hydraulic Flow Test of the Model C Prototype Fuel Assembly Non-Proprietary March, 1981 8103160364

SECTION 1 INTRODUCTION As a part of the verification tests of the Westinghouse Model C fuel assembly design, full-scale hydraulic flon tests were performed in the Fuel Assembly Test System (F/sTS) facility. This facility has *.he capability to test two full size fuel assemblies side by side. The fuel assembiv and FATS facility descriptions are given in section 2.

The hydraulic test included two full scale prototypes of the Model C fuel assembly. Test con-ditions simulated reactor flow conditions. Information was obtained on lift forces, lift-off margin, fuel rod vibration, fuel assembly vibration, grid AP and assembly AP.

The tests to determine the effect on fuel assembiy lif t . forces, fuel rod vibration and fuel assembly and bottom nozzle AP were run for three fuel rod locations. These were performed in the following series:

m Series I - Fuel rods at 0.80 0.05 inches above the bottom nozzle

- a Series J - Fuel rods at 0.2020.05 inches above the bottom nozzle a Series K - Fuct rods resting on the bottom nozzle Sections 2 and 3 describe the test setup. The results of the pressure drop, assembly hydraulic lift force and the fuel rod fretting wear data are given in section 4, and the test plan description is presented in table 41.

G l-1

SECTION 2 GENERAL DESCRIPTION 2-1 FUEL ASSEMBLY The Model C fuel assembly is designed for fabrication of reloat assemblies to fit into the Millstone 2 Power Plant supplied by Combustion Engineering. The Model C fuel assembly has nine grids, as shown in figure 2-1. The assembly has 176 fuel rods, and 5 thimbles. For the hydraulic test reported here two Model C prototype assemblies were used; the instrumented and the non instrumerMed. The instrumented assembly contained 26 zirca!oy-4 clad fuel rods filled with depleted UO2 pellets,139 rods filled with lead, and 11 hollow zircaloy-4 clad rods to carry strain gasa leads. The non-instrumented assembly contained 176 zircaloy- clad fuel rods filled with lead pellets. Its fuel rods, however, were filled with lead bars approximateif 12 inches long and 0.362 inches O.D. The density for the lead simulated the density for 95 percent dense UO2-The non instrumented Model C fuel assembly contained no instrumentation and was used only for its hydraulic characteristics.

Apart from the above noted modifications due to special instrumentation, the assemblics were accurate representations of an assembly designed for reactor use. Figure 21 shows the test fuel assembly.

Reference parameters for the Westinghouse Model C fuel assembly are given in table 2-1.

2 2. FUEL ASSEMBLY TEST SYSTEM (FATS) FACILITY 2-3. Facility Description Figure 2 2 shows a schematic of the fuel assembly test system. Water was supplied from the storage tank, pumped into the test vessel bottom and out the vessel top, and passed through a heat exchanger to maintain the desired fluid test temperature. Flow was controlled by a pneumatically operated proportional control valve (No.1) and continuously recirculated back

- through the pumps via the line bypass valve (No. 2). The loop flow rate was measured with a 10 inch Varco Venturi located on the outlet side of the test vessel. The two identical pump are capable of delivering up to 5500 gpm w.icn operating together. There are two heat 2-1

4 105-150* F,

- exchanger units, a water-water (W/W) unit to control system temperature between and an air water (A/W) unit to control temperatures between 150-300* F..Tt.4 filter removes particulate matter from the test water as may be required. During normal test operations the filter isolation valve (No. 3) is closed.

2-4. FATS Test Vessel and Test Assemblies Figurt 2 3 shows the placement of the test assemblies into the baffle enclosure and test vessel. Water enters the bottom of the rectangular baffle enclosure, flows up through the lower core plate simulator and test assemblies, and exits through the upper baffle enclosure and test vessel outlet pipe.

e k

4 O

9 2-2

, _ _ s.- , , 3 -.6

, z.

p .;; : . . ..~ q

.w,a. ' ,

!:: y p # i f

-  ! O,il/I 'I I l

w.u: ,

i I 1

i u i i i 1

\ l  ?

g-) -<--,ri .

~ N

=k=lnrx;o I

.a S,E:11mTf}'1: ,

i 11 :

mme p:a1 Emi

'i i

,.w n!Ilhits;aa.-

TJp2 3 G,~{ l

. /ll ,

g ,I!

,.7gsu- u.m.;

ij i ' -<

.. a 2w/* maid *m!

Lj_ L CDdliU D;

. 'mqqgi!

l

,rillillBN 2

/q . 3 i: .

k,  !,

I

' '+

- i i "4 -

yeaIE.y'  : .

MMUdi t? u f

@ ((,

w

~: O ,j '

L N 'y77gT g .71:@.*f ,

,Li ,t;,;dra w .

i5 l .

. ijl TSilld(f!' ,i;

!.; i- -

..fillilII52:  !'

. n  : i I p',i s ij! . trim U6CC!_ .,

2. :3 g '

. _ .,i 1\ , ; $ 3.[$' h -  !

"7'I[

41 4 1A

'Glt$,'@:v _.),

g *RW ~ '-

2 a

?

f:=E i

! I i e [

l s

.l .J t.

l

!iOM

! P00R ORIGINM l

l t

i TABLE 2-1 WESTINGHOUSE MODEL C FUEL ASSEMBLY DESIGN PARAMETERS Number of fuel rods / assembly 176 Nur iber of guide thimbles / assembly 4 Fuel rod pitch, in. 0.580 Fuel tube material Zircaloy 4 Fuel rod clad OD, in. 0.3805 Fuel rod clad thickness, in. 0.026 Guide thimble material Zircaloy-4

- Guide thimble OD, in. 1.111 Guide thimble wall thick.a.ess, in. 0.038 Structural materia' grids inconel Grid inner strap thickness, rmi (}*

- Grid outer strop thickness, mil []

Grid support for fuel rods 6 point, 2 springs and 4 dimples Grid height, in.

Bottom nozzle Not standard Top nozzle Not standard 2-4

~

n

I 14,201 1 STORAGE TANK 1500 GAL.

THERHAL EXPA:tSION  :

BELLDfS

, g[ . Y gg y

_)

( 2 10" VALVE e PtMP OPEN/CLOSE b Mo. 2 J L 3

q r PEN C OSE

- 8" VALVE b OPEN/CLOSE TC _

ee --

, pgp g0 3 m u a NO. i 5

we ,.

g.

x 3

W/ WHEAT EXCHANGER $

e -

10" PROP 0RT10 MAL TC heph CONTROL VALVE

__.{.

VENTURI w . 3 >

ISOLATION ELLOWS e PRESSURE

. GAGE PORTS TEST l

VESSEL Figure 2-2. Schematic of Fuel Assembly Test System (FATS) 2-5

l 14.038-1 f X r i

\  :

it i

- OuTtt1 oio  !

2' [Ft0w /

" ^ ^

a - . . 3_ u a j;- : SECTION A-A_

- UPPER CORE PLATE SIMULATOR

_ _A ,, _

iiFm!T wm

+ --NNG PORTS gill:li 'jijailj

-- ijilt .iML

,lllilill! ilPh!il, ,

FUEL ASSEMBLY Jllili!Il '!!!!:lif, I6'O liliiiift):lh!f

-- DAFFLE (ENCLOSES TWO FUEL

,l,l.;. j!!!,I!qO!!,"

ASSEM8 LIES) illh!!! i!6li!i

--/ llllil.i!j'llii9i 4

k-shu%

, c!.d

__% yfff" __

LOWER CORE PLATE SIMULATOR FLW u ,

p 4 n <

JL j

' JL lil 11IlliIliIllI 3 9

!!Ri!!!!!!!!!$t

. ,' i II I I Figure 2-3. FATS Test Vessel and Baffled Fuel Assemblies ,

26

- SECTION 3 PRE-TEST PREPARATION AND INSTRUMENTATION 3.1 PRESSURE DROP MEASUREMENTS Static pressure taps were used to measure the fuel assembly pres ure drops. These were located on the baffle enclosure within the test vessel as shown on figure 31. Each pressure measurement tap had a redundant tap located at the same elevation on a perpendicular baffle wall (90* apart). A data acquisition system was used to collect and condition the data, which consisted of approximately 100 AP readings for ec;h set of flow and temperature conditions.

Using the pressure ap locations iii figure 3-1, AP transducers were used to measure the overall fuel assembly APs. The AP transducers had an. accuracy of 0.5% and a mir inum frequency response of 50 Hz.

3.2 FUEL ASSEMBLY LIFT FORCE MEASUREMENTS Fuel assernbly lift forces were measured by recording the off-loading of two load cells mounted through the lower core plate. As flow was increased, the data provided the lift forces as a function of flow, i

Load cells were calibrated in the lower core plate before the baffle was assembled and during the loading of the fuel assemblies into the barrel at room temperature. Calibrations were then l

I performed at all test temperatures. The load cells were capable of accuracy within the test parameter ranges given in section 4.1.

i l

31

UPPER CORE PLATE (UCP)

[ g l l UPPER PRESSURE TAP ( NPT B)

O f Ir- G 1.0" BELOW UCP NMV NO. 9 TOP NOZZLE NON MIXING VANE GRID NMV NO. 8 NMV NO. 7 NMV NO. 6 NMV NO. 5 NMV NO. 4 NMV NO. 3 NMV NG. 2 BOTTOM NOZZLE NMV NO.1 I I LOWER PRESSURE TAP ( NPT 2)

O F i y 1.0" ABOVE LCP I M M LOWER CORE PLATE (LCP)

- Figure 3-1. Location of Fuel Assembly Pressure Drop M.?asurement ,

32

SECTION 4 FLOW TESTING PLAN AND RESULTS 4.1 TEST OPERATIONS Test operations for Series I, J and K were maintained at the co ditions described in table 4-1.

This table presents the data on temperature, pressure and the flow rates for the tests per-formed on pressure drop, assembly lift force, fuel rod vibration, and flow sweeps and lif t forces.

The load cells during the test were capable of maintaining the following accuracy:

Parameter Ranges Accuracy (%)

Loop temperature 50-300 F . 20.25 Loop pressure 0-220 psig 2.0 Loop flow rate 1000-6000 9pm 0.5

- Nominal fuel rod 1926 gpm 20.5 bundle flow All AP measurements Varies-psid 0.5

~

Assembly lift 0-2000 lbs 0.5 4.2 FUEL ASSEMBL* LIFT FORCES Lift force data were obtained during Series I, J and K with the test conditions given in table 4-1. Results given in figure 4-1 show lift forces calculated from measured assembly AP and measured from load cells. The load cell measurements were in good agreement with the lif t forces calculated from the measured assembly pressure drops. At a given flow rate the measured lif t forces are slig!. 'ly greater (about 10%) at 100 F coolant tempera,ture compared to a 300 F coolent temperatore.

4.3 PRESSURE DROP Pressure drno data were obtained from the static pressure taps shown in figure 3-1. For a

- given test condition, once the desired loop temperature was achieved, the test procedure was to stop the flow, zero the pressure transducers, restart the flow, and take the data when the flow stabilized. The data consisted of apprormately 100 AP readings for each set of flow and temperature conditions. .

4-1

The fuel assembly static pressure drop measurements can be obtained from figure 4-1, to provide a direct cc:*oarison of the hydraulic characteristics between the three fuel rod locations (cP%Lif t Force /(Fuel Assembly Pitch)2),

44. FUEL ROD CLAD WEAR The rormal operating support condition of a fuel rod in a grid consists of a six contact points, a spr ng, and two backup dimples in each of the two perpendicular planes of each cell. The wear producing motion between fuel rod and grid occurs at the side dimples when the maximum vibration amplitude is greater than the slippage threshold amplitude.

Once slippage initiates at the side dimples, the natural frec,uency, mode shapes, and system damping of the rod will change The modal damping due to the rubbing between the fuel damping of the rod will change. The modal damping due to the rubbing between the fuel rod and dimples becomes amplitude dependent, and the natural frequencies decrease due to l reduced effective tangential dimple stiffness. In the fuel rod wear analysis, it is assumed that the dynamic characteristics of the system do not change due to slippage.

' Using the 95 percent confidence, peak to-peak amplitudes measured in the f- ATS hydraulic tests, at 110-percent mechanical design flow, the wear volume is calculated as shown in

- figure 4 2.

Based on the 95-percent confidence, peak to-peak amplitudes measured in the FATS hydraulic tests, the predicted wear depth value at the end of fuel life (3 cycles) would be less than 0.3 mils.

For Westinghouse designed fuel rods, the design criterion for maximum allowable wear depth is equal to or less than 10 percent of the fuel rod clad thickness. In this case,2.6 mils maxi-mum wear depth is acceptable. Thus, the predicted wear depth at the end of fuel rod life (3 cycles) was acceptable.

i 0

4-2 V g w- n-m.

TABLE 4-1

~

MODEL C TESTS FOR SERIES 1. J AND K Temperature Pressure Flow per Number of Tests information Sought Data Recorded (* F) (psig) Assy (gpm)

~

+ k,c g,e _ esp _ ._.+ b,c Pressure dr aterminations AP (psi) '

Same as above Same Same as above Same

$ Assembly lift force Lift force (Ibs) i Same as above Same Same as above Same Fuel rod vibrations ye Same as above Same Same as above Same Flow sweeps and lift forces Lift force (Ibs)

I

\

l4.201-32 )

l l

1 I +bc

. 80 -  ;

j 1

60 -

40 -

20 -

^

w J

e 5

M 10 e -

,_ 8

. s>

6 4

2 -

, ~l l I I I ll l l l l l lil 2 4 6 8 10 20 40 60 80 100 2

ASSEMBLYFLOW(X10 GPM)

Figure 41. Fuel Assembly Lift Force Versuu Assembly Flow at 300 F .

4A

1G312-1 Fuel Rod Vibration Amplitude Determined in the FATS Testing u

Slippage Threshold Force -

t Instantaneous Grid Spring Force

(

v l Effective Sliding Distance Between Fuel Rod and Grid Support t Wear Coefficient and Friction Coefficient m Between Fuel Rod and Grid Support n

Calculate Fuel Rod Wear Volume (Archard Eq.)

l i

Wear Scar ,

Geometry Calculated Fuel Rod Wear Depth

~

l Figure 4-2. Flow Chart of Vibratory Wear Calculation l

' 4-5 er n ,---- - - - ,

7 ---,- , ,, - , - ---

1-l l

4 l

SECTON 5 l TEST CONCLUSONS i,

l l Fuel assembly lift forces determined directly from load cell measurements were consistent with lift forces calculated from pressure drop measurements.

The pressure drop tests demonstrated hydraulic compatibility betweca Model C and C.E.

- Millstone 2 fuel.

f' The predicted fuel red clad fretting wear at the end of fuel rod life (3 cycles) and based on the worst flowinduced RMS vibration amplitudes determined in FATS testing was found acceptable.

S h^

4 e

W l

l 1

5-1

.__-- - _ -ma,..m-__