ML20128H491

Fuel Assembly Drop

ML20128H491
Person / Time
Site:	Arkansas Nuclear
Issue date:	05/23/1996
From:	Costa D, Shepard J FRAMATOME
To:
Shared Package
ML20128H476	List: 1CAN099604, Provides Addl Info Re Open Containment Personnel Airlock During Core Alterations Per 950519,960610 & 0910 TS Change Requests ML20128H491
References
32-1244997, 32-1244997-00, NUDOCS 9610090363
Download: ML20128H491 (27)

Text

-[

PROPRIETARY 20697P-3 (12/95)

R'A M ATo M E CALCULATION

SUMMARY

SHEET (CSS)

TSCHM OLOO888 DOCUMENT IDENTIFIER 32 1244997-00 TITLE FUEL ASSEMBLY DROP PREPARED BY:

REVIEWED BY:

NAME D.E. COSTA H.T.

A SON NAME J.F. SHEPARD fgg[,

slGNATURE SIGNATURE DATE Ff,13 g TITLE PRINCIPAL ENGRS Y/U DATE g/fyg,_ TITLE SUPERVISO Y ENGR

[,

COST CENTER 41020 REF. PAGE(S) 7&8 TM STATEMENT: REVIEWER INDEPENDENCE

{This document including the information contained heroin and any associt.ted drawings,is the property t of Framatome Technologies. It contains confidential information and may not be reproduced or i

, copied in whole or in part nor may it be furnished to othere without the expressed written permission of Framatome Technologies nor may any use be made of it that is or may be injurious to Framatome l Technologies. This document and any associated drawings and any copies that may have been made lmust be returned upon request.

PURPOSE AND

SUMMARY

OF RESULTS:

PURPOSE:

The purpose of this analysis is to determine the number of fuel rods that will fail due to dropping a fuel assembly.

The assembly is assumed to fall vertically until impacting an object below and then assumed to fall over (rotate) where it impacts another object.

The number of failed rods will be used by the utility for determination of the amount of radiation that could be potentially released to the atmosphere by the broken rods.

RESULTS:

A summary of results is contained in Section 2.0. Based on the results of this anatysis, it is concluded that 6 rows of fuel rods (with guide tubes) or 82 fuel rods will fail as a result of the dropped fuel assembly.

9610090363 960913 PDR ADOCk 05000313 P

PDR THE FOLLOWING COMPUTER CODES HAVE BEEN USED IN THIS DOCUMENT:

THIS DOCUMENT CONTAINS ASSUMPT1oNS THAT MUST BE VERIFIED CODENERSION/REV CODENERSION/REV PRIOR TO USE ON SAFETY RELATED WORK O

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32-1244337 00 i

RECORD OF REVISIONS REVISION OESCRIPTION mg I

00 CRIGINAL RELEASE 5/96 l

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32-1244997-00 TABLE OF CONTENTS SECTION DESCRIPTION PAftg RECCRD OF REVISIONS 2

TABLE OF CCNTENTS 3

1.O INTRODUCTICN 4

2.0 SLMd.ARY OF RESULTS 4

3.0 CONCLUSION

5 4.0 LIST OF ASSUMPTIONS 5

5.0 REFERENCES

7 6.O GEOMETRY 9

7.O MATERIAL PROPERTIES 10 8.0 VERTICAL IMPACT CASE 11 8.1 MAXIMUM DROP HEIGHT 11 8.2 DISPLACED VOLUME / BUOYANCY FORCE 13 8,3 DRAG COEFFICIENT, VERTICAL DROP 14 8.4 IMPACT VELOCITY 15 8.5 IMPACT STRESS 19 8.6 ALLOWABLE IMPACT STRESS 19 8.7 NUMBER OF BROKEN FUEL RODS 19 8.8 FUEL ROD BUCKLING 20 9.O ROTATIONAL IMPACT CASE 21 9.1 FINITE ELEMENT MODEL GEOMETRY 21 9.2 FINITE ELEMENT MODEL MATERIAL PROPERTIES 22 9.3 FINITE ELEMENT MODEL BOUNDARY CONDITIONS 23 9.4 IMPACT VELOCITY CALCULATIONS 23 9.5 RESULTS OF ROTATIONAL IMPACT CASE 24 9.6 RESULTS OF INCREASED IMPACT AREA 24 10.0 ANSYS PROGRAM VERIFICATION 26 APPENDIX A MICROFICHE 27 I I!f6 PREPARED BY:

D.

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COSTA

((C DATE:

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3 REVIEWED BY: J.

F.

SHEPARD Y$

DATE:

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32 1244337 00 l

1.O INTPODUC"ij.Qll:

Framatome Technologies Inc. has been contracted to provide an assessment of fuel assembly (7A) drops. Tele purpose of the assessment is to determias how many fuel rods will break (rupture) as a result of dropping a fuel assemtly during fuel j

handling operatiens. The number of broken rods will be used by the utilities to j

deternine the potential radiation release caused by the escaping gases contained j

within the rods.

The assessment will consider drops of the fuel assembly in the vertical position impacting on the reactor vessel (RV) lower grid, RV pool floor, spent storage pool floor, and another fuel assembly in the RV or storage racks. An evaluation of the impact resulting from the FA falling over from the vertical position to a horizontal position (onte a protruding object) is also considered.

This assessment is valid for all B&W liark B 15x15 designated fuel assemblies.

2.0

SUMMARY

OF RESULTS:

This section conta).ns a summary of the pertinent results of the FA drop assessment.

Details of the analysis are provided in other sections of the' document.

VERTICAL DROP, FA AXIAL IMPACT:

l i

maximum drop height = 304" (from refueling mast to RV lower grid) impact velocity - 430 in/see FA impact stress = 41818 psi FA allowable impact stress > unirradiated Sy > 50 kai number of failed fuel rods = 0 (zero)

FA ROTATION TO HORJZCNTAL POSITIQ!:

impact velocity = 168 in/sec (maximum at end of FA) number of fuel rod rows failed - - 6 rows number of fuel rods failed = 82 rods PREPARED BY: D.

B.

COSTA OM'.

DATE:

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J.

F.

SHIPARD M

DATE:

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32-1244997-00

3.0 CONCLUSION

The maximum number of. fuel rods that will rupture from the postulated loading conditions is 82 rods.

This number can be used to assess the release of radioactive gases.

4.0 LIST OF ASSUMPTIONS:

i 1)

It is assumed that all the energy imparted by the impact of the vertical drop is absorbed by the fuel rods.

This assumption is conservative because the lower end fitting and pool floor or RV lower grid would deform and absorb some of the impact.

l 2)

For the drop from the vertical position, it is assumed that the FA remains l

approximately vertical until impact.

This assumption is based on the maximum drop heights which start with the fuel assembly fully retracted into the fuel handling mast.

The mast guides the fuel assembly through most of its fall, therefore maintaining a vertical position.

3)

It is assumed the vertical impact results in a uniform stress across the fuel rods. This assumption is supported by:

- The vertical position of FA upon impact, Assumption 2

- The fuel rods are " free" to slide relative to one another.

Therefore each rod impacts the lower end fitting independent of other fuel rods.

- The bullet nose on the bottom of the fuel rod helps distribute the load into the fuel cladding (tube).

4) For the case where the FA is dropped, hits on its end and falls over, it is assumed the rotation of the FA starts from a vertical position.

As a result of starting from the vertical position, the initial velocity of the fuel assembly when it starts to fall is 0.0 in/sec.

5) The analysis is based on elastic-perfectly plastic material strength.

Therefore no credit is taken for the strain hardening of the fuel rod.

6) It assumed that the temperature of the fuel assembly is less than 100F during the fuel transfer and fuel drop. The temperature is used only to fd1[A PREPARED BY: D.

E.

COSTA O/L DATE:

REVIEWED BY: J.

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SHEPARD DATE:

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32-1244997-00 i

establish the material properties (E, density, Sy) of the FA assembly.

Minor increases (or decreases) in the temperature will not significantly i

affect the results and conclusions of this evaluation.

1

7) For the vertical drop

case, the unitradiated yield stress ie conservatively used as the stress at which the fuel rod fails.

This is i

censervative since the irradiated yield stress is significantly (mere than twice) greater than the unirradiated yield stress.

8) The axial tensile stress in the fuel rod at end of life due to internal pressure is approximately 3600 psi.

This stress is based on the end of life rod dimensions and an internal pressure of approximately 1000 psi.

i 8

8 8

tensile stress = 1000(0.377 )/(0.42602 -0.377 ) = 3610 psi The axial pressure stress is considered in the failure analysis of the fuel rods by reducing the allowable stress of the rods (stress available for drop loads).

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5.0 REFERENCES

1)

FTI Fuel Assembly Drawings (partial listing) :

l 1.1)

1. 02-1223977F2, " Mark-B10 Fuel Assembly General Arrangement" 1.2)

1. 02-1224137F0, " Mark-B10+ ruel Assembly General Arrangement", uses i

D9 fuel rod assembly and B8 fuel rod cladding 1.3)

1. 02-1207077D4, " Fuel Rod Assembly", MK-B9 1.4)

1. 02-1190497C2, " Fuel Rod Cladding", MK-B8 1.5)

1. 02-1238299F2, " Mark-B10F Fuel Assembly General Arrangement" 1.6)

1. 02-1238277F0, " Mark-B10G Fuel Assembly General Arrangement" 1.7)

1. 02-1224242DS, " Fuel Rod Assembly", general assembly used for B10F 4

and B10G 1.8)

1. 02-1224240CO, " Fuel Rod Cladding", MK-B10 1.9)

1. 02-1238300F0, " Mark-Bil Fuel Assembly General Arrangement" i

1.10) #02-1238301DO, " Fuel Rod Assembly", B11 1.11) #02-1238275CO, " Fuel Rod Tubing", Bil 1.12) #02-1214171C2, " Guide Tube Tubing", Bil 1.13) #02-1003268F12, "MK-B Zircaloy Spacer Grid Assembly" 1.14) #02-1003269E13, "MK-B Zircaloy Spacer Grid Strip A" i

i 2)

Sterns-Roger Fuel Mandling Equipment Drawings:

j J

2.1)

" Main Fuel Hand. Bridge", drawing #21941-1 for ANO, #21901-1 for CR3, #21804-1 for TMI, #21771-1 for OCN1, #21832-1 for OCN2&3,

1. 22038-1 for DB1 4

2.2)

" Auxiliary Fuel Hand. Bridge", drawing #21942-1 for ANO, #21902-1 for CR-3, #21803-1 for TMI, #21772-1 for OCN1, #21833-1 for CCN2&3, i

1. 22037-1 for DB1 2.3)

" Fuel Storage Hand. Bridge", drawing #21943-1 for ANO, #21903-1 for CR-3, 21805-1 for TMI, 21777-1 for OCN1&3 (assumed same for OCN2),

i

1. 22039-1 for DB1 h

2.4)

"FT Mechanism Anchor Bolt Layout", (shows pool elevations), drawing l

1

1. 21940-3 for ANO, #22036-3 for DB1

" Plant Arrangement Fuel Handling System Elevations", (shows pool elevations), drawing # 22021-1 for CR3, 21802-1 for TMI, 21769-1 for OCN1, 21769-7 for OCN2, #21777-1 for OCN3 3)

FTI Document # 32-1173369-00, " Annealed Zircaloy-4 Tubing and Strip Material Properties", dated 8/7/89, (used for Young's modulus and density) s i

PREPARED BY: D. E.

COSTA 8(/.

DATX:

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REVIEWED BY: J.

F.

SHEPARD N

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32-1244997-00

)

4)

FA Weights (FTI Documents):

4.1) 32-1219009-00, "MK-B10 Fuel Assembly Component Weights", dated 11/5/92-4.2) 32-1240058-00, "MK-B FA Weights and CG", dated 9/12/95

)

i 5)

FTI Document # 32-1165955-00, " Impact Loading on Instrumentation Nozzles",

dated 12/11/86 (derives the formulas used for impact velocity calculation)

)

4 1

l 6)

Faupel, Joseph H., " Engineering Design - A Synthesis of Strass Analysis and Materials Engineering", John Wiley and Sons, NY 1964 l

7)

Blake, Alexander, " Practical Stress Analysis in Engineering Design",

Second Edition, Marcel Dekker, Inc., NY 1990 j

3 8)

Baumeister, Theodore, " Mark's Standard Handbook for Mechanical Engineers",

Eight Edition, McGraw-Hill 1978 j

i 9)

Giles, Ronald V., " Theory and Problems of Fluid Mechanics and Hydraulics",

Second Edition, Senaum Publishing, NY 1962 10)

• Effects of Irradiation and Hydriding on the Mechanical Properties of Zirealcy-4 at High Fluence", Zirconium in the Nuclear Industry: Eight International Symposium, ASTM STP 1023, L.F.P. VanSwam and C.M.

Eucken, Eds., ASTM, Philadelphia, 1989, pp. 548-569 l

Fuel Pin Thermal Analysis Code",

11)

FTI Document # BAW-10162-A, " TACO 3 dated 1989 (Table I-10 at 60000 mwd /mttU burnup yields 0.00199" corrosion) 12)

ANSYS Computer Code 12.J) " ANSYS" Finite Element Computer Code, Version 5.2, dated 1995, ANSYS INC., Houston, Pa.

12.2) FTI Doerment # 32-1213353-00, "ANSYS-366 Version 4.4A Val.dation Report" NOTE: Although this document is for version 4.4A, the same problems apply to other versions of ANSYS.

Therefore, if the verification problem is run on a later version of ANSYS (version 5.2 for this analysis) and the result.4 match the closed form results of the validation report, the other version of ANSYS is concluded to be acceptable.

13)

FTI Document # 32-1257376-00, " Hydraulic Draq on Unconfined FA In Cross Flow", dated May 1996 823dC PREPARED BY: D.

E.

COSTA 8/Z DATE:

REVIEWED BY: J.

F.

SHIPARD

%FS DATE:

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32-1244997-00

6.0 GEOMETRY

Since the majority (if not all) of fuel assemblies remain in the spent fuel pool, there are a number of dif ferent fuel assembly designs that potentially could be moved (and subsequently dropped).

The critical (pertinent) FA data for this evaluation as the fuel rod geometry and FA weights. Based on conversations with FTI fuels engineers, there is very little difference in the various fuel assemblies.

A brief description of the differences is provided below.

All of these assemblies are basically

- Mark B10 and earlier designs identical to the B10 design.

The B10 design actually used the fuel rod assembly from the B9 assembly which in turn uses the fuel rod cladding from the B8 design.

This assembly is the same as the B10 except that it is

- Mark B10+

equipped with a quick disconnect mechanism and new leaf spring end fitting design.

This design is similar to the B10 assembly but has a

- Mark B10F dif ferent size fuel rod cladding and a new leaf spring end fitting design.

- Mark B10G -- This assembly is the same as the B10F assembly except that it is equipped with a quick disconnect mechanism.

Mark Bil -- This is a new design and no B11 assembly is in service at this time.

The actual geometries of the B&W fuel assemblies are given in Reference (1). The weights of the assemblies are summarized in Reference (4).

A comparison of pertinent parameters for the different assemblies considered is shown in Table 6-1.

As previously stated, the review of Table 6-1 shows that there is very little difference in the dimensions and weights required for this analysis.

Therefore, it is concluded that the following dimensions are applicable for all the BWNT fuel assembly designs, fuel rod cladding OD = 0.43" BOL fuel rod cladding ID = 0.377" BOL fuel rod corrosion = 0.00199" wall thickness EOL Ref (11) fuel rod thickness = 0.0265" BOL,.0245" EOL PREPARED BY: D.

E. COSTA Afd DATE:

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SHIPARD C\\E DATE:

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32-1244997-00 length of fuel rod = 154.16" (- 154")

length of fuel assembly = 165.695"

(~ 166")

q I

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TABLE 6-1 i

l FUEL ASSEMBLY GEOMETRY Fuel Assembly Type Property

<:MK-B10 MX-B10F MK-Bil MK-B10+

MK-B10G 1

Fuel Rod Clad CD (BOL) 0.430" 0.430" 0.416" Fuel Rod Clad ID (BOL) 0.377" 0.380" 0.368" Clad thickness (BOL) 0.0265" 0.0250" 0.0240" Fuel Rod Length

-154"

-154"

-154"

\\

FA Length

-166"

-166"

-166" Corrosion (EOL) 0.00199" 0.00199" 0.00199" Clad thickness (EOL) 0.02451" 0.02301" 0.02201" Clad OD (EOL) 0.42602" 0.42602" 0.41202" FA weight 1520 lbs 1563 lbs 1480 lbs 7.0 MATERIAL PROPERTIES:

This section summarizes the fuel rod cladding material properties used in the l

analysis.

Young's Modulus and density come from Reference (3].

The material strengths, Sy and Su, come from Reference (3) for unirradiated zirconium (typical, BOL) and Reference (10) for irradiated zirconium (EOL).

FUEL ROD CLADDING: Zircaloy Young's Modulus (E) = 14.04E6 psi 8

Density (p) = 0.237 lb/in 8

Mass Density (7) = p/g = 0.237/386.4 = 6.13E-4 lb-sec /in' 2

2 386.4 in/sec g = gravity acceleration = 32.2 ft/sec

=

room temperature values Sy 2 50 ksi (BOL), 2 120 kai (EOL) room temperature values Su 2 70 kai (BOL), 2 120 kai (EOL) 80!M PREPARED BY:

D.

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COSTA M/L.

DATE:

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SHEPARD DATE:

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8.0 VERTICAL IMPACT CASE:

The vertical impact case involves dropping a fuel assembly from the vertical position onto an object below. Due to the velocities associated with this case, wave propage. tion theory is used for the evaluation of the impact loads.

1 As stated in Section 6.0, it is conservatively assumed that all the impact energy is taken by the fuel rods. In reality, a portion of the impact will be taken by deformation of the lower end fitting and the impacted object.

8.1 MAXIMUM DROP HEIGHT:

The maximum potential drop heights for the fuel assemblies occur when the fuel j

assemblies are fully retracted into the mast of the fuel handling equipment. The potential impacted objects consist of the RV lower grid plates, RV pool floor, spent fuel storage pool floor, and the top of another FA in the RV or storage stand.

The maximum potential drop heights are determined from the elevations reported on the Sterns-Rogers drawings of the fueling handling equipment, Reference (2). The pertinent elevations and resulting potential drop distances are shown in Table 8.1.

A review of Table 8.1 shows that the potential drop heights for the various plants are similar.

From Table 8.1, the maximum drop height required for evaluation is the drop of a FA back into the RV.

The maximum drop height is:

maximum droo heicht - 303.63" This value is used to determine the maximum impact velocity of the FA.

D!f6 PREPARED BY: D.

E.

COSTA Off DATE:

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SHEPARD M

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32-1244997 00 TABLE 8.1 FA DROP DISTANCES ELEVATICNS ANO-1 TMI-1 CR-3 OC-1,2,3 DB-1 MAIN MAST 377' 6H" 322' M" 136' H" 817' 6M" 579' M" AUX MAST 377' 6M" 322' H" 136' H" 817' 6W" 579' H" RV POOL FLOOR 362' 306' H" 118' 4"

802' 563' 64" TOP OF CORE 366' %"

310' 6%"

124' 6%"

806' %"

567' 6%"

STORAGE MAST 380' M" 324' H" 130' H" 820' W" 579' M" STORAGE FLOOR 362' 305' 118' 4"

802' 563' 6M" FA IN STORAGL 376' 3M" 319' 1-%"

132' 7k" 815' 9%"

577' 7%"

FA IN SHIPPING 372' 4%"

317' 10%"

132' 7M" 814' 7M" 571' 8%"

CONTAINER POTENTIAL DROP HEIGHTS TO RV POOL 186.5" 196.5" 212.5" 186.5" 186.25" TO RV BOTTOM 303.63" 303.63" 303.63" 303.63" 303.63" TO STORAGE 216.5" 228.5" 236.5" 216.5" 186.25" POOL TO FA IN CORE 137.63" 137.63" 137.63" 137.63" 137.63" TO FA IN RACK 44.75" 59.31" 64.75" 50.63" 17.32" TO FA IN SHIP.

92.37" 74.37" 64.75" 64.75" 105.13" CONTAINER NOTES:

1) All drop heights are from the bottom of the mast.

2) Per drawings, all Oconee units at same elevation.

3) Fuel assembly length is 166" (used for drop to P.V grid).

l PREPARED BY D.

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COSTA Oll.

DATE:

A f6 5'l23/ & PAGIr 12 _ _

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SHIPARD 9Mb DATE:

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• • FTI PROPRIETARY **

32-1244997-00 8.2 DISPLACED VOLUME / BUOYANCY FORCE:

The water volume displaced by the fuel assembly is used to determine the buoyancy force acting on the fuel assembly.

The displaced volume is based on the displaced volume of the sealed fuel rods and the volume of the other solid materials within the fuel assembly.

The volume of other solid materials is determined by dividing their reported weight by ' heir material density.

It should be noted th at some values are approximate but 'o not significantly af fect the results or conclusion of the analysis.

(EOL OD)2

• w/4

• L * # of rods Fuel rod volume

=

8

= 0.4260

• w/4

• 154

• 208 = 4566 in8 Remaining Zircaloy volume = (total zirc weight - fuel rod weight)/zire density total zircaloy weight = 305.032 lbs Ref (4) fuel rod weight = fuel rod clad + end plugs

= 24 9. 4 4 0 + 2 0. 0 00 + 2.170 = 2 72. 41 lbs Ref (4) 8 Zire density = 0.237 lbs/in Ref (4)

Remaining Zircaloy volume = (305.032 - 272.41) /0.237 = 138 in8 Stainless steel volume = total SS weight / density of SS total SS weight = 48.514 lbs Ref (4) 8 SS density = 0.29 lbs/in Ref (4)

Stainless Steel volume = 48.514/0.29 = 167 in' Inconel volume = total Inconel weight / density of Inconel total Inconel weight = 7.15 + 0.604 = 7.754 lbs Ref (4) 8 Inconel density = 0.297 lbs/in Inconel volume = 7.754/0.297 = 26 in8 Total displaced volume (v) 4566 + 138 + 167 + 26 = 4897 in'

=

This volume is considered applicable for all fuel assembly types discussed in this analysis. The buoyancy force resulting from the displaced water volume is determined by the following formula:

F,,,,= pv where p = density of fluid = 62.4/1728 = 0.03611 lbs/in8 v = displaced volume = 4897 in8 F

= 0.03611(4897) 177 lbs

=

%n..y l

PREPARED BY D.

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COSTA k(C DATE:

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SHEPARD CYb DATE:

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32-1244997-00 8.3 CRAG COEFFICIENT. VERTICAL DROP:

The movement of an object through a fluid is resisted by a drag force. The drag force is typically given by the following equation.

8 F,,, = C, ( p /g ) AV / 2 where:

C, = drag coef ficient p = density of fluid g = acceleration due to gravity A = cross sectional area of object resisting flow v = relative velocity of flow Due to the complexity of the fuel assembly geometry, an actual drag coefficient is difficult to determine.

A value will be determined however using some' text book examples.

Reference (8], page 11-68 Table 4, gives drag coef ficients for several geometric j

shapes.

These coefficients are independent of the Reynolds number as the AP 1

I (front to rear) provides most of the resistance (drag).

The Table shows that drag coef ficients for cylinders with various length-to-diameter ratios vary frem 0.85 to 0.99.

These values should be representative of single fuel rod. There are also coef ficients given for other shapes, including rectangular and circular plates.

The coefficient for a square plate is 1.16 and the coefficient for a j

circular disk is 1.11.

The shapes are similar to the projected area of the lower i

end fitting.

A review of other text books shows that these values are typical.

In addition, for the range of applicable Reynolds numbers, these values are also representative. For example, Reference (9) provides additional drag coef ficients for various shapes as a function of Reynolds number. The Reynolds number for a fuel rod / assembly is approximated by:

R. = V (D) /r 1 to 38 ft/sec (assumed, velocity - O to 450 in/sec where V

=

verified in Section 8.4)

D = diameter = 0.4260" = 0.0355' for a single fuel rod 0.73' for lcwer end fitting (width)

. - 8.75"

=

= kinematic viscosity = 0.74E-5 f t /r,ec for water a 100F 8

r R,

= 4.8E3 to 1.8E5 for single rod

= 9.9E4 to 3.7E6 for end fitting dud 6 PREPARED BY D.

E.

COSTA NC.

DATE:

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SHIPARD Yb DATE:

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32-1244997-00 From Diagram F of Reference (9), the drag coef ficient is 1.12 for a circular disk and 1.16 for a square plate.

Based on the previous discussions, a drag coef ficient of L._q will be used for the fuel assembly.

It should be noted that the fuel assembly is retracted into the fuel handling mast at the start of its projected fall.

As the fuel assembly moves down the mast, water will rush in to fill the void.

This motien will create additional drag on the fuel assembly.

For information, a figure showing the effect of drag coefficient on impact velocity is included in Section 8.4.

Results show that for the applicable conditions of the fuel rod drop, the drag coef ficient does not have a significant influence on the results.

4 8.4 IMPACT VELOCITY:

Reference (5) provides the details for determining the velocity of an object that is dropped in air, enters water, and then continues moving through water.

For this application, only the movement through water is required. The method starts with the summation of forces.

Z F = F,,

- F. - F,,,=

ma 4

where:

F,,= deadweight of dropped object = mg F. - buoyancy force = Ov 8

F,,, = WC (p/g) AV a = acceleration = (dV/dt) 8 m(dV/dt) therefore: mg - av - HC (p/g) AV

=

8 (mg - pv - HC,(p/g) AV ) dt = m(dV)

(mg - pv)/m 8

let: a =

1. 8 - H(p/g)C.A/m where:

m = mass of dropped object a = acceleration of' object g - acceleration of gravity a = density of fluid v = displaced volume C = drag coef ficient A = cross-sectional area of object resisting flow PREPARED BY: D.

E. COSTA 84*

DATE:

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PAGE:

15 REVIEWED BY J. F. SHEPARD Mh DATE: __

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FRAMATOME TECHNOLOGIES

• • FTI PROPRIETARY **

32-1244997-00 V = velocity By substitution and reduction, the following relationships for velocity (V) and drep height (Z) as a function of time (t) are derived.

(-o + oe *8') / ($ + Je *8')

2 2

V=

(In($ + B)) /J' Z=

-ot/S + (in ($ + Je'*8') ) /08 Note: The equations in Reference (5) include an additional term referred to as

" zeta".

The " zeta" term relates to the initial velocity of the object. For the j

fuel assembly drop case the initial velocity is 0.0 and the resulting " zeta" term is 1.0.

For the case of a dropped fuel assembly, m = mass of dropped object = F,/g F, = 1520 lbs Section 6.0 8

m = 1520/386.4 = 3.9337 lbs-sec /in 2

g = acceleration of gravity = 386.4 in/sec p = density of fluid = 62.4/1728 = 0.03611 lbs/in' v = displaced volume = 4897 in8 S3ction 8.2 C = drag coef ficient = 1.0 Section 8.3 (other values also investigated) 32 in8 A=

cross sectional area of object resisting flow (approximate -- based on projected cross sectional area of 225 assumed fuel rods) t = time = assumed values from 0.0 to 2.0 see These parameters and the equations for drop height and velocity where input to a LOTUS spread sheet. The resulting velocity as a function of drop height (and drag coef ficient for information) is tabulated in Table 8-2 and shown graphically in Figure 8-1.

From Table 8-2, the maximum velocity for a drop height of 303" (Section 8.1) and a drag coefficient of 1.0 (Section 8.3) is 430 in/sec, maximum fuel assembly impact velocity = 430 in/sec As shown by Table 8-2 and Figure 8-1, the drag coef ficient (for the ranges considered) has a negligible affect on the impact velocity.

i jd1[T0 PREPARED BY:

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E. COSTA MI.d DATE:

REVIEWED BY: J.

F.

SHEPARD OF. 6 DATE:

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32-1244997-00 i

l T;d3LE 8-2 L

IMPACT VELOCITY AND CROP HEIGHT (as function of drag coefficient)

IMPACT vtLOC17Y CF FALLING CBJECT IN H2O F'JEL ASSEMBLY ORCP REFERENCE 32 1165955-00, BY GLW deadweight of object (DW) =

15: lbs 32.L / in2 cross sectional area of object (A) 386.4 in/sec2 acceleration due to gravity (g) mass of object (m). DW/g.

3.93 lbs sec2/in 0.03611 lbs/in) density of fluid (p)

F p/g.

9.35E 05 (1bs-sec2/inl/in3 mass dancity of fluid (P) e 4897.00 in3 displaced volume (v)

=

l drag coefficient.

1 l

alpha =

18.47031 i

beta e 0.019518 l

time.

1.36 see height.

304 in velocity a 430 in/sec 0.00001 Cd.

0.5 Cd.

1 Cd.

1.5

}

i. 38.47831 alpha. 18.47831 alpha. 18.47831 alpha. 18.47831 0.000062 beta.

0.013802 beta.

0.019518 beta =

0.023905 i

TIME HEIGHT VELOCITY HEIGHT VELOCITY HEIGHT VELOCITY HEIGHT VELOCITY (sec)

(in)

(in/sec)

(in)

(in/sec)

(in)

(in/sec)

(in)

(in/sec) 0 0

0 0

0 0

0 0

0 0.1 2

34 2

34 2

34 2

34 0.2 7

68 7

68 7

68 7

68 0.3 15 102 15 102 15 102 15 102 C.4 27 137 27 136 27 136 27 135 0.5 43 171 43 170 42 169 42 168 0.6 61 205 El 203 61 202 61 200 0.7 84 239 83 237 83 234 83 232

[

0.8 109 273 109 269 108 266 108 262 O9 138 307 137 302 136 297 136 292 1

l 171 341 169 334 167 327 167 321 1.1 207 376 204 366 201 351 2nt 349 1.2 246 410 242 397 239 386 239 375 I

1.3 289 444 283 428 279 414 279 401 1.4 335 478 328 459 321 441 321 425 1.5 384 512 375 489 367 467 367 448 1.6 437 546 425 518 415 493 415 470 1.7 493 580 479 547 465 517 465 491 1.8 553 615 535 575 518 541 518 511 1.9 616 649 594 602 573 563 573 530 2

683 683 655 629 631 585 631 547 I

l 1

1 N !N PREPARED BY: p.

E.

COSTA

((i DATE:

bblP PAGE:

17 REVIEWED BY J.

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• • FTI PROPRIETARY **

32 1244997 00 FIGURE 8.1

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FRAMATOME TECHNOLOGIES

• • FTI PROPRIETARY **

32-1244997-00 8.5 IMPACT STRESS:

Section 9-2 of Reference (6) provides a detailed discussion of the wave propagation phenomena. Reference (6) provides details for propagation in both the elastic and plastic range.

Since irradiated fuel rods have very little available plastic deformation, the calculation of impact stresses and allowable stresses will be conservative based on only the elastic properties of the material.

From equation 9.15 of Reference (6), the equation for the impact stress in the elastic range is:

T c.V a,.cs

=

s where:

ai,... = impact stress (psi) e, - elastic wave velocity = (E/7), for a solid rod c, = (E/(1-y8 ) y) * ', for a cyclinder Ref (7) Table 16.1 8

y = material mass density = 6.13E-4 lb-sec /in' Section 7.0 E = 14.04E6 psi Section 7.0 v = 0.3 Assumed c, = l14.04E6/ (1.3 ) 6.13E-4)' ' = 158647 in/sec 8

V= impact velocity = 430 in/sec Section 8.4 a,,,, = 6.13 E - 4 158647

• V = 92.77V = 41818 esi compressive s

8.6 ALLOWABLE IMPACT STRESS:

The yield stress for the unirradiated fuel rod will conservatively be used for the allowable impact stress.

This is conservative since the irradiated yield stress is much greater (more than twice) than the unirradiated value and no credit for the plastic range is accounted for, a,.cs na=es. = Sy (BOL) 1 50000 psi Section 7.0 s

In addition, conservatively assuming the rod tensile axial stress due to internal pressure reduces the allowable stress available for impact loading, the allowable

= > 46400 psi) is greater than the impact loading stress

(>

50000 3600 compressive impact stress.

8.7 NUMBER OF BROKEN FUEL RODS:

Since the impact stress is less than the allowable yield stress of the fuel rod cladding, it is concluded that no fuel rods will fail.

PREPARED BY:

D.

E.

COSTA

[fL DATE:

.SYUh6 N4L PAGE:

19 REVIEWED BY: J.

F.

SHEPARD Of$

DATE:

4

3 p

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• • FTI PROPRIETARY **

32-1244997-00 NOTE: This conclusion is based on fuel rods without defects. If a fuel rod had a defect it could possibly rupture.

It is assumed that only a small portion of the rods actually have defects which could result in rupture and that number is less than the number of broken rods in the horizontal impact case of Section 9.0,

=,

8.8)

FUEL ROD BUCKLING:

Due to the short duration of the impact load, the initial compressive wave is less than 0.002 secs (2*L/co), the fuel rod will not buckle. This conclusion is confirmed with a finite element assessment of impact on the fuel rod.

A single-full length fuel rod is modeled using the ANSYS beam element. The model (vertical beam) is supported from lateral motion at the grid support locatiens.

The bottom of the fuel rod is fixed from vertical motion. To represent the free fall and impact, an initial velocity of 430 in/sec (downward) is applied to the model.

To allow for buckling, the large deflection option was used and an initial lateral velocity of 2 in/sec at the middle of the lower grid span was applied.

The model was allowed to complete several cycles of the stress wave. The model converged throughout the cycles, the lateral displacements were small, and the maximum stresses were comparable to those determined in Section 8.5 Since the large deflection analysis was able to converge, the fuel rod is elastica 11y stable.

This, coupled with the maximum impact stress less than the material yield insure the fuel rod will not buckle. The model input and results are given in microfiche BUCKLE.OUT.

\\

Jbb PREPARED BY: D.

E. COSTA Bfd DATE:

[9fa PAGE:

20 REVIEWED BY: J.

F.

SHEPARD DS DATE:

V

_m

}.

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^

• • FTI PROPRIETARY **

32-1244997-00 frRAMATOME TECHNOLOGIES 9.0 POTATIONAL IMPACT CASE:

The rotational impact case considers a fuel assembly, starting in an upright position, falling over and impacting an object.

The assembly is allowed to rotate through a 90 degree angle before impacting an infinitely thin rigid target. The assembly rotates about its base (the lower end fitting). The fuel rods impact the target at the midpoint of their uppermost span.

All of the impact force is applied at the target location; no credit is taken for the fuel assembly striking the floor and distributing the load.

These conservative assumptions were made in order to bound all potential impact targets.

In addition to the infinitely thin impact target, a case with a larger target area was also analyzed. The results of the larger impact area case are discussed in Section 9.6.

9.1 FINITE ELEMENT MODEL GEOMETRY:

A fuel assembly consists of 225 rods in a rectangular arrangement of 15 rows with 15 rods per row. The finite element model represents one row of 15 rods. Since the ratio of fuel rods to guide tubes is approximately 15:1, one guide tube is included in the model. The fuel rods and guide tubes are modelled with beam elements. The upper and lower end fittings are modelled with solid plane stress elements.

The spacer grids are also represented with beam elements.

The uppermost three spans of the rods have gap elements between the rod nodes to allow for rod-to-rod contact following impact.

Puel rod dimensions:

Section 6.0 ID = 0.377" Section 6.0 f

EOL wall thickness = 0.0245" CD = 0.377 + 2 (0.0245) = 0.4260" Guide tube dimensions:

Ref (1.12]

BOL OD = 0.53" Ref (1.12}

BOL wall thickness = 0.016" Section 6.0 EOL corrosion = 0.00199" 0.01202" EOL wall thickness = 0.016 - 2(0.00199)

=

EOL OD = 0. 5 3 - 2 (0. 0019 9) = 0.52602" Gap sizes:

Ref (1.13]

Fuel rod center-to-center spacing = 0.568" 0.4260 = 0.1420" Gap between rods = 0.568

(

i A DATE: MM'"I PREPARED BY: H. T.

HARRISON

/r '

REVIEWED BY D. E.

COSTA Off DATE:

dtNM PAGE:

21

s-

}.

=

^

• • FTI PROPRIETARY **

32-1244997-00 FRAMATOME TECHNOLOGIES 9.2 FINITE ELEMENT MODEL MATERIAL PROPERTIES:

The fuel rods and guide tubes were modelled as an elastic / perfectly-plastic material with a yield stress of 120 ksi and modulus of elasticity of 14.04E6 psi.

The remainder of the model used elastic material properties with a modulus of elasticity of 29E6 psi.

The material densitier were calculated as follcws:

Fuel rods and guide tubes 1520 lbs total weight of FA Ref [4]

- 17.77 lbs weight of upper end fitting Ref (4)

- 15.5 lbs weight of lower end fitting Ref [4]

1486.7 lbs weight to be distributed to fuel rods and guide tubes 1486.7 lbs / 225 rods = 6.61 lbs/ rod Volume displaced by fuel rod = 21.95 in' for CD of 0.4260 in., length of 154 in.

8 = 0.79 lbs Section 0.2

.03611 lb/in 8

• Buoyant force = 21.95 in Fuel rod weight for model = 6.61 - 0.79 = 5.82 lbs Volume of fuel rod material in model = 4.764 ins for CD of 0.4260", ID of 0.377",

length of 154.16".

Material density for model = (5.82 lbs/4.764 in ) / 386.4 = 0. 00316 lbs/in' 8

Upper end fitting:

8 (4.063 in) (7.966 in) (1 in) = 32.37 in Volume (in model)

=

^

Weight of end fitting = dead weight - buoyant force dead weight = 17.77 lbs Ref (4) 8 8

buoyant force = 17.77/0.29 lbs/in *0.03611 lbs/in Section 8.2

= 2.21 lbs l

Weight of end fitting = 17.77 - 2.21 = 15.56 lbs (15.56 lbs / 32.37 in ) /386.4 = 0.00123 8

Density (model)

=

8 For a 1/15th model, use 0.00123/15 =.0000820 lbs/in l

Lower end fitting:

8 Volume (in model): (3.516 in) (7.966 in) (1 in) = 28.0 in Weight of end fitting - dead weight - buoyant force dead weight = 15.5 lbs Ref (4]

i 4

54 i/f L PREPARED BY H.

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HARRISON DATE:

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32-1244997-00 1

FRAMATONE TECHNOLOGIES 3

i s

Section 8.2 buoyant force = 15.5/0.29 lbs/in'*0.03611 lbs/in j

= 1.93 lbs Weight of end fitting = 15.5 - 1.93 13.57 lbs 0.00125 i

8 Density (model): (13.57 lbs / 28 in ) / 386.4

=

For a 1/15th model, use.00125/15 =.0000833 lbs/in' i

4 9.3 FINITE ELEMENT MODEL BOUNDARY CONDITIONS:

The model is supported in the X and Y directions at node 793, located on the bottom surface of the lower end fitting.

The impact target is represented by 4

restraining the X displacement of node 16, located on rod 1 at the midpoint of

[

the uppermost span. The impact load is applied by specifying initial velocities l

to the entire model equal to the impact velocities determined in Section 9.4.

Gravitational acceleration is also applied in the X direction.

9.4 IMPACT VELOCITY CALCULATIONS:

j Reference (13) documents an analysis done with the computational fluid dynamics

}

code FLOTRAN to determine the drag forces on a fuel assembly moving through water 3

at different velocities.

The results of this analysis can be summarized as

{

follows:

VELOCITY (in/sec)

DRAG FORCE (cer unit lenoth) 20

.2358 lb 1

100 5.742 lb 200 22.81 lb I

These results can be expressed in equation form as 4

C P, = (v/100)8 F u.,

)

where F, = drag force at velocity v v = velocity 4

Fn., = drag force at v=100 in/sec = 5.742 lb A sinplified model of a fuel assembly was used to calculate the impact velocity The following a 90 degree rotation of the assembly with drag forces applied.

fuel assembly was modelled with beam elements. A single beam was used, divided into 200 elements along the length of the assembly. The length used was 163.688 inches. The beam was given an area of PREPARED BY: H. T. HARRISON DATE:

[*- d T dth 6 PAGE:

2)

REVIEWED BY: D. E. COSTA

( DATE:

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r FRAMATOME TECHNOLOGIES

• • FTI PROPRIETARY **

32-1244997-00 8

(.377/2)8)

A=

(3.14 ) * ( (. 4 2 6 0/2 ) 8 225 = f_J1 in to represent 225 fuel rods. The mass was uniformly distributed along the beam, resulting in a density of 8

0.003055 lb-sec /in' p=

(1520-177) / (6.95*163.688) / 386.4

=

The node at the bottom of the assembly (node 1) was restrained in the X and Y directions.

The model was generated with a 0.5 inch offset at the top of the assembly to start the fall. A transient dynamic analysis was run to allow the assembly to rotate until it was horizontal.

Since the drag force is velocity-dependent, the transient had to be divided into a number of increments (a time i

increment of 0.05 seconds was used). Af ter each increment of time, the solution i

is stopped, the nodal velocities during the last iteration are calculated, and 1

the drag forces are adjusted based on the drag force equation given above. After the assembly had rotated 90 degrees, the analysis was stopped. The results of this analysis, contained in fiche DRAG.OUT, showed that the top of the fuel assembly, at 163.688 inches above the base, was travelling at a linear velocity of 168 in/sec.

9.5 RESULTS OF ROTATIONAL IMPACT CASE:

A transient dynamic analysis was run on the model described in Sections 9.1 9.3, with both nonlinear geometric ef fects and nonlinear material properties considered.

The transient started at the moment of impact and was run until after the stress level in the fuel rods had peaked.

The results (in fiche l

HDROP.OUT) showed that the first six rows of fuel rods had yielded. Due to the lack of ductility in the material, failure stress is taken to be yield stress.

l Therefore it can be concluded that not more than six rows of rods will fail due to the effects of a rotational drop.

The number of fuel rods failed - (6 rows x 15 rods / row) - 8 guide tubes = 82 fuel rods.

9.6 RESULTS OF INCREASED IMPACT AREA:

This section provides the results of an additional case that was analyzed to investigate the effects increasing the impact target area. The fuel drop model and boundary conditions used for the infinitely thin target case were also used for the larger impact case. The target (impact area) was increased to a width l

/

PREPARED BY: N. T. HARRISON DATE: E"23* %

REVIEWED BY: D. E. COSTA (6 DATE:

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._m

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FRAMATOME TECHNOLOGIES

• • FTI PROPRIETARY **

32-1244337 00 of approximately 4 inches, centered on the upper span of the assembly.

The results of the analysis (microfiche HDROP2.OUT) showed six rows of rods failed.

l A review of the results show that the inertia of the fuel assembly caused it to rotate about the edge of the target following the initial impact. The rotation about the target edge resulted in conditions similar to those of the infinitely

)

thin target case and therefore six rows of failed rods.

1 l

f

/

52*7"N PREPARED BY M. T. FA**ISON DATE:

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D.

E.

COSTA af. DATE:

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y.

4.

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32-1244997-00 10.0 ANSYS PROGRAM VERIFICATION:

This section provides verification of both the PC used and the PC based AN3YS software. All verification cases were executed on the same PC and sof tware used for the calculation of production results reported in this document. Therefore, since the results from the verification cases match those of the closed form solutions, it is concluded that the PC and software are acceptable for use on this task.

The ANSYS verification problems are contained in Reference (12.1).

ELASTIC BEAM ELEMENT: Verification problem VM40 was used. Verification problem VM40 consists of large deflection and rotation of a beam pinned at one end. The results of the verification problem are contained in microfiche output VM40.OUT are compare to closed form results shown in the ANSYS verification manual, f

Reference (12.1).

PLASTIC BEAM ELEMENT: Verification problem VM24 was used. Verification problem VM24 consists of plastic hinge resulting from a moment applied to the ends of a rectangular beam.

The results of the verification problem are contained in microfiche output VM24.OUT are compare to closed form results shown in the ANSYS verification manual, Reference (12.1).

(

INTERFACE (GAP) ELEMENT:

Verification problem VM27 was used.

Verification problem VM27 consists of a gap element being closed by thermal loading (thermal expansion). The results of the verification problem are contained in microfiche output VM27.OUT are compare to closed form results shown in the ANSYS verification manual, Reference [12.1).

t W

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4

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Nd PREPARED BY: N. T. HARRISON DATE:

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FRAMATOME TECHNOLOGIES

• • FTI PROPRIETARY ee 33 1344997 00 i

l APPENDIX A MICROFICHE:

ANALYSIS RESULTS:

BUCKLE.OUT Fuel rod buckling check for impact loading from vertical drop, fiche dated 4/17/96 DRAG.OUT Determines impact velocity of FA f alling from a vertical position to a horizontal position, fiche dated 5/20/96 HDROP.OUT Determines stress / strain in fuel rods due to impact of FA on infinitely thin rigid target af ter rotating from a vertical position to a horizontal position. fiche dated 5/20/96 HDROP2.OUT Determines stress / strain in fuel rods due to impact of FA on a 4" wide rigid target after rotating from a vertical position to a horizontal position. fiche dated 5/23/96 ANSYS VERIFICATION CASES:

VM40.OUT ANSYS verification for elastic beam element, fiche dated 5/19/96 VM24.OUT ANSYS verification for plastic beam element, fiche dated 5/19/96 VM27.out ANSYS verification for 2-D gap element, fiche dated 5/19/96 M 2 N, PREPARED BY:

H.

T.

HARRISON DATE:

REVIEWID BY: D.

E.

COSTA

[(C DATE: 5/(& -

PAGE:

27

-