ML20115G354
| ML20115G354 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 05/28/1996 |
| From: | Sistos A SOUTHERN CALIFORNIA EDISON CO. |
| To: | |
| Shared Package | |
| ML20115G352 | List: |
| References | |
| M-DSC-330, M-DSC-330-R, M-DSC-330-R00, NUDOCS 9607190087 | |
| Download: ML20115G354 (30) | |
Text
I a
ICCN NO1 CALCULATION TITLE PAGE PREtiu. CCN p* ,
NO. _
PAGE F_
OCN CONVERSION.
Calc. No. M-OSC-330 DCP/FIDCN/FCN No. & Rev. CCN NO. CCN-Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet i of 30 _
System Number /Pnmary Station System Designator /FHS SONGS Unit 233 0-Class 11 Tech. Spec. Affecting? O NO O YES, Section No. -
Equipment Tag No -
CONTROLLE PROGRAM / DATABASE NAME(S) VERSION / RELEASE D 0 PROGRAM NO (S)
COMPUTER O ALSO, LISTED BELOW PROCNM/ O DATABASE DATAE,.SE ACCORDING TO SO123-XXIV-51 1 RECORDS OF ISSUES REV TOTAL PREPARED APPROVED DISC. DESCRIPTION SHTS HT. (Pnnt name/ initial /date) (Signature /date) 0 30 ORIG. M P. VALANDANI 577/9[
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N/M 30 IRE: d.O J.u for- DM Ut Other ANGEL SISTOS S/w/,u ar/J4/5 /
ORIG. GS Other IRE DM Other ORIG. GS Other IRE DM Other ORIG. GS Other IRE DM Other Space for RPE Stamp, identify use of an alternate calc., and notes as applicable.
T_ }l} W 2,5
- ' 291936 2s b UI Y,bf f 9607190087 960716 PDR ADOCK 05000361 P PDR This calc. was prepared for the identified DCP/FCN. DCP/FCN completion and turnover acceptance to be venfied by receipt of a memorandum directing DCN Conversion. Upon receipt, this calc. represents the as-busit condition. Memo date by BCE Nt21.s nEv e ase {PfFERENCE Sot 21-Amav713l
CALCULATION CROSS-INDEX l %"ac Nd "" "
CALCULATION No. M-DSC-330 se'ai a .
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Calc / Document No. """" YES/NO DBD-SO23-TR-PL 0 SO23-3-2.11 6 SD-SO23-360 3 DRAWINGS:
S O23-990-133 2 SO23-990-32 0 S O23-411-55-129 2 SO23-900-C-4-6 10 SO23-910-9 0 S O23-411-55-166 1 23065 14
NES&L DEPARTMENT l CALCULATION SHEET '""""
i CCN CONVERSION Prsject or DCP/MMP SONGS 2&3 Calc No. M-DSC-330 Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 3
, I REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE IRE DATE O P.VALANDANI 5/13/96 ANGEL SISTOS 5/16/96 l
l 1
d 9
i TABLE OF CONTENTS 4
2 4
PAGE l
- 1. PURPOSE ............................................................................ 4
- 2. R E S U LTS/C O N C LU S IO N S ........ ... ........................................ 5
- 3. A S S U M P TI O N S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6. . . . . . . . . . . . . . . . . .
- 4. DESIGNINPUT....................................................................... 7
- 5. METHODOLOGY ................................................................. 12
- 6. REFERENCES........................................................................ 18
- 7. N O M E N C LATU R E . . . . . . . . . . . . . .. . . .. . . . .. . .. . . . . .. . .. ... . . . . . . . . .. . .. .. . . . .. .20
- 8. CALCULATlONS .................................................................. 22 SCE 26-426 NEW 4/90
NES&L DEPARTMENT l CALCULATION SHEET """"
CCN CONVERSION Project or DCP/MMP SONGS 2&3 Calc No M.DSC-330 Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 4 REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE IRE DATE O P.VALANDANI 5/13/96 ANGEL SISTOS 5/16/96 I I
l
- 1. PURPOSE:
1.1 Background- The San Onofre 2&3 FSAR Section 9.1 (Fuel Storage and Handling) contains the following statement: l l
"The fuel transfer tube is sufficiently large to provide natural circulation cooling for a fuel assembly in the unlikely event that the transfer carriage should become inoperable while in the tube." l This statement implies that natural circulation cooling can be provided for only one fuel assembly, even though the transfer carriage is designed to hold two fuel assemblies. In the past, occasionally two spent fuel assemblies have been transferred simultaneously !
through the transfer tube. This practice has been prohibited since the discovery of the above statement in the FSAR, pending the resolution of this issue.
It is the purpose of this analysis to investigate the consequences of the transfer carnage becoming inoperable while carrying two fuel assemblies in the transfer tube, and to show l l
that there will be no boiling and no fuel damage as a result of such an event. Should the repair of the transfer carriage system involve physical access to the transfer tube, it will be done at a much lower pool temperature and at a later time when the decay heat rate is further reduced, leading to more favorable conditions than the ones considered in this analysis.
i 1
SCE 26-426 NEW 4/90
NES&L DEPARTMENT CALCULATION SHEET CCN CONVERSION Project or DCP/MMP SONGS 2&3 Calc No. M-DSC-330 subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE sheet No. 6 REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE 1RE DATE O P.VALANDANI 5/13/96 ANGEL StSToS 5/16/96 l
- 2. RESULTEiCONCLUSIONS:
The results of this analysis show that from a heat transfer point of view, the stoppage of two fuel assemblies in the transfer tube poses no danger of boiling of the water or excessive heating of the fuel rods. Using conservative values of decay heat and a minimum time between reactor shut-down and fuel off-load of only 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, the maximum calculated bulk water temperature in the tube is 180 F, at least 30 degrees below the boiling point at atmospheric pressure, and more than 60 degrees below the local saturation temperature. The maximum fuel rod surface temperature is 185 F, which again rules out any boiling on the surface of the fuel rods. The maximum calculated fuel temperature is only 187 F.
The conclusion of this analysis is that from a heat transfer point of view, the simultaneous transfer of two fuel assemblies did not pose any danger of boiling or excessive fuel temperature.
4 SCE 26-426 NEW 4/90
NES&L DEPARTMENT CALCULATION SHEET CCN CONVERSION Project or DCP/MMP SONGS 283 Calc No. M-DSC-330 Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 6 i
REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE IRE DATE O P.VALANDANI 5/13/96 ANGEL SISTOS 5/16/96 1
- 3. ASSUMPTIONS: l l
i
- 1. The decay heat rate remains constant at the value corresponding to the time of off-load (no credit taken for the exponential decay thereafter).
- 2. The spent fuel pool and the reactor side pool are maintained at 160, which is the maximum pool temperature.
1 i
, 3. The 2" diameter holes (193 total) drilled in the upper and lower cavities of the fuel l.
carrier provide sufficient flow area for the cooling water, to avoid hot pockets.
I Results of the analysis show (see Tables 1 and 2) the required flow area to be less than 0.1 ft2 compared with 1 ft 2area of fifty 2" diameter holes.
- 4. The minimum time between reactor shut-down and fuel off-load is 150 hours0.00174 days <br />0.0417 hours <br />2.480159e-4 weeks <br />5.7075e-5 months <br />.
A conservative value of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> will also be evaluated.
l l
l
- 5. Heat transfer from the fuel rods to the water is assumed to be by natural convection 4 only. The axial motion of the water in the transfer tube, and its effect on the rate of l heat transfer is ignored, for conservatism.
l i
SCE 26-426 NEW 4/90
NES&L DEPARTMENT CALCULATION SHEET CCN CONVERSION l
Pr: Ject or DCP/MMP SONGS 2&3 Calc No. M-DSC-330 l l Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 7 REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE IRE DATE O P. VALANDANI 5/13/96 ANGEL SISTOS 5/16/96
- 4. DESIGN INPUT:
1
- 1. The fuel transfer tube has an inside diameter of 35.5" and a length of 44'-8"(see Fig.1). The centerline of the tube is at the elevation 28' 6" and the low water level in the pool is at 60'-8" elevation (Ref. 4).
- 2. The fuel carrier assembly consists of an upper cavity and a lower cavity, each with a cross-sectional open area of 9"x9" and a length of 15'-9 7/8" (Ref.11)(see Fig. 2).
The fuel bundle has a cross-sectional area of 8"x8"(Ref. 6), which leaves a half inch space on each side and a one inch space at the top. A large number of 2" diameter holes in the upper and lower cavities allows the cooling water to reach the fuel bundles. The lower cavity has 48 holes on the bottom surface,16 holes on the sides,32 holes on the top, and 4 holes at the end, for a total of 100 holes (Ref.13).
The upper cavity has 40 holes on the bottom surface,24 holes on the sides,25 holes on the top, and 4 holes at the end, for a total of 93 holes (Ref.14). l i
- 3. Fuel assemblies consist of a 16x16 array of fuel rods with approximate outside I dimensions of 8"x8"x177"(Ref. 6). Each assembly consists of about 1,054 pounds of UO2,300 pounds of Zircalloy and the remainder (78 pounds) stainless steel (Ref.
3). There are 236 fuel rods (maximum) in each assembly (Ref.1).
- 4. Fuel rods consist of UO2 pellets in a Zr4 tube. The inside diameter of the tube is j 0.332" and the outside diameter is 0.382"(Ref. 7). The active length of the rods is l l
approximately 150" (Ref. 7) (see Fig. 3).
SCE 26-426 NEW 4/90
_. - -. _ . - . _ . = _ . . . . - . _ _ .- _ _ - _ .- . _ . _ __ .__ - _ - - _ _ _ _ _
, NES&L DEPARTMENT
- CALCULATION SHEET '""" '
I CCN CONVERSION j Project or DCP/MMP SONGS 283 Calc No M-DSC-330 l Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 8 4
REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE 1RE DATE l 0 P VALANDANI 5/13/96 ANGEL SISTOS S/16/96 i
1 i
l FIG.1- SPENT FUEL TRANSFER TUBE SCHEMATI.C i
i V L El 60'-8" l _
l 1
}
l FUEL TRANSFER FUEL TRANSFER l .
SPENT FUEL SIDE REACTOfLSIDE I
j EL. 28'-6" - - --
- - ID = 351/2"
~ ""
E<,,.,,,.. I ,< ;,. ,,,,.
I i
j 1
I 4
SCE 26426 NEW 4/90
)
NCb6L Utt'AK I MtN I
- CALCULATION SHEET CCN CONVERSION l Prgject or DCP/MMP SONGS 2&3 calc No. M-DSC-330 Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 9 REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE (RE DATE 0 P. VALANDANI 5/13/96 ANGEL SISTOS 5/16/96 i
l FIG. 2- DIMENSIONS OF FUEL CARRIER ASSEMBLY CAVnY r
UPPEA CAVfTY // bO-af.1 i
O 9 O O O 10 0 0 0 1 2" dla. holes (typ.)
LOWER CAVITY
/
8 25- 7,8-3; FUEL ASSEMBLY ELEVATION VIEW SCE 26-426 NEW 4/90 l
NES&L DEPARTMENT CALCULATION SHEET CCN CONVERSION Project or DCP/MMP SONGS 2&3 Calc No. M-DSC-330 Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 10 REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE IRE DATE O P VALANDANI 5/13/96 ANGEL SISTOS 5/16/96 l
FIG. 3- FUEL ROD DIMENSIONS b
A --*
.382" .332" UO2
~
+
}
150" ACTIVE FUEL LENGTH l
SCE 26426 NEW 4/90
NES&L DEPARTMENT CALCULATION SHEET CCN CONVERSION Project or DCP/MMP SONGS 2&3 Calc No M-DSC-330 Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 11 REv ORIGINATOR DATE IM DATE REV ORIGINATOR DATE 1RE DATE O P. VALANDANI S/13/96 ANGEL slSTOS S/16/96
- 5. The maximum pool temperature is 160 F (Ref.1, sect. 9.1.3.1)).
- 6. The density of UO2 pellets is 10.38 g/cu. cm (647 lb/cu. ft) (Ref.1, p 4.2-47), their specific heat is 0.056 Btu /lb-F (Ref.19), and their thermal conductivity is 4 Btu /hr/ft/F at 300 F(Ref.19).
- 7. Thermal properties of Zr4 are (Ref.19, p 29-15):
Density = 412 lb/cu.ft Thermal conductivity = 8.4 Btu /hr/ft/F l l
Specific heat = .( '3 Btu /lblF '
- 8. The decay heat per fuel assembly is given in Ref. 2 as:
2.29E05 Btu /hr After 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> 1.68E05 Btu /hr After 150 hrs.
These conservative values are for a fuel assembly that has been continuously irradiated for four (4) effective full power years. Peaking factors are already included in these numbers, since they are based on the maximum local decay heat rates. The values for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> are included and analyzed even though SONGS 2/3 have never begun core off-load in less than 150 hours0.00174 days <br />0.0417 hours <br />2.480159e-4 weeks <br />5.7075e-5 months <br /> from reactor shutdown (Ref.
17).
SCE 26426 NEW 4/90
NES&L DEPARTMENT CALCULATION SHEET CCN CONVERSION !
Project or DCP/MMP SONGS 2&3 Calc No. M-DSC-330_
Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No 12 REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE 1RE DATE O P.VALANDANI 5/13/96 ANGEL SISTOS 5/16/96
- 5. METHODOLOGY:
The analysis consists of two parts:
o A global analysis to determine the steady-state water temperature in the transfer tube, assuming a constant decay heat rate.
o A detailed heat transfer analysis of a single fuel rod to determine the maximum temperature at the surface and on the centerline.
5.1- Global Analysis:
)
For a given decay heat rate (Q" per assembly), the steady state temperature in the transfer tube is calculated from the energy balance equation, assuming two fuel assemblies: ;
1 l
20" = m C,(T - T,) (1) where:
Q"= Decay heat rate per assembly m= Mass flow-rate of cooling water by natural circulation C, = Specific heat of water T= Steady-state water temperature in the tube (at the top)
T, = Pool temperature This equation has two unknowns (m and T) which are interdependent. As the water in the transfer tube is heated, it rises to the top of the tube and moves outward until it reaches SCE 26426 NEW 4/90
NES&L DEPARTMENT CALCULATION SHEET ""'
CCN CONVERSION Project or DCP/MMP SONGS 2&3 Calc No. M-DSC-330 su2 ject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 13 REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE IRE DATE O P. VALANDANI 5/13/96 ANGEL SISTOS 5/16/%
l either end of the tube. The warm water then starts to rise to the surface of the pool, forming a column of warm water, similar to the smoke in a chimney. As the warm water leaves the tube (by buoyancy), it is replaced by colder water at the pool temperature (see Fig.4). The velocity of the water is proportional to the square root of the pressure I difference between a column of water at the pool temperature and one at the temperature T (Ref.16). The height of the column is from the top of the transfer tube to the pool surface:
i v = C(2AP/p)'4 (2) where:
v = Velocity p= Density of warm water C = A constant less than one to account for frictional losses.
and:
AP = (p - p,)gH (3) where:
p, = Density of pool water at bulk temperature g= Acceleration of gravity H= Distance from the top of the transfer tube to the pool surface.
Finally:
m = vpA (4)
SCE 26-426 NEW 4/90
NES&L DEPARTMENT CALCULATION SHEET CCN CONVERSION
' Pryject or DCP/MMP SONGS 2&3 Calc No. M-DSC-330 l
, Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 14 l 1
REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE 1RE DATE
, O P. VALANDANI $/13/96 ANGEL SISTOS 5/16/96 l
4 1
0 1
1 1
FIG. 4- NATURAL CIRCULATION PATTERN
! w--- -
.I i
180 F WATER <
i, r
l W=w=r*e -
)
- " "^ *T 160 F WATER 160 F WATER l
l l
i SCE 26-426 NEW 4/90 i.
NES&L DEPARTMENT CALCULATION SHEET CCN CONVERSION Prd^ ect or DCP/MMP SONGS 283 Calc No. M-DSC-330 Subject THERMAL. ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 15 REV ORIGINATOR DATE 1RE DATE REV ORIGINATOR DATE 1RE DATE O P.VALANDANI 5/13/96 ANGEL SISTOS 5/16/96 where:
m= Mass flow-rate A= Flow area The maximum value of A is one half of the cross-sectional area of the tube (hot water moving out through the upper half, and cold water coming in through the lower half of the tube). The actual required flow area is expected to be a small fraction of the available area.
5.2- Analysis of a Sinale Fuel Rod.
l This part of the analysis involves the transfer of heat from the fuel pellets, through the cladding to the surrounding water. Let q" be the rate of decay heat per unit volume of UO2, then:
q" = Q"/N/(nd2U4) (5) where:
Q"= Decay heat rate per fuel assembly N= Number of fuel rods per fuel assembly d= diameter of fuel pellets L= Active length of a fuel rod The temperature distribution in a rod with internal heat generation is (Ref.18):
SCE 26426 NEW 4/90
1 NES&L DEPARTMENT CALCULATION SHEET l CCN CONVERSION l Pr:Joct r CCP/MMP SONGS 2&3 Calc No. M-DSC-330 )
Subject.'MEMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 16 I
REV C AIGINATOR DATE IRE DATE REV ORIGINATOR DATE IRE DATE O P VALANDANI 5/13/96 ANGEL SISToS 5/16/96 2
T = T, + (q"/4k)(r,2 -r) (6) where:
T= Temperature at a distance r from the centerline of the rod.
T, = Surface temperature of the rod.
r, = Ins.de radius of the cladding.
K= Thermal conductivity of UO2.
J i
The heat generated per unit length of the rod is:
q' = q"(nd2/4) (7) <
this heat rate must be equal to the rate of heat transfer to the water. But the heat must pas.s through the cladding, therefore, using the combined resistance of the cladding and the surface, we have (Ref.18):
q' = (2nr o)(T, - T)/(r oLn(r o/r, )/K' + 1/h) (8) where:
r, = Outside radius of the cladding.
K' = Thermal conductivity of the cladding.
h= Heat transfer coefficient.
The heat transfer coefficient for free convection involving horizontal tubes can be obtained from (Rt' 18, p. 342):
SCE 26426 NEW 4/90
NES&L DEPARTMENT CALCULATION SHEET '
CCN CONVERSION Project or DCP/MMP SONGS 2&3 Calc No. M-DSC-330 .
Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 17 REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE IRE DATE O P. VALANDANI 5/13/96 ANGEL SISTOS 5/16/96 N, = 0.53(Gro Pr)'" (9) where:
No = hd/K" = Nusselt number.
Gro = Grashoff number.
f Pr = Prandtl number.
Using the above 9 equations, it is possible to calculate the following for steady-state conditions:
o Maximum temperature in the fuel.
o Surface temperature of the fuel.
o Maximum water temperature in the transfer tube, o Rate of flow due to natural convection.
The problem is ideally suited for a spreadsheet program where various assumptions can be examined and an ite/ative solution be obtained.
SCE 26-426 NEW 4/90
NES&L DEPARTMENT CALCULATION SHEET CCN CONVERSION Pr$ct or DCP/MMP SONGS 2&3 Calc No. M-DSC-330 Subject THERMAL Ab; ALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 18 REV ORIGINAT.JR DATE IRE DATE REV ORIGINATOR DATE tRE DATE O P. VALANDANI 5/13/96 ANGEL slSToS 5/16/96 6.REFERENCESl
- 1. UFSAR Section 9.1, " Spent Fuel Storage", Rev. 11,3/18/96.
- 2. Letter from R. Y. Chang to B. Conklin, dated August 27,1991.
Subject:
" Fuel Assembly Decay Heat, San Onofre Units 2 and 3."
- 3. DBD-SO23-TR-PL, Rev. O, Plant -Level Design Bases Document.
- 4. SO23-3-2.11, Spent Fuel Pool Operations.
- 5. SD-SO23-360 System Description, Reactor Coolant System.
- 6. Drawing SO23-990-133-2, Fuel Bundle Assembly.
- 7. Drawing SO23-990-32-0, Fuel Rod Assembly.
- 8. Drawing SO23-411-55-129-2, Install: Fuel Transfer Tube Rail Assembly Unit 3 and SO23-411-55-72-3 for Unit 2.
- 9. Drawing SO23-900-C-4-6, Rev.10, Reactor Refueling Arrangement.
- 10. Drawing SO23-910-9, Dimension Outline 16x16 Fuel Bundle 3410 MWT.
- 11. Drawing SO23-411-55-166-1 Install: Fuel Carrier Assembly.
- 12. Drawing #23065-14, Containment Structure, Fuel Transfer Assembly.
- 13. SO23-939-150, Vendor drawing #AD-18895D, Lower Cavity Assembly.
- 14. SO23-939-148-1, Vendor drawing #AD-24424D, Upper Cavity Assembly.
- 15. " Handbook of Tables for Applied Engineering Science", The Chemical Rubber Company,1970.
l SCE 26-426 NEW 4/90 l
NES&L DEPARTMENT l CALCULATION SHEET CCN CONVERSION Pr: Ject or DCP/MMP SONGS 283 Calc No M-DSC-330 l Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 19 l l
REV ORIGINATOR DATE IRE D*.TE REV ORIGINATOR DATE IRE DATE l 0 P. VALANDANI 'J13/96 ANGEL SISTOS 5/16/96 !
- 16. " Standard Handbook of Engineering Calculations", McGraw-Hill Book Co.,1972. l
- 17. Decay Heat Management Practices During Refueling Outage, Doc. No: IN 95-54, I Independent Safety Engineering Group Operating Experience Evaluation, March )
29,1996.
- 18. Pn'nciples of Heat Transfer, Frank Kreith, International Textbook Company,1966.
- 19. Steam /Its Generation and Use, Babcock and Wilcox,1975.
- 20. ASME Steam Tables, fifth edition,1983. I 1
l l
l l
I l
l l
SCE 26426 NEW 4/90
NES&L DEPARTMENT CALCULATION SHEET CCN CONVERSION Project or DCP/MMP SONGS 2&3 Calc No. M-DSC-330 Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 20 REV ORIGINATOR DATE 1RE DATE REV ORIGINATOR DATE IRE DATE O P. VALANDANI 5/13/96 ANGEL SISTOS 5/16/96
- 7. NOMENCLATURE:
Symbol Descriotion Units A Flow or heat transfer area ft^2 C, Specific heat at constant P Btu /lb/F D Transfer tube diameter ft d Diameter of fuel pellets ft y Acceleration of gravity ft/sec^2 ge Conversion factor 32.2 lb/ slug Gr, Grashoff number Dimensionless H Submergence of top of tube ft h Heat transfer coefficient Btu /hr/ft^2/F K Thermal conductivity of UO2 Btu /hr/ft/F K' Thermal conductivity of Zr4 Btu /hr/ft/F K" Thermal conductivity of H2O Btu /hr/ft/F L Active length of fuel rod ft m Mass flow rate Ib/hr Nu Nusselt number Dimensionless Pr Prandtl number Dimensionless Q" Decay heat rate per assembly Btu /hr/ assembly q' Decay heat per unit length Btu /hr/ft q" Decay heat per unit volume Btu /hr/ft^3 r Distance fro the centerline of rod ft r, inside radius of cladding ft SCE 26-426 NEW 4/90
NES&L DEPARTMENT CALCULATION SHEET CCN CONVERSION Prsject or DCP/MMP SONGS 2&3 Calc No M-DSC-330 l
Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 21
. REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE 1RE DATE O P. VALANDANI 5/13/96 ANGEL SISTOS 5/16/96 Symbol Descriotion Units 4
r, Outside radius of cladding ft p Density Ib/ft^3 i
T Maximum water temperature F T, Pool temperature F 1
T, Interface temperature F
, V Volume ft^3 v Velocity ft/sec I I
a i
I SCE 26-426 NEW 4/90
NES&L DEPARTMENT CALCULATION SHEET '""""
i CCN CONVERSION Project or DCP/MMP SONGS 2&3 Calc No. M-DSC-330 Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 22 REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE IRE DATE O P.VALANDANI S/13/96 ANGEL slSToS S/16/96 '
l r ,
I
)
- 3. CALCULATIONS:
A spreadsheet program was developed to calculate the following for any given maximum water temperature:
o Water flow rate, and the corresponding flow area as a percentage of the transfer tube cross-sectional area.
o Maximum temperature at the surface of the fuel rods. l o Maximum temperature at the interface of UO2 and cladding.
o Maximum temperature at the centerline of any fuel rod.
The results are shown in Table 1. The input quantities, including properties and design input values are listed at the top of the Table. The first quantity in the table is the number of hours since reactor shut down (150 hour0.00174 days <br />0.0417 hours <br />2.480159e-4 weeks <br />5.7075e-5 months <br />) and the second one is the corresponding heat rate in Btu /hr for two assemblies. The third entry is the assumed maximum water temperature in the tube (180 F). The fourth entry is the delta density between 180 F water and 160 f water, in Ib/cu. ft. The fifth entry is the delta p corresponding to a U tube with a height of H = 30.75 ft (distance between the top of the transfer tube and the pool surface),
filled with water, with one side at 180 F and the other side at 160 F. This delta P is only 13.069 psf, but it is sufficient to create a velocity of 3.715 ft/sec. To be on the conservative side, we take only one fifth of that (C = .2 in the F column), or 0.743 ft/sec. Based on this SCE 26-426 NEW 4/90
m 0 o D 1"
7
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TABLE 1- SPREAD SHEET CALCULATION OF FUEL, CLADDING AND WATER TEMPERATURES f
_2 3 $ "o S Io 3 ================================================_____============================ $
INPUT QUANTITIES m m g pm
_4 5 WATER
================ ,
g g g
% qy FUEL CLADDING _
6 ========================== =======================
p -t g
======================= 2
_7 TP = 160 F CP UO2= 0.056 BTU /LB/F CP ZR4=
Ln g m 0.073 BTU /LB/F
} p 8
9 CP H20=
RO H20=
1 BTU /LB/F 61.01 LB/CU. FT RO UO2=
K 002=
647 LB/CU.FT RO ZR4= 412 LB/CU.FT m -t I Z$
4 BTU /HR/FT/F K ZR4= 8.4 B/HR/FT/F 10 K H20= 0.39 BTU /HR/FT/F Q150= ZRID=
$ g H= 336000 BTU /HR (2 BNDL) 0.028 FT g o 11 30.75 FT Q72 = 458000 BTU /HR (2 BNDL) ZR OD= 0.032 FT y
6 @
12 ID TUBE = 2.96 FT LACTIVE= 12.47 FT g 5" 8 13 LTUBE= 44.60 FT m 6 NRODS= 236 PER 14 _ PR = 2.22 Arod= 0.000601 FT^2 d g
15 16 GR/DT/d^ 8.4E+08 Vfuel= 3.537504 FT^3 2 BUNDLES m
Q g
Vrod= 0.007495 FT^3 17 d 18 HOURS Q T DRO DP C v A one side % TOTAL TS TC 19 Btu /hr Ib/ft^3 psf ft/sec ft^2 o y 20 F g
==============.,==================================================================F g 21 150 336000
====. y i 180 0.425 13.069 0.2 0.743 0.051 0.728 22 23 184.1 185.3 m
{; g o "
24_ T Gr Nu h Tclad 25 ===================================_______. 3 26 180 108647.2 11.7 143.9 g 3 5 184.0 m 5 5
m m
NES&L DEPARTMENT l' CALCULATION SHEET CCN CONVERSION Pr: Ject or DCP/MMP SONGS 2&3 Calc No. M-DSC-330 Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 24 4 REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE IRE DATE O P. VALANDANI 5/13/96 ANGEL SISTOS 5/16/96 4
i velocity, we calculate a flow area needed to remove all the heat generated by the two fuel assemblies. This calculated flow area is less than 1% of the total flow area of the tube, which shows that only a thin layer of hot water needs to exit the tube and rise to the 2
surface of the pool, in order to have sufficient cooling.
i
{' The maximum temperatures at the surface of the fuel rod, at the interface of UO2 and Zr cladding, and the centerline of the fuel are calculated for the worst case, i.e. the top fuel rods that are in contact with water at 180 F. The results are:
Maximum Fuel rod surface temperature = 184.0 F (cell E26)
)
Maximum interface temperature (UO2 and Zr) =184.1 F (cell j21)
Maximum temperature inside fuel = 185.3 F (cell K21)
. The formulas used in this analysis were developed in Section 5 and are also listed in Table 3 for ease of reference.
Following is a step by step calculation of the quantities shown in Table 1:
i
- 1. Number of hours = 150 (Assumption, supported by Ref.17)
- 2. Q = 2x1.68E05 Btu /hr (Design input)
- 3. T = 180 F Assumed and later verified.
4 SCE 26-426 NEW 4/90 a
i l NES&L DEPARTMENT CALCULATION S H E ET j""" '
CCN CONVERSION Pr: Ject or DCP/MMP SONGS 2&3 Calc No. M-DSC-330 Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 25 l
REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE IRE DATE O P. VALANDANI 5/13/96 ANGEL SISTOS 5/16/96 l
- 4. Delta Rho, or change in density, from 180 F to 160 F is (Ref. 20) :
1/0.016395 - 1/0.016510 = .425 lb/ft
- 5. Delta P, The pressure difference is based on the above delta Rho, the acceleration of gravity (32.2 ft/sec2 ), and the submergence H = 31.25 ft:
Delta P = .425 *32.2* 31.25/32.2 (Ib/ slugs) = 13.3 psf (or 0.092 psi)
- 6. The constant C is a measure of the efficiency of the conversion of daltc P to velocity A very conservative value of 0.2 (20%)is used. This value only affects the required flow area.
- 7. The yelocity is calculated from the following equation:
v = C(2 GAP /p)"
=0.2(2*32.2*13.3/60)%
=0.755 ft/sec
- 8. The required flow area (for one side) is obtained from the energy balance equation:
Q" = pvAC,(T - T,)
A = Q"/pvC,(T - T,)
2
=168000/(60*0.755*3600*1*(180-160)) = 0.0515 ft SCE 26-426 NEW 4/90
NES&L DEPARTMENT CALCULATION SHEET CCN CONVERSION l
Prsject or DCP/MMP SONGS 2&3 Calc No M-DSC-330 i l
Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 26 REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE IRE DATE O P. VALANDANI 5/13/96 ANGEL SISTOS 5/16/96
- 9. Percent total available area is:
100*A/(nD2/4) = 100*0.0515/(3.14*8.75/4) = 0.71% or <1%
- 10. The next item is Gr on line 26. Since Gr depends on the temperature difference between the fluid and the surface, it has to be calculated by trial and error. We skip the intermediate steps and start with the final answer which is a surface temperature of 184 F. The value of Gr/(d (AT)) = 8.42E08 is obtained from Ref.18 for 182 F, therefore:
Gr = 8.42E08*.032*.032*.032*4 = 110,360 The difference between this number and the number in Table 1 is due to rounding off the numerical value of d.
- 11. Using the calculated Gr and Pr = 2.22 from Ref.18, we calculate the Nu:
Nu = 0.53*(Gr*Pr) "
= 0.53*(110360*2.22)'"
= 11.792 A
- 12. The heat transfer coefficient is calculated from the definition of Nu:
Nu = hd/K" SCE 26-426 NEW 4/90
NES&L DEPARTMENT
. CALCULATION SHEET
+
CCN CONVERSION Project or DCP/MMP SONGS 2&3 Calc No. M-DSC-330 Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 27 RE\' ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE IRE DATE
< 0 P. VALANDANI 5/13/96 ANGEL SISTOS 5/16/96 4
c h = Nu*k"/d
- h = 11.792*0.39/.032 = 143.7 Btu /hr-ft2 .p
- 13. Now the surface temperature can be calculated and compared with the assumed value of 184 F. We need the rate of decay heat per unit length of the fuel:
q' = O"/N/L j q' = 168000/236/12.47 = 57.1 Btu /ft But: q' = hA(Tc - T) Where A is per unit length (nd).
- or Tc = T +q'/hA = 180 + 57.1/(143.7*3.1416*0.032) =183.95 or 184 F
- 14. Now we can go back to line 21 and calculate the interface temperature between UO2 and Zr4:
T, = T + q' (r oLn(r o/r, )/K' + 1/h)/nd
= 180 + 57.1(.5*.032Ln(.032/.028)/8.4 + 1/143.7) /(3.1416*.032)
- = 184.1 F
- 15. Finally the temperature at the center of the fuel rod is calculated:
T = T, + (q"/4k)r,2 Where:
q" =q'/ (nd: /4) = 57.1/( 3.1416*.028*.028/4) = 92732 Btu /hr/ft SCE 26-426 NEW 4/90
NES&L DEPARTMENT '
CALCULATION SHEET CCN CONVERSION l Project or DCP/MMP SONGS 2&3 Calc No M-DSC-330 l su2 Ject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No. 28 REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE IRE DATE 1
0 P.VALANDANI S/13/96 ANGEL SISTOS 5/16/96 T = 184.1 + (C2732/4/4)*.028*.028/4 = 185.24 F Since these results show a comfortable margin of more than 30 degrees from boiling, it j was decided to run a case where the off-load takes place only 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after shutdown l (see Table 2). The only difference in this case is the heat load, which is about 30% higher.
The results are not significantly different from the standard case. The flow area is about 30% higher (as expected) but still less than 1% of the transfer tube flow area. The calculated temperatures are one or two degrees higher than before, but the margin is still about 30 degrees, and if the saturation temperature corresponding to the local pressure is used, the margin is more than 60 degrees.
The above results correspond to steady-state conditions and show that a small delta T of a few degrees is needed to remove the decay heat. If the fuel assembly is initially at a higher temperature, the heat loss to the water will exceed the decay heat rate, and the fuel assembly will cool off until the steady-state temperature is reached. At that point the rate of decay heat is balanced with the rate of heat removal.
The results show that the system is capable of handling two fuel assemblies simultaneously and to remove the decay heat, without boiling, should the assemblies become stuck in the transfer tube for an extended period of time.
SCE 26-426 NEW 4/90 j
m m m
=
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2 3-TABLE 2- SPREAD SHEET CALCULATION OF FUEL, CLADDING AND WATER TEMPERATURES (72 HOURS)
=====================================================================================.
g g o m A
z yyy INPUT QUANTITIES P 4
5 WATER
====
FUEL m
m M
c m
n l-QEzm 6 CLADDING o r z -4
========================== ======================= "
~7 TP = 160 F CP UO2= 0.056 BTU /LB/F
======================= $
8 CP ZR4= 0.073 BTU /LB/F CP H20= 1 BTU /LB/F @ ?:
N RO UO2= 647 LB/CU.FT RO ZR4=
9 RO H20= 61.01 LB/CU. FT K UO2=
412 LB/CU.FT g g q @
4 BTU /HR/FT/F K ZR4-10 K H20=
11 _ H=
0.39 BTU /HR/F'.F 30.75 FT Q150= 336000 BTU /HR (2 BNDL) ZRID=
8.4 B/HR/FT/F 0.028 FT R a g y
o Z
12 ID TUBE = 2.96 FT G72 =
LACTIVE=
458000 BTU /HR (2 BNDL) 12.47 FT ZR OD= 0.032 FT C E 13 LTUBE= 44.60 FT NRODS= iR $ M 236 PER <
14 15 PR =
GR/DT/d^; 8.4E+08 2.22 Arod= 0.000601 FT^2 q Vfuel= 3.537504 FT^3 2 BUNDLES 16 Vrod= p; 0.007495 FT^3 17 @ 9 18 HOURS O T E 5 DRO DP C v A one side % TOTAL TS TC 5 * '
19 Btu /hr Ib/ft^3 psf ft/sec ft^2 F F o 8 20- "
21
====================================================================================== g O 72 458000 180 0.425 13.069 0.2 0.743 0.070 0.993 185.3 186.9 22 8 23 5 24 T Gr Nu h Tclad k 5
25 9
===============================
26 180 135809 12.4 152.2 185.1 m
M
NES&L DEPARTMbN I CALCULATION SHEET CCN CONVERSION Project or DCP/MMP SONGS 2&3 Calc No. M-DSC-330 Subject THERMAL ANALYSIS OF SPENT FUEL TRANSFER TUBE Sheet No 30 REV ORIGINATOR DATE IRE DATE REV ORIGINATOR DATE IRE DATE O P. VALANDANI 5/13/96 ANGEL SISTOS 5/16/96 l
l Table 3- Formulas used in the Soreadsheet Proaram l
A:A21: 150 ,
A.B21: +F10 l A:C21: 180 A:D21: +0.425*(C21-$B$7)/20 A:E21: +D21*$B$11 A:F21: 0.2 A:G21 +F21*@SQRT(2*32.2*E21/$B$9)
A:H21: + B21/(2*3600*$ 859*G21 *$ 858 *(C21 -$ B$7))
A:121: +100*H21/(9*3.1416/4)
A:J21: +C21 +(B21 *$ FS 14/$FS 15)*(0. 5*$J S 1 1 *@LN($J$ 1 1/5J$ 10)/$J$ 9+ 1/D26)/(3.1416*$JS 1 1 )
A:K21: +J21 +(B21/$ FS 15)*($JS 10*$J S 10/4)/(4*$ F$ 9)
A:A26: +C21 A:B26: +$B$15*$JS11*$JS11*$JS11*4 A:C26: +0.53*(B26*$BS14)^0.25 A:D26: +C26*$8510/$JS11 A:E26: + A26 +($ B$21 *$ F $ 14/$ F$ 15)/D26/( 3.1416*$ J S 1 1 )
SCE 26-426 NEW 4/90
-