ML092520265

Attachment 3, Corrected Pages to WCAP-17072-NP (Non-Proprietary)

ML092520265
Person / Time
Site:	Byron, Braidwood
Issue date:	09/04/2009
From:	Exelon Generation Co, Exelon Nuclear
To:	Office of Nuclear Reactor Regulation
References
RS-09-120 WCAP-17072-NP
Download: ML092520265 (24)

Text

Attachment 3 Corrected Pages to WCAP-17072-NP (Non-Proprietary)

1-5 Prior calculations assumed that contact pressure from- the tube would expand the tubesheet bore uniformly without considering the restoring forces from adjacent pressurized tubesheet bores. In the structural model, a tubesheet radius dependent stiffness effect is applied by modifying the representative collar thickness (see Section 6.2.4) of the tubesheet material surrounding a tube based on the position of the tube in the bundle. The basis for the radius dependent tubesheet stiffness effect is similar to the previously mentioned "beta factor" approach. The "beta factor" was a coefficient applied to reduce the crevice pressure to reflect the expected crevice pressure during normal operating conditions in some prior H*

calculations and is no longer used in the structural analysis of the tube-to-tubesheet joint. The current structural analysis consistently includes a radius dependent stiffness calculation described in detail in Section 6.2.4. The application of the radius dependent stiffness factor has only a small effect on the ultimate value of H* but rationalizes the sensitivity of H* to uncertainties throughout the tubesheet.

The contact pressure analysis methodology has not changed since 2007 (Reference 1-9). However, the inputs to the contact pressure analysis and how H* is calculated have changed in that period of time. The details describing the inputs to the contact pressure analysis are discussed in Section 6.0.

The calculation for H* includes the summation of axial pull out resistance due to local interactions between the tube bore and the tube. Although tube bending is a direct effect of tubesheet displacement, the calculation for H* conservatively ignores any additional pull out resistance due to tube bending within the tubesheet or Poisson expansion effects acting on the severed tube end. In previous submittals, the force resisting pull out acting on a length of a tube between any two elevations hi and h2 was defined in Equation (1-1):

2 Fl = (h 2 - h,)FHE + txdJ Pdh where:

FHtE = Resistance per length to pull out due to the installation hydraulic expansion, d = Expanded tube outer diameter, P = Contact pressure acting over the incremental length segment dh, and,

= Coefficient of friction between the tube and tubesheet, conservatively assumed to be 0.2 for the pull out analysis to determine H*.

The current H* analysis generally uses the following equation to determine the axial pull out resistance of a tube between any two elevations hi and h2:

K 1 a,c,e (1-2)

Where the other parameters in Equation (1-2) are the same as in Equation (1-1) and

]apc e A detailed explanation of the WCAP- 17072-NP May 2009 Revision 0

1-6 revised axial pull out equation are included in Section 6.0 of this report. However, the reference basis for the H* analysis is the assumption that residual contact pressure contributes zero additional resistance to tube pull out. Therefore, the equation to calculate the pull out resistance in the H* analysis is:

h, F, =/pri dfPdh h, (1-3) 1.3.2 Leakage Integrity Analysis Prior submittals of the technical justification of H* (Reference 1-9) argued that K was a function of the contact pressure, P,, and, therefore, that resistance was a function of the location within the tubesheet.

The total resistance was found as the average value of the quantity /uK, the resistance per unit length, multiplied by L, or by integrating the incremental resistance, dR = /K dL over the length L, i.e.,

R = .K (L 2 - LI) = A KdL (1-4)

Interpretation of the results from multiple leak rate testing programs suggested that the logarithm of the loss coefficient was a linear function of the contact pressure, i.e.,

InK =a, +alP,, (1-5) where the coefficients, ao and a, of the linear relation were based on a regression analysis of the test data; both coefficients are greater than zero. Simply put, the loss coefficient was determined to be greater than zero at the point where the contact pressure is zero and it was determined that the loss coefficient increases with increasing contact pressure. Thus, K = ea°+-lec (1-6) and the loss coefficient was an exponential function of the contact pressure.

The B* distance (LB) was defined as the depth at which the resistance to leak during SLB was the same as that during normal operating conditions (NOP) (using Equation 1-4, the B* distance was calculated setting RSLB = RNOP and solving for LB). Therefore, when calculating the ratio of the leak rate during the design basis accident condition to the leak rate during normal operating conditions, the change in magnitude of leakage was solely a function of the ratio of the pressure differential between the design basis accident and normal operating plant conditions.

The NRC Staff raised several concerns relative to the credibility of the existence of the loss coefficient versus contact pressure relationship used in support of the development of the B* criterion:

WCAP- 17072-NP May 2009 Revision 0

1-13 Table 1-1 List of Conservatisms in the H* Structural and Leakage Analysis (Continued)

Assumption/Approach Why Conservative?

A [ This is conservative because it reduces the stiffness of the solid and perforated regions of the tubesheet to the lowest level for each operating condition (see Section 6.2.2.2.2).

a,c,e Pressure is not applied to the Applying pressure to the

]..... (see Section 6.2.2.2.4).

The radius dependent stiffness Including these structures in the analysis would reduce the tubesheet displacement and limit the local deformation of the analysis ignores the presence of tubesheet hole ID (see Section 6.2.4.4).

the [

]a,c,e The tubesheet bore dilation [ Thermal expansions under operating loads were

]a..ce (see Section 6.2.5).

2250 (NOP conditions).

WCAP- 17072-NP May 2009 Revision 0

5-3 5.3 CALCULATION OF APPLIED END CAP LOADS The tube pull out loads' (also called end cap loads) to be resisted during normal operating (NOP) and faulted conditions for the bounding Model D5 plant (Byron Unit 2 , Braidwood Unit 2) for the hot leg are shown below. End cap load is calculated by multiplying the required factor of safety times the cross-sectional area of the tubesheet bore hole times the primary side to secondary side pressure difference across the tube for each plant condition.

AP (psi) (Ppi- Area (in 2 ) End Cap Factor of H* Design End Operating Condition (Note 1) Load Safety ap Load (Lbs.)

Psec) ((lbs.)

a,c,e Normal Op. (maximum)

Faulted (FLB)

Faulted (SLB)

Faulted (Locked Rotor)

Faulted (Control Rod Ejection)

Notes:

Tubesheet Bore Cross-Sectional Area = ]a,c,e 1.

The above calculation of end cap loads is consistent with the calculations of end cap loads in prior H*

justifications and in accordance with the applicable industry guidelines (Reference 5-3). This approach results in conservatively high end cap loads to be resisted during NOP and faulted conditions because a cross-sectional area larger than that defined by the tubesheet bore mean diameter is assumed.

The end cap loads noted above include a safety factor of 3 applied to the normal operating end cap load and a safety factor of 1.4 applied to the faulted condition end cap loads to meet the associated structural performance criteria consistent with NEI 97-06, Rev. 2 (Reference 5-3).

Seismic loads have also been considered, but they are not significant in the tube joint region of the tubes (Reference 5-1).

H* values are not calculated for the locked rotor and control rod ejection transients because the pressure differential across the tubesheet is bounded by the FLB/SLB transient. For plants that have a locked rotor with stuck open PORV transient included as part of the licensing basis, this event is bounded by the FLB/SLB event because the peak pressure during this transient is significantly less than that of the The values for end cap loads in this subsection of the report are calculated using an outside diameter of the tube equal to the mean diameter of the tubesheet bore plus 2 standard deviations.

May 2009 17072-NP WCAP- 17072-NP May 2009 Revision 0

5-5 Table 5-1 Operating Conditions - Model D5 H* Plant Plant Parameter and Units Byron Unit 2 and Catawba Unit 2(2) Comanche Peak Unit 2(3)

Braidwood Unit 2(_)_ _ _ _ _

Power NSSS -

MWt 3600.6 3499 3628 Primary Pressure psia 2250 2250 2250 Psia (Low Tavg/ a,c,e S e c on da ry Pr e s s u re HighYTv,)

High T a , 9) ____ _

Reactor Vessel Outlet 'F (Low Tavg/

Temperature High Tavy)

SG Primary-to- Psid (Low Tavg/

Secondary Pressure High Tavg)

Differential (psid) HighTa__)

(1) PCWG-274 1, Bryon/Braidwood Units 1 and 2 (CAE/CBE/CCE/CDE) "Approval of Category IV PCWG Parameters to Support an Uprating Program," March 22, 2002.

(2) CN-SGDA-03-85, "Input Data for the H*/P* Effort Pertaining to Both Model D-5 and Model F Steam Generators," September 30, 2003.

(3)PCWG-06-35, Rev. 1, "Comanche Peak Units 1 & 2 (TBX/TCX): Approval of Category III (for Contract) PCWG Parameters to Support the Uprate Program," October 3, 2006.

WCAP- 17072-NP May 2009 Revision 0

5-6 Table 5-2 Steam Line Break Conditions Byron Unit 2 and Catawba Unit 2 Comanche Peak Parameters and Units~l) Braidwood Unit 2 Unit 2 Peak Primary-Secondary Pressure (psig) 7 -_ a,c,e Primary Fluid Temperature (0 F) (HL and CL)

Secondary Fluid Temperature (0F) (HL and CL)

( All Model D5 H* plants are 4-loop plants.

HL - Hot Leg CL - Cold Leg WCAP- 17072-NP May 2009 Revision 0

5-7 Table 5-3 Feedwater Line Break Conditions Byron Unit 2 and Catawba Unit 2 Comanche Peak Parameters and Units Braidwood Unit 2 Unit 2 Peak Primary-Secondary Pressure (psig) [,c,e Primary Fluid Temperature ('F)

(No load - HL and CL)

Secondary Fluid Temperature ('F) (HL and CL)

HL - Hot Leg CL - Cold Leg WCAP-17072-NP May 2009 Revision 0

5-8 Table 5-4 Locked Rotor Event Conditions Byron Unit 2 and Comanche Peak Parameters and Units ParametersandUnits_ Braidwood Unit 2(1) Catawba Unit 2(1) Unit 2()

Peak Primary-Secondary Pressure (psig) F a,c,e Primary Fluid Temperature (OF)* (HL/CL)

Secondary Fluid Temperature (OF)* (HL and CL)

Primary Fluid Temperature (OF)** (HL and CL)

Secondary Fluid Temperature (OF)** (HL and CL)

( Active Loop

• Low Tavg

• • High Tavg HL - Hot Leg CL - Cold Leg NA - Not Applicable WCAP- 17072-NP May 2009 Revision 0

5-9 Table 5-5 Control Rod Ejection P Byron Unit 2 and Catawba Unit 2 Comanche Peak Parameters and Units Braidwood Unit 2 Unit 2 Peak Primary-Secondary Pressure (psig) - a,c,e Primary Fluid Temperature (OF)* (HL and CL)

Secondary Fluid Temperature (OF)* (HL and CL)

Primary Fluid Temperature (OF)** (HL and CL)

Secondary Fluid Temperature (OF)** (HL and CL)

• Low Tavg

• • High Tavg HL - Hot Leg CL - Cold Leg NA - Not Applicable WCAP-17072-NP May 2009 Revision 0

5-10 Table 5-6 Design End Cap Loads for Normal Operating Plant Conditions, Locked Rotor and Control Rod Ejection for Model D5 Plants Low Tavg High Tavg Control Rod Ejection Plant End Cap Load End Cap Load Locked Rotor End Cap Load w/Safety Factor w/Safety Factor End Cap Load (lbf)

(lbf) (lbf) (lbf)

Byron Unit 2 and ac'e Braidwood Unit 2 Catawba Unit 2 Comanche Peak Unit 2 L I WCAP-17072-NP .May 2009 Revision 0

6-10 Therefore, hnominal = [ ]a,c,e inch (i.e., [ ]a,c,e and i = []a¢' when the tubes are not included. From Slot (Reference 6-5), the in-plane mechanical properties for Poisson's ratio of 0.3 are:

Property Value a,c,e E; E, V -

Gp/ Gp E** Ey y y Gy Gy Elastic modulus of solid material where the subscripts P, d and y refer to the pitch, diagonal and thickness directions, respectively. These values are substituted into the expressions for the anisotropic elasticity coefficients given previously. The coordinate system used in the analysis and derivation of the tubesheet equations is given in Reference 6-4.

Using the equivalent property ratios calculated above in the equations presented at the beginning of this section yields the elasticity coefficients for the equivalent solid plate in the perforated region of the tubesheet for the finite element model.

The three-dimensional structural model is used in two different analyses: 1) a static structural analysis with applied pressure loads at a uniform temperature and 2) a steady-state thermal analysis with applied surface loads. The solid model and mesh is the same in the structural and thermal analyses but the element types are changed to accommodate the required degrees of freedom (e.g., displacement for structural, temperature for thermal) for each analysis. The tubesheet displacements for the perforated region of the tubesheet in each analysis are recorded for further use in post-processing. Figure 6-2 and Figure 6-3 are screen shots of the three-dimensional solid model of the Model D5 SG. Figure 6-4 shows the entire 3D model mesh.

WCAP- 17072-NP May 2009 Revision 0

6-18 ace K

with the elasticity coefficients calculated as:

I a,c,e I I I 1 a,c,e E J a,c,e a,c,e a,c,e I I and I I where I ] a,c,e and I ] a,c,e The variables in the equation are:

= Effective elastic modulus for in-plane loading in the pitch direction,

= Effective elastic modulus for loading in the thickness direction, v- = Effective Poisson's ratio for in-plane loading in the thickness direction, GUp = Effective shear modulus for in-plane loading in the pitch direction,

,z = Effective shear modulus for transverse shear loading, Ed = Effective shear modulus for in-plane loading in the diagonal direction, vd = Effective Poisson's ratio for in-plane loading in the diagonal direction, and, v = Poisson's ratio for the solid material, E = Elastic modulus of solid material, yRz = Transverse shear strain rRz = Transverse shear stress,

[D] = Elasticity coefficient matrix required to define the anisotropy of the material.

WCAP- 17072-NP May 2009 Revision 0

6-21 Table 6-6 Summary of H* Byron Unit 2 Analysis Mean Input Properties Plant Name Byron 2 Plant Alpha CBE Plant Analysis Type Hot Leg SGTye D5 Input a Vdalue T e unit IRefeence A ccident and Normal Temnerature InDuts FLB Prim AT SLB Prim AT SLB :Secondary AT Secondaiy Shell AT Hi

.Secondary Shell AT Low Czold Leg AT Hot StandlbTemperature WCAP- 17072-NP May 2009 Revision 0

6-22 Table 6-7 List of SG Models and H* Plants With Tubesheet Support Ring Structures General Plant Alpha SG Model TS Support Ring? Arrangement Drawing Braidwood - 2 CDE D5 [ _ a,c,e 1103 J99 Sub 3 Byron - 2 CBE D5 1103J99 Sub 3 SAP - Use Callaway (SCP)

Wolf Creek - 2 SG Drawings F 1104J54 Sub 2

.PSE - Use Seabrook -2 (NCH) SG Salem - 1 Drawings F 1104J86 Sub 9 Surry- 1 VPA*** 51F 1105J29 Sub 3 Surry - 2 VIR*** 51F 1105J29 Sub 3 Turkey Point - 4 FLA*** 44F 1105J45 Sub 3 Millstone - 3 NEU F 1182J08 Sub 8 Comanche Peak - 2 TCX D5 1182J16 Sub 1 Vandellos - 2 EAS F 1182J34 Sub 1 Seabrook- 1 NAH F 1182J39 Sub 3 Turkey Point- 3 FPL** 44F 1183J01 Sub 2 Catawba - 2 DDP D5 1183J88 Sub 2 Vogtle - 1 GAE F 1184J31 Sub 13 Vogtle - 2 GBE F 1184J32 Sub1 Point Beach - 1 WEP** 44F 1184J32 Sub 1 Robinson - 2 CPL** 44F 6129E52 Sub 3 Indian Point - 2 IPG 44F 6136E16 Sub 2

• • Model 44 F - These original SGs have been replaced.

• • • Model 51F - These original SGs have been replaced.

WCAP- 17072-NP May 2009 Revision 0

6-29 Table 6-8 Conservative Generic NOP Pressures and Temperatures for 4-Loop Model F (These values do not exist in operating SG and are produced by examining worst-case comparisons.)

Normal Operating, Bounding a,c,e Secondary Surface Temperature Primary Surface Temperature Cold Leg Hot Leg Primary Pressure Cold Leg Hot Leg Secondary Pressure End Cap Pressure Structural Thermal Condition Reference Temperature Table 6-9 Generic NOP Low Tavg Pressures and Temperatures for 4-Loop Model F Normal Operating, Low Tav, a,c,e Secondary Surface Temperature Primary Surface Temperature Cold Leg Hot Leg Primary Pressure Cold Leg Hot Leg Secondary Pressure End Cap Pressure Structural Thermal Condition Reference Temperature Table 6-10 Generic NOP High Tavg Pressures and Temperatures for 4-Loop Model F Normal Operating, High Tavg a,c,e Secondary Surface Temperature Primary Surface Temperature Cold Leg Hot Leg Primary Pressure Cold Leg Hot Leg Secondary Pressure End Cap Pressure Structural Thermal Condition Reference Temperature WCAP- 17072-NP May 2009 Revision 0

6-30 Table 6-11 Generic SLB Pressures and Temperatures for 4-Loop Model F Main Steam Line Break a,c,e Secondary Surface Temperature Primary Surface Temperature Cold Leg Hot Leg Primary Pressure Cold Leg Hot Leg Secondary Pressure End Cap Pressure Structural Thermal Condition Reference Temperature Table 6-12 Generic FLB Pressures and Temperatures for 4-Loop Model F Feedwater Line Break a,c,e Secondary Surface Temperature Primary Surface Temperature Cold Leg Hot Leg Primary Pressure Cold Leg Hot Leg Secondary Pressure End Cap Pressure Structural Thermal Condition Reference Temperature Table 6-13 Conservative Generic SLB Pressures and Temperatures for 4-Loop Model F (These values do not exist in operating SG and are produced by examining worst-case comparisons.)

Main Steam Line Break, High Temp a,c,e Secondary Surface Temperature Primary Surface Temperature Cold Leg Hot Leg Primary Pressure Cold Leg Hot Leg Secondary Pressure End Cap Pressure Structural Thermal Condition Reference Temperature I _L_ J WCAP- 17072-NP May 2009 Revision 0

9-24 Table 9-1 Reactor Coolant System Temperature Increase Above Normal Operating Temperature Associated With Design Basis Accidents (References 9-12 and 9-13)

Steam Locked Rotor Locked Rotor Line/Feedwater (Dead Loop) (Active Loop) Control Rod Ejection Line Break SG Type SG Hot SG Cold SG Hot SG Cold SG Hot SG Cold SG Hot S Leg (°F) Leg (°F) Leg (OF) Leg (°F) Leg (OF) Leg (OF) Leg (OF)

Model F F a,c,e Model D5 Model 44F Model 51F

• Best estimate values for temperature during FLB/SLB are used as discussed in Section 9.2.3.1.

WCAP-17072-NP May 2009 Revision 0

9-25 Table 9-2 Reactor Coolant Systems Peak Pressures During Design Basis Accidents (References 9-12 and 9-13)

Steam Line Feedwater Line Locked Rotor Control Rod Ejection SG Type Break (psia) Break (psia) (psia) (psia)

Model D5 a,c,e F/

Model F Model 44F Model 51F WCAP-17072-NP May 2009 Revision 0

9-26 Table 9-3 Model F Room Temperature Leak Rate Test Data Test No. EP-31080 EP-30860 EP-30860 I EP-29799 I EP-31330 I EP-31320 EP-31300 Collar Bore P-1 - a1c3 Dia. (in.) L Test Pressure Leak Rate (drops per minute - dpm)

Differential (psi) a,c,e 1000 1910 2650 3110 AP Ratio Leak Rate Ratio (normalized to initial AP) Average LR Ratio 1 a,c,e 1.91 2.65 3.11 May 2009 WCAP- 17072-N1~

WCAP-17072-NP May 2009 Revision 0

9-27 Table 9-4 Model F Elevated Temperature Leak Rate Test Data

-r r i Y i Y 0 0 ON ON 0 0 0 00 ON ON 0~ 0 0 00 N N 00 00 ON ON CIA Test No. Cl Cl a,c,e Collar Bore Dia. (in.)

Test Pressure Differential (psi) Leak Rate (drops per minute -dpm) 1910 2650 F

1___ ___ ________ ________ ________ ____I a,c,e 3110 AP Ratio Leak Rate Ratio (normalized to initial AP) Average LR Ratio 1 ,c,e 1.39 1.63 WCAP-17072-NP May 2009 Revision 0

9-28 Table 9-5 H* Plants Operating Conditions Summary (1)

Pressure Pressure Differential Differential Across Temperature Temperature Temperature Across the the Tubesheet Number Temperature Cold Leg (F) Hot Leg (F) Cold Leg (F) Tubesheet (psi)

Plant Name SG Type of Hot Leg (F)

Loops High Tavg High Tavg Low Tavg Low Tavg (psi) Low Tavg High Tavg ac,c Byron Unit 2 and Braidwood Unit 2 Salem Unit 1 F 4 Robinson Unit 2 44F 3 Vogtle Unit 1 and 2 F 4 Millstone Unit 3 F 4 Catawba Unit 2 D5 4 Comanche Peak D5 4 Unit 2 Vandellos Unit 2 F 3 Seabrook Unit 1 F 4 Turkey Point Units 44F 3 3 and 4 Wolf Creek F 4 Surry Units 1and 2 51F 3 Indian Point Unit 2 44F 4 Point Beach Unit 1 44F 2 (1) The source of all temperatures and pressure differentials is Reference 9-21.

WCAP-17072-NP May 2009 Revision 0

9-29 Table 9-6 H* Plant Maximum Pressure Differentials During Transients that Model Primary-to-Secondary Leakage (1 FLB/SLB Pressure Locked Rotor Pressure Control Rod Ejection Normal Operating Pressure Differential (psi) Differential (psi) Pressure Differential (psi) Differential High Tavg (psi)

Byron Unit 2 and Braidwood Unit 2 Salem Unit 1 Robinson Unit 2 Vogtle Unit 1 and 2 Millstone Unit 3 Catawba Unit 2 Comanche Peak Unit 2 Vandellos Unit 2 Seabrook Unit 1 Turkey Point Units 3 and 4 Wolf Creek Surry Units 1 and 2 Indian Point Unit 2 Point Beach Unit 1 (1) The source of all pressure differentials is Reference 21.

WCAP-17072-NP May 2009 Revision 0

9-30 Table 9-7 Final H* Leakage Analysis Leak Rate Factors Transient SLB/FLB Locked Rotor Control Rod Ejection FLB- 3 SLB/FLB SL/LRRNPLake R3 Leak Ajse R/O V Leak ae Adjusted CELF Plant Name SLB/NOP VR 3 @ Leak Rate LRRate Adjusted CRE/NOP @ Rate CR1 LRF' AP Ratio 2672 psia Factor(LRF) AP Ratio 2711 Factor LR LRF' AP Ratio 3030 Factor (High Taviz) 2 (LRF) psia (LRF)

-- -- a,c,e a,c,e Byron Unit 2 and 1.93 Braidwood Unit 2 Salem Unit 1 1.79 Robinson Unit 2 1.82 Vogtle Unit 1 and 2 2.02 Millstone Unit 3 2.02 Catawba Unit 2 1.75 Comanche Peak 1.94 Unit 2 Vandellos Unit 2 1.97 Seabrook Unit 1 2.02 Turkey Point Units 3 1.82 and 4 Wolf Creek 2.03 Surry Units l and 2 1.80 Indian Point Unit 2 1.75 Point Beach Unit 1 1.73

4. Includes time integration leak rate adjustment discussed in Section 9.5.

5. The larger of the AP's for SLB or FLB is used.

6. VR Viscosity Ratio WCAP- 17072-NP May 2009 Revision 0