RS-05-040, Technical Documentation Related to Analysis and Design of New Quad Cities Steam Dryers, and Responses to Requests for Additional Information Related to EPU Operation at Dresden and Quad Cities Nuclear Power Stations

Technical Documentation Related to Analysis and Design of New Quad Cities Steam Dryers, and Responses to Requests for Additional Information Related to EPU Operation at Dresden and Quad Cities Nuclear Power Stations

ML050980319
Person / Time
Site:	Dresden, Quad Cities
Issue date:	04/01/2005
From:	Simpson P Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-05-040
Download: ML050980319 (35)

Text

ExekenM www~exeloncorpxcom Exelon Generation 4300 Winfield Road Nuclear Warrenville, IL 60555 RS-05-040 April 1, 2005 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-19 and DPR-25 NRC Docket Nos. 50-237 and 50-249 Quad Cities Nuclear Power Station, Units 1 and 2 Renewed Facility Operating License Nos. DPR-29 and DPR-30 NRC Docket Nos. 50-254 and 50-265

Subject:

Technical Documentation Related to Analysis and Design of New Quad Cities Steam Dryers, and Responses to Requests for Additional Information Related to EPU Operation at Dresden and Quad Cities Nuclear Power Stations

References:

1. Letter from J. A. Benjamin (Exelon Generation Company, LLC) to U. S. NRC, "Commitments and Information Related to Extended Power Uprate," dated April 2, 2004

2. Letter from K. R. Jury (Exelon Generation Company, LLC) to U. S. NRC, "Commitments and Plans Related to Extended Power Uprate Operation,"

dated May 12, 2004 In the referenced letters, Exelon Generation Company, LLC (EGC) made several commitments regarding the operation of Dresden Nuclear Power Station (DNPS), Units 2 and 3, and Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2, including a commitment to limit operation of the QCNPS units to pre-extended power uprate (EPU) power, except for brief periods to collect data, until NRC approval is obtained to return to long-term operation at EPU power. In anticipation of a request from EGC to return the QCNPS units to long-term operation at EPU power, the NRC requested that EGC provide additional information to support a review of issues related to operation of the DNPS and QCNPS units at EPU power levels. The enclosures to this letter contain information to support the NRC's review.

Enclosure 1 contains information developed by General Electric (GE) in support of EGC's Integrated Steam Dryer Project. Enclosure 2 provides a discussion from Dr. Fred J. Moody on fluid-structure interaction, and Enclosure 3 contains a summary of the start-up test plan for QCNPS Unit 2.

April 1, 2005 U. S. Nuclear Regulatory Commission Page 2 Information contained in Enclosure 1 is proprietary to GE. Therefore, EGC requests that this information be withheld from public disclosure in accordance with 10 CFR 2.390, "Public inspections, exemptions, requests for withholding," paragraph (a)(4), and 10 CFR 9.17, "Agency records exempt from public disclosure," paragraph (a)(4). An Affidavit attesting to the proprietary nature of these documents in included in Enclosure 1. EGC plans to provide non-proprietary versions of these documents at a later date.

Should you have any questions concerning this letter, please contact Mr. Thomas G. Roddey at (630) 657-2811.

Respectfully, Patrick R. Simpson Manager - Licensing

Enclosures:

1. GE-ENG-DRY-044, "Exelon Integrated Steam Dryer- Documents for NRC Review,"

dated April 1, 2005

2. A Note On Quad Cities Steam Dryer Fluid-Structure Interaction (FSI), F. J. Moody, dated March 24, 2005

3. Startup Test Plan Summary- Quad Cities Unit 2 cc: Regional Administrator- NRC Region IlIl NRC Senior Resident Inspector - Dresden Nuclear Power Station NRC Senior Resident Inspector - Quad Cities Nuclear Power Station

ATTACHMENT 6 "Affidavit, George B. Stramback, dated April 1, 2005

General Electric Company AFFIDAVIT I, George B. Stramback, state as follows:

(1) I am Manager, Regulatory Services, General Electric Company ("GE") and have been delegated the function of reviewing the information described in paragraph (2) which is sought to be withheld, and have been authorized to apply for its withholding.

(2) The information sought to be withheld is contained in Attachments 1, 2, 3, 4, and 5 to GE letter GE-ENG-DRY-044, Exelon Integrated Steam Dryer - Documents for NRC, (GE Proprietary Information), dated April 1, 2005. The proprietary information is Attachments 1, 2, 3, 4, and 5, in their entirety and marked General Electric Co ProprietaryInformation, are internal GE engineering design documents.

For each attached document, paragraph (3)of this affidavit provides the basis for the proprietary determination.

(3) In making this application for withholding of proprietary information of which it is the owner, GE relies upon the exemption from disclosure set forth in the Freedom of Information Act ("FOIA"), 5 USC Sec. 552(b)(4), and the Trade Secrets Act, 18 USC Sec. 1905, and NRC regulations 10 CFR 9.17(a)(4), and 2.390(a)(4) for "trade secrets" (Exemption 4). The material for which exemption from disclosure is here sought also qualify under the narrower definition of "trade secret", within the meanings assigned to those terms for purposes of FOIA Exemption 4 in, respectively, Critical Mass Energy Project v. Nuclear Regulatory Commission.

975F2d871 (DC Cir. 1992), and Public Citizen Health Research Group v. FDA, 704F2d1280 (DC Cir. 1983).

(4) Some examples of categories of information which fit into the definition of proprietary information are:

a. Information that discloses a process, method, or apparatus, including supporting data and analyses, where prevention of its use by General Electric's competitors without license from General Electric constitutes a competitive economic advantage over other companies;

b. Information which, if used by a competitor, would reduce his expenditure of resources or improve his competitive position in the design, manufacture, shipment, installation, assurance of quality, or licensing of a similar product;

• c. Information which reveals aspects of past, present, or future General Electric customer-funded development plans and programs, resulting in potential products to General Electric; GBS-05-02-af Exelon GE-ENG-DRY-044 Integrated Dryer Program - GE Eng docs 14-05.doc Affidavit Page I

d. Information which discloses patentable subject matter for which it may be desirable to obtain patent protection.

The information sought to be withheld is considered to be proprietary for the reasons set forth in paragraphs (4)a., and (4)b, above.

(5) To address 10 CFR 2.390 (b) (4), the information sought to be withheld is being submitted to NRC in confidence. The information is of a sort customarily held in confidence by GE, and is in fact so held. The information sought to be withheld has, to the best of my knowledge and belief, consistently been held in confidence by GE, no public disclosure has been made, and it is not available in public sources. All disclosures to third parties including any required transmittals to NRC, have been made, or must be made, pursuant to regulatory provisions or proprietary agreements which provide for maintenance of the information in confidence. Its initial designation as proprietary information, and the subsequent steps taken to prevent its unauthorized disclosure, are as set forth in paragraphs (6) and (7) following.

(6) Initial approval of proprietary treatment of a document is made by the manager of the originating component, the person most likely to be acquainted with the value and sensitivity of the information in relation to industry knowledge. Access to such documents within GE is limited on a "need to know" basis.

(7) The procedure for approval of external release of such a document typically requires review by the staff manager, project manager, principal scientist or other equivalent authority, by the manager of the cognizant marketing function (or his delegate), and by the Legal Operation, for technical content, competitive effect, and determination of the accuracy of the proprietary designation. Disclosures outside GE are limited to regulatory bodies, customers, and potential customers, and their agents, suppliers, and licensees, and others with a legitimate need for the information, and then only in accordance with appropriate regulatory provisions or proprietary agreements.

(8) The information identified in paragraph (2), above, is classified as proprietary because it contains GE Design Record File design record documentation for internal use and typically only is available for NRC audit review access. This information is

-not available for public disclosure, nor prepared for such disclosure, and contains GE's detailed design, analyses and calculational methodology, including process control details, as they relate to the design, procurement and analyses of the BWR Steam Dryer. Development of the design, procurement and analyses methodologies and processes for the Steam Dryer was achieved at a significant cost to GE, on the order of approximately two million dollars.

The development of the evaluation process along with the interpretation and application of the analytical results is derived from the extensive experience database that constitutes a major GE asset.

GBS.05-02-af Exelon GE-ENG-DRY-044 Integrated Dryer Program - GE Eng docs 1-4-05.doc Affidavit Page 2

(9) Public disclosure of the information sought to be withheld is likely to cause substantial harm to GE's competitive position and foreclose or reduce the availability of profit-making opportunities. The information is part of GE's comprehensive BWR safety and technology base, and its commercial value extends beyond the original development cost. The value of the technology base goes beyond the extensive physical database and analytical methodology and includes development of the expertise to determine and apply the appropriate evaluation process. In addition, the technology base includes the value derived from providing analyses done with NRC-approved methods.

The research, development, engineering, analytical and NRC review costs comprise a substantial investment of time and money by GE.

The precise value of the expertise to devise an evaluation process and apply the correct analytical methodology is difficult to quantify, but it clearly is substantial.

GE's competitive advantage will be lost if its competitors are able to use the results of the GE experience to normalize or verify their own process or if they are able to claim an equivalent understanding by demonstrating that they can arrive at the same or similar conclusions.

The value of this information to GE would be lost if the information were disclosed to the public. Making such information available to competitors without their having been required to undertake a similar expenditure of resources would unfairly provide competitors with a windfall, and deprive GE of the opportunity to exercise its competitive advantage to seek an adequate return on its large investment in developing these very valuable analytical tools.

I declare under penalty of perjury that the foregoing affidavit and the matters stated therein are true and correct to the best of my knowledge, information, and belief.

Executed on this /,aL day of 4 L ~ 2005.

G ~rge B./Stramback General Electric Company GBS.O5-02-af Exelon GE-ENG-DRY-044 Integrated Dryer Program - GE Eng docs 1-4-05.doc Affidavit Page 3

ENCLOSURE 2 A Note On Quad Cities Steam Dryer Fluid-Structure-Interaction (FSI), F. J. Moody, dated March 24, 2005

1 A NOTE ON QUAD CITIES STEAM DRYER FLUID-STRUCTURE INTERACTION (FSI)

F. J. Moody March 24, 2005

SUMMARY

Dryer wall dynamic stresses are calculated by applying a transient pressure disturbance, which is based on predictions from an acoustic circuit model of the dryer region. The acoustic circuit model includes both the dryer, dome, and steam line geometry of a plant, and employs rigid dryer walls. Consequently, the predicted wall pressure corresponds to a rigid wall boundary. However, actual vibratory motion of the dryer walls can introduce a fluid-structure interaction (FSI) effect that causes wall pressures to differ from the rigid wall predictions. Since the FSI effect can introduce errors into the pressure loading applied in a dryer dynamic stress model, it is desirable to determine when the FSI effect is negligible, and when it should be included.

This study describes a simplified analytical model for comparing the sinusoidal pressure response on flexible dryer walls and the pressure response that would occur on a rigid, nonflexible wall. The reason for such a model is to determine if the acoustic circuit method for determining transient pressures on rigid dryer walls is relatively consistent with that pressure that would be exerted if the dryer walls were flexible. If a pressure force is applied to a flexible wall, movement of the wall can alter the force by fluid -

structure interaction (FSI). However, if the calculated rigid wall and flexible wall pressures are relatively close, then it is justified to apply the predicted force on a rigid wall to the flexible wall for determining the wall dynamic motion response and stresses.

The idealized wall in this study is treated as a simple undamped spring - mass system with fluid of infinite extent on both sides. Mechanical damping is expected to be negligible for small amplitude oscillations, and fluid damping is excluded for conservative predictions of wall movement. An oncoming sinusoidal pressure disturbance arrives at the left side of the wall shown in Fig. 1. It was found that for various flexible wall natural frequencies,fixt, there are ranges of the oncoming acoustic pressure frequency,f, which will result in flexible wall pressures that are closely approximated by pressures that would result on a rigid wall. The FSI error that could be introduced by assuming that the rigid wall pressure acts on a flexible wall can be

2 estimated from Figs. 3 through 9, which also include a coupling frequency,fF, that involves the wall density and thickness. Based on example calculations, FSI should not impose significant errors over a vast range of acoustic pressure disturbance frequencyf, and the flexible wall frequency,fixi.

BACKGROUND One phenomenon that potentially can affect the steam dryer unsteady pressure load is movement of the dryer itself. If a solid object moves when fluid forces are applied to its surface, motion of the object can affect the actual force that is exerted.

When both the applied fluid force and structural motion are strongly coupled, then fluid-structure interaction, FSI, can play a role in the dynamic response.

The CDI acoustic circuit analysis for predicting transient forces on dryer elements is generally based on interconnected fluid (steam) regions, with rigid mechanical boundaries and structural components. However, if FSI of some mechanical boundaries should occur, it can introduce another degree of freedom to be accommodated in the analysis. The so-called "tuning" of the acoustic circuit model is expected to be simpler if FSI is either absent or insignificant.

One form of FSI is associated with applied pressure forces. If the structure is completely rigid without motion, fluid transients exert rigidstnrctureforces. The actual forces exerted on a moving structure are called moving structureforces, which may differ from the rigidstrictureforces. If it can be shown that, for a given flow field, the dryer structure is sufficiently rigid that the moving strictureforces are relatively close to the rigidstnrctureforces,then the rigid structure forces obtained from an acoustic circuit analysis can be applied directly to a dynamic structural model to determine the resulting stresses.

This objective of this study is to provide a simple method for determining if wall pressures, calculated from an acoustic circuit model with rigid walls, can be applied to an actual dryer wall which is flexible, without introducing significant FSI, which could introduce errors into calculated dynamic stresses.

A SIMPLE MODEL FOR PREDICTING FSI FROM PRESSURE FORCES An unsteady one-dimensional acoustic pressure wave is assumed to originate at a distant source. The propagating pressure front is planar, and it arrives parallel to the flat surface of a wall boundary of area A , shown in Fig. 1. The pressure disturbance in this analysis is exerted on the left side of the wall, and waves are reflected leftward from the wall back toward the originating source. The wall is assumed to respond as a spring-mass system of mass M and spring constant K. Mechanical damping of a flexible wall is generally negligible for small amplitude motion. Furthermore, the wall is submerged so that fluid contacts both sides, and movement of the wall will create pressure

3 disturbance transmission into the undisturbed fluid on both the right and left sides. These pressure disturbances on both sides of the wall will affect the wall dynamic response. If fluid drag or viscous damping were included, it would require substantial computational capability. Fortunately, such viscous forces are small for low amplitude vibration of a wall normal to its plane, and neglecting these resistive forces will result in conservative predictions of wall motion in this study.

If the wall is rigid, pressure exerted on the wall would oscillate at the same frequency as the arriving disturbance, but at twice the pressure amplitude. However, if the wall moves in response to the arriving pressure, the actual pressure exerted on the wall at a given instant would differ from that pressure associated with a non-moving rigid wall. An analysis of the time-dependent moving wall pressure is discussed next in order to determine how the fluid and structural parameters and the disturbance determine the importance of FSI.

ANALYSIS The acoustic equations which govern pressure propagation in an inviscid fluid of density p and sound speed C are given by [1]

DEs: DP+PD 0(1) at go ax a+ g 0P (2) at paDX The wall dynamic boundary condition is obtained from Newton's law for an undamped spring - mass system. Fluid pressure PI acts on the left side of the wall, and pressure P2 act on the right side. Therefore, pressure force PA acts on the wall to the right and force P2A acts on the wall to the left, as shown in Fig. 1. Also, a spring force Kx acts to the left. Fluid drag forces and mechanical damping forces have been neglected. The active forces cause a wall acceleration dV,/Idt, so that the wall dynamic equation provides the fluid boundary condition, BC: .(PI -PM _V= (3) go dt Initially, the fluid is at rest with zero gage pressure, relative to the fluid steady pressure.

The corresponding initial conditions are ICs: PI (xO) =P2 (x,O) =0 (4)

VI (xO) = V 2 (xO) = (5)

4 These initial conditions will not affect the ultimate steady state pressure and velocity oscillation solutions to be obtained. However, they are needed for specifying the acoustic fluid response in any model based on idealized fluid of infinite extent, surrounding the moving plate.

The oncoming sinusoidal pressure disturbance is expressed as ONCOMING: P0 (x,t) = (AP)sin at . C) (6) where AP is the oncoming amplitude, o) is the circular frequency, related to the oscillation frequency f by

= 2nf (7) and C is the sound speed in the fluid.

General solutions to Eqs. (1) and (2) for both sides of the wall can be expressed as PF(Xt) = FL, l C) + I -( C (8)

V,(~)=PC[L( C) ( C)]

on the left side, and P2 (x,t) = FL2 (t+ C +FR2 ( C-)J (10) and V2 (XIt = gC L2( C) F2( C)] (11) on the right side, assuming that the same fluid exists on both sides. Functions FL and FR are constant on the left and right - traveling wave trajectories, shown in Fig. 2.

Values of FL and FR are determined throughout the time - space plane from the initial and boundary conditions. The arriving disturbance is the result of a distant boundary condition, such as a controlled wall vibration or resonating acoustic noise in another part of the system. It arrives as the time - dependent pressure of Eq. (6), based on the assumption that its source is unaffected by acoustic reflections from the wall, or the wall motion itself.

The oncoming pressure of Eq. (6), and the initial condition of Eq. (4) show from Eq. (8) that FRI arriving at the wall, x = 0 , is

5 FRI (t) = FRI (0,t) = APsin tC (12)

Also, FL1 (0)= FLI (x,O) =0 (13) with FR2(0) = FR2(X,O) = 0 (14) and FL2 (X, t) = 0 (15)

It is necessary to solve for the functions FL,(Ot) = FLI(t), and FR2(0,t) = FR2(t) in order to determine actual pressure on the moving wall, as well as the wall motion.

The wall boundary condition of Eq. (3) is first differentiated with respect to time, and combined with Eqs. (8), (10), (12), and (15) to give the following differential equations:

(dFLI p)CS, dFR2 =V2+M 2 (I +APA=cosax- A - KV,+ML-d2'KV 2+ d 2 (16) dt dt ) go di2 go dt2 Fluid velocity on both sides of the wall, VI and V2 , are both equal to the wall velocity V= Vh,.. Further combining Eq. (16) with Eqs. (9) and (11) yields 2

dFLI dFR2 =_/pWCOS - go -A sin ox) - (L d(FLF + Ap sin a) dt dt pCA pCA dt2 (17) and dFLI dFR2 (_pOOSC+Kg 0 FR2 (M dFR 2 2 (

dt dt =-~w(ari )F pCA R (CAj ) dt2 (18)

The following nondimensional variables help in organizing the results to be obtained:

t* = ox = 2;fzt (19) p* = P (20)

AP FL1 * = FL (21 -a)

AP FRI FRI (21-b)

AP FL2* FL2 (21-c)

AP FR2 FAP (21 -d)

6

=~g( 0 !LP) (22) pCW X* ( CV AP )(23)

G*= z= FLI *-FR2 (24)

AP The mechanical frequency,fii, and another "coupling" frequency associated with both the structure and fluid,fF, are defined by

- = 241;7 Mechanical (25)

AM-and pC4 = pCA = pC6 =2nF Fluid/Stnrcture Coupling (26)

E-M pvfASJ PM8 where the wall thickness a has been introduced. Equations (17) and (18) are now written in nondimensional form as dt* =-cost*4 fjFf k(FLI -*sint*)- ( d *2 +sint*) (27) and dG ~ + LI2') i d2 FR2 (8 dt

• C fFf )R 2

f *2dt (28)

If Eqs. (27) and (28) are added together, the result is d 2 d + G*=- I- sin t-2 cost* (29)

When G* is determined, Eqs. (27) and (28) or (24) can be used to obtain FL,* and FR2* for later obtaining the pressures PI and P2 acting on both sides of the wall, and also the wall velocity V* and displacement x*.

A particular solution for G* is given by G * (t*) = a sin t * +b cos t* (30) where

7

[i(SEXI -C#

aL-(" =.2-(31)

.4 [I-f

{4fFt + 2

+ ]

and

{C91 (32)

Incorporating G* from Eq. (30), Eq. (28) becomes d F' 2 dtrfrf

+(fs) y R 2 *=fj)(os*+ di*' ) (33 for which a solution is FR2 *(t*) = R sin t * +Scos t* (34) where R=f 4t F )

(35)

{(fJ +[(f2]2}

and

{

{[ +[cy} - (36)

It follows from Eqs. (30) and (24) that

8 FLI * (t*) = G*(t*)+FR2 *(t*) = (a+ R) sint*+(b+S)cost* (37)

The functions FL,, FRI, FL2, and FR2 at the wall, x* = O,are summarized as follows:

FLI *(t*)=(a+R)sint*+(b+S)cost* FromEq.(3 7) (38-a)

FRI * (t*) = sin t Specified disturbance. Eqs. (12) (38-b)

FL2 *(t*) = 0 Knoiwn from Eq. (15) (38-c)

FR2 * (t*) = R sin t * +S cost

• FromEq. (34) (38-d)

When Eqs. (8) and (10) are written in nondimensional form, solutions for wall pressures PI* and P2* are given by, Pl*(t*) =Cl sint*+C 2 cos t* = (2-R) sint*-Scost* ; PressureLeft Side (39) and P2 * (t*) = Rsint *+Scost *  ; Pressure. Right Side (40) wheretheconstants C, and C2 ,givenby C1 =(I+a++R)=(2-R) and C2 =(b+S)=-S (41-ab) are plotted in Figs. 3 -9. The wall velocity V*, obtained from either Eqs. (9) or (11),

yields the normalized solution, V * (t*) = -(R sin t * +S cos t*)  ; Wall Velocity (42) which can be integrated to give the wall displacement x* as x * (t*) = fV * (t*)dt* = R cost *-S sin t

• Wall Displacement (43)

Equation (39) gives the left side wall pressure for a flexible wall. A rigid wall corresponds to f, RiWid wall (44) for which Eqs. (35) and (36) give R =S < O Rieid wall (45)

9 and the left side pressure of Eq. (39) becomes PI * (t*) -< 2sin t

• RiL-id wall (46)

Equation (46) shows that oncoming pressure doubles at a rigid wall, which is a well-known result. No FSI occurs for a rigid wall.

If the disturbing frequency f matches the plate natural frequency f,,,, a "resonance" occurs, for which R -) 1 and S- O ; "Resonance" (fd= r) (47) for which Eq. (39) gives pressure on the left side as PI * (1*) -4 sin t * "Resonance" "fL= 4,) (48) and Eq. (40) gives pressure on the right side as P2 * (t*) -4 sin t * "Resonance" ff = fad (49)

Note that at "resonance", pressures on both sides of the wall are equal. This can be explained by noting that the rigid wall pressure would have an amplitude of 2 , as shown in Eq. (46). However, motion of the flexible wall to the right at resonance reduces the amplitude to I , Eq. (48), but also creates a right side pressure of amplitude I , Eq. (49).

The reverse is true when the wall is moving to the left, still experiencing the same pressure on both sides. The "resonance" results of Eqs. (48) and (49) suggest that wall velocity and displacement are bounded at the "resonant" condition. This can be seen by writing the wall velocity and displacement of Eqs. (42) and (43) at this "resonant" condition to obtain, V * (t*) = -sin t * "Resonance" tL (50) and x* (t*) = cost *  ; "Resonance" (f = Ad (51)

Even without structural and fluid damping in the model, both the wall velocity and displacement are bounded, if the acoustic disturbance occurs at a wall natural frequency.

This simply shows that both energy input to the wall and its reflected energy reach a balance so that the wall and its elastic energy storage no longer change with time.

These results show that at the "resonance" condition, the fluid - structure interaction, FSI, is sufficiently prominent that structural motion reduces the exciting force to zero.

Several examples are given next to determine how much a flexible wall pressure differs from a rigid wall pressure. If the difference is small, a determination of the

10 disturbing pressure can be obtained from a model which treats the flexible wall boundary as if it were a rigid wall.

EXAMPLES Example 1: Consider one of the lower dryer plates and a sinusoidal pressure oscillation. Parameters of Table I are for a relatively stiff plate.

Table 1 Parameters for Example I A =4ft' plate area K= (22)106lbf/ft plate equivalent spring constant M = 200 Ibm plate mass p = 2.24 Ibm/ft 3 steam density C = 1600fl/s steam sonic velocity fit = 300 Hz platefundamentalfrequency ofEq. (24) f = 25 Hz oscillatingpressurefrequency fF= 11.4Hz couplingfrequency of Eq. (25)

It follows that fat = 12 and fF= 0.456 f

for which R = (4)10' S= 0.006 The left side flexible wall pressure of Eq. (39) becomes P. * (t*) = (1.999) sin t *-(0.007) cos t *. Flexible, but stiff wall Comparing to Eq. (46) shows less than a 2 percent variation of wall pressure from that of a rigid surface.

Example 2: Consider one of the large dryer plates and a sinusoidal pressure oscillation. Parameters listed in Table 2 are for a relatively flexible plate.

I1 Table 2 Parameters for Example 2 A = Soft 2 plate area, Sft x l Oft K= (221)06lbf/ft plate equivalentspring constant M = 2500 Ibm plate mass, 1" thick, Sft x lOft p = 2.24 ibm/ft3 steam density C = 1600ft/s steam sonic velocity fAi = 85 Hz platefundamentalfrequency of Eq. (24) f =25Hz oscillatingpressurefrequency fF= 11.4 Hz couplingfrequency in Eq. (25)

Table 2 gives fAt =34 and fF = 0.456 f f for which R=0.007  ; S=0.086 The left side flexible wall pressure of Eq. (39) becomes pi * (t*) = (2.003) sin t * -(0.092) cos t

• Flexible wall (flexible plate)

Comparing to Eq. (46) shows about a 5 percent variation from a rigid wall.

WHEN IS RIGID WALL PRESSURE PREDICTION NON-REPRESENTATIVE ?

When the flexible wall is acted upon by an arriving sinusoidal pressure disturbance, Eq. (39) gives the pressure applied to the wall during its motion, which includes fluid-structure interaction (FSI) effects. A comparison of Eq. (39) with Eq. (46),

which gives the pressure that would act on a rigid wall, shows that if coefficient C, = 2.0 and coefficient C2 = 0.0, pressure on the flexible wall will be exactly the same as the pressure that would be exerted on a rigid wall. The departure of coefficients C, and C2 from these values, provide a measure of how much error will be introduced by employing the calculated rigid wall pressure as input to a flexible wall dynamic stress analysis. This error is conservatively defined as if the sin t* and cos t* terms of Eq. (39) added together, so that

=AP" IC,.- 2.01I+1C 21 ERROR == 2.

N P *RIGID 2.0 (52)

12 The model described in this study can help to estimate a conservative FSI error that could be introduced by using the rigid wall pressure prediction in a flexible wall dynamic stress analysis.

Equations (35), (36), and (41) show that the frequency ratios fil/f and fF/f, given by Lf EKg 1 Kg0 Stnrcturalfregueencv ratio (53) f Mfw PAIA3 and f ft(M) - I( Couplingfreguencv ratio (54) are the two parameter groups that affect the values of coefficients C, and C2 of Eq.

(41-a,b). Figures 3 through 9 give calculated values of C, and C2 as functions of the wall mechanical frequency ratio fuif for constant values of the coupling frequency ratio fF/f .

Each of Figs. 3 through 9 show that coefficient C, = 1.0 has its greatest departure from the rigid wall value of 2.0 when the disturbing frequency f exactly matches the wall natural frequency fif . Coefficient C2 also departs from the rigid wall value of 0.0 at other values of fAt/f . However, when coefficient C, =2.0, the error introduced by the corresponding C, departure from 0.0 appears to be relatively small.

Since the model in this study is based on a wall that is represented by a vibrating spring and mass system, there is only one fundamental wall natural frequency fit for a given wall mass M and spring constant K, as shown in Eq. (25). This model is intended to approximate a fundamental wall vibration mode with only one central amplitude. However, higher wall vibration modes can be addressed by calculating the mass M and spring constant K associated with one of the smaller vibrating nodes, and determining the corresponding fM . However, no new calculation for another mass M and spring constant K for a smaller node is needed if the wall natural frequencies are already known, which is the case. That is, if the wall structural frequencies fi, are known for the fundamental and higher wall vibration modes, they can be used directly in Figs. 3 through 9 to determine if FSI strongly affects the rigid wall pressure.

It is expected that the incoming pressure disturbance is introduced from a steam pipe, located in a position off center from the dryer structure. This geometric consideration raises questions about the multidimensional wave propagation characteristics moving across the dryer surface. Some attenuation will occur for those parts of the dryer that are farther from the source. However, propagation effects across the dryer surface should not be a concern if the disturbance wave length is greater than a characteristic dryer dimension. A disturbance frequency of f = 20 Hz and a sound speed in the steam of C = 1600fps would result in a wave length of

13 A = C = 80ft f

and a frequency of f = 80 Hz would have a wave length of A = 20 ft. These wave lengths are greater than dryer dimensions, but high disturbance frequencies could introduce multidimensional wave propagation effects.

It follows from Figs. 3 through 9 that over extensive ranges of the parameters fillf and flf/, FSI will not introduce significant error from the rigid wall assumption.

However, there are regions on both sides of the "resonant" condition fief = 1.0 where significant FSI can be introduced. It is the general objective to control the disturbance frequency f by various mechanical features, and to also control the structural frequency fA, by stiffening the walls so that the region fir/f = 1.0 is widely avoided.

CONCLUSIONS It is desirable to employ acoustic pressures calculated on rigid dryer walls to predict the dryer wall response and resulting stresses. However, if FSI is important, the actual pressure disturbance on a wall will differ from the rigid wall pressure, thus introducing errors that will affect a dynamic stress analysis of the wall.

This study is based on a sinusoidal pressure disturbance of frequency f, arriving at a flat, flexible wall, represented by a simple spring - mass system with a natural frequency, ft . Structural damping is neglected because it is small for low amplitude oscillations. Fluid damping also is neglected in order to simplify the analysis, and ensure that predicted results are conservative. The structural frequency fMI can apply to both the known fundamental and higher vibration modes of the wall. Both f and fit can be adjusted by design to ensure that the calculated disturbance pressure on a rigid wall can be applied to the dryer flexible wall without significant fluid-structure interaction (FSI).

An alternative approach is to predict structural dynamic stresses from a combined acoustic and wall model that includes FSI, and introduce mechanical features that reduce calculated stresses to tolerable limits. This alternative could present an unnecessary, unrealistic amount of model development.

NOMENCLATURE A Vibrating plate area a, b Coefficients, Eqs. (31) and (32)

C Sound speed in fluid Cl, C2 Coefficients, Eqs. (41-a,b)

FLI, FL2, FRI, FR2 Functions for pressure propagation, Eqs. (8) - (11) f Acoustic pressure disturbance frequency fit Wall structural frequency, Eq. (25) fF Fluid/structure coupling frequency, Eq. (26)

14 G* Function, Eq. (24) go Newton's constant, 32.2 (lbm-ft)/(lbf-sec 2 )

K Spring constant M Wall mass P Pressure AP Disturbance pressure amplitude I Time V Velocity x Wall displacement p Fluid density PM Wall density a5 Wall thickness w Circular frequency Nondimensional quantity REFERENCES

1. Moody, F. J., "Introduction to Unsteady Thermofluid Mechanics," Wiley, 1990.

WALL, MASS M SPRING, CONSTANT K I

-I I I x,It ) I I I P11.4 I I I I P2 A ARRIVING PRESSURE 1-x 0i 0. V.Nt DISTURBANCE FIGURE 1, PRESSURE DISTURBANCE ARRIVING AT FLEXIBLE WALL

15 FL (x,t)

FR2(X,t)

I 2I (X,t)

FRI (X,t)

-*~ x 0

FIGURE 2, WAVE DIAGRAM

16 FIGURE 3, COEFFICIENTS Cl AND C2 FOR fFtf = 0.01 2.5 -

2 aX X----

ew

.( 1.5 0

co 0 *Seies1 0 I_MSedes2i z

0 0

U

.0.5 go PLATE FREQUENCY RATIO, fMM FIGURE4,COEFFICIENTS Cl AND C2 FOR fFf O0.10 2.5 2

mu a

1.5 Cn

[+Series1 l I-*-Seri s2l z I e

_0.

4..5 z

0

-0.5 PLATE FREQUENCY RATIO. fMlf

17 FIGURE 5, COEFFICIENTS Cl AND C2 FOR fFf 0.50 uj s 1.5 n

0 C [lSeresil

, I l_ W Seri s2l 0

zi 0.5 ZU PLATE FREQUENCY RATIO. fMlf FIGURE 6, COEFFICIENTS Cl AND C2 FOR fF/f 1.0 w

c mi 2

EC

-l-Series Il 0

0 l -mSeries2 1 co -05 z

en I

2 _ P

_ _ , _ E_ _ _ _ _ I f, I I f 1 PLATE FREQUENCY RATIO. MMf

18 FIGURE 7, COEFFICIENTS Cl AND C2 FOR fFf = 5.0 a

MU W

2

-4Senes1 n IOSeres2 0

z z

A:

a PLATE FREQUENCY RATIO, fM/f FIGURE 8, COEFFICIENTS Cl AND C2 FOR fFHf ' 10.0 2- ~

en 1.5 w

a<9) 0W.

1 a

z --*Seriesi I - S-ees2i1 0 0.5.

2c 0

S c

a

________ _ __ _ __ _ -- __ ____-I____

PLATE FREQUENCY RATIO, fMMf I_______

19 FIGURE 9, COEFFICIENTS Cl AND C2 FOR fFff = 50 2.5 2- ~

1.5 w

so a

Co I -. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

0 I+Sedesi

.~S.ns a

z 0.5 0

2.

e

-0 1 _

A. _I_

.11 __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

PLATE FREQUENCY, flf

ENCLOSURE 3 Startup Test Plan Summary - Quad Cities Unit 2

Startup Test Plan Summary - Quad Cities Unit 2 Obiective:

The objective of the start-up test plan is to provide steps that are necessary to perform the Start-up Test Program to extended power uprate (EPU) conditions, with the instrumented replacement reactor vessel steam dryer (steam dryer) in place. The incremental power increase methodology ensures a carefully monitored approach to the targeted higher power level. First and foremost in the performance of the start-up plan is the safety of the reactor and nuclear plant. The Startup Test Procedure is written specifically with this objective in mind, and provides the necessary criteria, instruction, oversight, and precautions to successfully execute the Replacement Reactor Vessel Steam Dryer Power Ascension Test Program.

Plan Overview:

Reactor power will be raised to the pre-EPU power level of 2511 MWt over a 3.5-day period. Data will be taken at 33 test conditions (TCs) up to 2511 megawatts thermal (MWt). A hold period of approximately 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is planned at TC 33 while:

1. An evaluation of the data taken up to that point is performed,

2. A presentation of the results of the evaluation is made to PORC, and

3. Approval is given by PORC and the Site Vice President to proceed with power ascension.

Power will then be raised over a 29-hour period to 2957 MWth, or 930 megawatts electric (MWe) if full EPU thermal power is not achievable. During this power increase, data will be taken at an additional eight TCs (TC 34 through TC 41). For power levels both above and below EPU, there will be four primary methods to obtain data at each TC.

1. A temporary Data Acquisition System (DAS) supplied by General Electric (GE) will gather data on the 42 sensors on the dryer and the 56 strain gauges installed on main steam line (MSL) piping in the drywell, main steam isolation valve (MSIV) room, and feedwater heater bay.

2. High-speed data recorders will capture data from:

• 3 reactor steam dome pressure sensors

• 4 pressure measurements at the MSL flow venturis

• 4 main turbine control valve positions

• 33 accelerometers on MSL components in the drywell

3. System equipment parameters will be obtained by computer points and by Operator round inputs. This data will be comprised of approximately 1000 data points.

4. Data will be manually gathered using handheld instruments for local vibration levels on small bore piping on the feedwater system and local area temperatures.

Page 1 of 8

This data will be taken at only two of the TCs, namely the pre-EPU rated power level and the maximum EPU power level.

Data Acceptance Criteria:

There are three levels of acceptance criteria documented in the Startup Test Procedure:

1. Plant Equipment Acceptance Limits: Normal alarm points or established equipment operating limitations based upon historical performance data.

2. Level 2 Criteria: This will not necessarily result in altering plant operation or test plan, but will result in initiating an Issue Report (IR) to enter the station's Corrective Action Program.

3. Level 1 Criteria: Actions include the initiation of an IR and seeking immediate resolution. Power will be held at a known safe level based on prior testing until the condition is resolved. The test portion will be repeated to verify Level 1 can be satisfied. The test procedure will document actions taken to resolve the condition. (Examples: dryer strain gauges and moisture carryover criteria)

Exelon and GE are developing acceptance criteria for dryer measurements (i.e., Go/No-Go criteria) that will provide an immediate decision on whether the loading on the dryer is acceptable. Attachment 1 contains details of the dryer acceptance criteria. In summary, the current plan for the acceptance criteria includes three acceptance criteria for the dryer, plus a criterion for the minimum number of operable front hood strain gauges:

A. Criteria "A" will be reached when the dryer strain gauges indicate that the peak dryer stress levels have reached American Society of Mechanical Engineers (ASME) Fatigue Curve "B" (16,500 psi). If this criterion is exceeded, power will be reduced to a level below this criterion. A detailed load mesh will be generated by acoustic circuit analysis and a finite element analysis (FEA) will be performed.

If the FEA results are acceptable, new acceptance criteria will be generated based on plant data. If FEA results are not acceptable, this power level will not be exceeded. This criterion will be considered a Level 1 criterion.

B. Criterion "B" provides an alert indication that strain gauge results are high. The FEA will determine the peak stress locations of the dryer and application of appropriate weld quality and stress concentration factors. A Design Flow Induced Vibration Criteria of 10,800 pounds force per square inch (psi) will be applied for outside dryer components, and 13,600 psi will be applied for inside dryer components. This criterion will be a Level 2 criterion and, if exceeded, will result in an IR being written to enter the Corrective Action Program, and be communicated per the startup test procedure.

C. Criterion "C" will be checked only when EPU power levels have been reached and the dryer strain gauges have reached 50% of the Criterion A levels.

Criterion C will entail a comparison of the dryer pressure gauge data to load case time history pressure inputs to the dryer design. Six pressure gauges on the steam dryer will have criteria developed. These criteria will be used to compare the two load case frequencies and amplitudes against actual plant pressure data.

A fast Fourier transform will be applied to the locations of the six pressure gauges for both load cases. The resulting frequency and amplitude plots will be used to compare against actual plant data. The acceptance criteria will be that Page 2 of 8

the measured pressure loading must be within + 20% for frequency, and + 30%

for amplitude, when compared to the load cases. This criterion will not be employed until EPU power levels are reached and 50% of the Criteria "A" have been exceeded. If Criterion C is exceeded, power will be reduced to the last acceptable power level. A detailed acoustic circuit and FEA will then be performed. This criterion will be considered a Level 1 criterion.

D. Minimum Number of Operable Front Hood Strain Gauges: at least two of three strain gauges. If a condition where less than two strain gauges on the front hood were to occur, a detailed acoustic circuit (after benchmarking) would produce a refined load mesh that would be analyzed in the finite element model and compared against the design flow induced stress criteria for each power level.

Page 3 of 8

Attachment 1 Quad Cities New Dryer Acceptance Criteria High Level Strategy:

As shown by the flow chart below the high level strategy for the start up test plan involves three parts which include establishing the acceptance criteria, the critical number of gauges required to continue the start up test plan and the application of the criteria during startup.

High Level Strategy r

l umber o Establishing Acceptance Criteria:

Three action levels will be developed for the Quad Cities dryer startup test plan after the strain gauge and pressure gauge criteria have been developed.

• Level A will be based on ASME Fatigue Curve "B". If this criterion is exceeded, power will be reduced to a level where measurements are below the criterion.

Detailed load mesh will be generated by acoustic circuit analysis and finite element analysis will be performed. If the FEA results are acceptable, new acceptance criteria will be generated based on plant data. If FEA results are not acceptable, this power level will not be exceeded.

• Level B provides an alert indication that strain gauge results are high.

• Level C provides a comparison of the dryer pressure gauge data to load case time history pressure inputs to the dryer design.

Establish Acceptance Criteria - Overview Page 4 of 8 Cj: I

Attachment 1 Quad Cities New Dryer Acceptance Criteria Developing the Dryer Strain Gauge Acceptance Criteria:

Nine strain gauges will be placed on the new steam dryer. These strain gauges (via associated readouts) will provide indication for comparison with Level A and Level B acceptance criteria. Acceptable strain gauge readings will provide justification for continued power ascension. Because two load cases are used to create the new dryer flow induced vibration design loads, strain gauge criteria will be developed for each load case per the following process:

• Identify the peak stress intensity location on the dryer for each FEA.

• Normalize the 9 strain gauges to the peak stress intensity location o For the load case considered this involves identifying the peak stress intensity at each pressure gauge location and ratio the results to the peak stress intensity location on the dryer.

Establishing the Strain Gauge Level A Criteria For one-dimensional (uni-axial) structural response with a strain gauge at the maximum stress location the determination of strain measurement acceptance criteria is:

c= a / (f x E)

Where: a = peak stress intensity allowable limit E = Young's Modulus 25.8 x 106 psi at 550° F for stainless steel f = a fatigue strength reduction factor to account for stress concentration and weld quality factors For the Level A criterion, the dryer peak stress intensity allowable limit is defined as follows:

• Identify the peak stress intensity location on the dryer based on FEA stress results and application of appropriate weld quality and stress concentration factors.

• A normalized factor is derived such that the dryer peak stress intensity is equaled to ASME Fatigue Curve "B" (16,500 psi).

• The applicable normalized factor is applied to maximum strain at each strain gauge location above the water level.

• The resulting strain gauge results provide the Level A acceptance criteria for which test measurements are to be screened.

Establishing the Strain Gauge Level B Criteria For one-dimensional (uni-axial) structural response with a strain gauge at the maximum stress location the determination of strain measurement acceptance criteria is:

C= a / (f x E)

Where: a = peak stress intensity allowable limit Page 5 of 8

Attachment 1 Quad Cities New Dryer Acceptance Criteria E = Young's Modulus 25.8 x 106 psi at 550° F for stainless steel f = a fatigue strength reduction factor to account for stress concentration and weld quality factors For the Level B criteria, the dryer peak stress intensity allowable limit is defined as follows:

• Identify the peak stress intensity location on the dryer based on FEA stress results and application of appropriate weld quality and stress concentration factors.

o Apply Design Flow Induced Vibration Criteria

• 10,800 psi for outside dryer components

• 13,600 psi for inside dryer components

• A normalized factor is derived such that the dryer peak stress intensity is equaled to Design Flow Induced Vibration Criteria.

• The applicable normalized factor is applied to maximum strain at each strain gauge location above the water level.

• The resulting strain gauge results provide the Level B acceptance criteria for which test measurements are to be screened.

Establishing Pressure Gauge Level C Acceptance Criteria Six pressure gauges on the steam dryer will have developed criteria. These criteria will be used to compare the two load case frequencies and amplitudes against actual plant pressure data.

A Fast Fourier Transform will be applied to the locations of the six pressure gauges for both load cases. The resulting frequency and amplitude plots will be used to compare against actual plant data.

This criterion will not be employed until EPU power levels have been reached and 50% of the Level A criteria have been exceeded.

Establish Acceptance Criteria - Pressure QC2 Data SMT Data At 6 Gauge At 6 Gaugel Loaios Page 6 of 8 Cff2

Attachment 1 Quad Cities New Dryer Acceptance Criteria Establishing the Minimum Number of Strain Gauges to Continue the Startup Test:

Previous strain gauge applications with in-vessel testing have shown high reliability performance for 6 months of operation. It is unlikely that more than one strain gauge location will become inoperable for the initial startup testing. However, the question how many strain gauges would be required to use the Level A and Level B criteria. of In order to reasonably use the Level A and Level B criteria, a Design Review Meeting with GE, SIA, and Exelon personnel was conducted. The expert panel concluded minimum of two strain gauges on the dryer front hood had to remain in operation that a for the criteria to be meaningful.

If a condition where less than two strain gauges on the front hood were to occur, a

detailed acoustic circuit (after benchmarking) would produce a refined load mesh that would be analyzed in the finite element model and compared against the design flow induced stress criteria for each power level.

Minimum Number of Strain Gauges Page 7 of 8 Cayo

Attachment 1 Quad Cities New Dryer Acceptance Criteria Application of Startup Test Criteria:

Level B Strain Gauge Criteria:

Should the Level B strain gauge criteria be exceeded for operational strain gauge locations, the issue would be documented in the Quad Cities corrective action and communicated per the startup test procedure.

Level A Strain Gauge Criteria:

Should the Level A strain gauge criteria be exceeded for any of the operational strain gauge locations or if the pressure data from the six gauges on the dryer were to significantly deviate from the design load response above steam EPU and 50% of the Level A criteria a reduction in power to the last acceptable power level is required; while a detailed acoustic circuit and finite element analysis is performed.

If the detailed finite element analysis shows acceptable peak stress intensities new acceptance criteria will be developed. If the detailed finite element a analysis shows unacceptable peak stress intensities a power level that supports the design criteria will be established.

Applying Acceptance Criteria - Level A Strain Gauge Strain Gauge Criteria Criteri M

- - -M Page 8 of 8 CO@-