ML20217F539
| ML20217F539 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 07/31/1997 |
| From: | Bamford W, Brad Bishop, Duran D WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| To: | |
| Shared Package | |
| ML19317C557 | List: |
| References | |
| WCAP-14955, WCAP-14955-R, WCAP-14955-R00, NUDOCS 9708060073 | |
| Download: ML20217F539 (71) | |
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l l I Westinghouse Non Proprietary Class 3 . . l
- 1 i
1 L WC AP - 14955
+ + + + + + + + +++ Revision 0 l
l l l l 3robaaiistic anc Economic l Evaluation of Reactor -
~
1 ' 1 Vessel C osure Head i
- 1
. Penetration IntecritY f or - j i Virgil C. Summer Nuclear , 1 Plant . i j h t i
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j i) . i i j 1 Westinghouse Energy Systems N ! l :,,3x 3 .n .7- . j rro cgw ) . p ,: a0 ' 1. ; 4 e , ' nf. -
WESTINGHOUSE NON PROPRIETARY CLASS 3 WCAP 14955 l Probabilistic and Economic Evaluation of Reactor Vessel Closure Head Penetration Integrity for the Virgil C. Summer Nuclear Plant W. H. Bamford B. A Bishop J. F. Duran July 1997 Work Performed Under Shop Order STGP-105 Prepared by Westinghouse Electric Corporation for the South Carolina Electric & Gas Company Reviewed by: bl W G.V.Nao n in ' g & Materials Technology
)
Approved' D. A. Howell, Manager \ Mechanical Systems Integration Westinghouse Electric Corporation Nuclear Services Division P.O. Box 355 Pittsburgh, PA 15230-0355 C1997 Westinghouse Electric Corporation All Rights Reserved
TABLE OF CONTENTS 1.0 Introduction Summary of Safety Case 11 2.0 Development of a Crack Growth Rate Model for Alloy 600 Head Penetrations 21
- l 3.0 Technical Description of Probabilistic and Economic Decision Models 31 ,
I 4.0 Results of Probabilistic and Economic Decision Models 41 5.0 Summary / Conclusions 51 6.0 References 61 Appendix A Output Files from VHPNPROF program A1 Appendix B Output Files from VHPNECON for the Economic Decision Analysis B1 I July 1997
4 i
1.0 INTRODUCTION
. P')MMARY OF SAFETY CASE ;
Primary Water Stress Corrosion Cracking (PWSCC)in Alloy 600 reactor vessel head i penetrations is a relatively new issue in the nuclear industry. The issue was first brought to ! attention in 1991 when, after 10 years of operation, a leak was detected during a hydrotest of the reactor coolant system at the Bugey Unit 3 plant in France. Since that time a significant 1 number of research programs have been funded by the industry to determine the causes of the problem and develop strategies for repair and management. Through these studies is was concluded that the reactor vessel head penetration cracking is a thermally activated stress corrosion process in primary water environments. The process is a slow one that causes no !
; immediate safety concern. Based on conservative evaluation results, the NRC and industry .
concluded that cracks were most likely to initiate from the inside surf ace of the penetrations,in l' the axial direction, and would take at least six years to propagate through the wall under typical plant operating conditions. Fracture mechanics evaluations have determined that the crack is
- non critical until its axial length reaches 8.5 inches to 20 inches, depending on plant design.
l Extemal circumferential cracking is less probable. It may occur only in the presence of an j above the attachment weld through wall crack, with active leakage. Assuming coolant is present on the outer diameter of the penetration, one conservative analysis estimated that it ] would take more than 90 years before penetration failure would occur. In the presence of
- reactor coolant, corrosion of the alloy steel reactor vessel head is possible Conservative
, evaluations estimate that it would take longer than six years after a through wall crack occurs before the ASME Code structuralintegrity margin for the reactor vessel head would be l Impacted by corrosion, it was concluded that periodic visualinspection of the reactor vessel ! head in accordance with Generic Letter 88 05 is adequate and sufficient to detect leakage prior to significant cracking and vessel head corrosion. i Based on the above, evaluations using 10CFR50.59 requirements concluded that head penetration cracking is not an unreviewed safety question, j On April 1,1997 the NRC issued Generic Letter 97 01, " Degradation of Control Rod Drive j Mechanism Nozzle and Other Vessel Closure Penetrations". The purpose of the letter is to request licensees to describe, in writing, their program for ensuring timely inspection of vessel , closure head penetrations. This description is to include programs / plans to deal with PWSCC of vessel head penetrations and to perform an assessment of any resin bed Ingress into the RCS. The purpose of this report is to provide South Carolina Electric and Gas with an analytical basis for developing a response to Generic Letter 97 01 relative to PWSCC of the vessel head penetrations. f 4 1 ,i , i 4 Rev. 0 11 July 1997 ; o2694non doc:1b-07/2797
- - . - - , . - _ , - . . . - . . . _ . , .,c- , _ - - . ., m_.~ . ,- , _. - . . _ , _ . , _ . - . , , - , . , - . , , . . . . _ , - . .
l l I 2.0 DEVELOPMENT OF A CRACK GROWTH RATE MODEL FOR ALLOY 600 HEAD PENETRATIONS Crack growth rate testing has been underway since 1992 to characterize the behavior of head . penetration materials. The modified Scott model, as described below was initially used for safety evaluation calculations in submittals made in 1992 and 1993. The goal of this work is to review the applicability of that modelin light of the past five years of testing, during which over forty specimens have been tested representing 15 heats of material. The original basis of the model will be reviewed, followed by all the available laboratory results, and finally a treatment of the available field results. The effort to develop a reliable crack growth rate model for Alloy 600 began in the Spring of 1992, when the Westinghouse, Combustion Engineering, and Babcock and Wilcox Owners Groups were developing a safety case to support continued operation of plants. At the time there was no available crack growth rate data for head penetration materials, and only a few publications existed on growth rates of Alloy 600 in any product form. The best available publication was found to be that of Peter Scott of Framatome, who had developed a growth rate model for PWR steam generator materials [1]. His model was based on a study of results obtained by McIlree and Smialowska [2] who had tested short steam generator tubes which had been flattened into thin compact specimens. His model is shown in Figure 21. Upon study of his paper there were several arnbiguities, and several phone conversations were held to clarify his conclusions. These discussions indicated that reference 1 contains an error, in that no correction for cold work was applied to the, McIllree/Smlalowska data. The correct development is given below. An equation was fitted to the data of reference [2] for the results obtained in water chemistries that fell within the standard specification for PWR primary coolant. Results for chemistries outside the specification were not used. The following equation was fitted to the data for a temperature of 330EC:
= 2.8 x 10* (K 9)"' m/ see where K is in MPa[m)". This equation implies a threshold for cracking susceptibility,
. K,,cc = 9 MPa[m)". Correction factors for other temperatures are shown in Table 21. The next step described by Scott in his paper was to correct these results for the effects of cold - work. Based on work by Chssagne and Gelpi [3), he concluded that dividing the above equation by a factor of 10 would be appropriate to account for the effects of cold work. This step was inadvertently omitted from Scott's paper, even though it is discussed. The crack growth model for 330'C then becomes: Ua
= 2.8 x 10" (K 9)"' m/ see dt Rev.0 21 July 1997 o \3694non doc:1b'07/2'L'97
l This equation was verified by Scott in a phone call in July 1992. Scott further corrected this model for the effects of temperature, but his correction was not used in the model employed here, instead, an independent temperature correction was developed based on service experience. This correction uses an activation energy of 32.4 kCal/ mole, which gives a smaller temperature correction than that used by Scott (44 kcal/ mole), and will be discussed in more detail below. l Scott's crack growth model for 330'C was independently obtained by B. Woodman of ABB CE [4), who went back to the original data base, and did not account for cold work. His equation was of a slightly different form:
= 0.2 exp [A + B in (In (K 0)))
Where A = 25.942 B = 3.595 Q=0 This equation is nearly identical with Peter Scott's original model uncorrected for cold work. This work provided an independent verification of Scott's work. A further verification of the modified Scott model used here was provided by some operational crack growth rates collected by Hunt, et al (5). The final proof of the usefulness of Peter Scott's model wl!I come from actual data from head penetration materials in service, as will be discussed further below. To date 15 heats have been tested in carefully controlled PWR environment. One heat did not crack, and of the fourteen heats where cracking was observed, the growth rates observed in twelve were bounded by the Scott model, TV o heats cracked at a f aster rate, and the explanation for this behavior is being investipated. A compilation was made of the laboratory data obtained to date in the Westinghouse laboratory tests at 325'C, and the results appear in Figure 2 3. Notice that much of the data is far below the Scott model, and a few data points are above the model. These results represent 14 heats - of head penetrations. The effect of temperature on crack growth rate was first studied by compilin0 all the available - crack growth rate data, for both laboratory and field cracking of Alloy 600. This information is summarized in Figure 2 2, where the open symbols are for steam generator tube materials, and the solid symbols are for head penetration materials. The results are presented in a simple format, with crack growth plotted as a function of temperature. The effect of different applied stress intensity factor values has been ignored in this presentation, and this doubtlese adds to the scatter in the data. The remarkable result is a consistent temperature effect over a temperature range from 288'C to 370'C, more than covering the temperature range of PWR plant operation. The work done originally in 1992 results in a calculated activation energy of 32.4 Kcal/ mole, which has been used to adjust the base crack growth law to account for different operating temperatures. Rev.0 22 July 1997 oV694non.coc:1b:07/2y97
A series of crack growth tests is in progress under carefully controlled conditions to study the temperature effect for head penetration materials, and the results are shown in Figure 2 3. Sufficient results are available to report pmliminary findings. The tests were performed with an , applied stress intensity factor of 23 Ksl 8n' (25,3 MPa[m)"), periodic unload / reload i parameters of a hold time of one hour and a water che nistry of 1200 ppm B + 2 ppm L1 + l 25 cc/kg Hz. The results are consistent with the previous steam generator and head penetration material work, in the case of heat 69, the inree results in the middle of the ' temperature range,309'C,327'O and 341'O have the same trend as the scatter band, almost . exactly, while the high temperature and low temperature results are both lower than would be predicted by the activation energy, as shown in Figure 2 2. The results for heat 20 show a similar behavior, with the results at 325'C and 340'O also with the scatter band and nearly , . parallel to the heat 69 specimens, but at a lower crack growth rate, as shown in Figure 2 2. The effects of several different water chemistries have been investigated in a closoly controlled series of tests, on two different heats of arch;ve material. Results showed there is no measurable effect of Boron and Lithium on crack growth. The key test of the laboratory crack growth data is its comparison to field data. Crack growth from actual head penetrations has been plotted on Figure 2 2 as solid points. The solid circles are from Swedish and French plants and the solid stars are from a US plant. Figure 2 4 shows a summary of the inservice cracking experience in the head penetrations of French plants, prepared by Amzallag (6), compared with the Westinghouse laboratory data, corrected for temperature. This figure shows excellent agreement between lab and field data, further supporting the applicability of the lab data. Therefore it can be seen that the laboratory data is well represented by the Scott model corrected for temperature using an activation energy of 32.4 kcal/ mole. Also the laboratory results are consistent with the crack growth rates measured on actual installed penetrations. Theiefore the use of the Scott modelin the safety evaluations is still justifiable, in light of both laboratory and field data obtained to date, Rev.0 23 July 1997 cA3694non doc:1ti 07/23'97
TABLE 21 TEMPERATURE CORRECTION FACTORS FOR CRACK GROWTH: ALLOY 630 Temperature Correction Factor (CF) Coefficient (Co) i 330C 1.0 2.8 x 10 " 325 0.798 2.23 x 10 " 320 0.634 1.78 x 10'" 310 0.396 1.11 x 10 " 300 0.243 7.14 x 10 " 290 0.147 4.12 x 10'"
= Co (K 9)"' m / s where K la in MPa[m)"
Rev.0 2-4 July 1997 c:\3694non doc:1b:07/2317
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I Comparison of Field & Laboratory Data 10
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3.0 TECHNICAL DESCRIPTION OF PROBABILISTIC AND ECONOMIC DECISION MODELS The following two sections of this report describe the models and software for calculating the probability of failure with time and performing the economic decision analysis. The input to these models and the calculated results are described in Section 4 of this report. 3.1 PROBABIL!STIC MODEL 0 To calculate the probability of failure of the Alloy 600 vessel head penetration as a function of operating time t, Pr(t s t,), structural rollabikty models were used witit Monte Carlo simulation methods. This section describos thoso structural rollability models and their basis for the primary falluto mode of crack initiation and growth due to primary water stress corrosion cracking (PWSCC). The models used for the evaluation of the V.C. Summer vessel head penetration nozzles are based upon the economic decision tools developed previously for the Westinghouse Owner a Group (WOG). The capabilities of this software have already been verified in the followir g ways:
- 1. Calculated strosces compare well with measured stresses (sea Figure 31),
- 2. A wide range (both high and low values) of calculated probabilities are consistent with plant observations as discussed below.
The model predictions have been used to justify the scope for the second inspection performed at D. C. Cook Unit 2, when the cracked penetration was successfully repaired. The model accepts measured microstructure (replication) and has capability to ignore its effects, if desired. Recent improvements have also been made by Westinghouse to the software models in order to maximite their utility for individual plant predictions. Among the changes were:
- 1. Improved the relationship of initiation time to material microstructural effects and yield strength to more closely match the observations from the recent inspection at North Anna Unit 1,
, 2. Added statistically based Bayesean updating of probabilities due to initialinspection results (e.g. the lack of any indications at any given plant),
. 3. Updated the uncertainty on crack growth rate after initiation to reflect that observed in the recent Westinghouse test data and the recent in reactor measurement data to be published by EdF (see Figure 3 2) and
- 4. All models have been independently reviewed by APTECH Engineering (Begtey and Woodman), including an improved model for the effect of monotonic yield strength on tinie to initiation.
Rev.0 31 July 1997 oM694non doc.1b.07/2397
The (nost Jmportant parameter for estimating the failure probability is the time to f ailure, t,in hours it is defined as follows: t, a t, + (a, . a ) / daldt (31) whew i, a time to inW.ition in hours, o a, = failure err.t;k depth in inches, a, = grad Ctptt, at initiation in inches and da/dt = crack powth rate in inch / hour. in equation (31), both the crack depths at failure and initiation may bp specified as a fraction of the penetrabon wall thickness, w. The failure depth a, depends upon the failure mode being calculated. Since the failure mode of concern is cracks in the penetration that are deeper than the structurallimit of 75% of the penetration wall thickness W,it would be specified as: a, = 0.75 w (32) The time to PWSCC crack initiation, t,in hours, is defined by a model that includes the following terms and their uncertainties:
- a. a log normal distribution on an initiation coefficient, which was based upon the data of Hall and vihers (8) for forged Alloy 600 pressurizer nozzles, with only the uncertainty based upon the data of Gold and others (9),
- b. a grain boundary coverage factor, which is based upon the data of Norring and others
[10),
- c. the residual and operating stress level derived from the detailed elastic plastic finite-element analysis from the WOG study of Ball and others [11] as shown in Figure 31.
Its normally distributed uncertainty was derived from the variation in ovality from Duran and others (12)(see Figure 3 3), which is a trigonometric function of the penetration diameter and setup angle (local angle between the head and longitudinal axis of penetration).
- d. an initiation a:tivation energy, which is also normally distributed, e, the penetration material temperature, which is uniformiv distributed based upon the calculated variation of the nominal head operating temperature, and
- f. the hours at temperature per operatinD cycle (year), which is normally distributed.
Rev.0 32 July 1997 c:\3694non 00c:1b:07/2317
I i l Either replication data can be used or a model can be used for grain boundary carbide coverage. The model[7]is a statistical correlatiori of measured values with the following materials certification parameters: Carbon content, l Nickel content. Manganese content.
- Ultimate tensile strength and Yield strength.
The uncertainty on this model, which is as shown in Figure 3 4, applies equally well to both the predicted and measured values. Once the crack has initiated,it is assumed to have a depth of a, and its growth rate, da/dt in inches per hour, is calculated by the Peter Scott model, which matches the latest Westinghouse and EdF data and the previous data given in the WOG report on the industry Alloy 600 PWSCC growth rate testing results [13), and discussed in Section 2. The key parameters in the model are: ,
- a. a log normally distributed crack growth rate coefficient (see Figure 3 2),
- b. the stress intensity factor conservatively calculated assuming a constant stress through the penetration wall for an axial flaw at the inside suriace with a length 6 times its depth using a simplification of the Raju and Newman equations for pressure vessel evaluation ,
[14), and
- c. an activation energy for PWSCO crack growth, which is also normally distributed.
To calculate the effects of an in service inspection ('31) for the economic decision analysis of Section 3.2, the structural reliability ISI model uses a sunple but conservative assumption that the probability of detection is directly proportional to the ratio of the depth of the crack to the wall thickness (e.g. 50% detection probability for a crack depth of 50% of the wall. No credit is given for previous inspections so that the ehect of the f!rst inspection can be calculated for each , year of operation. , The probability of f ailure of the Alloy 600 vessel head penetration as a function of operating . time t, Pr(t s t,), is calculated directly for e ach set of input values using Monte Carlo simulation. To apply the simulation method for vessel head penetration nozzle (VHPN) failure, the existing Westinghouse PROF (probability of failure) Software System (object library) was combined with the PWSCC structural ieliability models describad previously. The Westinghouce PROF library provided standard input and output, including plotting, and probabilistic analysis capabilities (e.g. random number generation, importance sampling). The result was program VHPNPROF for calculation of head penetration failure probability with time. The Westinghouse PROF Software Library has been verified by hand calculation for simple models and alternative methods for more complex models. Recently the application of this Rev.0 33 July 1997 , 0:0694non doc:1tr07/2W97 1
,.- _,-..,,---o ..__ ,. y
I samo Westinghouse PROF methodology to the WOG sponsored pilot program for piping risk based inspection has been extensively reviewed and verified by the ASME Research Task Force on RBI Guidelines [15) and other independent NRC contractors. Table 31 providos a summary of the wide range of parameters that were considered in this comprehensive benchmarking study that compared the Westinghouse PROF calculated probabilities with thoso from the pc PRAISE program (16). As shown in Figure 3 5, the comparison of calculated probabilities af ter 40 years of operation is excellent for both small and large leaks and full breaks, including those reduced due to taking credit for leak detection. To verify the proper operation of the VHPNPROF Program in predicting the probability of getting a given crack depth due to PWSCC, calculated results were compared for four plants where sufficient head penetration information and inspection results were available. The four plants are identified in Table 3 2 along with the values of the key input parameters and calculated failure probabilities. For comparison, the latest available inspection results are also provided. Table 3 2 shows acceptable agrooment between the observed plant and VHPNPROF calculated failure trends due to PWSCC. The input and output parameters for the VHPNPROF program runs for the 65 V.C Summer head penetration nozzles are provided in Appendix A and discussed in Section 4.1. Rev.0 34 July 1997 eM694non.coc;1b 07/2397
TABLE 31 PARAMETERS USED FOR THE PC PRAISE BENCHMARKING STUDY Type of Parameter Low Value High Value Pipe Matenal Ferntic Stainless Steel l Pipe Geometry 6.62S' O.D. 29.0'O.D. 0,662' Wall 2.5" Wall Failure Modes Small Leak. Full Break. Through Wall Crack Unstable Fracture last Pass Wold inspection No X Ray Radiographic [ Pressure Loading 1000 psi 2235 pal i Low Cycle 25 ksi Range 50 kol Range Loading 10 cycles / year 20 cycles / year l High-Cycle' 1 kol Range 20 kai Range Loading 0.1 cycles / min. 1.0 cycles /sec. ! Design Limiting Stress 15 kai 30 kai l Disabling Leak Rate 50 ppm 500 gpm : Detectable Leak Rate None 3gpm
- Note: Mechanical Vibration (;ow stress range and high frequency) for small pipe, L Thermal Fatigue (high stress range and low frequency) for large pipe, i
b l i - l I i -. Rev,0 35 July 1997 o:0694non.coc:1tr07/2317
~ ~ . . . . - ~ - - . . _ _ . . _ _ _ . - - . _ _ _ _ _ . _ . . _ .
i TABLE 3-2 C000PARISON OF VHPNPROF CALCULATED PROBASILmES 1HTM PLANT OBSERVATIONS fr Parameters Almorar 1 - D. C. Cook 2 Ringhals 2 M Anno 1 Hours of Operabon 85.400 87.000 106.400 91.000 38.6 I Setup Angle (*) 42.6 50.5 I Temperature CF) 6043 598.5 605.6 600.0 , Yield Strength (ksi) 37.5 58.0 51.2 51.Z Percent GBCC 57.0 44.3 3.0 2.0 Flaw DepthfWa5 0.10 0.43 0,25 0.10 ! r 15.3 % i trubation Probabshty 1.1 % 41.4 % 37.6 % 15.3 % fi Failure Probabihty" 1.1 % 38.1% 34.6 % i Penetrahons 0 1 3 0 With Irdcahons (2 with suoi.;s)
- Calculahons performed at an equevalent setup angle for the 2nd twghest stress location that could be inspected.
" Defined here as the probability of reachmg the speched flaw depth for the Imling penetrahon.
l 1 i t r ' Rev. 0 3-6 July 1997 j o:cepenon.doestro7tzyr7 l
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3.2 ECONOMIC DECISION ANALYSIS MODELS The basis for the economic decision analysis modelis the influence Diagram for Plant Life Extension (PLEX) shown in Figure 3 6. The relationships shown by the dashed lines are not included since VHPN cracking due to PWSCC is not a safety issue. The component mitigative strategy in this case is the first inspection of the outer three rows of vessel head penetration nozzles and repair of those with detectable cracks. The probability of failure, which is a crack depth 75% of wall, and probability of inspection detection (1 PND) for each year of operation and group of penetrations come from the output files for the VHPNPROF analysis runs. The effectiveness of this mitigative strategy on future failure costs can also be calculated directly usi..g this same information instead of being estimated as is done in other decision analysis models. The output files for the V. C. Summer vessel head penetration nozzle decision analyses are included in Appendix B. The first page of the output file summarizes the input, which is described in Section 4.2. The next two pages are the results of model calculations, which can be described as follov s for each column heading on each page. CYCLE: Number of operating cycle (year) when values of the parameters below are calculated. MAX PROB: This is the maximum failure probability calculated by VHPNPROF for all the penetration nozzles. PROB-ONE: This is supplementary information about the probability that at least one of the head penetration nozzles will fail. AVG PROB: This is the average failure probability, which is the expected number of failures that is used to calculate the f ailure cost divided by the number of head penetration nozzles. NPVFC-50: The Net Present Value of the median (50% probability) failure cost, which is the product of the expected number of failures and the median cost per penetration nozzle failure. NPVFC-05: 5% Lower confidence bound on the NPV of the failure costs. NPVFC-95: 95% Upper confidence bound on the NPV of the failure costs.
~
CYlSI: Number of operating cycle (year) after which the first in-Service Inspection (ISI) would be performed. NPV-CISI: This is the NPV of the median inspection cost, which is the number of nozzles in the outer three rows times the average inspection cost per nozzle. Because of the time value of money, the later the inspection is performed, the lower its NPV. NPV-CREP: This is the NPV of the median repair costs, which is the average repair cost per nozzle times the fraction of inspected nozzles with cracks large enough to lead to Rev.0 3-12 July 1997 oM694non. doc:1b 07/397
failure and to be detected during ISI. The value of this fraction is calculated directly from the VHPNPROF output for the groups of nozzles being inspected. NPV CBEN: This is the NPV of the median cost benefit of doing the inspection. The benefit is the elimination of the future failure costs for those nozzles that have been _ repaired. _ There is no reduction in failure probability and the associated expected failure cost contribution unti! a partially cracked nozzle is repaired. NPVTC 50: This is the median NPV of tne total cost integrated over a 60 year plant life. It is the sum of the NPV of the failure cost for all nozzios at 60 years and the inspection and repair costs less the NPV of the cost benefit of the repairs. The best economic decision would be to perform the first inspection when the NPV of this cost is a minimum. NPVTC-05: 5% Lower confidence bound on the NPV of the total cost. NDUTC 95: 95% Upper confidence bound on the NPV of the total cost. The input to these models and the output values calculated by the decisioa analysis program VHPNECON are described in Section 4.2 for the V. C. Summer vessel head penetration nozzles. Rev,0 3 13 July 1997 i oM694non.docib:07/23/97 i ewt+ -w w -+- ,- 7 y-
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_ . . _ _ _ _ _ . _ . . _ _ ___ _._ _.._.._._ _ _ _ ._ . _ _ m_. _ . d . 4.0 RESULTS OF PROBABILISTIC AND ECONOMIC DECISION MODELS 4.1 INPUT AND RESULTS OF PROBABillSTIC ANALYSIS 1 The V. C. Summer reactor vessel and closure head were manufactured for Westinghouse by the Chicago Bridge and Iron Company. The closure head contains 65 head penetrations fabricated from Alloy 600 tube which are welded to a stainless steel flange. This assembly is . then welded to the low alloy steel closure head utilizing a J. groove weld. An outside view of the ] closure head which shows the penetration numbers is provided in the following sketch. These [* penetrations are utilized for a number of purposes. These purposes are for Control Rod Drive Mechanisms (CRDM), capped latch housings (CLH), part length mechanisms (P/L), thermocouple column locations (TCC), reactor vessel level instrumentation system connection
- (RVLIS), and spare penetrations, i
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l y' A review of the fabrication records for V.C. Summer indicates that the closure head penetrations were fabricated from two different heats of Alloy 600 material. Both of these heats of material were supplied by Babcock and Wilcox and are designated as M6369 and M6370. , Rev.0 41 July 1997 c:0694non. doc:1b;07/23f97
I Table 41 provides a summary of each head penetration and its use and associated heat of material. Table 4 2 provides the input values to the probabilistic analysis and Table 4 3 provides the results of the analysis in terms of the probability of failure (%) after 10,20,30,40,50, and 60 years of operation (note that penetrations 1 through 25 are bounded by penetrations 26 through . 33 since they utilize the same heats of material and their set up angle is less than that of penetrations 26 through 33). The detailed input and calculated results for the V.C. Summer vessel head penetration nozzle probabilistic analysis are given in the VHPNPROF output print files in Appendix A. The first page of each file is a description of the input for each analysis, including the standard uncertainties that were used for the probabilistic analysis. The second page of the output file
- lists the calculated probabilities.
The first column is the cycle number; the second is .he probability of failure during the cycle; the third is the accumulated probability at the end of the cycle. The fourth and fifth columns are the same types of probability as the second and third columns respectively but for an in service inspection (ISI) each cycle. This is of course an unrealistic assumption, but provides useful information for the economic analysis. Figure 41 shows the increase of the best estimate crack depth with time for the penetrations with the highest failure probability in some of the outer rows. The shortest mean time to failure (depth of 75% of the wall thickness or approximately 0.5 inch) of ( )" years is for group 1 (penetrations 58 to 65) or case 1 in Appendix A. For the second row in (penetrations 49 to 52), the residual stresses are lower so that the time to crack initiation is longer and the crack growth rate is smaller. In this case, the mean time to failure increases to almost [ }" years. Likewise, for the third and fourth rows in the mean times to failure are approximately [ }" and [ ]" years, respectively. Because of the effects of all the uncertainties that are considered in the probabilistic analysis, the uncertainty band on the time to failure is quite wide. Even with a mean time of failure of ( )" years for the case 1 penetrations (58 to 65), there is about an [ }"% probability of failure by year 60 (see Table 4 3). However , as the mean time to failure increases for the inner rows, then the probability of failure at a given time, say 60 years, decreases. For the case 8 penetrations (34 to 38), there is only a [ ]"% probability of failure by year 60 because the mean time to failure increased to [ ]" years as shown in Figure 41. To calculate the combined effects for all the vessel head penetration nozzle (VHPN) failures (crack depths of 75% of the wall), a second program (VHPNECON) was run. The results of these calculations are given in the VHPNECON output file, which is shown in the first page of < Appendix B. The column headings used in the output file and their meaning are described below. CYCLE: Number of operating cycle (year) when values of the parameters below are calculated. Each cycle has 7446 hours at temperature. For these calculations each cycle was assumed to be one year. Rev.0 42 July 1997 o:\3694non doc:1b:07/2197 i , s
MAX PROB: This is the maximum failure probability calculated by VHPNPROF for the penetration nozzle most likely to fail. PROB-ONE: This is the probability that at least one of the head penetration nozzles will fa;,. It la calculated as follows: P = 141,,(1 p,)* (41)_ . where pr = failure probability for the ith group nl = number of penetrations in the ith group - N = number of groups AVG-PROB: This is the average failure probability, which is the expected number of failures divided by the number of head penetration nozzles. E(NUMFS): This is the expected value of the number of failures in all the penetrations, it is calculated as follows: E(N,) = I,, ni p, (42) Table 4 5 provides the results of the analysis for the probability of at least one penetration failure in the head. Figure 4 2 shows the failure probability with time for each of the penetrations (58 to 65) in the highest group (1 or case 1 in Table 4-2 and Appendix A), This figure also shows the increase in the average failure probability with time for all 65 penetration nozzles for the V.C. Summer vessel head. This average probability is 1/65th of the expected number of failures used in the economic decision analysis of S6ction 4.2. For reference,[ T*% is the calculated failure (75% wall depth) probability in the worst penetration in D.C. Cook Unit 2 when a crack depth of 43% of the wall thickness was found after 87,000 hours of operation. The corresponding average failure probability is [ T*% and the probability of at least one failure is [ T*%for all 78 penetration nozzles in D.C. Cook 2. 4.2 . INPUT AND RESULTS OF ECONOMIC DECISION ANALYSIS The output files for the economic decision analysis on when to perform the first inspection of the outer three rows of vessel head penetration nozzles in V. C. Summer is listed in Appendix B. The first page of the output is a summary of the input to the VHPNECON Program. The reference year for the net present value calculation was set to cycle (year) 14 based upon the total hours of operation at temperature to date and an average 7,446 hours per cycle used - in the VHPNPROF analyses. The interest rate of 5% is based upon an assumed discount rate of 9% less an assumed 4% escalation rate. The range of costs for failure inspection and repair were calculated using the same method to combine uncertainties as was used for the simple WOG cost model. The cost calculations for Rev. O . 43 July 1997 o:\3694non. doc:1b:07/24/97
the V. C. Summer decision analysis are summarized in Table 4 4. The cost of inspection would include eddy current inspection of all the sleeved and unsleeved penetrations in the outer three rows and a ultrasonic inspection of one flaw in one penetration. The repair costs are based upon excavation of one flaw in one penetration. The failure costs are based upon excavation of one deep flaw and weld overlay repair for one penetration only. Also included are the additionalindustry/NRC interaction costs and ALARA penalty costs from the simple cost model developed for WOG. Not included in the f ailure costs were the follow on inspection costs for the repaired nozzle. Replacement power costs for extension of critical path time or unexpected shutdown due to leakage of a nozzle were not included in the subtotal of the f ailure costs in Table 4 4. This cost penalty at an assumed
, [ ]* per day significantly increases the total failure cost in Table 4-4 as well as the cost avoidance benefit of the penetration nozzle inspection and repairs.
Figure 4 3 shows the 5,50 (median value) and 95% confidence bounds on the NPV of the minimum total costs of failure through 60 years including the NPV of the inspection and repair costs at the time (cycle) for the first inspection. The minimum failure costs do not include the high downtime replacement power penalty costs. As can be seen, the minimum NPV cost would occur for no inspection at *". (cycle 59). Because of the low failure cost for the low failure probabilities of the V. C. Summer vessel head penetration nozzles, the expected benefit of repairing the detected cracked penetrations never offsets the inspection and repair costs. However, the benefits of the first inspection and repair of detected cracks are increased significantly when the total failure coct includes the replacement power costs for an unplanned repair of failed penetration nozzle. Figure 4-4 shows the 5,50 (median value) and 95% confidence bounds on the NPV of the maximum total costs of failure through 60 years, where the maximum total failure costs include the replacement power penalty costs. For this maximum cost case, the minimum NPV cost would occur for inspection at end of cycle [ ] (calendar year [ ]'*). Rev.0 44 July 1997 o:\3694non doc:1b:07/24/97
TABLE 41 HEAD PENETRATION USES AND ALLOY 600 HEAT NUMBER Row Penetration No. Use Thermal Sleeve Heat Number 0 1 P/L YES M6369
~
1 2 CRDM YES M6369 3 CRDM YES M6369
- YES M6370 4 CRDM 5 CRDM YES M6369 2 6 CRDM YES M6369 7 CRDM YES M6369 8 CRDM YES M6370 9 CRDM YES M6369 3 10 CRDM YES M6370 11 CRDM YES M6370 12 CRDM YES M6370 13 CRDM YES M6370 4 14 SPARE NO M6370 j 15 SPARE NO M6369 16 RVLIS NO M6369 17 SPARE NO M6369 5 18 P/L YES M6370 19 P/L YES M6370 20 P/L YES M6369 21 P/L YES M6370 6 22 CRDM YES M6369 23 CRDM YES M6369 24 CRDM YES M6369 25 CRDM YES M6369 7 26 CRDM YES M6370 27 CRDM YES M6370 28 CRDM YES M6369
. 29 CRDM YES M6369 30 CRDM YES M6369 31 CRDM YES M6370 32 CRDM YES M6369 33 CRDM YES M6369 Rev.0 45 July 1997 o:\3694nortdoc:1b:07/2197
. - . - . . . _ . .. .=__ . - - - - _- . - - . . . . . _ . . - . - . . = - .
TABLE 41 (Continued) 4 Row Penetration No. Use Thermal Sleeve Heat Number 8 34 CRDM YES M6370 35 CRDM YES M6370 36 CRDM YES M6370 4 37 CRDM YES M6370 38 CRDM YES 4 M6370 39 CRDM YES M6369 !. 40 CRDM YES M6369 l 41 CRDM YES M6369 9 42 CRDM YES M6370 l 1 43 CRDM YES M6370 44- CRDM YES M6369 45 CRDM YES M6369 10 46 CLH YES M6369 j ~47 TCC NO M6369 i 48 CLH YES M6369 I 49 TCC NO M6370 i 50 CLH YES M6370 51 TCC NO M6370 M6370 52 CLH YES $ 53 TCC NO M6369 11 54 CRDM YES M6369
; 55 CRDM YES M6369
$ 56 CRDM YES M6369 57 CRDM YES M6369 12 58 CRDM YES M6369 59 ~CROM YES M6369 60 CRDM YES M6369 61 CRDM YES M6369 62 CRDM YES M6369 63 CRDM YES M6369 64 GRDM YES M6369 65 CRDM YES M6369 Rev.0 46 July 1997 oM6Hnon coc:1b:07/23'97
TABLE 44 INPUT VALUES FOR PROBABILISTIC ANALYSIS Case Pen.No, Temp. SA Y.S. (ksi) GBC (%) 1 58 thru 65 557.3 'F 46.1 40.531 12.3 2 54 thru 57 43.1 40.531 12.3 3 49 thru 52 41.6 42.034 2.1
- 46,47,48 & 53 12.3 4 41.6 40.531 5 44 & 45 40.1 40.531 12.3 6 42 & 43 40.1 42.034 2.1 7 39 thru 41 35.5 40.531 12.3 8 34 thru 38 35.5 42.034 2.1 9 28,29,30,32 & 33 30.6 40.531 -12.3 10 26,27 & 31 30.6 42.034 2.1 l
i l TABLE 4 3 RESULTS OF PROBABILISTic ANALYSIS (PROBABILITY OF FAILURE %) Case Pen.No. 10 Years 20 Years 30 Years 40 Years 50 Years 60 Yes a.b 1 58 thru 65 2- 54 thru 57 3 49 thru 52 4 46,47,48 & 53
~
5 44 & 45 6 42 & 43 7 39 thru 41 8 34 thru 38 9 28,29,30, 32 & 33 10 26,27 & 31 _ _ Rev.0 4-7 July 1997 c:0694non. doc:1b:07/23/97
TABLE 4 COST CALCULATIONS FOR V. C. SUMMER VHPN ECONOMIC ANALYSIS Inspection of Noules in outer Three Rows ($K)- High Median Variance . _d W Cost Range Utility Cost Range Total Cost Range
. Total Cost Range / Nozzle -
l Repair of 1 Nonle in Outer Three Rows
- ($K)
Low High Median Variance _ _ d Utility Cost Range PCI Cost Range Total Cost Range _ Failure of 1 Noule Anywhere ($K) Low Hioh' Median Variance -
- -d W Cost Range Utility Cost Range PCI Cost Range NRC/ Industry Interaction Costs ALARA Penalty Subtotal Cost Range
. Down Time Penalty Total Cost Range l w/DTP Rev.0 48 July 1997 o:\3694non. doc:1b:07/23/97
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TABLE 4 5 PROBABILITY (%) OF A FLAW WITH DEPTH = 0.75T IN AT LEAST ONE PENETRATION 10 Years 20 Years 30 Years 40 Years 50 Years 60 Years (74500 hrs.) (149,000 hrs.) (223,500 hrs.) (298,000 hrs.) (372,500 hrs.) (447,000 hrs.) _, i i Rev.0 49 July 1997 oN1694non. doc:1b:07/23/97
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SUMMARY
/ CONCLUSIONS A detailed evaluation of the reactor vessel closure head penetrations has oeen completed for the Virgil Summer plant. One of the two degradation mechanisms covered by Generic Letter 97 01 has been addressed: Primary water stress corrosion cracking (PWSCC).
An in depth probabilistic assessment has been completed for all of the reactor vessel closure head penetrations, using state of the art methods which have been independently reviewed. These methods have also been verified by comparison with actual inspection results, as shown in Table 3 2, and discussed in Section 3. The results of the assessment sho',v that the mean time to failure for the worst penetration is [ ]" years, Indicating that the V.C. Summer plant is not at risk for this issue. The probability of a flaw initiating and reaching 75% of the wall thickness in 40 years was calculated to be [ ]'" percent. For 60 years, the probability increases to [ }" percent. The probabilistic results combined with the economic decision analysis model, and the conclusion reached was that the optimum time (minimum cost) for a head penetration inspection at V.C. Summer would be at [ )" calendar years of service, as shown in Figure 4 4. 4 Rev.0 5-1 July 1997 c:0694non coc:1b:07/23,97 j
6.0 REFERENCES
[1] Scott, P. M.,'An Analysis of Primary Water Stress Corrosion Cracking in PWR Steam Generators," in Proceedings, Specialists Meeting on Operating Experien':e With Steam Generators, Brussels Belgium, September 1991, pages 5,6. [2] Mc liree, A. R., Rebak, R. B., Smiatowska, S., 'Rolationship of Stress intensity to Crack Growth Rate of Alloy 600 in Primary Water," Proceedings International Symposium Fontevraud 11, Volume 1, p. 258-267, September 10 14,1990. [3] Cassagne, T., Gelpi, A.,' Measurements of Crack Propagation Rates on Alloy 600 Tubes in PWR Primary Water," in Proceeding of the 5th International Symposium on Environmental Degradation of Materials in Nuclear Power Systems Water Reactors," August 25 29,1991, Monterey, California. [4] Personal Communication, Brian Woodman, Combustion Engineering, October 1993. [5] Hunt, S. L. and Gorman, J.," Crack Predictico and Acceptance Criteria for Alloy 600 Head Penetrations"in Proceedings of the 1992 EPRI Workshop on PWSCC of Alloy 600 in PWRs, December 13,1992, Orlando Fl (published in 1993). [6] Personal communication - C. Amzallag to W. Bamford, Feb. 26,1997. [7] G. V. Rao and T. R. Leax, Microstructural Correlations with Material Certification Data in Several Commercial Heats of Alloy 600 Reactor Vessel Head Penetration Materials - WCAP 13876, Rev.1, June 1997. [8) ' Evaluation of Leaking Alloy 600 Nozzles and Remaining Life Prediction for Similar Nozzles in PWR Primary System Application," Hall, Magee, Woodman and Melton,in Service Experience and Reliability Improvement, ASME PVP Vol. 288,1994 [9] "The Status of Laboratoiy Evaluations in 400*C Steam of the Stress Corrosion of Alloy 600 Steam Generator Tubing," Gold, Fletcher and Jacko in Proceedings of 2nd Intemational Topical Meeting on Nuclear Power Plant Thermal Hydraulics and Operations,1986 [10] "Intergranular Stress Corrosion Cracking in Steam Generator Tubing, Testing of Alloy 690 and Alloy 600 Tubes," Norring, Engstrom and Norberg, in Third lnternational Symposium on Environmental Degradation of Materiais in Nuclear Power Systems - Water Reactors - Proceedings, The Metallurgical Society,1988 [11} WCAP 13525, Rev.1, RV Closure Head Penetration Alloy 600 PWSCC (Phase 2), Ball et al., December 1992 (Class 2) [12) WCAP-13493, Reactor Vessel Closure Head Penetration Key Parameters Comparison, Duran, Kim and Pezze, September 1992 (Class 2) Rev.0 0-1 July 1997 o:\3694non doc;1b:07/23/97
lib) WCAP 13929, Rev. 2, Crack Growth and Microstructural Characterization of Alloy 6Lv Head Penetrafion Materials, Bamford, Foster and Rao, November 1996 (Class 2C) (14] Newman, J.C. Jr, And Raju, l.S. " Stress Intensity Factors for Internal Surface Cracks in Cylindrical Pressure Vessets" Transactions ASME, Journal of Pressure Vessel j
- Technology, Volunie 102,1900, pp,342 346,
, \15) Risk BasedInspection Development of Guidelines, Volume 1, GeneralDocument,
- ASME Research Task Force on Risk Based Inspection Guidelines Report CRTD-Voi, 20-1 (or NUREG/GR-005, Vol.1), American Society of Mechanical Engineers,1991 (16) NUREGICR 5864, Theoreticaland User's Manualforpc-PRAISE, A Probabilistic Fracture Mechanics Computer Code for Piping Reliability Analysis, Harris and Dedhia, July 1992 l
Rev.0 6-2 July 1997 oM694non. doc:1b:07/2T97
d Apoendix A , Output Files From VHPNPROF for Probabilistic Failure Analysis of the V.C. Surnmer Vessel Head Penetration Noules Rev.0. A1 July 1997 c:\3694non. doc:1b:07/23/97
WESTIN3 HOUSE VESSEL HEAD PEN, NOZZLE ECONOMIC DECISION ANALYSIS VHFNE00N ESBU NSD 65 Nozzles at Virgil C. Summer Plant on 05-31-97 06/06/97 CYCLE MAX-PROB PROB ONE AVG PROB E(NUMFS) _ - c.b 14 15 16 17
- 18 19 to 21 22 23 24 25 24 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 A2
Output Print File VHPNPROF. Pol Opened at 16:44 on 05 12 1997 Limit Depth Fraction of Wall 0.750 Monotonic Yield Strength (Kai) 40.5 Penetration Setup Angle (degrees) 46.1 hnetration Temperature (F) 557.3 Center Penetration Stress (Ksi) 34.4 Grain Boundary Carbide Coverage (%) 12.3 Months in operating Cycle 12.0 LOG 10 of Years Between ISI 0,00
- Wall Fraction for 50% Detection 0.500 Operating Cycles per Year 1.000 STRUCTURAL RELIABILITY AND RISK ASSESSMENT (SRRA)
WESTINGHOUSE PROBABILITY OF FAILURE PROGRAM VHPNPROF ESBU SMPD INPUT VARIABLES FOR CASE la RV Head Penetration CGE 58-65
~
0.b i i n 9 4 manuse A-3
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4 ammuun O A-4
l l l Output Print File VHPNPROF.P02 Opened at 16:51 on 05 12-1997 Limit Depth Fraction of Wall 0.750 Monotonic Yield Strength (Kai) 40.5 Penetration Setup Angle (degrees) 43.1 Penetration Temperature (F) 557.3 Center Penetration Stress (Kai) 34.4 Grain Boundary Carbide Coverage (%) 12.3 Months in Operating Cycle 12.0 LOG 10 of Years Between ISI 0.00
. Wall Fraction for 50% Detection 0.500 Operating Cycles per Year 1.000 i STRUCTURAL RELIABILITY AND RISK ASSESSMENT (SRRA)
- ESBU SMPD
- WESTINGHOUSE PROBABILITY OF FAILURE PROGRAM VHPhPROF INPUT VARIABLES FOR C7.SE 2
- RV Head Penetration CGE 54-57
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l l l l l Output Print File VHPNPROF.P03 Opened at '17:00 on 05-12 1997 Limit Depth Fraction of Wall 0.750 Monotonic Yield Strength (Ksi) 42.0 Penetration Setup Angle (degrees) 41.6 Penetration Temperature (F) 557.3 Center Penetration Stress (Kai) 34.4 Grain Boundary Carbide Coverage (%) -2.1
-Months in Operating Cycle 12.0 LOG 10 of Years Between ISI 0.00
- Wall Fraction for 50% Detection 0.500 Operating Cycles per Year 1.000 STRUCTURAL RELIABILITY AND RISK ASSESSMElff (SRRA)
WESTINGHOUSE PROBABILITY OF FAILURE PROGRAM VHPNPROF ESBU SMPD INPUT VARIABLES FOR CASE 3: RV Head Penetration CGE 49-52
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Output l'r i nt File VHINFROF.lD4 Opened at 17: 00 en 00 12 1997 Limit Dept h f raction cf Wall 0.700 Menotonic Yield Strength (Est) 40.5 Fenetration Setup Angle (degrees) 41.6 ter.etration Temperature (F) $57.) Center Fenetration Stress (Ksi) 34.4 Orain boundary Carbide Ccverage (%) 12.) l Months in Operating Cycle 12.0 l LO310 of Years between 151 0.00 l Wall Fraction for 50% Detection 0.500 Operating Cycles per Year 1.000 STRUCTURAL AELIABILITY AND RISK ASSESSMEllT (SRRA) WESTIN3HOUSF l'ROBABILITY OF FAILURE itD3FJ#. VHFNFROF ESBU-SMPD INPUT VARIABLES FOR CASE 4i RV Heel Penetration CGE 46 47 48; 5)
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output Print File VHINikOF.P05 C'pened at 17: 12 on 06 12 1997 Limit Depth Fractic>n of Wall 0.7tC Monotonie Yaeld Strength (Kat) 40.5 Penetration Setup Angle (degrees) 40.1 Tenetration Temperature (F) 557.3 Cente Penetration Staess (Km.) 34.4 Orain Boundary Cart >tde Coverage (%) 12.3 Months in Cperating Cycle 12.0 3 LCG10 of Years between ISI 0.00
- Well Fraction for 504 Detection 0.500 Operating Cycles per Year 1.000 STRUCTURAL RELIABILITY AND RISK ASSESSMENT (SRRA)
WESTIN3 HOUSE PROLABILITY Of FAILURE PRCCRAM VHPHPROF ESBU SMPP
................................ ............e=================================
INPUT VARIABLES FOR CASE 5: RV Head T'enetration CGE 44 & 4$
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Output Print File V)R!iTROF, Pot Ctened at 17: 17 on 01 12 1997 Limit Depth Fraction of Wall 0.750 Monotonic Yield Strength ( r,s i ) 42.0 Tetietration Setup Angle (degrees) 40.1 l'enetration Temperature (F) 557.3 Centet Tenetration Stress (Esi) 34.4 Grain Boundary Carbide Coverage 1%) -2.1 Months in Operating Cycle 12.0 LO310 of Years Between ISI 0.00
- Wall Traction for 50% Latection 0.$00 Operating cycles per Year 1.000 1
STRUCTURAL RELIABILITY AND RISK ASSES $ MINT (SRRA) l WESTIN3 HOUSE PROBABILITY OF FAILURE PROGFJsM VHPNPROF ESBU+SMPD INPUT VARIABLES FOR CASE 6: RV Head t'enetration CGE 42 & 43 o.b 9 musene A 13
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Output trint File VHINFROF.F07 Orened at 17:2; on Of. 12-1997 Limit Depth Fraction of Wall 0.750 Monotonic Yield Strength (Fsi) 40.5 tenetration Setup Angle (degrees) 35.5 Penetrat2on Temperature (F) $$7.3 C' *er Penetration Stress (Ksi) 34.4 Ot 4n boundary Carbide Coverage (%) 12.3 Months in Operating Cycle 12.0 LOG 10 of Years Between 151 0.00 Wall Fraction for 50% Detection 0.500 Operating Cycles per Year 1,000 STRUCTURAL RELIABILITY AND RISK ASSESSMENT (SRRA) WECTINGHOUSE FROBABILITY OF FAILURE FROGRAM VHFNFROF ESBU SMFD 1HPUT VARIABLES FOR CASE 'l : RV Head Penetration CGE 39 41
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Output Print File VHPHPROT.POB Opened at 17:28 on 05 12 1997 Limit Depth Fraction of Wall 0.750 Monotonic Yield Strength (Ksi) 42.0 Tenetration Setup Angle (degrees) 35.5 Penetration Temperature (F) 557.3 Center l'enetration Stress (Esi) 34.4 ~ Grain boundary Carbide Coverage (%) -2.1 Months in Cperating Cycle 12.0 LO310 of Years Between ISI 0.00 Wall Fract2on f or 50% Detection 0.500 Operating Cycles per Year 1.000 STRUCTURE RELIABILITY AND RISK NSSESSMENT (SRRA)
- ESBU-SMPD WESTIN3 HOUSE PROBABILITY OF FAILURE PROGRAM VHPNPROF se........................e....................... 6...........................
INPUT VARIABLES FOR CASE et RV llead Penetration CGE 34 38
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Output l'r i nt File WINIROF.P05' Opened at 17:33 on 05 12-1997 Limit Depth Fraction of Wall 0.*150 Monotonic Yield Strength (Esi) 40.5 . l'enetration Setup Angle tdegrees) 30.6 lenetration Temperatute (F) 557.3 Center Penetration Stress (Ksi) 34.4 Grain Boundary Carbide Coverage (n) 12.3 Months in Operating Cycle 12.0 LO310 of Yeare between ISI 0.00 \ Wall Fraction for 50% Detection 0.500 Operating cycles per Year 1.000 j STRUCTUFE RELI ALILITY AND RISK ASSESSMENT (SRRA) WESTINGHOUSE FROBADILITY OF FAILURE FROGRAM VHPNFROF ESDU-SMFD INPUT VARIABLES FOR CASE 9: RV Head Fenetration CGE 28:29 30:32;33 ( l
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______ _ _ _ _ - - , _ - - - - - . - , - . - - - - - - - - - - - - - - - - - - - - - - - ~ - ~ - - " - " ~ ~ --' ' M O ti e phemuMED m I O e G A 20
Output l'r i nt File VHtNikOF. 010 Ctened at 17: 37 cn C0 12 1997 Limit Depth F action of Wall 0.750 Monotonic Yield Strength (Psi) 42.0 fenetration Setup Angle (degrees) 30.0 l'enetration Tempetature (F) $$7.3 Center tenetration Stress (Esi) 34.4 Orain boundary Carbide Coverage (t) 2.1 Months in Operating Cycle 12.0 LO310 of Years Between 151 0.00 Wall Fraction for 50% Detection 0.500 Operating Cycles per Year 1.000 STRUCTURAL RELI AD1LITY AllD k!SK ASSESSMENT (SkRA) i WEST!H3 HOUSE FROBABILITY OF FAILURE FRO 3kAM VHINFROF ESBU SMPD l ............................................................................... l INPUT VARIABLES FOR CASE 10: RV Head lenetration CGE 26 21 31 i -- ab 1 l l I A 21
Ob e 9
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l i I l l e e A-22
Appendix B Output Files From VHPNECON for Economic Decision Analysis of the V.C. Summer Vessel Head Penetration Nozzles I Rev.O B1 July 1997 oV694non doc:1b'07/2397
WESTINOHOUSE VESSEL HEAD IEN. ICTZLE EOONDMIC PE0lS10N ANALYSIS VHPNEODN ESisU NSD 65. Hostles at Virgil C. Summet flant cr. 06 10-97 06/06/97 Ref. Year 6 Interest Rate (%) for NPV Calculations e 1.400E*01 f. 000E*00
- - d Min. and Max. Failure Cost per ienetration ($K) e Min. and Max. Inspection Cost per Tenetration ($K) . . Min, and Max. Repair Cost per Fenetration ($K) . -
Reading Probabilities for B Norales in Group 1 From File: VHPNPROF.001 Reading Probabilities for 4 Nozzles in Group 2 From File VHPNPROF.002 Reading Probabilities for 4 Nozzles in Group 3 From File: VHPNPROF.003 Reading Prvbsbilities for 4 Hostles in Group 4 From File VHPNPROF.004 l Reading Probabilities for 2 Nortles in Group 5 From File VHPNPROF.005 Reading Probabilities for 2 Nottles in Group 6 From File: VHPNI'ROF.006 l Reading Probabilities for 3 Nortles in Group 7 From File VHPNPROF.007 l Reading Probabilities for 5 Nozzles in Group 8 From Filei VHPHPROF.000 l l Reading Probabilities for 5 Nottles in Group 9 From File: VHPNPROF.009 Reading Probabilities for 28 Nozzles in Group 10 From F11ei VHPNPROF.010 A e B-2 l
WESTIN3} LOUSE VESSEL llEl.D T Ell. 130 ZLE ECONOMIC DECis!Ott JJ:ALYSIS VHPNECON EsDU.HSD 65 Hogales at Vargal C. Summer Flar.t on 06 10 97 06/06/97 CYCLE MAX IROb PROB +0NE AV3 l' ROD NFVFC 05 NPVrt 50 NPVrC 95 _,, - a.b 14 15 16 17 18 19
. 20 21 22 23
+
24 25 26 27 28 l 29 30 f 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
$1 52
. 53 54 55 56
, 57 58 59 60 f A B-3 o
WESTINGHOUSE VESSEL HEAD PEN. !JDZZLE ECONOMIC LE0!SION ANALYSIS VHINECON ESbU.NSD 65 Nortles at Virgil C. Sumnier Plar.t on C6 10-97 06/06/97 CYISI NPV-CIS! NPV CREP NPV CBEN NPVTC-05 NPVTC-50 NPVTC 95
-. - Ab 14 15 16 17 18 19
. 20 21 22 23
. 24 25 26 27 20 29 30 33 32 33 34 35 l 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
$1 52
, 53 54 55 56
, 57 59 59 B-4 a ->
WESTINGHOUSE VESSEL HEAD IEN. NOZZLE ECONOMIC DECISION A!4ALYSIS VHPNECON ESBU NSD 65 Nortles at Virgil C. Summer l'1 ant on 06-10 97 06/06/97 Ref. Year & Interest kate (%) for NPV Calculations - 1.400C+01 5.000E+LO
- - d Min. and Max. Failure Cost per Penetration ($K) .
Min. and Max. Inspection Cost per Penetration ($K) = Min, and Max. Repair Cost per Penetration ($K) . Randing Probabilities for 0 ifortles in Group 1 From Files VHPNPROF.001 Reading Probabilities for 4 Norsle6 in Group 2 From File VHPNFROF.002 1 . ! Reading Probabilities for 4 Norries in Group 3 From File: VHPNPROF.003 1 1 Reading Probabilities for 4 Nottles in Group 4 From Files VHPNPROF.004 Reading Probabilities for 2 Nozzles in Group 5 From File VHPNPROF.005 Reading Probabilities for 2 Nozzles in Group 6 From File: VHPNPROF.006 Reading Probabilities for 3 Nortles in Group 7 From Files VHPNPROF.007 Feading Probabilities for 5 Nozzles in Group 8 From File VHPNPROF.000 heading Probabilities for 5 Nostles in Group 9 From Files VHPNPROF.009 Reading Probabilities for 28 Nortles in Group 10 From File VHPNPROF.010 e
! O B-5
WESTINGHOUSE VESSEL HEAD TEN NDZELE ECONOMIC LECISION ANAI.YS!$ VH M4E CON E!BU NSD 6b Nortles at Vargal C. Summer llant c.n 06-10 97 C6/0(/97 CYCLE MAX fP.OD PROB ONE AV3 TROD NPVFC-05 NPVFC LD NOVFC 9f,
- - a.b 14 15 16 17 le 19 e 20 21 22 23 24 25 26 27 20 29 30 31 33 33 34 35 36 37 3B 39 40 41 42 43 44 45 46 47 48 49 50
$1 52
. 53 54 55 56 i 57 58 59 60 B-6
WEST!!J3}lDUst VESSEL HEAD PLti. 14DZZLF ECONOMIC EECISICli Af4ALYSIS VHi tiECON ESBU.NSD (5 Norales at Virgil C. Sumn.er f lant on 06 10 97 00/06/97 CY151 NPV CISI NPV CREP Hl'V CB EN tit >VTC- 0 5 NIVTC-50 Ni'VTC 9 5
- a..b 14 15 10 17 19 19
, 20 21 22 23 i , 24 l 25 1 2G l
27 28 29 l 30 31 32 33 34 35 36 37 30 39 40 41 42 43 44 45 46 47 48 49 50 51 52
, 53 54 55
) 56
, 57 58 U
59 B-7 _ _ . . . . . . . . _ . . . . . . . . . .}}