ML20214P909
| ML20214P909 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 09/30/1986 |
| From: | Poole A HOUSTON LIGHTING & POWER CO. |
| To: | |
| Shared Package | |
| ML20214P894 | List: |
| References | |
| NO.308.04-001, NO.308.04-1, NUDOCS 8609240099 | |
| Download: ML20214P909 (26) | |
Text
__
Enclosure 1 ST-HL-AE-1758 File No.: G9.10 Report No.
NO3.08.04-001 JUSTIFICATION FOR USE OF CUF - 0.4 AS A SCREENING CRITERIA FOR THE POSTULATION OF PIPE BREAKS IN PWR CLASS 1 LINES
(
A. B. P0 OLE The Light souwmas company September, 1986 Houston Lighting & Power iaci.,c ci .o ae 8609240099 860917 PDR ADOCK 05000498 A PDR
g ., -
)
y .
CONTENTS PAGE LIST OF FIGURES..................................................... vi LIST OF TABLES...................................................... vii ACKN0WLEDGEMENTS.................................................... viii
- ABSTRACT............................................................ I I. INTRODUCTION................................................... 2
- 2. PROBLEM DESCRIPTION............................................ 3
- 3. CODE SECT. III CONSERVATION.................................... 3
- 4. ENVIRONMENTAL EFFECTS FOR PWR LINES............................ 4
- 5. EFFECTS OF INITIAL DEFECTS ON LIFETIME......................... 5
, 6. EFFECTS OF LOADS NOT INCLUDED IN SECT. III ANALYSIS............ 6
- 7. DISCUSSION..................................................... 7
- 8. CONCLUSIONS.................................................... 8 REFERENCES........................................................... 20 4
d I
l l
l l
r n
. t vi LIST OF FIGURES FIGURE PAGE 1 Fatigue Crack Growth For Typical PWR Class 1 Piping 17 2 Justification For Increased Usage Factor 18 3 Margin on Failure 19 l
l
b .e . ,
8 yr >
vii LIST OF TABLES TABLE PA_G.E 1 PWR Service Experience 10 2 PWR Water Chemistry 11'
, 3 PWR Environmental Effects on
. Stainless Steel 12 j 4 NUREG/CR-3982 Crack Growth Data 13 5 Estimates of Failure Lifetime Based on CUF 14 6 Lifetime Predictions for CUF 0.1 and
, CUF 0.4 With Flaw Present 15 7 Comparison of Lifetimes for No Defects and Defects Present 16 f
i i
I l
i l
4~ r
. viii ACKNOWLEDGEMENTS The author wishes to acknowledge the contributions of W. H. Bamford, K. C. Chang, D. A. Roarty, E. .R. Johnson and S. A. Swamy of Westinghouse Electric Corp. who provided input on fatigue usage factors and fracture mechanics work completed on PWR reactor coolant system components.
Thanks are also due to D. Landers of Teledyne Engineering, W. W. Watson of Bechtel Energy Corporation, and K. S. Siedle, Consultant to HL&P for their comments and assistance. Special thanks is provided to M. R. Wisenburg of HL&P for his comments and editorial help.
1
1 ABSTRACT A review of existing literature on ASME Code Section III fatigue usage factor evaluation procedures and their correspondence to crack growth during the 40-year design life of nuclear power plants was completed. Additional data points of a general nature were obtained with the help of Westinghouse Electric Corporation. These various inputs were then used to establish a general correlation between usage factor and fatigue crack growth.
Using the above established correlations, the effect on plant design margins was determined for various Code Section III fatigue usage factors.
This review of design margins demonstrates that a location on a PWR Class 1 piping system stressed with a resultant cumulative usage factor (CUF) equal to 0.4 would provide a design margin between I,680 years and 360 years to failure depending upon whether a defect is present early in life. The 360-year minimum margin to failure is calculated assuming the presence of a ten (10) percent through wall defect at the point of highest cyclic stress. This margin, which would result from use of a CUF of 0.4 as a screening criteria on pipe break postulation, is considered to be appropriately conservative.
4
,T 2
- 1. INTRODUCTION The fatigue design approach of Section III of the ASME Boiler and Pres-sure Vessel Code is based on the experimentally determined relationship
! between elastically calculated stress range and fatigue life. Fatigue damage accumulated by the component at different stress ranges is accounted for by linearly adding the fraction of life consumed at each stress range. This cumulative usage factor (CUF) must be less than unity. The design cycles and stress loadings for a Section III fatigue calculation are conservative esti-l mates made by the design engineer to account for plant transients which could accumulate over a plant lifetime of 40 years.
In the design of the Class 1 piping components in a pressurized water
- reactor (PWR), a CUF for each Class 1 piping joint is calculated using Section III of the ASME Code. To ensure adequate design margin for the plant lifetime (40 years) for fatigue, each of these CUF values is required to be less than i 1.0. Also during the design, construction, and testing of a PWR, significant effort is devoted to reviewing the effects of postulated ruptures of high energy piping. The Standard Review Plan (SRP), NUREG 0800 (Ref.1), and BTP MEB 3-1 provide a methodology for defining those joints in Class 1 piping systems where breaks are postulated to occur. This methodology specifies that
~
breaks be postulated where the ASME Code III fatigue CUF exceeds 0.1 and/or the ASME Code equations 10,12, or 13 stress intensity range is greater than 2.4 Sm.
The South Texas Project piping analysis completed by Bechtel Energy Corp.
has identified seventy-seven (77) locations where the CUF exceeds 0.1. Using the SRP guidance, the designer would postulate a circumferential and/or longitudinal break at each location. Evaluation of damage due to pipe whip-ping and discharging fluids in the break area must then be completed. If components and/or equipment needed to bring the plant to a safe shutdown condition are impacted, then these items must be protected. The standard means of protection are the design and installation of. pipe whip restraints and/or fluid jet impingement barriers. Due to the large loads resultant from postulated pipe breaks, these pipe whip restraints and jet impingement barri-ers are massive additions to the nuclear plant. This protective hardware occupies large amounts of room and results in plant congestion. The reduction j in space for maintenance and inspection result in increased worker radiation
r ,
exposures and decreased effectiveness of in-service inspections of the piping components. This is of particular concern since the area where CUF is larger than 0.1 is primarily in Class 1 piping inside the containment building.
l 4
j 2. PROBLEM DESCRIPTION The American Nuclear Society (ANS-58.2) Working Group on pipe break has l proposed increasing the CUF criteria for pipe break postulation from 0.1 to a
, value of 0.4. This increased value, if used, would result in a significant reduction in the number of postulated Class 1 pipe breaks which must be evaluated and reviewed in the design of a nuclear power plant. Specifically
) for South Texas there are fifty-seven (57) locations in Class 1 piping where
, the CUF is between 0.1 and 0.4. Deleting these 57 postulated breaks from the design -is expected to eliminate approximately 20 associated pipe whip re-
- straints and jet impingement barriers. During the review of the potential for j increasing the CUF screening criteria, it was determined that each of the l following questions should be explored in detail
i o Is adequate conservatism included in the ASME fatigue curves and Section III calculational methodology?
- o Could environmental effects cause earlier crack initiation and increased crack growth rates than those represented by the tested ASME samples?
o If small cracks were present in piping prior to start of operations, what would be the impact on design margin?
o What is the potential design impact of certain loads not included in the Section III analysis such as water hammer and steady state vibration?
The following sections will review each of these questions in turn and examine their potential impact on a PWR nuclear power plant such as South
- 3. CODE SECTION III CONSERVATISM The fatigue design approach of Section III of the ASME Code is based on relationships between plastic strain amplitude and fatigue life. The rela-tionship between plastic strain amplitude and fatigue life has been estab-
- lished by extensive strain-control push-pull fatigue testing of smooth one-quarter-inch diameter, unflawed, hourglass-shape specimens. The design curves of ASME Code Section III are based on a best-fit curve drawn through
.w-- -. - ._ ,.-c-y- - , ,,.,,,,-r+.__,-.- _e..-.... , , , - . , - . - - - . - --,n.__,,m. +y-... . , . . -._,., . , , - - _ _ , . , - - -
4 the test data that has been lowered by a factor of either two on stress or twenty on cycles, whichever is more conservative at each point. The fatigue curves of ASME Code Section III are logarithmic plots of stress-intensity amplitude (S) versus number of cycles to failure (N). A fatigue usage factor is calculated by summing the ratios of the number of cycles expected to the number of allowable cycles determined from the S-N curve for stress cycles that are postulated to occur over a forty-year plant lifetime.
Conservatism is included by the designer when establishing the number and type of transients to be evaluated. The peak stress is used in the fatigue 4
calculation and conservatism is known to be present in the worst case lumping of transient conditions. When the combined conservatisms are considered, it is not difficult to understand the resultant PWR service experience as listed in Table 1.
- 4. ENVIRONMENTAL EFFECTS FOR PWR LINES Temperature and environment can have an effect on fatigue crack initia-tion and growth. For example, the ASME fatigue crack growth law for carbon steel shows a large environmental effect. In addition, Boiling Water Reactors j (BWR) environmental testing of SA 333 GR 6 carbon steel piping shcws that the l carbon steel S-N curve contains very little, if any, conservatism. These results are considered to be caused by the increased oxygen content in air and l BWR environments.
For PWR Class 1 piping the environment is pressurized water at an operat-ing temperature of approximately 600 F. The primary water chemistry specifi-cations for a PWR such as South Texas are listed in Table 2 (Ref. South Texas Project FSAR, Table 5.2-4).
As seen in Table 2, the oxygen concentration must be tightly controlled so' as not to exceed 0.005 ppm during operation. This low oxygen content together with the use of austenitic stainless steel piping has provided very good operating PWR service experience as previously illustrated in Table 1.
The environmental effects that would be important to fatigue calculations would be those which might affect either the fatigue threshold stress intensi-ty factor or the fatigue crack growth rate. Westinghouse has reviewed these possible affects and provided ^.he results shown in Table 3. These results l
illustrate that the PWR water environment affect is to increase the threshold stress intensity factor for crack growth and to have very little influence on crack growth rate.
i
5 The time required to reach critical flaw size in a PWR pipe to " safe-end" connection from Reference 2 was calculated using a threshold stress intensity factor of 4.6 KSI h. Therefore, these values of lifetimes should be repre-sentative of PWR piping and have some inherent conservatism based upon West-inghouse estimated values listed in Table 3. In general, Reference 2 crack growth times to failure were in excess of 1320 years. This result together with the crack growth specimen data developed over the years by Westinghouse show that the PWR operating environment has no significant impact on fatigue lifetimes.
- 5. EFFECTS OF INITIAL DEFECTS ON LIFETIME The ASME Code Section III fatigue calculations do not provide a mechanism to evaluate the impact of an initial flaw on the cumulative usage factor. The previously discussed conservatisms together with high quality control practic-es on components and field fabrication processes are generally considered adequate to assess designs using the cumulative usage factor method.
The actual testing of stainless steel piping has been completed by several investigators. Appendix C of Reference 3 provides a listing of various austenitic stainless steel piping product cyclic moment fatigue data.
Using this data, one can determine the CUF value which would be obtained for the through wall failure cycles. An average CUF to failure using this data would be a value of CUF equal to 50.0. These piping products would have a time to through wall failure of at least 2000 years (no detectable initial
- defects assumed in test case) for a CUF loading of 1.0.
l Fracture mechanics methods can also be used to establish the predicted times to failure for postulated initial defects. Reference 2 provides an assessment of crack growth to failure for a PWR " safe-end" to piping connec-l tion with assumed initial defects of various sizes.
The piping in the Reference 2 analysis was SA-376 type 316 stainless steel material with a nominal inside diameter of 29 inches and wall thickness of 2.5 inches. The time to grow a critical flaw based on worst case analysis results is shown in Table 4.
For the Reference 2 analysis case, the pipe loading corresponded to a worst case calculated CUF of 0.069. This data shows significant margin to failure.
b Westinghouse has provided the crack growth data predictions shown on Figure 1. This crack growth was calculated for a piping location that had a loading corresponding to a CUF greater than 0.20. As Figure I shows, minimum crack growth has occurred over one plant lifetime of 40 years. In addition, Westinghouse has provided crack growth data for a piping location with a relatively high cumulative usage factor. The CUF at this point was calculated to be approximately 0.60. The worst case predictions of time for a crack to grow to critical flaw size was 220 years. The margin for this higher loading case is less but still shows significant time required to develop a critical fl aw.
The effect of having an initial defect is seen to reduce the margin, but not significantly, for points of moderate cyclic loading. The existence of initial flaws is assumed to have a very low probability because of high quality standards in plant fabrication and in-process inspection. Pre-service inspections of Class I welded joints add to the low probability of an existing iaitial flaw.
- 6. EFFECT OF LOADS NOT INCLUDED IN SECTION III ANALYSIS There are some loading conditions that are not generally included in a Section III fatigue analysis. Potential water hammer loads and steady state vibratory loads are normally not included in the fatigue analysis of compo-nents. These two loadings have not been required for PWR Class 1 piping fatigue analysis because:
- 1) The Class I piping lines which are associated with the RCS main loop have been designed to minimize the potential for water hammer.
Safety In.iection All lines are water solid at ambient temperature.
Chemical and Volume Control System The high temperature lines have been designed to maintain water solid conditions during normal operation.
Reactor Coolant System System designed to preclude steam void formaticn and water hammer not a concern.
Residual Heat Removal System All lines in the system are designed to be water solid and water hammer not a concern.
I
7
- 2) During hot functional testing, the Class I lines are monitored to ensure that no excessive steady state or operational transient vibrations are present. If noticeable vibrations are present, the vibration amplitudes are measured, then related to stress levels and confirmed to be less than the material endurance limit.
Therefore, the conservatism in cumulative usage factor calculations is not considered to be affected even though these loadings are not included.
- 7. DISCUSSION The problem with using cumulative usage factor (CUF) as a basis for postulation of pipe breaks is the difficulty in quantifying various values of CUF relative to actual margin to failure for a piping component. In an attempt to achieve this goal, two different correlations have been developed.
The first correlation is based upon actual piping failure data for stainless steel piping. The second correlation is done using fracture mechanics and assumes an initial flaw is present.
As discussed previously in Section 5, Appendix C of Reference 3 provided failure data for stainless steel piping. Failure (through wall leakage) of piping components occurred at an ASME Code calculated usage factor of 50 (average). This value of CUF=50.0 shows conservatism of the code curves, stress indices, stress equations, ke factor, and material strength variations.
Based upon a review of this failure data, a CUF of 15 can conservatively be justified as representative of the loading required for wall penetration failure (see Figure 2). This factor of 15 can then be used to estimate lifetimes to failure for various loading conditions as represented ty a code CUF. For the cases of CUF=0.1 and CUF=0.4 loadings, the estimated lifetimes to failure are shown in Table 5.
Fatigue crack growth of a) = 0.05 to a)= acritical was estimated as five lifetimes, and this was the value used in Table 5. These lifetimes are assumed to represent an actual piping case where no initial flaw is present.
When converted to years, it provides 6,200 years to failure for CUF=0.1 and 1,720 years to failure for CUF=0.4.
l The second correlation uses the fracture mechanics work discussed in l
Section 5 to establish a relationship between CUF and time to failure assuming an initial flaw is present. This correlation is considered to be a worst case l
l l
l
8
, assumption based on an assumed flaw and inputs used in fracture mechanics calculations. The points used are one provided in Reference 2 for CUF=0.069 and one obtained from Westinghouse for CUF=0.6. The CUF=0.069 provided a time to failure of 33 plant lifetimes or 1,320 years. The CUF=0.60 case provided an estimated minimum time to failure of 5.5 plant lifetimes or 220 years. In order to determine lifetimes for other CUF loading values, the plot of Figure 3 was developed. The correlation curve is known to have a convex shape relative to the origin with lifetimes increasing as CUF decreases. The two determined points were used to plot this type curve as shown on Figure 3.
Using Figure 3 lifetimes can be estimated for CUF=0.1 and CUF=0.4 assum-ing an initial flaw present as evaluated using worst case fracture mechanics.
These lifetime values are listed in Table 6.
- 8. CONCLUSIONS The piping locations at South Texas where the ASME Code cumulative usage factor (CUF) would be used to postulate breaks meet the following conditions:
- 1) All piping is Class 1.
- 2) All piping is austenitic stainless steel.
- 3) All piping systems are operated with fluid meeting PWR water chemistry specifications (oxygen < 0.005 ppm).
- 4) All piping welds involved are butt welded joints.
- 5) All the Class 1 piping systems have been carefully designed, l fabricated, and inspected.
l 6) All the Class 1 piping systems have had welded joints examined during j pre-service inspection program and no defects found.
- 7) The systems are designed to mitigate potential for water hammer.
- 8) Piping vibrations will be monitored during hot functional testing and confirmed to produce stress levels below endurance limit.
For the STP Class 1 piping, the use of CUF=0.1 as a screening criteria to postulate breaks is extremely conservative. The discussion in Section 7 illustrates that the time for a crack to grow to the critical flaw length can be quantified with respect to pipe loading combinations and compared to the l
resulting cumulative usage factor. These results have been correlated to initial conditions in the pipe material. The two initial conditions which i provide the most insight are no initial defect and a 10 percent through defect at a local point of high cyclic stress. The tabulation of lifetimes is shown in Table 7.
l
9 The Class 1 piping systems at the South Texas Project have no defects of a detectable size. Notwithstanding the integrity of the STP Class 1 piping, the presence of a 10 percent through wall defect coupled with a CUF=.04 would provide as a worst case 360 years of margin to failure based upon fracture mechanics. HL&P believes the use of CUF=0.4 as a criteria for pipe break postulation provides more than adequate margin. The use of CUF=0.1 is ex-tremely conservative.
I l
l
- I l
l i
,g----y -7 y - ry,---- - -rs---- -
94 -- ----- -- - - - - - --
. . . .- - . - . - - .. .= - - - - - - - -
1 :- :-- -
. 10 d
v Table 1 - PWR Service Experience
{
o Over 400 reactor years of operation o No service-induced cracking of Class 1 stainless PWR lines >
c 1
i l
l l
l;-
1 t
- e-~ vn -, en - , -----m-.. , , ,.- . ,, ,-. , ,-,=.,-,, en, -- , , , , - - , . . . - - - - - - -.,-.-,, .-- , . , , - e.-w, . - - - , , , -. - , - - - , , mn,- , .--.---m,-
r ;;
Table 2 - PWR Water Chemistry Electrical Conductivity Determined by the concentration of boric acid and alkali present. Egpectedrange is < 1 to 40 mhos/cm at 25 C.
Solution pH Determined by the concentration of boric acid and alkali present. Expected values range between 4.2 (high boric acid concentration) to 10.5g (low boric acid concentration) at 25 C. Values will be 5.0 or greater at normal operat-ing temperatures.
a Oxygen 0.005 ppm, max Chloride 0.15 ppm, max Fluoride 0.15 ppm, max Hydrogen 25-50 cc (standard temperature and pressure)/kg H O 2
Suspended solids 1.0 ppm, max 7
pH control agent (Li 0H) 0.7 - 2.2 ppm as Li Boric acid Variable form 0 2 4,000 ppm at B Silica 0.2 ppm, max Aluminum 0.05 ppm, max j Calcium 0.05 ppm, max Magnesium 0.05 ppm, max 8
0xygenconcentrationmustbecont5 lled to less than 0.1 ppm in the reactor coolant at temperatures above 180 F by scavenging with hydrazine. During power operation with the specified hydrogen concentration maintained in the coolant, the residual oxygen concentration must not exceed 0.005 ppm.
t 1
1 m--- -- a + g -.n,- e w-
12 Table 3 - PWR Environmental Effects on Stainless Steel FATIGUE THRESH 0LD STRESS INTENSITY FACTOR o PWR Environmental effect is to increase the threshold stress intensity factor for crack growth TP 304 at Room Temlerature (USAMI):
KTH = 2.8 KSI yin Dry Air K 5.0 gSI fn Wet Air TP3dNa=t472F(USAMI):
K 6.0gSI'lfIn Wet Air TP4b$=in600FSteam(LIAU):
K increasesbyapproxi-mIUely2KSIVInvs.DryAir Estimated value for PWR environment KTH = 8.0 KSI fn FATIGUE CRACK GROWTH RATE o Type 304 and 316 were studied in PWR environment along with associated welds.
o Results showed very little influence of environment on crack growth (Bamford, Trans ASME 1979).
~ _ __. . _ . _ . . , _ _ . . _ _ . _ .
4 .
j ..
- ^ ^,. l1
- ' .
~
}3 1
3 f
Table 4 - NUREG/CR-3982 CRACK GROWTH DATA Years Required to Grow j Initial Flaw Size Flaw to Critical Size 2 percent (0.050 in.) 6200 years j 8.6 percent (0.216 in.) 1320 years T
i l
fi l
l'.
i t
l l.
. . _ . . , . . . . - - . _ , _ . . . . , . - _ , _ . . _ , - - , , . . , ~
.- - .-. . . . _ . . .= .-. . . .
d ..w- -
}
. 14 1
I f
Table 5 - Estimates of Failure lifetime Based Uoon CVF Load Condition Estimated Lifetime Lifetime (i.e.. CUF) to Wall Penetration to Failure i
j 0.1 15/.1 = 150 lifetimes 155 lifetimes O.4 15/.4 - 38 lifetimes 43 lifetimes 1
t 4
f i
?
i L
l
-~ tc 1 - -
e t
4 .
4 r
i e
t Table 6 - Lifetime Predictions for CUF=0.1 and CUF=0.4 with Flaw Present CUF Lifetime to Failure 0.1 1072 years 0.4 400 years i
f I
1 4
1 i
(
.j .
t 4
J e
J 1
l
g.
1e i
4 4
j Table 7. Comoarison of Lifetimes for no Defects and Defects Present Local Pipe Loading as Number of Years to Grow Quantified by Cumulative a Crack to the Critical
. Usage Factor Flaw Length
. No Initial Initial 0.IT
- Defect Depth Defect CUF=0.1 6,200 years 1,072 years-CUF=0.4 1,720 years 400 years 1
l 3
i t
4 i
l
17 ncuar 1 - FATIGUE CRACK GROWTH FOR TYPICAL PWR CLASS 1 PIPING WallThickness 1.0 T Crack growth over one plantlifetime for and initially assumed flaw of = 0.1T and =:= 0.15T. The Points used had usage factors >0.2 0.2 T -
0.1 T ~
l l l l 10 20 30 40 t
Time (Years) One Plant Lifetime
r1- 2 -JUSTIFICATION FOR INCREASED USAGE FACTOR Crack Depth / Leak Before Break .
- Thickness (alt) l Failure 1.0 C O'Q. - b Tested stainless steel pipe \ j\
0.8 through wallleak' age Leakage CUF [Iof at CUF = 50.0 (average) 50.0 NUREG - CR 3243 Appendix C l Worst case example based on NUREG -CR I 0.4
- 3059 /
- Detectable 0.2 7 Initiation j 0
9 9 CUF= 0.1 CUF = 0.+ CUF = 1.0 CUF = 15.0 Operating Lifetimes
-- . , - - - , - . - . , - . , - n.y ,,--n-._,_-,. -,.e_, -- y,n., - - - - , , - - . _ .
19 7
FI= 3 - MARGIN ON FAILURE s,ction iii Usage Lifetimes ~l/CU F Factor ~ cuF (1 = 40 Years) 1.0 1.0 0.9 -
Best estimate for worst case Section 111 Fatigue Analysis using highest 0.8 -
possible stress concentration. -
1.2 0.7 -
0.6 - a W Point, CUF == 0.6 -
1,7 0.5 -
A NUREG/CR-3982 0.4 -------- 400 Years -
2,5 1
0.3 -
1 I
0.2 -
l 5
- 0. , _ . _ . _ . _ . _ . 3 . _ . _ . _ . __.. _ _ , . _ . _ .1,072 2.0 Yea rs l i l l I I I O
O 5 10 15 20 25 30 35 Lifetimes (1=40 Years) Based Upon Time For Crack Growth To Critical Flaw With Initial Flaw Of S810% Through Wall
t 20 REFERENCES
- 1. Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants, NUREG-0800, U.S. Nuclear Regulatory Commission, July, 1981.
- 2. G.T. Yahr, A.K. Richardson, R.C. Guritney, and W.L. Server, " Case Study of the Propagation of a Small Flaw Under PWR Loading Conditions and Comparison with the ASME Code Design Life," NUREG/CR-3982, November, 1984.
- 3. E.C. Rodabaugh, " Comparisons of ASME Code Fatigue Evaluation Methods for Nuclear Class 1 Piping with Class 2 or 3 Piping," NUREG/CP.-3243, June, 1983.
.2 ST-HL-AE-1758 File No.: G9.10 ENCLOSURE 2 STP UNIT 1 CUMULATIVE USAGE FACTOR BREAKS BY' SYSTEM NUMBER OF LINE IDENTIFICATION BREAKS PIPE SIZE CUF RANGE Normal Charging - Loop 1 3 4 .12 to .17 Alternate Charging - Loop 3 4 4 .14 to .26 Aux. Press. Spray 2 2 .12 to'.19 Excess Letdown Loop D 3 2 .12 to .26 Pressurizer Surge 14 16 .10 to .35 Spray Line 2 6 .34 to .39 Accumulator Injection - Loop 1 11 12 .11 to .21 Accumulator Injection - Loop 2 11 12 .11 to .16 Accumulator. Injection - Loop 3 _7_ 12 .10 to .29 -
Total 57 BY CUF RANGE CUF RANGE Pipe Size NUMBER OF BREAKS 2" 3 4" 6
.1 to .2 12" 27 16" -
11 Subtotal 47 2" 2
.2 to .3 4" 1 12" -
2 Subtotal 5
.3 to .4 6" 2 16" -
3 Subtotal 5 Total 57
- 1. No socket-weld breaks included above.
- 2. Based on analyses performed as of September 15, 1986.
7 747N:0292N