ML20138L037
| ML20138L037 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 02/12/1997 |
| From: | Diane Jackson NRC (Affiliation Not Assigned) |
| To: | NRC (Affiliation Not Assigned) |
| References | |
| NUDOCS 9702200227 | |
| Download: ML20138L037 (138) | |
Text
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UNITED STATES y
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February 12, 1997 j
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APPLICANT: Westinghouse Electric Corporation j
FACILITY:
AP600
SUBJECT:
SUMARY OF MEETING TO DISCUSS WESTINGHOUSE AP600 PIPING DESIGN ANALYSIS i
I l
The subject meeting was held at the Nuclear Regulatory Commission (NRC) office in Rockville, Maryland, on December 5 and 6,1996, between representatives of i
-Westinghouse and its consultant and the NRC staff and its consultant, Brookhaven National Laboratory (BNL). The main purpose of this meeting was to discuss and resolve the remaining unresolved piping and pipe support design open items identified in Section 3.12 of the NRC AP600 Draft Safety Evaluation l
l Report (DSER). Additionally, Westinghouse presented further information j
regarding their proposal to apply the leak-before-break (LBB) methodology to the feedwater (FW) line for the staff's consideration. Attachment 1 is a list of meeting participants.. Attachment 2 is a summary of the DSER Section 3.12 i
8 issues reviewed at this meeting. Attachment 3 is a summary of the open items, l
other than DSER Section 3.12, discussed at the meeting.
t Based on the Westinghouse's interpretation of the NRC letter dated November 4, 1996, Westinghouse performed a probabilistic evaluation of a water hammer
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event on the FW line. The staff discussed this presentation with Westing-house. The staff did not agree with the starting assumptions for the evalua-tion due to the high degree of uncertainties. The staff agreed to internally j
discuss its concerns regarding the application of the LBB methodology to the feedwater line and provide Westinghouse any additional comments. Attachment 6 j
is the Westinghouse presentation material for the probabilistic evaluation.
i The staff reviewed the Westinghouse AP600 thermal stratification report and the EPRI report on thermal stratification as background. Westinghouse provided the staff with loading information which may be used in selected piping systems to perform LBB confirmatory analysis (Attachment 4). Westing-house suggested the use of the General Electric Report NED0-21985, dated p1%E,Y 200050 f)G7 2
i 9702200227 970212 PDR ADOCK 05200003 E
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I t February 12, 1997 l
September 1978, " Functional Capability Criteria for Essential Mark II Piping,"
and the Westinghouse Functional Capability Requirements for Comanche Peak
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Steam Electric Station for certain cases in AP600 piping, and agreed to provide a SSAR revision for staff review (Attachment 5).
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original signed by:
4-Diane T. Jackson',. Project Manager 4
i Standardization' Project Directorate' Division of. Reactor Program Management !
Office Of Nuclear Reactor, Regulation ~
Docket No.52-003
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NAME DTJacksonTA GB6gcWi TQuay-OW DATE 02/ge /97 0
02/10/97 02/p/97 0FFICIAL RECORD COPY
Westinghouse Electric Corporation Docket No.52-003 i
cc: Mr. Nicholas J. Liparulo, Manager Mr. Frank A. Ross Nuclear Safety and Regulatory Analysis U.S. Department of Energy, NE-42 Nuclear.and Advanced Technology Division Office of LWR Safety and Technology Westinghouse Electric Corporation-19901 Germantown Road P.O. Box 355 Germantown, MD 20874 Pittsburgh, PA 15230 l;
Mr. Ronald Simard, Director i
Mr. B. A. McIntyre Advanced Reactor Program 4
i Advanced Plant Safety & Licensing Nuclear Energy Institute i
Westinghouse Electric Corporation 1776 Eye Street, N.W.
Energy Systems Business Unit Suite 300 Box 355 Washington, DC 20006-3706 i
Pittsburgh, PA 15230 Ms. Lynn Connor Mr. John C. Butler Doc-Search Associates Advanced Plant Safety & Licensing Post Office Box 34 Westinghouse Electric Corporation Cabin John, MD 20818 Energy Systems Business Unit Box 355 Mr. James E. Quinn, Projects Manager Pittsburgh, PA 15230 LMR and SBWR Programs l
GE Nuclear Energy 4
Mr. M. D. Beaumont 175 Curtner Avenue, M/C 165 Nuclear and Advanced Technology Division San Jose, CA 95125 Westinghouse Electric Corporation One Montrose Metro Mr. Robert H. Buchholz 11921 Rockville Pike GE Nuclear Energy Suite 350 175 Curtner Avenue, MC-781 Rockville, MD 20852 San Jose, CA 95125 Mr. Sterling Franks Barton Z. Cowan, Esq.
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U.S. Department of Energy Eckert Seamans Cherin & Mellott i
NE-50 600 Grant Street 42nd Floor i
i 19901 Germantown Road Pittsburgh, PA 15219 Germantown, MD 20874 i
Mr. Ed Rodwell, Manager i
Mr. S. M. Modro PWR Design Certification Nuclear Systems Analysis Technologies Electric Power Research Institute l
Lockheed Idaho Technologies Company 3412 Hillview Avenue Post Office Box 1625 Palo Alto, CA 94303 j
Idaho Falls, ID 83415 l
Mr. Charles Thompson, Nuclear Engineer 4
AP600 Certification I
i NE-50 i
19901 Germantown Road
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Germantown, MD 20874 I
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NRC/ WESTINGHOUSE AP600 PIPING DESIGN MEETING DECEMBER 5 AND 6, 1996 MEETING PARTICIPANTS
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Goutam Bagchi NRC/NRR/DE/ECGB Barry Elliot (P/T)
NRC/NRR/DE/EMCB Shou Hou NRC/NRR/DE/ECGB Diane Jackson NRC/NRR/DRPM/PDST Alan Levin (P/T)
NRC/NRR/DSSA/SRXB Matthew Mitchell (P/T)
NRC/NRR/DE/EMCB Gulliano DeGrassi BNL (NRC Consultant)
Don Lindgren Westinghouse-Licensing 1
Ed Johnson Westinghouse-Piping Rao Mandava Westinghouse-Plant Engineer Pat Strauch Westinghouse Kevin Accornero Westinghouse Joel Witt Westinghouse Consultant j
(P/T) = part time participant i
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NRC/ WESTINGHOUSE PIPING DESIGN MEETING i
DECEMBER 5 AND 6, 1996 DSER SECTION 3.12 SUP94ARY 1.0 PURPOSE lhe main purpose'of this meeting was to' discuss and resolve the unresolved piping and pipe support design open items identified in Section 3.12 of the hRC AP600 Draft Safety Evaluation Report (DSER).
2.0 BACKGROUND
i This meeting wss conducted in support of the Westinghouse application for design certification of the AP600 standard plant design in accordance with the 10 CFR 52 process.
Previous AP600 piping design meetings were conducted in April 1994, July 1994, and April 1995. During these meetings, the audit team reviewed detailed design procedures, criteria documents and sample piping problems. Based on the review of these documents and discussions with 4
Westinghouse, a number of issues of concern were identified. The open items were originally summarized in Section 3.12 " Piping Design", of the NRC Draft i
Safety Evaluation Report (DSER) which was issued by the staff in November 1994. Westinghouse addressed the open items in a letter dated June 12, 1996.
The responses were discussed during a followup piping design review meeting i
held on June 25 and 26, 1996, and a number of the open items were technically resolved. sBased on those discussions, Westinghouse made further changes to standard safety analysis report (SSAR) Sections 3.7 and 3.9 in Revision 9 4
l dated August 9, 1996. Westinghouse provided additional information including proposed draft SSAR revisions in submittals dated October 23, 1996, and i
November 11, 1996. These additional responses were reviewed and evaluated and the remaining open items were the subject of this meeting.
j 3.0 MEETING SUP94ARY i
i The major meeting activities included the review of the Westinghouse thermal cycling and stratification' calculation and discussion of the remaining DSER p
open items including functional capability limits, composite modal damping and j
modeling uncertainties in time history analysis. A summary of these reviews and discussions is given below:
3.1 Review of the Thermal Cyclina and Stratification Calculation (Items 836.
J 8311 i
In the DSER, it was reported that SSAR Subsection 3.9.3.1.2 did not have sufficient information to assess the adequacy of the methodology applied to identify systems susceptible to thermal cycling, the methods to define the thermal loading, or the methods to calculate the effects of the thermal loads on susceptible systems. Westinghouse needed to provide further justification for their conclusion that no piping systems in the AP600 are susceptible to
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i isolation valve leakage that are normally associated with thermal cycling.
In addition, Westinghouse needed to provide a copy of Electric Power Research Institute (EPRI) report TR-103581, " Thermal Stratification, Cycling, and Striping" (TASCS) for review.
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During the June 1996 meeting, Westinghouse agreed to provide the EPRI TASCS j
report to NRC for review on the AP600 docket. However, they would not provide copies of their proprietary calculation on the AP600 thermal cycling and i
stratification evalustions but instead offered to make it available for review either in their offices or at NRC offices. A copy of the EPRI report was i
received after the meeting and reviewed by Brookhaven National Laboratory (BNL). The report provides screening criteria for identifying portions of piping systems that may be susceptible to thermal cycling; analysis methods l
for defining thermal loads and numbers of cycles in the susceptible systems; l
and a summary of thermal hydraulic test programs and correlations to develop j
and verify the methods. The EPRI TASCS report had been submitted to NRC in i
support of Bulletin 38-08 programs for several operating plants.
It is currently undergoing NRC staff review but has not yet been approved for e
i generic a~pp11 cation. Therefore for this review, the EPRI TASCS report was reviewed as background information only and the Westinghouse AP600 calculation was evaluated on its own merits.
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At this meeting, Westinghouse provided a copy of calculation GW-PLC-001, "AP600 Stratification", dated June 25, 1996, for BNL review. The stated i
i purpose of the calculation was perform a systems review of all the AP600 lines i
connected to the reactor coolant system (RCS) to determine whether unisolable sections of piping connected to the RCS can be subjected to stresses from temperature stratification or temperature oscillations that could be induced j
by leaking valves as described in NRC Bulletin 88-08. However, in reviewing s
the calculation, it was seen that the review extended beyond the Bulletin 88-08 valve leakage concern and investigated other potential cases of thermal t
stratification and cycling in thes j
Bulletin 79-13 for feedwater lines,e lines including those described in and Bulletin 88-11 for pressurizer surge i
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lines. Based on operating experience, five root causes of thermal stratifica-tion, thermal cycling and thermal striping were identified.
They include the following:
1.
Operating Case: Operating a system with low flow rates could result in stratification and possibly striping in horizontal piping sections.
This root cause is associated with Bulletins 79-13 and 88-11.
2.
Leak Case: A pipe section without flow during normal operation (dead-end) could be subject to stratification and cycling if a leak were to occur though a valve as described in Bulletin 88-08. Cases of in-leakage, out-leakage and cross-leakage are possible.
3.
Convection Heating Case: A pipe section without flow during normal operation could be subject to thermal stratification if the geometry of the pipe permits the convective flow of warmer fluid into a cooler section.
This has been observed through plant monitoring.
2 h
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Steam / Water Stratification: A pipe section open to a steam environment can have steam condensed and partially fill a horizontal section.
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Certain geometric configurations may be susceptible to this type of stratification.
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Turbulent Penetration Operational Changes: A pipe section without flow during normal operation, connected to a pipe with high temperature, high velocity fluid, may be susceptible to temperature changes resulting from i
operational changes. This may result in changes in turbulent penetra-i tion length. This mechanism alone or in combination with leakage-
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induced stratification may be a source of thermal cycling in the pipe i
section.
The review for susceptibility was accomplished by reviewing systems or pipe sections for susceptibility for each root cause.
In evaluating susceptibility for the leakage case, it was assumed that single isolation valves can leak but two or more closed valves in series are sufficient to limit leakage to a negligible amount; valves may leak through the valve seat and packing for the 4
out-leakage case and additional closed valves in series would not be benefi-cial; any pressure difference should be considered a leak source; and cross-leakage could occur between interconnected lines that are attached to differ-ent reactor coolant pipes and isolated by single check valves.
Pipe lines that are less than or equal to one-inch nominal diameter and lines with slopes greater than 45 degrees were not considered susceptible based on their
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geometry and on operating experience.
i The audit team reviewed the calculation and spot checked the reference j
material including piping isometrics and piping and instrumentation drawings.
l The majority of lines were found to be not susceptible due to low potential l
temperature differential or low pressure differential.
In addition, a number 1
of lines were equipped with temperature indicators which would detect leakage.
The calculation identified the following lines as susceptible to adverse l
stresses resulting from stratification:
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1.
Pressurizer Surge Line:
It is known that stratification is possible due to the large temperature differences which exist between the pressurizer and the hot leg especially during heatup and cooldown. These thermal loads are considered in the stress analysis of the surge line. The I
temperature distributions and displacements will be confirmed through a l
monitoring program for the first AP600 plant.
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2.
Cold Leg Piping: The cold leg piping may experience thermal stratifica-l tion during periods when the main coolant pumps are not in operation and relatively cold water flows from the passive residual heat removal (PRHR) return line through the steam generator channel head and into the l
cold leg where it joins the hot water coming from the steam generator U-tubes. Using the RELAP5 code, Westinghouse evaluated a number of loss-
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of-coolant-accident (LOCA) scenarios which could result in stratified L
flow in the cold leg. Worst case stratified temperature profiles were i
defined for both upset and faulted conditions. These thermal loads are j
considered in the stress evaluation of the cold leg pipes.
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Although Westinghouse concluded that no other piping sections are susceptible to adverse stresses resulting from stratification, three open items were identified and further confirmatory analysis and confirmatory monitoring may be required for the following:
1.
Automatic Depressurization System (ADS) Stage 4 Lines: These lines are oriented upward fr& the hot leg and the piping is sloped down 45 degrees to a horizontal section of piping which contains isolation valves. The valves are explosively actuated and leaktight. Westing-house assumed that the piping will be hot from the hot legs to the beginning of the sloped piping and cool by conduction beyond that point.
The horizontal piping upstream of the valves was assumed to be at 120*F based on the cold trap layout. However, it was noted that the sloped section was only 1.5 feet long which may not be sufficient to provide a cold trap.
If that is the case, thermal stratification may occur in the 10 foot long horizontal piping which contains the valves. Westinghouse judged that the piping and supports could accommodate the stratifica-tion. However confirmatory analysis using a computational fluid dynamics code such as Flow-3D was recommended and confirmatory plant I
monitoring may be required depending on the results of the analysis.
2.
Normal RHR Suction Line from the Hot Leg: This line extends downward 3 feet from the hot leg to a 90 degree elbow and then slopes slightly downward over a distance of 73 feet to a tee connection.
The vertical l
drop over this distance is 1.25 feet.
From the tee connection, the piping extends horizontally 5 feet to isolation valves. Westinghouse i
assumed the unisolable piping from the hot leg to the valves to be close to the hot leg temperature due to turbulent penetration and convective currents which heat the line. However, due to the long length of piping and its downward slope, there is a potential for thermal stratification to occur in this section of pipe as well as for the development of l
adverse stresses due to valve leakage and/or turbulent penetration thermal cycling. Confirmatory analysis using a computational fluid dynamics code was recommended and confirmatory plant monitoring may be required based on the results of the analysis.
3.
PRHR Return Line: This line extends from the PRHR heat exchanger to the steam generator channel head. The piping is routed continuously from the heat exchanger to an elbow just below the steam generator connec-tion. The piping length from the steam generator down to the horizontal pipe is only 3.7 feet. A 3-inch purification line connects to the PRHR return line near the steam generator nozzle. Westinghouse assumed that based on the cold trap layout, the horizontal piping below the steam generator is at 120*F and that turbulent penetration into the PRHR line is minimal. However, the combined effects of turbulence from the steam generator flow, the purification line flow, and thermal conduction from the steam generator could result in potential heating and thermal cycling in the horizontal piping directly below the steam generator.
Confirmatory analysis using a computational fluid dynamics code was recommended and confirmatory plant monitoring may be required based on the results of the analysis.
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h Based on the review of the Westinghouse AP600 Thermal Cycling and Thermal Stratification calculation, the audit team concluded that the methodology for identifying susceptible systems was reasonable and acceptable. The methodolo-j gy was based on operating experience and considered all thermal stratification and thermal cycling mechanisms that have been identified to date.
The
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j Westinghouse review appeared to be very thorough and complete in identifying l
1 systems susceptible to thermal stratification and cycling. However, it was i
noted that there are three sections of piping which Westinghouse judged to be i
j acceptable even though there is a fairly high degree of uncertainty regarding their susceptibility to thermal stratification and cycling. Based on further i
discussions among the audit team, it was agreed that further evaluation of l
4 these systems is required prior to design certification to reduce the uncer-tainty. Westinghouse should either perfom a bounding analysis to demonstrate that the piping can accommodate worst case thermal stratification and cycling l
loads or perfom additional detailed fluid dynamics calculations and commit to plant monitoring to reduce the uncertainties in the piping evaluation.
Westinghouse agreed to consider these options and will provide a plan of action to resolve this issue.
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3.2 Discussion of Remainino Pinino Desian Open Items a
3.2,1 Functional Canability Limits (Items 832f 5) and 838)
The functional capability stress limits defined in the SSAR do not meet all of the limitations of NUREG-1367 as required by the staff.
Following the June 1996 meeting Westinghouse was asked to provide functional capability require-l ments consistent with NUREG-1367.
In SSAR Revision 9, Table 3.9-11 was j
revised to include the Equation (9) stress limits specified in the NUREG but three restrictions from the NUREG were not included. They are as follows:
(1) the equation (9) Level D stress limit is applicable to reversing dynamic i
loads, not to slug flow loads: (2) steady state stresses shall be limited to 0.255,; and (3) dynamic moments must be calculated using an elastic response 4
spectrum method with 115 percent broadening and with not more than 5 percent i
damping.
In their October 23, 1996 submittal, Westinghouse stated that the NUREG does not recommend an alternative limit on Equation (9) for slug flow i
loads or. for time history analysis. The Westinghouse position is that the current code limits assure the functional capability for all loads and j
analysis methods and that this is consistent with Westinghouse operating i
plants. Westinghouse agreed to meet the stress limit of 0.255 for deadweight stress but not for steady state safety relief valve loads. A fiigher limit of l.0 S, was proposed for those loads.
1 At the meeting, the audit team reiterated the staff position on meeting NUREG-1367 and stated that for cases which do not meet the restrictions, earlier NRC-accepted functional capability criteria may be used (such as Level C stresslimits). Westinghouse stated that the Level C criteria are too restrictive and that the staff had accepted alternate functional capability 4
1 limits for other Westinghouse operating plants. The justification for the
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alternate limits was based on work performed for Mark 11 plant piping systems J
documented in General Electric Report NED0-21985 and additional work performed i
by Westinghouse to justify Level D stress limits for thick-walled Class 1 i
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piping. Westinghouse stated that they could propose similar limits for AP600 for cases where the NUREG-1367 restrictions are not met and asked if such an approach would be acceptable. The audit team stated that alternate limits may be acceptable if justified. Westinghouse agreed to provide a revision to Table 3.9-11 of the SSAR to include the alternate limits for staff review and approval. Further communication on this issue is needed.
3.2.2 Time History Analysis Modelina Uncertainties (Item 822-f 2b))
l The DSER stated that the SSAR should include a description of the method to account for modeling uncertainties in time history analysis (such as time history broadening).
In SSAR Revision 9, Westinghouse revised Subsection 3.7.3.17 to include a description of their method to account for uncertainties by time history broadening for seismic analysis and other dynamic analyses.
In their November 11, 1996 submittal, Westinghouse proposed an additional l
revision to this section to explain that for seismic analysis they consider l
four separate soil cases. Westinghouse proposed that the COL may either perform four separate time history analyses for each soil case or perform time 1
history analysis for the hard rock soil case and a single response spectrum analysis for the remaining three soil cases. For time history analysis of piping system models that include a dynamic model of the supporting concrete l
building, either the building stiffness is varied by 30 percent or the time l
scale is shifted by 15 percent to account for uncertainties. Alternately, when uniform enveloping time history analysis is performed, modeling uncer-tainties are accounted for by the spreading that is included in the broadened response spectra. The audit team did not find this approach acceptable. The staff stated it was unacceptable to mix the analysis methods for the four soil sites. Westinghouse was asked to specify in the SSAR that for all four soil sites the either the time history analysis or the response spectra analyses could be used. Additionally, Westinghouse agreed to include the following sentence in the SSAR: "At each location, the envelope of the individual force and moment components from the SSE analysis cases is used in the stress j
analysis." A SSAR revision is necessary.
l 3.2.3 Comoosite Modal Damoina (Items 833(1). 833(2). 833f3b). 839)
The.DSER reported that composite modal damping is acceptable for piping systems analyzed by the uniform envelope response method with 5 sercent damping for piping and Regulatory Guide (RG) 1.61 damping for otier compo-nents. The Westinghouse practice was to use 5 percent damping for the entire model.
In their October 23 submittal, Westinghouse agreed to revise the SSAR to reflect the staff position. The audit team found this acceptable but there was some further discussion on the methodology used to determine the composite l
modal damping values. Subsection 3.7.3.15 of the SSAR states that either the weighted mass or stiffness method may be used. Westinghouse was asked to i
specify the method that has been used in piping analyses performed'to date.
Westinghouse stated that the weighted stiffness method had been used in the Reactor Coolant Loop analysis. The audit team had previously reviewed this calculation and found the damping acceptable. The audit team asked Westing-i house to revise the SSAR to include only the weighted stiffness method for piping analysis and Westinghouse agreed. This technically resolved the staff's concerns on this issue.
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4.0 CONCLUSION
S Significant progress was made in resolving the remaining open items. At the meeting, Westinghouse agreed to (1) provide a plan of action to reduce the uncertainties in thermal stratification / cycling evaluations for the ADS Stage 4 Lines, Normal RHR Suction Line and PRHR Return Line (0 pen Item 836), (2) provide alternate functional capability stress limits for cases where NUREG-l 1367 restrictions are not met (0 pen Items 832(5) and 838), and (3) revise the i
SSAR for time history analysis (Item 822(2b).
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Based on meeting discussions and the review of proposed SSAR revisions, I
technical resolution was reached on several items. ~ The issues involve l
modeling uncertainties in composite modal damping (Item 833(1), (2), (3b) and 839), and snubber dynamic testing (Item 848(Ic)). Final resolution of these i
l items requires a formal SSAR revision to incorporate the proposed changes that i
were agreed upon.
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l NRC/ WESTINGHOUSE PIPING DESIGN MEETING DECEM8ER 5 AND 6, 1996 I
OPEN ITEM STATUS (OTHER THAN DSER 3.12)
DSER 3.9.2.3-2 OITS 783 Action W Revise the SSAR to include the Westinghouse October 14, 1996, response.
DSER 3.9.2.4-1 OITS 785 Action W Provide justification for the qualification of the con-trol rod drive mechanism for seismic loads.
DSER 3.9.7-1 OITS 812 Action W i
Revise the SSAR to explain the design basis for LOCA l
loads for the integrated head package.
DSER 3.10-1 OITS 813 Action W Revise response to issue A-46 in WCAP-13054. This issue l
is technically resolved.
l DSER 3.10-2 OITS 814 Action W l
Revise the SSAR to define the method and size of the l
equivalent static pressure for the dynamic loads on the feedwater valve disk RAI 210.213 OITS 3372 Resolved l
This issue is administrative 1y resolved.
The issue will be technically resolved by DSER 3.9.5-1 (0ITS 3517).
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DSER 3.9.5-1 OITS 3517 Action W Provide a reference for the approval of 20 percent damp-l ing.
l RAI 210.217-224 OITS 3507-3515 Action W Westinghouse will send in responses.
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r October 15,1981
. Dr. Narold R. Denton Director of Nuclear Reactor Regulation Office of Nuclear Reactor Regulation U. S. Nuclear Re Nashington 0.C.gulatory Commission 20555 n
SUBJECT:
COMANCHE PEAK STEAN ELECTRIC STATION STAINLESS STEEL ELB0WSFUNCTIONAL CAPAB
Dear Dr. Denton:
In response to the Safety Evaluation Report (SER) open itas concerning the functional capability of ASME Code Class 2 and 3 1
stainless steel elbows. CPSES pmposes the following stress limits I
be used to screen these elbows for acceptable functional capabili J
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,82h*I'8 I
31 where 8
=
3
(-0.1+0.4h)and0 1By 1 0.5 and 8
g 0.5 for 8
~= 1.0
=
2 P 1.3/(ht/3) for =, > 90' R
=
o 0.895/(h.912)f,,,= = 90' 2
1i but not less i
1.0 for =, = 0' '
kthan1.0 L Linear interpolation.for 0 < =, < 90'I where h=
and, is the angle of the bend.
Other terms are as defined in NC/ND-3600 of Section III Code.
There are no Class 2 and 3 stainless steel elbows or be 0,/t > 50.
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CPSES proposes to demonstrate that these stri,:s iintts have for a random sample of Class 2 and 3 stainle een the piping systems Ifsted be, low:
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Safety Injection Chemical and Volume Control Residual Heat Removal
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Service Water Containment Spray stainless steel piping.The sample will encompass the full te i
Twenty-five (25) percent of elbows in each system will be sampled.
For these systems whers twenty-five ~
) percent of the elbows is less than five (5), a minimum of elbows will be evaluated.
e transmitted to the staff by April 1,1982.It is anticipate
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Should you have any questions, please contact me at (214)
Sincerely.
Y BSD: tis H. C. Schmidt e
COMANCHE PEAK STEAM ELECTRIC STATION UNITS 1 AND 2
.f WESTINGHOUSE FUNCTIONAL CAPABILITY REQUIREMENTS (ASME Code Class 1, 2 and 3)
Rev.
Description l'
0 Original Issue I
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I siso etiste 0132s 10-c210s7
TABLE OF CONTENTS 1.0 PURPOSE 2.0 SCOPE
3.0 REFERENCES
4.0 DISCUSSION
/
5.0 FUNCTIONAL CAPABILITY REQUIREMENTS 5.1 Class 1 Piping 5.2 Requirements for ASME Code Class 2 and 3 Piping Components CTSD 0116' 8 C132) 10,-C1104 7
l 1.0 PURPOSE
- This procedure outlines the functional capability evaluation criteria for ASME Class 1 and ASME Class 2 and 3 essential
- piping systems.
2.0 SCOPE This procedure will apply to all CPSES Unit 1 and 2 piping systems within the Westinghouse scope as described in WCPS 2.1 and 2.2, References 1 and 2 respectively.
3.0 REFERENCES
1.
WCPS 2.1, " Unit 1 Stress Problem Boundaries," Rev. 2, 8/29/86 2.
WCPS 2.2, " Unit 2 Stress Problem Soundaries," Rev. 2, 8/29/86 3.
NEDO-21985, Functional Capability Criteria for Essential Mark 11 Piping, September 1978, prepared oy Sette'le Columbus Laberatories for General Electric Company 4.
WCAP-7503, Supplement 1.
5.
Letter:
PT-SSD-663, 3/17/63, " Piping Functional Capability".
6.
" Stress Criteria for Demonstrating Functional Capability of ASME Class 2 and 3 Stainless Steel Elbe-s." Kestinghouse Letter No. NS-LT-9447, TBX/TCS-4705, 9/81.
7.
TUGC0 Letter to NRC Prc:csing Stress Limits, TX N a14, 10/6/81.
8.
ASME Boiler and Pressu e Vessei Code,Section III, Division 1. '.9M Edition,-including the Summer 1974 Addenda, Subsection NB, (Subarticle NS-3600) NC and ND.
9.
NUREG-1038, Supplement Nc. 2, " Safety Evaluation Report Related to the Operation of Sherron Harris Nuclear Power Plant Unit No. 1", Docket No.
STN 50-400, June 1985.
- 10. Westinghcuse Report:
Functional Canability Criteria of Essential Piping Systems, T. H. Lin, January 1986.
11.
Letter: NLS-84-247, 6/7/84, " Functional Capability of Class 1 Piping".
l 4.0 DISCUSSION Functional capability is defined as the capability of piping to deliver the rated flow and retain its dimentional stability under specified service level conditions. The reliability c' a ci;ing system depends both on its structural
~
- An ' essential" piping system is ::e'ine: in this procedure as any syste-required to bring the plant to a ccic s Niccan ccnditicn following a level B, C, or D event.
Systems which must maintain structural integrity but are not essential for plant shutdown are the RC trains and stress problems 38A and 38B. as defined in references 1 and 2.
GTED 0110' 8
.an.ww
integrity and functional cap;bility; demonstration of structural integrity does not n:cessarily ensure functional capability. Th3 rules contained in th>
ASME code (referenco 8) are intended to ensure structural integrity of the pressure retaining boundary but do not provide guidance for evaluating functional capability.
This procedure outlines the criteria to be used for the evaluation of functional capability of ASME Class 1 and ASME Class 2 and 3 essential piping systems. These recommendations are based on experimental and analytical studies performed at Battelle Columbus Laboratories for General Electric Company (ref. 3) and experimental studies performed by Westinghouse (ref. 4) and by EBASCO for the Caroline Power and Light Company (ref. 11).
The functional capability criteria given in this precedure are additional requirements and are not to be substituted for any existing requirements of the code.
The criteria for the evaluation of tne functional capability of Class 1 piping components is given in section 5.1.
The criteria is based upon tests performed by Westinghouse and interpretation of those results as they apply to functional capability.
Section 5.2 lists the criteria for the ASME Class 2 and 3 piping components.
This criterion, along with the applicable stress indices were extracted frem ref. 3 and as presented can only be used for pipe with Do/t < 50.
5.0 FUNCTIONAL CAPABILITY REQUIREMENTS 5.1 Class 1 Piping Faulted condition analysis of Class 1 picing systems, Appendix F of tne ASVE Code, Section 111, permits the use cf Ecuation (9) cf subsecticn NS-3552 s !-
a stress limit of 35 This criteria is currently being used by WestinghouseforClais. 1 piping evaluation.
In spite of the fact that Appendix F states that these limits are intenced only to assure structural integrity, the Shearon Harris nuclear pcwer plant SER (ref. 9) and stucies oescribed in ref.10 and 11 support the position that these limits do, in fact, provide sufficient assurance that the piping will not collapse or experience gr.oss distortion such that the function of the system would be impared (ref. 5).
Therefore, for Class 1 Piping Systems, to qualify the piping to ASME Code allowables for structural integrity also assures functional capability and no additional evaluation is necessary.
5.2 Requirements for ASME Code Class 2 and 3 Piping Components A.
The following requirements are for piping components with D /t <50.
This is applicable for piping within the Westinghouse scope (Eef. I 0
and 2).
Functional capability is ensurec oy satisfying the conditions beloa:
1.
Determine the FCI from Table 2 or B indices from Table 3 as applicable.
I GTSC 0116' 8 f W'. 9 "lM w sh m
~+T2-*
2.
Calculate the stress in accordanco with Table 1.
l.
3.
Compare the calculated stress with the allowable stress from Table 1.
/
B.
To ensure functional capability of ASME Code Class 2 and 3 stainless steel elbows and bends with D /t <50, the following alternate conditions may be met.
(RefePences 6 and 7).
PDo M
Byy+B2 7 < 1.8 S y
where:
By=
(-0.1 + 0.4h), but not less than 0 nor greater than 0.5 and also B3 = 0.5 for 82 = 1.0 2/3 1.3/h for o > 90' B2 may not be less than 1.0 g
0 B
0.895/h.912 for o 2
90'
=
Linear interpolation may be g
used for the bend angle, a wheh 0 < a < 90' c,
g 1.0 for o 0'
=
g where ine eleca flexibility charetteristic, n, 2.s cefined as h = 4tR/D CiE0 0116' t
/'
TABLE 1 l'
FUNCTIONAL CAPABILITY ACCEPTANCE CRITERIA (Ref.3)
Plant Components (1)
Calculated Stress (2) Criteria (3)
Condition (4) Allowables Straight PD M
F. C.
N/0, E, F 1.5 5 Pipe (5)
W + IFCI) I Class 2/3 7
M PDo b
"r F. C.
N/U, E, F 2.0 S Byy+B2b T
- 02r T Class 1 (8)
F b
r Tee (7)
N/U, E, F 1.5 S 4
Class 2/3 J
PD M
F. C.
N/U, E, F 1.8 S B1E+B2I Stainless Y
Steel Elboa (6)(7)
F29+(FCI)4 M
F. C.
N/U, E, F 1.5 S It Class 2/3 Y
M N
F. C.
b PDo
- 02b T + E2r TClass 1 (B)
N/U, E, F 2.0 S b
r Branch l 4t b
r Y
Gt&D 0116f 4
...?'8!! !*-c!288' n
, -- ' e y s
1 n
NOTES TO TABLE 1
- 1) Also applicable to butt weld, t > 3/16 in. and 6/t < 0.1, butt weld, t < 3/16 in. or 6/t > 0.1, full fillet weld, and 30-deg tapered Iransition (ANSI B16.25).
where:
6 = mismatch, in.
- 2) FCI = Functional Capability Index - See Table 2.
For B, B2r, B2b 1
~ US* I"DI' 3' 3)
F. C. = Functional Capability
- 4) N/U = Normal and Upset Conditions E
= Emergency Condition F
= Faulted Condition 5)
I Includes fillet-welded joint, socket welded flange, single welded slip-on flange, brazed joint anc concentric reduce (ANSI B16.9 or MSS SP-48).
l 6)
For ASME Code Class 2 end 3 stainless steel elbows and bends, see Subsection 5.2 (B).
7)
Either one of the twc criterie can be used in order to ensure functicncl capability.
8)
Reference 3 criter a 'c use c ASME Code Class 2 and 3 rio'ne within i
Westinghouse scope (ref. I and 2).
t i
CTSO 0110f 0
TABLE 2 VALUES OF (FCI) TO BE USED FOR FUNCTIONAL CAPABILITY EVALUATION FOR USE IN EQUATION (9) 0F NC-3652.2 OR ND-3652.2, CLASS 2 OR 3 PIPING Description (2)
(FCI)
I Straight pipe (1) 1.0 4
Welding elbow or pipe bend 2/3
> 90*, 1.3/h but not o g
= 4 5 *, 1.17/h. 56
),33 0
q c
I
= 0*, 1.0 than 1.0 o g 1
Interpolate linearly for otner alues of o v
g Reinforced fabricated tee 0.75i, but not less than 1.0 Use i as defined in Figure NC-3673.2(b)-1 Unreinforced fabricated tee 0.75i, but not less than 1.0 Use i as defined in igure NC-3673.2(b)-1 Welded tee in accordance with 0.90i, but not less than 1.0 ANSI B16.9 Use i as cefine: in O ' g,r e NC-3673.2(b)-1 Fillet welded joint, socket weicec 1.0 flange, or single welce: sli;-:-
flange Brazed joint 1.0 Concentric reducer (ANSI E16.9 or 0.75i, but not less than 1.0 MSS SP-48)
Use i as defined in Figure NC-3673.2(b)-1 o -
4 GT&D 01ISt 6 C132s 10-021067 a,,.
. ?,
L, a p.,
I NOTES TO TABLE 2
- 1) Also applicable to butt weld, t > 3/16 in and 6/t < 0.1, butt weld, t < 3/16 in. or 6/t > 0.1, full fillet weld, and 30-deg tapered transition (ANSI B16.25).
where:
6 = mismatch, in.
2)
Piping products included in Figure NC-3673.2(b)-1 but not covered by this criteria are:
" Closely space miter bend;" "Wicely spaced miter bend;"
- branch connection," " threaded pipe joint or tnreaded flange" and
" corrugated straight pipe or corrugated or creased bend." Functional capability of these piping products shall be demonstrated by appropriate methods.
For " branch connection," the Class 1 criteria are applicable.
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GT5D 011814
TABLE 3 B-INDICES FOR FUNCT10NAL CAPABILITY EVALUATION, FOR USE IN EQUATION (9) FOR BUTT WELDING TEES AND BRANCH CONNECTIONS Piping Products or Joints B
B y
2 Branch connections in 0.5 except if 82b = 0.50 C2b' accordance with either B r
/
2n but not less than 4/3 NB-3643 8
is 4/3, B2r = 0.75 C2r' 2r p
then By = 2/3 but not less than 4/3 jl
- l 4
Butt-welded tees in 0.5 except if B2b = 0.40 (R,/T )
accordance with ANSI either B r
r 2b but not less than 4/3 B16.9, MSS SP-48, or B
is 4/3, B
2r 2r = 0.50 (R,/T )
MSS SP-87 then By = 2/3 but not less than 4/3 r
Primary plus secondary stress indices 2b = 3(R,/T ) / (r;/R,)1/2(Tf/T ) (r;/r ), but not less than 1.5 C
r r
p C2r = 0.8(R,/T )
I"m'E ), but not less than 1.0 r
m Equation (9):
H N
PDo # 0 b
r 2b {
- 02r {
1 lit CTSD C1188 6 0132s 10 021047 e,,
,9
.f 3
TABLE 4 NOMENCLATURE B,B See Table NB-3681(a)-1 of Ref. 8. Primary stress indices
=
7 2
8 Primar
=
2b pipe. y str ss index to moment leading applied to branch See Table NB-3681(a)-1 of Ref. 8.
B Primary stress index to moment loading applied to
=
2I transversing the run pipe. See Table NB-3681(a)-1 of Ref. 8.
C Primary plus secondary stress incex to loading applied to
=
2b transversing the run pipe. See Table NB-3681(a)-1 of Ref. 8.
C Primary plus secondary stress incex to loading applied to
=
2r transversing the run pipe. See Table NS-3681(a)-1 of Ref. 8.
0 Mean pipe diameter of run pipe for branch connections anc tees
=
Do Outside diameter of pipe or of the run pipe for branch
=
connections and tees 4tR/D2 = elbea h
=
parameter i
Stress intensification factor.
See Table NC-3673.2(b)-1 cf
=
Ref. 8.
M Resultant moment due te weight, eartnquake (considering cr.ly
=
one-half of the range of the ear thcuake and excluding the effects of anchor displacements due to earthquake), and other sustained mechanical leads M
Resultant moment on branch pipe
=
b M
Resultant moment on run pipe
=
r P
Design pressure
=
t R
Bend radius of an elbow
=
R, Hean radius of run pipe. See Figure NB-3686.1-1 of Ref. 8.
=
r; Mean radius of branch pipe.
See Figure NB-3686.1-1 of
=
Ref. 8.
r
=
See Figure NS-368601-1 of Ref. 8.
p S
Basic material alicwable stress at maximum (hot)
=
h temperature, osi 5,
Yield strengin cf material.
See Table 1-2 of Ref. 8.
=
CTED 0116' 8
T Hetal temperature
=
with the occurrence (dsgree F) of a piping component coincident of the loads tf Nominal thickness of branch pipe. See Figure
=
NB-3686.1-1 of Ref. 8.
T Wall thickness of run pipe with a branch pipe. See Figure
=
F NB-3686.1-1 of Ref. 8.
t
=
Nominal wall thickness of pipe or of branch pipe for branch connections and tees.
See NS-3683.1 of Ref. 8.
23 Section modulus of branch pipe
=
Z Section modulus of run pipe
=
r Arc angle (degrees) of an elbow o
=
g t
}>
GT50 0116t S
tf Nordnal thickness of branch pipe. See Figure
=
NS-3686.1-1 of Ref. 8.
T Wall thickness of run pipe with a branch pipe. See Figure
=
r NB-3686.1-1 of Ref. 8.
t
=
Nominal wall thickness of pipe or of branch pipe for branch connections and tees.
See NB-3683.1 of Ref. 8.
Zb Section modulus of branch pipe
=
Z Section modulus of run pipe
=
r "o
Arc angle (degrees) of an elbow
=
GTSD 0110t 8
l sQ-7 N E oo.a1...
l 78NE0174 l [#
CLASS 1 l
SEPTEMBER 1978 t
DOCUMENT LIBRitRY j
MAR %
1979 OA$vanaranoDe i
l FUNCTIONAL CAPABILITY CRITERIA FOR ESSENTIAL MACK ll PIPING i
REPRO f
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NEDO-21985 78NED174 Class I September 1978 1
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I FUNCTIONAL CAFABILITY CRITERIA FOR i
ASSENTIAL MARK II PIPING
(
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This technical report has been prepared by E. C. Rodabaugh
{
of Battelle Columbus Laboratories l
j for the General Electric Company
)
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f NUCLEAR ENERGY ENGINEERING Divis10N
- GENERAL ELECTRIC COMPANY SAN JOSE. CALIFORNI A 95125 i
I GENER AL $ ELECTRIC
NED0-21985 DISCLAIMER OF RESPONSIBILITY This document was prepared by of for the General Electric Company.
Neither the General Electric Company nor any of the contributors to this document; Makes any varranty or nynsentation, express op implied, uith A.
nspect to the accuracy, completeness, or usefulness of the information contained in this document, or that the use of an-,
information disclosed in this doewnent may not infringe privately ovned rights; or B.
Assumes any Naponsibility for liability or damage of any kind l
uhich may result from the use of any information disclosed in this document.
4
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NEDO.-21985 TABLE OF CONTE!tTS Page vii NOMENCLATURE ix l
ABSTRACT xi SIMERY 1
1.
INTRODUCTION 3
2.
FUNCTIONAL CAPABILITY CRITERIA 3
2.1 Class 1 Piping j
6 2.2 Class 2 or 3 Piping a
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BASIS FOR THE CRITERIA P
i 31 NUREG/CR-0261 Report 9
l 32 Straight Pipe 9
33 Curved Pipe or Butt-welding Elbows 9
331 Pressure Term Index, B3 10 332 Moment Term Index and (0.751) = B2 j
15 3.h Branch comections and Tees 15 3 4.1 Branch Connectiers, Class 1 Piping 3. ':. 7 'ei-reaeed vd Unreinforced Fabricated Tees, Class 2/3 Piping 19 343 Butt-weldirs Tees, class 1 Piping 19 3.4.4 Butt-welding Tees, Class 2/3 Piping 21 35 Other Products / Joints 21 i
35.1 Class 1 Piping 21 3 5.2 class 2/3 Piping 22 3.6 Limits for Do/t > 50 23 3.6.1 Temperature Effect on Material Properties 23 3.6.2 Intemal Pressure Effect 25 3.6.3 Products / Joints other than Straight Pipe j
25 3.7 Dynamic Effects 33 4
REFERENCES l
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LIST OF ILLUSTRATIONS Figure Title Page 1.
Test Data on Butt-welding Elbows with Arc Angle, s, of 900 or o
1800, 'frwa Table 4 of NUREG/CR-0261 12
' 2.
Load-Displacement Plots Elbows Identified as (13)10 and (13)11 in NUREG/CR-0261 14 3
Test Data en Straight Pipe with 6/t > 50, From Table 2 of NURE0/CR-0261 24 4
Typical Feedwater Fluid Transient Forces 26 5.
Typical Main Steam Transient Steam Hammer Forcing Function 27 6.
Typical Piping Elastic Response to OBE 28 7.
Piping Systes Subjected to Pressure Transients, From Reference 4 30 8.
Por :. ion of ** ping System with Highest Calculated Staasses, From Reference 4 31 LIST OF TABLES Table Title Page 1
B-Indioes for Functional Capability Evaluation, D /t j 50, i
o 4
For Use in Equation 9 of NB-3652, Class 1 Piping 2
Values to be Used in Place of (0.751) for Functional Capability Evaluation, Do/t j 50, For Use in Equation 9 of NC-3652.2, Class 2 or 3 Piping 5
3 Summary of Limit Moments on Branch Connections, From Table 9 16 of NUREG/CR-0261 4
Test Data on Butt-welding Tees, Frois NUREG/CR-0261 20 l
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NEDO-21985 NOMDiCLATURE S1 pressure loading index B2 a moment loadirig irdex soment loading index, moments applied to branch pipe B2b :
a moment loading irdex, moments traversing run pipe B2r moment loading index, moments applied to branch, pipe, see Code Table C2b NB-3682.2-1 2r soment loading index, moments traversing run pipe, see Code Table C
NB-3682.2-1 D
mean diameter of pipe, of run pipe for branch connections and tees i
Do = outside diameter of pipe, of rtri pipe for branch connections and tees d a mean diameter of branch pipe 2
b: 4tR/D, elbow parameter i = strass i..tevification f actor, see Code Figure NC-3673 2(6)-1 4
Kd: %/Sy K9 : Sn/Sy M = moment M' = M /MC4' MC4 calculated by equation 4 of NUREG/CR-0261 L
test-determined limit moment at 6 = 26 M2 e
moment applied to branch, see footnote (5) to Code Table NB-3682.2-1 Mb:
C1 a code allowable moment, Class 1, Equation (9) of NB-3652 with right-hand-t M
4 side limit of S y C2 = code allowable moment, Class 2, Equation (9) of NC-3652.2 with right-hand-M 4
side limit of S y Mrj = functional capability antenna allowable moment, Class 1, with right-hand-side limit of S y f2 m functional capabili'ty criteria allowable moment, Class 2/3, with right-hand-M side limit of S y i a resultant aceent (see Code definitions for details)
M j
ML test-deter 9ained limit moment M
s maximum lead applied during a test aax M,M,M a set of moments applied on elbow, see Figure 9a of NUREG/CR-0261 x
y g
Mx3' My3' Mz3 s set of moments applied to branch pipe, see Table NB-3682.2-1 P
internal pressure, see pages 2 and 4 for criteria definition R = bend radius of an elbow Rm s mean radius of run pipe, see Figure NB-3686.1-1 vii i
NEDO-21985 NO!ENCLATURE (Contirued)
Sn allowable stress, tabulated in Code Table I-7.0 S a allowable stress intensity, tabulated in Code Table J-1.0 m
S a yield strength of material.
y In test evaluations, S is the actual yield strength of material used y
in the test specimans.
T temperature (deg. F) in the criteria Tr wall thickness of run pipe, see Figure NB-3686.1-1 t: nominal wall thickness of pipe (branch pipe for branch connections and tees), see NB-3683 1 T a lesser of T or (i)(t) g p
3 a section modulus of pipe a a multiplier of S, to define right-hand-side of Equation (9) in NB-3652 co arc angle (degrees) of an elbow B = multiplier of S to define right-hand-side of Equation (0) in NC-3652.2 n
6 = displacement in test 6, = extrapolated elastic displacement in test viii
_- :M
=
NED0-21985 i
ABSTRACT l
l i
j This report addresses the functional capability of essential piping.
Functional capability criteria are presented.
'"hese criteria are based principatty on data contained in NUREG/CR-0261.
The criteria make use of equations and definitions given in the ASW Code but give limits in tenn of material yield Strenght (5,).
The. functional capability criteria presents combinations of tirrits, stress indices i
I and stress intensification factors such that functional :apability is assured.
The criteria are supptimental requirements and are not j
intended to supersede ASW Code requirements.
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NEDo-21985 SUW4ARY i
This document gives " Functional Capability Criteria" for the evaluation of piping in Mark II nuclear power plants. The criteria were selected to be conservative and yet avoid excess conservatism whers possible to assist in assuring maximum reliability of piping considering all aspects of design, fabrication, in-service inspection and operation.
The criteria discussed in this document are structured to make maximum use of the equations and definitions contained in the Code.' However, the functional capability criteria are not intended to be substituted for or supercede any require-nent of the Code.
These criteria are based mostly on the conservative approach contained in NUREG/CR-0261:
1.e., on the single-hinge, limit moment concept with little or no consideration of strain hardening or dynamic effec *:
Recommendt. tic.ts or For elbows with l
concepts given in NUREG/CR-0261 for B-indices are also used.
c s < 900, excess conservatism has been avoided by using the recommendations o
given in Reference 2.
The criteria uniformly uses a right-hand-side limit of 1.5S or 2.0S rather than the less-applicable factors on S CP Sh as used in m
y y
the Code for A, B, C, or D Limits.
> I For the ratio of Do/t > 50, the allowable moments are decreased by increasing indices and equivalents of (0.751). This is based on test data on straight the B2 pipe of ferritic materials at room temperature with a temperature factor based on ratios of allowable longitudinal compressive stresses from Reference 3 Dynamic effects may make the criteria very conservative when used for oonditions where the loadings are dynamic in nature.
'The term " Code" used in this document is the ASIE Boiler and Pressure Vessel Code,Section III, Division 1. " Nuclear Power Plant Components," 1977 Edition with Addenda to to and including Summary 1978.
References to portioris of the Code are indicated by identification used therein; e.g., NB-3652.
xf/xif
NEDo-21985 1.
INTRODUCTION Functional capability of piping is defined as its fluid-flow capability. The functional capability of piping may be impaired by large reductions in the cross-sectional flow area and the criteria given in this document were selected to Ossure that significant reductioni., in cross-sectional area do not occur.
The criteria given in this document were selected to be conservative 8 when used with an elastic analys!s of piping systems.
It may be possible to show that functional capability is assured by using more sophisticated analysis tech-niques, such as determining loads to produce a collapse mechanism, or by con-ducting an elastic plastic analysis. The criteria contained herein are not to be construed as prohibiting more sophisticated analysis methods.
The basis The criteria identified in this document are listed in Section 2.
for tha criteria is discussed ir the remairde.- of t.11s document.
I sThe term " conservative" means more-than-adequate for the specific aspect of functional capability.
However, excessive conservatism in any one aspect of combination of loads, designing a piping system (e.g., in postulation of loads, combinations of stress, etc.) does not necessarily mean that the piping system Excess conservatism may require unnecessary will be of optimum reliability.
snubbers or supports, that must be attached to the pipe, with potential problems at the attachment points, reduced inspectibility and the possibility of additional Therefore, loads due to malfunction of snubbers or to the mass of snubbers.
each aspect of design should be as accurate as possible so that the final design is of optimum reliability.
1
~;
- * $ 7h
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The criteria are structured to make maximum use of the equations and defindtions i
contained in the Reference 1.
However, the functional capability criteria given j
j in this document are not intended to be substituted for or supercede any requirement of the Code. These criteria are for functional capability and do not depend upon Service Levels (i.e., A, B, C or D) used in the Code.
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2.
FUNCTIONAL CAPABILITY CRITERTA l
2.1 CLASS 1 PIPING Equation (9) of NB-3652 shall be satisfied with the rollowing requirements:
{
The right-hand-side of Equation (9) shall be 1.5S for products other 1
y a.
j for branch con-nections than branch connections or tees, and shall be 2.0Sy l
or tees.
i i
The B-irdices shown in Table 1 shall be used, l
b.
i shall be divided by; For Do/t > 50, B B2b, and B2r 2
c.
i
- l (1 3 - 0.006 D /t)(1.033 - 0.00033T) f or territic materials, o
and by (1 3 - 0.006 D /t) for ther caterials.
i o
i l
100.
The irdices are not applicable for D /t >
o 1
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Table 1 B-INDICESPORFUNCTIONALCAPABILITTEVALUATION,D,/tj50,PORUSE IN EQUATION (9) 0F NB-3652, CLASS 1 PIPINO B2 89 Piping Products or Joir.ts Straight Pipe (*)
0.5 1.0 l
o390,13/hM i but not Curved Pipe or butt-welding
(-0.1 + 0.4h),
l 0
S 1.17/h.56{1ess 0
elbows per ANSI B16.9, but not less l
o = 450, c
ANSI B16.28, MS SP-48 or than 0.0 or l
o: 0, 1.0 than 1.0 3
0 MSS SP-87 greater than
]
0.5.
For 82*
j 1.0, B3 s 0.5 0.50 C2b, but not less Branch Connections per 0.5 except if B2b NB-3643 either B2b or cnaa 4/3 B2r is 4/3, B2r = 0.75 C2r, but not less l
B3 s 2/3 than 4/3 Butt-welding-tees per 0.5 except if B2b 0.40 (Ra/T )2/3, but not p
ANSI B16.9, MS SP-48 either B2b or less than 4/3 B r = 0.50 (R,/Tp)2/3, but not or MS SP-87 B2r is 4/3, 2
B1 s 2/3 less than 4/3 Butt-welding reducers per 1.0 1.0 ANSI B16.9, MS SP-48 or MSS SP-87 Girth fillet veld to socket 0.50 1.0 weld fittings or valves, I
slip-on flanges, or socket welding flanges
(*) Applicable to all piping products / joints which have B1 0.5, B2s 1.0 in Table NB-3682.2-1.
4
NEDO-21985 d.
The definitions given in NS-3652 are applicable except that:
(1) P is the pressure coincident with the moments, and (2) S 'is the yield strength of the product material at the metal y
temperature, T (deg. F), coincident with the occurrence of the loads; from Table I-2.
o = are angle (degrees) of an elbow (3) a L
5 l
NEDo-21985 Tchio 2 VALUES TO BE USED IN PLACE OF (0.751) FOR FUNCTIONAL CAPABILITY EVALUATION, D /t < 50, FOR USE IN BOUATION (9) 0F Nc-3652.2, o
CLASS 2 OR 3 PIPING (0.751)
Description W 1.0 Straight Pipe (D} -
2/3 Welding elbow or pipe bend a g goo, 1.3/h lbutnot 450, 1.17 /ho.56 lless G s o
than 1.0 Go 00, 1.0 Interpolate linearly for other values of o.
o 0.751, but not less than 1.0.
Reinforced fabricated tee Use i as defined in Figure NC-3673 2(b)-1 0.751, but not less than 1.0.
Unreinforced fabricated tee Use i as defined in Figure NC-3673 2(b)-1 l
0.901, but not less than 1.0.
Welding too per ANSI B16.9 Use i as defined in Figure NC-3673 2(b)-1 1.0 Fillet welded joint, socket welded flange, or single welded slip on flarge I
1.0 i
Brazed joint t
Concentric reducer (ANSI B16.9 or l
0.751, but not less than 1.0.
Use i as defined in Figure MSS SP48)
NC-3673 2(b)-1 products included in Figure NC-3673 2(b)-1 but not covered by this (a Pi
" Closely spaced miter bend;" "Widely spaced miter bend;"
criteria are:
" branch connection," " threaded pipe joint or threaded flange" and "corru-Functional capability gated straight pipe or corrugated or creased band."
For of these piping products shall be demonstrated by appropriate methods.
" branch connection," the Class 1 criteria are applicable.
(b) Also applicable to " butt weld, en > 3/16 and 6/tn 5 0.1;" " butt veld, tn1 3/16 or 6/tn > 0.1;" " full fillet weld" and "30 tapered transition (ANSI 0
B16.25)."
6
2.2 CLASS 2 OR 3 PIPING Except as permitted in e. below, Equation (9) of NC-3652.2 shall be satisfied with the following requirements.
The right-hand-side of Equation (9) shall be 1.5S.j a.
l b.
The values to be used in place of (0.751) are shown in Table 2, except for " branch connection" where Class 1 criteria shall be used.
c.
For D /t > 50, the values to be used in plate of (0.751) shall be o
divided by:
(1.3 - 0.006 D /t)(1.033 - 00033T) for rerritie materials, and o
by (1.3 - 0.006 D /t) for other materials.
o The values to be used in place of (0.751) are not applicable for D /t > 100.
o d.
The definitions given in NC-3652 are applicable, except that:
(1) P is the pressure coincident with the moments, and t.
sax i
(2) S is the yield strength of the product material at the metal y
temperature, T, (deg. F) coincident with the occurrence of the loads; from Table I-2 or, if the material is not included in Table I-2, from other authoritative sources, adjusted to mini-aus expected yield strength like Table I-2 data.
o = are angle (desrees) of an elbow (3) s Piping constructed in accordance with the code rules for Class 2 or e.
3 any be evaluated for functional capability using the criteria given herein for Class 1 piping. idhen using this alternative, Sy shall be established as in d.(2).
7 e
3 BASIS FOR THE CRITERIA 31 NUREG/CR-0261 REPORT NUREG/CR-0261, (Reference 1) addresses the Code rules which are for pressure boundary integrity and not necessarily for functional capability. However, the report points out that if allowable moments are restricted to limit moments (de-fined as that moment of which 6 s 26,) then restrictions in flow area will be small (less than 55) and functional capability will be assured. Test data from Reference 22 of NUREG/CR-0261 indicates that reduction in cross sectional area of elbows at the limit moment M2 never exceeding 21.
Accordingly, the data and recommendations given in NUREG/CR-0261 are pertinent to and used as a main basis for the functional capability criteria.
At present (Sep*. ember 1978), the recommendations contained in NUREG/CR-0261 are being reviewed by the Code Conunittee, Working G. owp on Piping Design. However, any actions that may be taken are not directly relevant to the functional capability criteria given herein.
NUREG/CR-0261 addresses the adequacy of the Code criteria as judged by the existence of limit moment conditions at some point in the piping system that cause a single " hinge /." The report points out that, for gross plastic defor-mation to occur, a " collapse mechanism" must be developed by occurrence of more than one " hinge"; and gives a simple example where the collapse-mechanism load is 33 percent higher than the load creating the first hinge. The report uses theory (for straight pipe) which ignores strengthening by strain hardening, and dynamic effects are not taken into account.
As discussed at the end of this chapter, dynamic effects should make the criteria very conservative when used for conditions where loadings are dynamic in nature.
Accordingly, NUREG/CR-0261 recommendations are based on conservative evaluations and the functional capability criteria share that conservatism.
As additional data becomes availabis, the functional capability criteria should be reviewed and modified as appropriate to remove excess conservatism.
I 8
NEDO-21985 32 STRAIGHT PIPE i
The criteria for Class 1 and Class 2 or 3 piping are identical. Both can be expressed as:
PD M
g3) 0.5
+ 1.0 i 1 1.5 Sy o
j This criteria is deemed appropriate by NUREG/CR-0261; see Recommendation 4.
Houever, for functional capability, we simply use the more significant limit
' of 1.SS, rather than a constant times S or Sh as used in the Code. These y
m cro more restrictive criteria than Code C-Limits for SA312-TP304 above 100 F (Class 1) or aoove 5000F (Class 2 or 3).
33 CURVED PIPE OR BUTT. WELDING ELBOUS The criteria for Class 1 and Class 2 or 3 piping are identical except for the coefficient of PD /2t, which varies from 0.0 to 0.5 for Class 1 and [because o
in Equation (9) of NC-3652.21 is 0.5 for Class 2 there is no equivalent of B1 cr 3 piping.
3 3.1 Pressure Tern Inder, B1
~
As pointed out in Maceendation 5 of NUREG/CR-0251, imernal pressure tends to increase the limit moment. These criteria implement t.ae concept that 3; can be small when the elbow behavior is predominant (which occurs when h is small), however, B1 should be 0.f the same as for straight pipe, when the elbow
- ehavior is predominantly like straight pipe. The elbow behavior is charac-terized by the parameter h = 4tR/D, where t is the wall thickness, R is the 2
bend radius and D are the cross section mean diameter. The criteria for B1 is j
such that Bi = 0.0 for h $,0.25 fat h : 0.25 B2s 3 28 for so: 900) and 53 1.00, the same as for straight pipe'..
Ac-0.5 for h : 1.5 (at h > 1.5, B2 cordingly, the criteria for 31 recognizes that pressure does not reduce functicnal capability when h is small but also recogni:es that, when the elDow behaves like straight pipe, the limit moment may be reduced by pressure.
l 9
) l
i NEDO-29985 3.3 2 Moment Tens Inder and (0.751) = B2 t
l The criteria for Class 1 and Class 2 or 3 piping are identical for the coefficient i
of M /Z.
For 3, = 900,. Recommendation (6) of NURED/CR-0261 has been used; i.e.,
t a
B2 = 0.67C2 rather than B2 = 0.75C.
However, recognizing that so (the elbow 2
i are angle) may be less than 90 and to remove excess conservatisa from this 0
particular aspect of piping evaluation, the criteria askes use of recommendations j
given in Reference 2.
This report gives the results of an extensive parametric j
study of calculated elastic stresses and shows that as ao decreases below 90,
0 the maximum calculated stress for an "in-plane" soment also decreases. ORNL/Sub-2913/7 recommends that the C2 index, for in-plane soment (identified therein as C22, see page 23 of Reference 2) be given by:
l C2 = 1.95/h 2/3 for ao >,, 9 0 f.
0.56 450 l
C2 = 1.75/h for a a o
i i
l C2 1.0 for ao: 0 l
i l
Linear interpolation with s shall be used, but C2 shall o
l not be less than interpolated for ao = 300 and not less j
than 1.0 for any s.
o
]
l The criteria uses this recommendation with B2 a 0.67C, but not less than 1.0, 2
except that the piaovision in Reference 2 that "C2 shall not be less than extrapo-f 0
lated for ao = 30 " is not used in the functional capability criteria. This j
is because the bound at so = 30 was motivated by concern over possible intwaction 0
between two closely spaced welds from a fatigue standpoint and hence is not relevant '
to functional capability.
The criteria are based on "in-plane" moment loading; this in-plane moment produces higher elastic stresses and lower limit moments than the other two aosents asking up M ; i.e., out of-plane and torsion.
Accordingly, the criteria is conservative i
if all of Mi is in-plane nosent and any be excessively conservative if Mi is mostly out-of-plane or torsional noments.
10
.t..
Unfortunately, this possible excess conservatism cannot be removed from the sim-j plified approach used in this criteria, but could be used in more sophisticated cnalysis methods which are not prohibited by this criteria.
I Test data on elbows from Table 4 of NUREG/CR-0261 are shown in Figure 1.
The criteria, for ao 2 900, h < 0.25, is:
j 4
Mj g
j B2 5.1.5Sy 2
(w/4) D t cc, in terms of the parameters used in Figure 1, recalling that B2 = 1 3/h2/3, I
Mf1 (w/4) x 15 2/3 = 0.906h2/3 h
l 2
D tS 13 (2) y 3
5 Equation 2 is plotted in Fighe 1, providiI18 a visual comparison oY test data ~~
with the functional capability criteria for elbows. Variation in the test data with h by roughly h2/3 as used in the criteria can be seen in Figurs 1.
Recall-4 ing that the theoretical limit moment for straight pipe is M2
- O DS, the ftet y
2 that the test data M/(D tS ) values are less than 1.0 indicates that elbows with y
h < #0.4 are not as strong as straight pipe. However, the l'sportant aspect is that the criteria conservatively evaluates this " elbow-effect" for all but two i
points which are briefly discussed below.
One of the two points slightly (#105) below ~the criteria is from Reference 23 i
of NUREG/CR-0261. The reference tests were different as +M was applied first z
6 to a magnitude of about 1 3 x 10 in.-lb, then -M was applied to about the same g
cagnitude. 'this cycle was repeated approximately 10 times, and each time the maximum moment was increased. On the final cycle, the magnitude of +M was 3.8 g
x 105 in.-lb (with load increasing with increasing deflection) and the magnitude 6
of -Mg was about 3 3 x 10 in.-lb (with load not increasing with increasing de-1 flection indicating that the maximum -Mg load had been reached). The maximum soment was therefore 3 3/1.5 times M2 on the first half cycle. The maximum moment is indicated in Figure 1 by the leader to "Maax* "
i a
11
I Code 2/3 i
g.5 Sy d
ra with 16 Tei&guchi l
dgmic 1.0 Mm 09 Y
e 08 o
6 a
o e
S 8
m 4
Mm og 05 enteno
/
a290' Ia u_ m y j
D,t S f
(13)11 c3 NoPressure With Pressure (23),-M, Ref.(22)or(23)
O A
02 Ref. (13)or (24)
A I
I I
I I
I I
I I
03 04 0.5 06 47 08 09 LO Qi O2 Ol 2
h=4tR/0 0
Test Data on Butt-welding Elbows with Arc Angle, Go, of 90 or Figure 1.
fmm Table 4 of NUREG/CR-0261
- 1800, 2
The other of the two points slightly (#14%) below the criteria, is the test identified as (13)11 in Table 9 of NUREG/CR-0261. This test is anomalous in that pressure decreased the limit moment, when compared to a presumably identical lo2 ding with P = 0; that b~eing'the test-identified as (13)30. Data in Figure 2 shows the complete load versus deflection plots of these two tests. Unfortu-nately, the yield strengths of the materials in the elbows tested are not known; stainless steel elbows were assumed to have a yield strength of 30,000 psi.
Accordingly, the seeming anomaly of pressure reducing M, as shown in Figure 2, 2
say be due entirely to a higher yield strength in the elbow tested with P 0.
In any case, the substantial stiffening effect of internal pressure at high loads is apparent in Figure 2 and the maximus applied moment is indicated by Figure 2 by the leader to "Maax"*
The criteria for Class 1 with P 0, ao 900 arv more restrictive than tne Code C-limits for SA-312 TP304 at temperatures above 1000F.
a 900 arv almost always significantly more The criteria for Class 2/3 with so restrictive than the Code C-limits. This because B2 is larger than (0.751);
i.e.,
B2 1 3/h2/3 0.751 0.75 x 0 9/h2/3 0.675/h2/3 3
B /(0 751) = 1 3/0.675 1.93 2
This aspect is shown in Figure 1 by the line identified as " Code Class 2/3 with Bgg 1.5S." 8 is the right-hand-side limit of Equation (9) of NC-3652.2, y
gg and for SA312-TF304 at #5000F, is equal to 1.5S. This is one of the aspects y
where the Code rules are not supported on the basis of the conservative single-hinge, limit load concept used in NUREG/CE-0261.
This is not to say that the Code rules are necessarily unconservative because a more sophisticated approach considerin6 collapse mechanisms, strain hardening, dynamie effects, etc., might show the Code rules to be appropriate.
13
i 6
83 M,nox > 338,000 in-Ib -
PW2t = 18.6 ksi 5
(13)ll 4
I Mmax W 199,COOin-b P=0 3-(g3)io l
~
Mr = 160,000 in-Ib for P= 0,(13) 10 2-
= 123,000 in-Ib for PD/2t = 18.6 ksi,(I3)ll Mcrnent (kg-mm)is 707 xload l-O O
KIO 200 300 400 500 600 End DWTwo,mm Figure 2.
Load-Displacement Plots, Elbows Identified as (13)10 and r
i (13)11 in NUREG/CR-0261 11 i
l-NEDO-21985 3.4 BRANCN CONNECTIONS AND TEES For Class 1 rules, the equation to be satisfied is:
M l
PD Mb r
o +B2B - + 82 R """ < GKai l
81 Z
l 2t Zb r
l 2b' M ' Z, B2r' M and Z are given in footnotes 5, 7 and 9 Definitions of B b
b r
r of Table NS-3682.2-1, and ciq represents the right-hand side limit of Equation (9) of NS-3652.
The equation to be satisfied for Class 2/3 piping is:
M PD0+ (0.751) I < B K8 4t Z
1 j
For Claas 2/3 piping, each end of the branch connection or tee is checked separately in accordance with NC-3652.4(c) or (d). For checking the run ends, l
Z is simply the section modulus of' the run pipe A = (w/4) D 7r.
For checking 2
2 the branch end, however, Z is defined as (w/4) d t, where ts is the lesser s
of Te or (i)(t).
3.4.1 Branch Connections, Class 1 Piping Limit soment test data or branch connections are summarized in Table 9 of NURE/CR-0261. Table 3 of this document is Table 9 of NURE/CR-0261 with one cdditional column (the column headed M /Mri) where Mri s the acaent permitted i
L The value M /Mri s the ratio L
i by the criteria given herein for Class 1 piping.
of test limit soment (essentially M ) to the moment permitted by the criteria 2
with the right-hand-side limit of Equation (9) of N8-3652 equal to S. The cri-y teria set the right-hand-side limit as 205.
Accordingly, to justify the criteria 7
limit of 2.0S, all values in the column of Table 3 headed M /Mri should be 2.0 L
y l
'or higher.
As shown in Table 3 this is the case, except for the test identified es (34)6, where M /Mf1 = 1.95 In most tests, the criteria is very conservative L
(Mg/Mr1.>> 2) but, as can be seen by oomparing M /Mri with M / Met not as excessively L
L conservative as the present Code with a right-hand side-limit of the same value.
i l
t 15 Jm
NEDo-21985 Table 3 SUMERY OF LIMIT MODENTS ON BRANCE CONNECTIONS FROM TABLE 9 0F NURE0/CR-0261 Ref. D/
d t
PD Type of M'
No.
T D
7 2T Moment B2b Mc1 Mc2 Mf1 p
p p
(a)
(kai)
(b)
(c)
(d)
(e)
(f)
(33)1 24 0.52 0.52 0
Mz3 0.91 4.25 4.9 2.1 33 2 25 0.75 0.75 0
Mz3 0.84 7.57 8.1' 2.9 5.4 3 25 1.00 1.00 0
Hz3 0.64 11.65 9 58 30 63 4 25 0.75 0.75 12.5 Mz3 0.49 7.57 6.8' 2.0 3.6 5 27 1.00 1.00 6.8 Mz3 0.50 12 30 10.5' 2.8 59 (34)1 56.5 1.00 1.00 0
Hz3 0.50 20.51 13 1' 4.0 8.7 2 34.5 0.40 0.80 0
Mz3 0.70 7.18 6.4 32 4.3 (35)1 31.0 0.65 0.66 0
Hz3 0.66 7.21 6.1' 23 4.0 (36)1 30.1 0.79 0.79 0
Mz3 0.63 9 32 7.5' 2.6 5.0 z3 0.46 13 24 7.8'. 2.4 5.2 2 30.0 1.00 1.00 0
H (33)1 25 0.5 0.5 0
Mx3 0.72 4.12 3.8 1.7 2.5 2 34.5 0.7 1.27 0
Mx3 0.480 15.16 9 3' 35 6.2 3 25 1.0 1.0 0
Mx3 0.59U 11.65 8.8' 2.7 5.8 x3 0.49U 16.73 10.4' 3.2 7.0 4 42 1.0 1.0 0
M 5 34.5 0.7 1.27 17 3 Mx3 0 33 15.16 14.0' 32 5.7 (34)1 34.5 0.4 0.8 0
Mx3 0.57U 7.18 5.2 2.6 35 2 34.5 0.6 1.2 0
Mx3 0.46U 13 20 7.7' 32 5.1 3 34.5 03 0.6 0
Mx3 0.75 4.67 4.5 2.6 3.0 4 34.5 0.8 1.6 0
Mx3 0 33U 20 32 8.5' 30 5.7 5 25.0 0.7 0.7 0
Mx3 0 700 6.82 6.1' 23 4.0 6 34.7 0.2 0.4 0
Mx3 09 2.55 2.9 2.1 1 95 7 35.0 0.97 1 94 0
Mx3 0.27U 27.41 9 4' 3.0 6.3 8 45.0 0.4 1 33 0
Mx3 0 33U 14.05 6.9 30 39 9 45.0 0.6 2.00 0
Mx3 0.22U 25.86 7.2' 30 4.8 16
NED0-21985 Table 3 (continued)
Ref. D, d,
t PD Type of M'
ML No. T D
T, 27, Moment B2b Mel Mc2 Mf1 j
e (a)
(ksi)
(b)
(c)
(d)
(e)
(f) c 0.16U 39.87 8.1' 2.9 5.4 (34)10 45.0 0.8 2.67 0
Mx3 0.17U 52 34 11 3' 37 7.5
]
11 45.0 0.96 32 0
Mx3 1.0 2.95 3.8 1.9 2.5 12 25.0 0.4 0.4 0
Mx3 13 25.0 0.6 0.6 0
Mx3 0.77 5.42 5 3' 2.1 35 1.1 5.00 7.0 5.0 4.7 14 45.0 0.2 0.67 0
Mx3 15 45.0 0.3 0.9 0
Mx3 0.62 8.29 6.5 3.8 4.4 (35)1 31.0 0.65 0.66 0
Mx3 0.50 7.21 4.68 1.8 3.1 0.84 3 50 37*
1.4 2.5 2 22.9 0.65 0 39 0
Mx3 (36)1 30.0 0.6 0.59 0
Mx3 0.69 6.06 5 3' 2.1 35 2 29.7 0.79 0.77 0
Mx3 0.52 9.01 6.0*
2.1 4.0 3 30.0 1.0 1.0 0
Mx3 0.41 13 24 6.98 2.1 4.6 x3 0.58 6.25 6.1' 2.1 3.4 4 30.0 0.6 0.61 10.5 M
0.61 9 36 9.9e 2.8 5.5 5 30.0 0.8 0.79 12.0 Mx3 x3 0.47 13 24 10.98 2.8 6.0 6 30.0 1.0 1.0 12.0 M
(13)1 25.4 0.76 0.87 23 7 Mx3 0 97 7.5 24.8 5.1 8.0 1.69 4.5 27.
7.4 9.0 2 25.4 0.45 0.70 23 7 Mx3 3 25.4 0.76 0.87 23 7 Mx3 0.58 8.9 17.*
31 5.7 x3 1 36 5.4 26.
6.2 8.7 4 25.4 0.45 0.70 23 7 M
5 25.4 0.76 0.87 27.4 Mx3 0.67 7.5 56.
3.6 5.7 6 25.4 0.76 0.87 20.6 Mx3 0.69 B.9 22.'
37 6.8 0.82 4.5 49 4.2 5.0 7 25.4 0.45 0.70 27.4 Mx3 0.70 5.4 14.
32 4.5 8 25.4 0.45 0.70 20.6 Mx3 1 32 75 33.'
7.0 99 j
9 25.4 0.76 0.87 23 7 My3 1.07 4.5 17.
4.9 5.2 10 25.4 0.45 0.70 23 7 My3 1.24 8.9 36.'
6.5 11.0 11 25.4 0.76 0.87 23 7 My3 1.08 5.4 21.*
h.9 6.3 12 25.4 0.45 0.70 23 7 My3 0.82 7.5 68.*
4.4 6.3 13 25.4 0.76 0.87 27.4 My3 17
NEDO-21985 Table 3 (Contir2ed) f Ref. o e
t to Type of Me N
N N
No.
7 D
f 2T Moment B2b Met Mc2 Mri p
p p
(a)
(ksi)
(b)
(c)
(d)
(e)
(f)
(13)14 25.4 0.76 0.87 20.6 My3 0.55 8.9 17.8 29 4.9 15 25.4 0.45 0.70 27.4 My3 0 91 4.5 54 4.7 5.0 16 25.4 0.45 0.70 20.6 My3 0.85 5.4 17.
39 5.0 (13)17 25.4 0.76 0.87 27.4 Mx3 y3 0.76 7.5 65.*
4.8 6.2
/M 18 25.4 0.76 0.87 20.6 Mx3'My3 0.63 8.9 20.8 4.0 6.1 19 25.4 0.45 0 70 27.4 Mx3'My3 0.67 4.5 42.
5.2 4.1 20 25.4 0.45 0.70 20.6 Mx3/My3 0.70 5.4 15 4.8 4.5 i
(a)These are reference numbers in NUREG/CR-0261. Material is carbon steel except for Reference 13. Figures 5-8,13-16, and 17-20, which were stainless steel like TP304. Construction was like Figure 14b in NUREG/CR-0261 except Reference 13, Figures 1, 2, 5, 7, 9, 10, 13, 15, 17 and 19, which are believed to be like Figure 14e in NUREG/CR-0261.
(References and Figures are those of NUREG/CR-0261.)
(b)M' s M /M g, where M g is calculated by equation 4 of NUREG/CR-0261 L e e
M is the experimental limit mesent g
Values followed by U" are deemed unstable by authors of sited references.
I (c)B2b : stress index calculated by Code rules.
I 4
(d)M j = allowable moment by Code Equation (9) with nKm: 1.0, Class 1.
a Values followed by e are tests with d/D larger than covered by B2b' (e)Mc2 s allowable nosent by Code Equation (9) with 8Kg 1.0, Class 2.
(f)Mri s allowable moment by functional capability criteria with right-hand side limit of Sy 18
NEDO-21985 3 4.2 Reinforced and Unreinforced Fabricated Tees, Class 2/3 Piping The column in Table 3 headed M /Mc2 is the ratio of the test limit moment L
(essentially M ) to the acaent permitted by the criteria for Class 2/3 piping 2
with the right-hand-side limit of Equation (9) of NC-3652.2 equal to S. The y
criteria set the right-hand-side limit as 1.5S. Accordingly, to justify the y
criteria limit of 1.5S, all values in the column of Table 3 headed M /Mc2 should y
L be 1.5 or higher.
In Table 3, the ratio M /Mc2 is greater than 1.5 L
exoept for the test identified as (35)2, Mx 3' "h'"' M 'Mc2
- l'"*
In " 8t L
tests, the criteria are very conservative (M /Me2 n 1.5), although not as L
conservative as the criteria for Class 1 piping.
3 4.3 Butt-welding Tees. Class 1 Piping Table 4 shows data fra the. insert table on page 49 of NUREG/CR-0261. The column hesded M /Mr1 is the ratio of the test limit moment to the moment per-L citted by the criteria for Class 1 piping with the right-hand-side limit of Equation (9) of NS-3652 equal to S. The criteria set the right-hand-side limic y
as 2.0S. Accordingly, to justify the criteria limit of 2.0S, all values of y
y Table 4 in the column headed M /Mri should be 2.0 or higher. Table 4 shows L
that this is essentially the case.
3.4.4 Butt-veldins Tees, Class 2/3 Pipias The column headed M /Mf2 in Table 4 is the ratio of the test limit moment to L
the moment permitted by the criteria for Class 2/3 piping with the right-hand-side limit of Equation (9) of NC-3652.2 equsi to S. The criteria set the right-y hand-side limit as 1.53.
Accordingly, to justify the criteria limit of 1.5S,
7 y
all values in Table 4 in the column headed M /Mf2 should be 1.5 or higher. Table L
4 shows that this is essentially the case.
19
I Table 4 l
TEST DATA ON SUTT-WELDIN0 TEES (a), FROM NUR50/CR-0261 i
S k
k -
k k
y i
Spoo.'
in.-lb psi Mel Me2 Mf1 Mf2 No.
(b)
(c)
(d)
(d)
(d)
(d)
I j
PT-1A 421,200 44,600 2.70 1 35 2.15 1.62 i
PT-18 442,800 44,600 2.84 1.43 2.27 1.71 f
I PT-1E 422,100 44,600 2.71 1 36 2.16 1.63 I
l PT-2A 396,900 42,250 2.69 1 35 2.14 1.60 PT-28 411,300 42,250 2.79 1.40 2.22 1.67 l
PT-2 E 362.000 42.250 2.46 1.23 1 95 1.47 (a)6x6, Ser 40 (0.M0 nom. wall), D/Tc 2'.7, d/D 1.0; T;.
1.0.
l (b)4 limit moment.
In first three tests, the branch pipe yielded without j
any visible plastic deformation of the tee. In the second three tests, the teos deformed appreciably while the branch pipe remained straight.
i i
l i
i (c) Yield strength of tee material.
I I
i (d) Met allowable nosent by Code Class I with 1.0Sy limit j
Mc2 allowable moment by Code Class 2 with 1.057 limit j
Mri allowable moment by Functional Capability Criteria Class 1 with l
1.05 limit y
l Mf2 s' allowable moment by Functional Capability Criteria Class 2/3 with 1.0S limit y
i 20
NEDo-21985 35 OTHER PRODUCTS / JOINTS The coverage of products / joints in the criteria is intended to be the same as the Code.
3.5.1 Class 1 Piping Footnote (a) to Table 1 uses the concept given in NUREG/CR-0261, page 52, " Piping Products with Bi = 0.5, B2 =
1.0."
For reducers, the criteria uses the B3 and B2 irriices given in the Code.
However, the 1 5S limit in the criteria provides y
additional conservatism as compared to Code rules where the limit exceeds 1.55 ;7 0
o.g., for Level C-Limits, SA312 TP304 above 100 F.
For girth fillet welds, the Code gives B1 0.75, B2 = 1.50 in piping, fillet welds tJ11ch are used to join the pipe to socket welding fittings, socket welding valvw, slip-on flanges or socket welding flanges. From a functional capability standpoint, the fitting, valve or flange reinforces the pipe at the weld so that the pipe cross section will not deform to the extent that straight pipe, remote from such reinforcing, would deform under the same loads.
Accordingly, the criteria conservatively uses the same indices for fillet welds as for straight pipe; i.e.,
B1 = 0.5, B2 1.0.
As discussed in Reference 5, pages 56 and 57, the Code Bi cnd B2 indices are higher than for straight pipe to encompass the possibility (albeit remote) that a full fillet weld (a weld with legs not less than 1.4 times the pipe wall thickness) may not be achieved with ANSI D16.11 socket welding fittings. However, this is an aspect related to pressure boundary integrity; not functional capability.
It should be recalled that the functional capability criteria given herin are not intended to supercede any requirement of the Code.
3 5.2 Class 2/3 Pipins Although stated differently, footnote (b) to Table 2 uses the same concept es Footnote (a) to Table 1.
Footnote (a) to Table 2, for completeness, recognizes that there are some products covered by Figure NC-3673 2(b)1 which are seldom used in Mark II piping systems.
It also recognizes that, for " branch connections,"
the equation given in Figure NC-3673 2(b)1 is not appropriate and points out that Class I criteria may be used.
21
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~.. - -.. ~ - - _ -....... - ~... - -.,. - - -..... -. - - -..... -. -
1 NED0~21985 i
For concentric reducers, the criteria uses (0.751) from Figure NC-3673 2(b)-1.
However, the 1.5S limit in the criteria provides additional conservatism as y
compared to Code rules where the limit exceeds 1.5S ; e.g., for Level C-Limits, y
0 SA312 TP304 above 500 F.
4 4
For girth fillet welds and brazed joints, the criteria applies the same value i
of (0.751) used for straight pipe; (0.751) = 1.0.
The bases for this is the same as-discussed under Class 1 Piping; the presence of a fitting at a fillet l
welded or brazed joint increases the functional capability load capacity as compared to straight' pipe remote from reinforcement, hence use of (0.751) :
1.0 is conservative for functional capability.
i I
l 36 '2TS FOR D,/t > 50 l
l NUREG/CR-0261 points out that for D/t > 50, it is not prudent to assume that j
the limit load theory is an adequate assessment of the soment capacity of straight pipe.
}
Considerable test data on the moment capacity of straight pipe with D/t > 50 I
is included in Table 2 of NUREG/CR-0261. These data are plotted in Figure 3 An indication of relative acaent capacity of pipe as a function of D/t can also i
be obtained from Paragraph UG-23(b) of Reference 3 This paragraph provides rules for establishing anximum allowable longitudinal compressive stresses on l
cylindrical shells. This is applicable ice a uniform (around the circumference' longitudinal stress and hence is conservative for evaluating acaent loadings, where the maximum ooapressive stress occure at only one point around the circumference.
Nevertheless, the relative values of allowable longitudinal stress as a function
{
of D/t should be applicable to bending of straight pipe. The relative values.
l for carbon steel with specified miniaua yield strength of 30 to 38 kai at temperature I
up to 3000F are shown in Figure 3 Based on this data, a criteria factor for D,/t > 50 has been established as indicated in Figure 3 4
i
.l 1
i 22 f
i
4 NEDO-21985 Such l
It may be noted that a few test points lie beneath the criteria line.
data, of coume, is expected to exhibit some scatter due to variations in test sensurements, dimensions of test specimens and determination of material yield j
strength. It is significant to note that S, as used in the criteria, is the y
einimum specified yield strength at 1000F and is the minimus expected yield j
strength at higher temperature. Most piping materials will have yield strength I
well above the specified or expected minimums, hence there is a statistical l
1 j
targin-of-safety in the criteria.
3 6.1 Temperature Effect on Material Properties At All of the data in Figure 3 represent data from room temperature tests.
decreases.
olevated temperatures, the allowable acaent decreases because Sy To assess whether this is adequate to compensate for buckling, the data given in Pan raph UG-23(b) of Reference 3 were usad. For austenitic stainless steel, the decrease in allowable longitudinal stress with increasing temperature is essentially proportional to the decrease in yield strength with temperature.
However, for ferritic steels like SA106 Grade B, the decrease in allowable 0
longitudinal stress with increasing temperature from 100 to 700 F is about 255 more than the decrease.in yiel.d strength with increasing temperature from Accordingly, a factor of (1.033-o.00033T) has been used in the 0
100 to 700 F.
criteria for ferritic steels to account for the temperature effect on material j
properties.
1 3.6.2 Internal Preasure Effect As All of the data in Figure 3 represent tests with zero internal pressure.
discussed in NUREG/CR-0261 (pages 18 and 19, on " Buckling With Internal Pres-sure"), some test data indicate that internal pressure will increase _ the accent capacity of pipe with D /t > 50. However, these criteria take the conserva-o tive approach that internal pressure does not increase soment capacity; i.e.,
indices are not a function of D /t.
the B1 o
23
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SO 60 70 80 90 10 0 110 Wt 1
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Figure 3 Test Data on Straight Pipe with D/t > 50, From Table 2 of NURE/CR-0261 2a i
i
NEDO-21985 3.6.3 Products / Joints other than Straight Pipe, All available test data are on straight pipe; the data are deemed to be directly applicable to girth-butt welds and transition joints.
For elbows with small h, the criteria are probably very conservative because the B 2 index for elbows reflects the tendency for the cross section to become out-of-round.
- However, in the absence of supporting data, these criteria apply the corrections for D /t > 50 to all products and joints.
)
o 3.7 DYNAMIC EFFgCTS In many nuclear power plant piping systems, the large and therefore design-controlling loads are caused by dynamic conditions such as steam hanner, relief valve transients, postulated earthquakes or pipe breaks. These have the characteristic of rapidly oscillating loads with relatively short total time I
dura" 6n.
Some examples of the load characteristic are shawn in Figures 4, 5, and 6 herein.
The test data cited in NUREG/CR-0261, with the exception of one set of data, represent tests in which loads were slowly applied. Tests in Figure 1 are the l
one exception. The five data points bracketed and identified as "Teidoguchi j
Dynamic Tests." These were tested under dynamic loadings (on a shake-table) j at a frwquency of about 3 Hertz. These test data, shown in Figure 1, are about a factor-of-two higher (stronger) than would be expected from the other static loading test data. The elbow did not lose functional capability during the tests, although fatigue failure was to be expected and did occur. This set of tests suggests that, under dynamic loading, the criteria given in this document may be excessively conservative but the single set of data is not sufficient to provide a more realistic basis over the parameter ranges covered by the criteria.
Water hammer occurs in industrial piping systems and for piping ande of brittle material such as cast iron can cause failure of the piping. However, for piping cade of ductile material, the ability of piping to absorb these dynamic loads l
without failure is impressive.
Reference 4 gives a quantitization of a service occurrence which is relevant to dynamic effects and discussed below.
4 l
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Typical Main Steam Transient Steam Hammer Forcing Function 27
d NED0-21985 4
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F Figure 6.
Typical Piping Elastic Response to OBE 25
NEDO-21985 Because of abnormal operation of a regulation valve, pressure transients occurred in the piping systes shown in Figures 7 and 8.
The location of the portion of piping shown in Figure 8 with respect to the entire piping system are shown by noting correspondence at Points 58 and 94 on the two figures. During shutdown following the incident, the piping system was examined for damage to the piping but none was found. Estimates were also made of the pipe movements as indicated by the physical evidence. These movements were then used as imut data for statie i
analysis of the piping system.
Several combinations of movements were evaluated, ircluding the oosbination of interest identified in Reference 4 as Case I.
A transient banding stress of 13,328 psi ins calculated at point "X" as shown in Figure 8.
While moet of i
5 the piping in the system was 24-inch, Schedule 120 (1.812-in. wall), the i
U-shaped bypass shown in Figure 8 was 6-inch, Schedule 160 (0.718-in. nominal wall).
To evaluate this incident in terms of the criteria, note that:
a.
P operating pressure : 1250 psi 0
b.
T : operating temperature 340 F c.
Material was SA-106 Grade B, S 0
30.5 kai (at T = 340 F) a y
d.
Point "X" in Figure 8 is " straight pipe" e.
The bending stress due to weight at Point "X" was 651 psi.
29
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26 WM NEDO-21985
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Portion of Piping System with Highest Calculated Stresses, From Reference (4) 31
l NEDO-21985 I
Accordirgly, the criteria gives:
PD g < 1.5 x 30500 i
B1
+B o
2t 2Z i
J 1
1250 x 6.625
-x
+ 1.0 x (53,328 + 651) < 45,750 2
2 x 0.718 2883 + 53,979 1 5,750 4
4 56,862 1 45,750
]
2 3
The ratio of 56,862 to 45,750 is 1.24, hence the stress in this incident exceeded the criteria limit by 24 percent. However, there was no evidence of loss of "unc* ion =1 capability or any daMM6e to the pipe i
This bit of quantified service experience adds confidence to the adequacy of i
the criteria.
Additional evidence of this type any be developed and should i
aid in removing excess conservatism in the criteria.
I s
4 I
i 32
_ -.. _ ~
NEDO-21985 4.
REFERENCI'S 1
l 1.
E. C. Rodabaugh, and S. E. Moore, Evaluation of the Plastic Characteristics of Piping Products in Relation to Code Criteria, NUREG/CR-0261, July 1978, 3
ORNL/Sub-2913/8.
I 2.
E. C. Rodabaugh, S. K. Iskander, and S. E. Moore, End Effects on Elbows i
Subjected to Moment Loadings, March 1978, ORNL/Sub-2913/7.
4 3
ASif Boiler and Pressure Vessel Code,Section VIII, Division 1, Pressure i
f Vessels,1977 Edition with Addenda up to and including Sumer 1978.
1 1
3 j
4.
Analysis of Reactor Feedwater (Piping System) Under Pressure Transients, bartent & Lundy Report, Dresden-3, Project No. 4989, October 1974.
i 5.
E. C. Rodabaugh and S. E. Moore, Stress Indices for Girth Welded Joints, i
4
]
Including Radial Weld Shrinkage, Mismatch and Tapered-Wall Transitions, September 1978, NUREG/CR-0371, ORNL/Sub-2913/9 4
4 l
1 i
i t
i 1
9
't 33 4
NUCLEAR ENERGY DIV15 tons e GE WERAL ELECTRIC COMPANY j
2 l
SAN JOSE, CALIFORNIA 96125 GENER AL $ ELECTRIC TECHNICAL INFORMATION EXCHANGE TITLE FAGE 1
AUTNOR SUSJECT TIE NUMSER 78NEDt74 E. R. Rodabaugh Nuclear Science DATE (Battelle Lab)
& Technology 9/78 TITLE GE class I
Functional Capability Criteria oOysRNMENT class for Essential Mark II Piping REPRODUCISLE COPY FILED AT TECHNICAL NUMJEre OF PAGES SUPPORT saRvlCas, RauO, SAN JOSE.
39 3
CALIPORNIA 96125 { Mail Code 211)
I
SUMMARY
This document gives " Functional Capability Criteria" for evaluation of piping in Mark II nuclear power plants. The criteria were selected so as to be con-servative and, equally important, excess conservatism has been avoided where possible to assist in assuring maximum reliability of the piping considering all aspects of design, fabrication, in-service inspection, and operation.
j i
i Oy curing out mis rectangle and folding in half, the above informet!on can be fitted into a standard card file.
T 4
1 DOCUMENT NuestR NEDO-21985 INFORM ATION PREPARE D F OR Nuclear Energy Projects Division _
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Main Feedwater Line Description
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Feedwater Piping Materials l
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Justification for Applying Leak-Before-Bret.k Methodology to the Main Feedwater Line of the Westinghouse Advanced l
Power Reactor, The AP600 i
l "A reliability evaluation of the main feedwater lines of the i
AP600" 4
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QUOTE FROM NOVEMBER 4,1996 LETTER i.
I "Since the potential for water hammer cannot be ruled out, and Westinghouse has not provided a quantitative analysis demonstrating an extremely low probability of this event, the staff has concluded that the criteria in general j
design criteria-4 (GDC-4), i.e. the probability of pipe rupture due to water l
hammer is extremely low, has not been met."
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Introduction
OUTLINE l
1.
Introduction 2.
Fe-edwater Piping Materials 3.
Main Feedwater Line Description 4.
Historical Experiences of Water Hammers in Westinghouse Type PWRs 5.
Water Hammer Mechanisms Applicable to the Main Feedwater Lines of the AP600, 6.
Mechanistic Probability of Water Hammer occurring in the AP600 Feedwater Line 7.
Probability of Pipe Rupture in the AP600 Feedwater Lines i
8.
Conclusions 2tmewtrWm
i 1
i Results of Probabilistic Evaluation of AP600 Feedwater Line Water Hammer l
Probability of Water Hammer Occurrence = 8.6 x 10*per Reactor Year i
l Probability of Pipe Rupture Due to Water Hammer = 3 x 10-8 Over the Life of the Plant l
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l Feedwater Line Leak-Before-Break 1
Backeround Information j
Westinghouse has applied LBB to the main feedwater piping inside containment from the beginning of the AP600 Project i
Westinghouse designed AP600 feedwater line to address water hammer issues j
Westinghouse conducted a detailed water hammer evaluation for AP600 feedwater line and included maximum credible loads in the LBB analyses 4
The benefit of LBB is reduced plant hardware and improved access for j
inspection and maintenance i
i i
NRC upper management agreed that application of LBB to the feedwater line should be considered based on technical merits similar to other LBB lines l
i j
Westinghouse has responded to all of these issues and has implemented design i
changes to ensure the successful application of LBB to the feedwater line.
j Certain inservice inspections and special analyses were included.
The curTent presentation addresses the probability of a water hammer event causing a pipe break in the main feedwater piping inside containment. (NRC l
letter dated November 4,1996) l Westinghouse requests full evaluation of the process and results I
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i Mechanisms for Severe Water Hammers Mechanism Number Brief Deecription l
1 Subcooled water with condensmg steam in a vertical pipe (Water Cannon) i 2
Steam and water counterflow in a hortzontal pipe (Steam / Water j
Counterflow) 3 Pressunzad water entenng a vertical steam-filled pipe (Steam. Pocket l
Collapee) l 4
Hot water entering a lower pressure line (Iow Pressure Ducharge) i l
5 Steam-propelled water slug (Water Slug)
(
j 6
Rapid valve actuation (Valve Slam) 7 Filling of a voided line (Column Rejoirung) l 8
Other or unknown C
Cavitation / Valve Instability 4
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Damage Severity Levels for Water Hammers Which Have Occurred in the Main l
Feedwater Lines and Steam Generators of Westinghouse Type PWRs l
Damage Severity 14 vel Main Feedwater Line Steam Generator
)
- 1. Pressure Boundary IAakage 1
1 l
- 2. Damage to Components,'
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- 3. Snubber or Support Damage 7
5
- 4. No Physical Damage 6
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.- _ _ - = - -. i 9 i 1 i i 4 Mechanisma for Severe Water 14a====s Mechanism Number Brief Description i 1 Subcooled water with condenseg steam in a vertical pipe (Water Cannon) f 2 Steam an1 water counterflow in a honzontal pipe (Steam / Water i Counter 69w) 3 Prussunned water entenng a vertical steam-filled pipe (Steam Pocket j Collapse) ) 4 Hot water entering a lower pressure line (Imv Pressure Discharge) 5 Steam-propelled water slug (Water Slug) 6 Rapid valve actuation (Valve Slam) 7 Filling of a voided line (Column Retomwj) 8 Other or unknowr* C Cavitation / Valve lastability i i 4 4 Damnage Severity Levels for Water Hammers Which Have Occurred in the Main ] 4 Feedwater Lines and Steam Generators of Westinghouse Type PWRs j l Damage Severity level Main Feedwater Line Steam Generater f.
- 1. Pressure Boundary IAakage 1
1 l
- 2. D-=p to Components, 12 9
i Flange or Instrument Tube IAakage
- 3. Snubber or Support Damage 7
5
- 4. No Phy=W Damage 6
9 q 1 l 4 i 1
s 5. Water Hammer Mechanisms Applicable to the Main Feedwater Lines of the AP600 i
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- a. Inittel conditions when valve opens Tseteessed
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- b. Possible water hammer when hot water I
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-'e first valve wMeh will propel cool water l causing slug flow water hanemer aspen 7 * *' / y """* **'*" impact with downstream valve N7 '~ C (See Mechantess El i eAMGI henshantone 4 - Hot Water Entering a Lower Pressure Line (Leer Prosauro Diecharge) j i
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6 l i i i t 1 i 1 i i I Mechanisms for Severe Water Hamunese ummmmmmmmmmmmmmmmmmu Mechanism Number Brief Description j 1 9tW water with condensing steam in a vertcal pipe (Water Cannon) 2 Steam and water counterflow in a honzontal pipe (Sinam/ Water Counterflow) 3 Pressurized water entering a verbcal steam-filled pipe (Steamfocket Collapse) 4 Hot water entering a lower pressure line (Low Pressure Discharge) 5 Steam-propelled water slug (Water Slug) 6 Rapid valve actuation (Valve Slam) 7 Filling of a voided line (Column Rejoining) 8 Other or unknown C Cavitation / Valve Instatality 4 4 i I i k e
t a i 1 1 l 4 4 Table 5.21 The Machanisms Associated with Water Ha==*r which have occurred in the Main ) Feedwater Lines and Steam Generators of Westinghouse Type FWRs and Associated Damage Severity Levels Main Feedwater Lines Steam Generators 1 i i No. of Damage No. of Damage ^ Mechanism Occurrences Severity Levels Occurrences Severity Invels 1 0 0 2 4 2,4,2,2 24 2,2,2,1,4,2,2,3,4, f 2,4,4,2,2,4,3,4,4, 4,4,3,2,3,3 i 3 0 0 l 4 4 2,3,2,4, O l 5 1 4 0 6 2 3, 4 0 7 2 1, 2 0 8 4 3,3,3,2 0 l C 9 3,3,2,4,4,2,2,2,2 0 l 1 i l 1 i i i l i l d i
l; Feedwater Line Water Hammer PROJECT Mitigation Features New Emphasized Old Continuous rising feedwater line x Feedwater control valve with stacked disk x trim Separated feedwater and stanup feedwater x Wide control rangeability allows slow x restart Controlled closure feedwater check valve x SG Water Hammer Mitigation Features New Emphasized Old J Tubes / spray tubes x Shon horizontal piping to SG feed nozzle x Welded joint between feedring and nozzle x
- hwn,
i Steam Generator Water Hammer (Mechanism 2) i 1 4 i Top discharge through spray tubes (similar to J-tubes) that reduces possibility of void formation when steam generator level drops below the feedring level. i Higher temperature startup feedwater (auxiliary feedwater in other plants) which is supplied from the deaerators storage tank at a j temperature of approximately 250 F. For both the steam generators, the horizontal feedwater piping at the l steam generator inlet nozzle is an elbow sloping downward at an l angle of 45 with the horizontal. This very short length of horizontal piping helps in the prevention of steam generator water hammer. The feedwater piping is sloped up to the steam generator nozzle allowing self venting of any vapor to the steam generator. This prevents vapor accumulation in these lines. Limit the cold auxiliary feedwater flow rate below a threshold flow i rate of 150 gpm. This is based on the 200 gpm upper limit i experimentally determined in the steam generator water hammer tests at the Indian Point Unit 2 Plant. However, it may be undesirable in some plant transients to limit this flow to less than 150 gpm. Therefore, this limit has not been commonly used in the past. t i 4 i 2099strWlut
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c. 1 Feedwater Control Valve Stability Variable speed main feedpump Stacked disc trim to provide range of feed control Greater steam generator water level stability i l M
ITEMS CONSIDERED FOR SUSCEPTIBILITY TO WATER HAMMER r 1 Steam Generator (Mechanism 2) 1 Feedwater Control Valve (Mechanism 6) ] Feedwater Isolation Valve (Mechanism 6) i Feedwater Check Valve (Mechanism 6) System Start-up (Mechanism 4) Normal System (Mechanism 3) System Shutdown (Mechanism 2 & 6) Main Feedpumps (Mechanism 6) i Loss of: Offsite Power (Mechanism 6) Turbine Trip (Mechanism 6) Turbine Trip w/ Check Vol. (Mechanism 6) Switch to Condensate Storage Tank (Mechanism 6) 1 Feedwater Line Depressurization (Mechanism 2) d n I 4 s
1 i i i t l I The following quote is directly from GDC-4: I I' The term " extremely low" is used in this amendment to GDC-4 with reference to the probability of fluid system pipe rupture. For reactor coolant loop piping, a representative value which would qualify as i " extremely low" would be of the order of lx10 per reactor year when all 4 rupture locations are considered in the fluid system piping or portions thereof. For other piping, representative values will be developed consistent with this definition as the need arises. Alternatively, a ] deterministic evaluation with verified design and fabrication in addition to adequate inservice inspection, can meet the extremely low probability criterion. The deterministic evaluation is based on the requirement that structures and components are correctly engineered to meet the applicable regulations and NRC-endorsed industry codes. j 1 4 1 } 4 tmwas
i It is judged that the design portion of the alternative deterministic i evaluation of GDC-4 has been met. Thus an " extremely low" probability of water hammer occurring in the main feedwater line and steam generators of the AP600 which impact in any significant way the main j feedwater line inside containment is claimed. .N
-. ~.. - -... -..... - ~.. - -.... - _... -..-. - -- gt t i 6 9
e 1 i 1 i l 1 l t i i j Biasing Factors Based on Damage Severity Levels l Damage Severity Level Biasing Factor l
- 1. Pressure Boundary Leakage 1
4 M l
- 2. Damage to Components, 102 Flang,e or Instrument Tube i
Leakage
- 3. Snubber or Support Damage 104
~ l
- 4. No Physical Damage 104 4
i h i i i 1 j i 1
I 1 Table 6.2-1 Mechanistic Probability of Water Hasanner Occurring in the Main Peedwater umas ei the Arte0 (Note: Discussions of the applicability of the various anschanisms to the AP600 are found la Sections 5.2 and $.e b Named Medasestic Damage 6a 6m i Oenusence in Can it PseheMiley Osmaps Sevesley FisheMitsy Meshamiens Beisf WeaW No, of Oerne per FW/ Sevestoy 14eet porpW/ Number Desssiption TypeFWRa Osnweeness in APess Why SG Year tavel BW SC year l Sidscooled wease with No 0 No Has not ocnarred in it' N/A' N/A N/A W __ f _- - g.; PWR. condmuseg senem in a verucal pipe (Weenr Cannsa) i 2 Sesem and water Yes 4 No Only honaonaal pipes ase e it' N/A N/A N/A counearnow m a twhine W with hade hereennemi pipe sw no attact en ennen (Sesem/Waest 8::av sane mande Commeereew) contamment. j 3 Psessunand waest No 0 No Has not occurred in It' N/A N/A N/A f entenng a verocal Wesunghouse-eype PWRs. sesem-Alied pape (Sesam Podet ] Collapee) I 4 Hoe was:r entertng a Yes 4 No Stastup feedwater lane and it' N/A N/A N/A low poussure bne slow opening valve mitigate (IAte h thts event. Dediarge) S ^ ' wasst Yes i No The apt 00 does not have it' N/A N/A N/A r, slug (Water sag) suds a design. See Section 5.4. d 6 Rapid valve actuation Yes 2 Yes A valve could actuaUy fad 74 a10* 4 10* 7A a 10* J (Valve Slas) structurauy, one such event occurred. 7 Pdleng of a voeded lane Yes 2 No No elevated components, 10' N/A N/A N/A (Column Rapenmg) no relatsvely low system 4 pm -- See Secnon 5 4 e other on unkmassa Ya 4 Has not Amumed to occur, the 2 6 a 10' 3.3.3.2 33 a10-8 84 a10* toen so occurrences are most laely idenulmed Mechansms 6's and 4's C Cavnsmen/Yahe Yes 9 No Vanable apsed ' it' N/A N/A N/A l 4 and SC water level omnesol Insesheimy assagsee this evuet. 33 a It8 84 a le* MA1.
- Me bus as prereesd, that h $se eiere than one event the blaming doctors ist the eyeses ase sunneesd and divsied by the pusnhor of evose6
' Nas appiscsNe l
Mechanism 8: Other or unknown This classification includes events reported with insufficient information available for classification as to one of the seven mechanisms described above, or those due to less severe classical water hammer. For the AP600 loads due to this mechanism are enveloped by calculated loads of applicable mechanisms. t 2099et:We
~ Judgement by Two Experts: "If the primary mechanism cannot be an 8, then what is your best estimate of c ~ what it is based on information available" Criticality Plant Event Operational Initial Postulated Damage to Piping Damage Corrective Date Date Mode Indications Primary Components / lxvel Action Taken Mechanisms Equipment 1967 San 5/15/80 Refueling Damage / 3, 6 Suppons damaged 3 Repairs Onfre 1 outage inspection 693 Turkey 6/1109 0% power Damage / 3, 2 Snubber-damaged 3 Snubber size Point 4 inspection increased 10/82 V.C. 12/5/83 Prewarming Support 3,2,6 Suppons damaged 3 Prewarming Summer FW, startup damage valve lineup modified 4/84 Diablo 12/23/86 Stanup Valve 5 Valve plug and 2 Stem and Canyon 1 inoperable stem assembly plug replaced aw.awa
l e 4 7 4 i l 7. Probability of Pipe Rupture in the AP600 Feedwater Lines l i e i 0 e / d w
ji;' ,1 i i i ~ n o it au lavE eru tpu R ep iP c i ts i l i b a bo r P 1 i 1
as i 1 1 1 l 4 I i l i a i I I i t l I f I I l l i l 1 \\ 1 E t y t 4 i l I 1 3 i i i i ) i e I i 1 l l 1I..-.-...-...-,-........-......-...---.---.---
? Summary of Main Feedweser Desire Transione6 Plaot Opereelag Number of i New Desip Transiemie Condie6en ewh osenesenses t l 1 Urut Loadeg Beeween Zeen and IS% of Fd Power PC 1 Normal 500 j 2 Crut Unioedeg Bosween Zero and 15% of Full PC 1 Norrnal R10 Power 3a Urut Loadeg se 5% of Full Power /%nues (50100%) PC 1 Normal 19.300 3h Urue Loades at 7% of Fd Peaver/Mewee (15100%) PC-1 Normal 500 t j 4e Unst Unlanding at 5% of Fd Power / Minute PC-1 Nonnel 19,300 t (50 100 %) 4b Unse Unisadog at 3% of Full Power /Minues PC-1 Norsnel 500 j j (15 100 %) i S Soup tand Increase of 10% of Full Power PC 1 Norsnel 3000 1 6 Semp tard Dunesse of 10% of Full Power PC 1 Normal 3000 7 Large 5 esp land Decrease Wrsh Sesam Dwnp PC 1 Nonnel 300 O Case Lafesune Emeansson PC 1 Nesmal 40 - 9 Pendweest Hessen Out of Servise PC-1 Nesmal 100 i 1 i 10 Secondary tankap Test PC 1 Normal 80 t i 11 Less of land PC4 Upest 30 { 12 taas of Power PC4 Upest 30 1 i 13 Reecear Tnp From Reduced Power PC 2 Upest 100 e 14 Renner Trop From Fd Power PC4 Upest 13 i i l 4 15 Case A - Rearter Tny Wish No inadverumw PC 2 Upsse 50 Canidown a i i le Case 8 - Renner Tnp Wish Casidown and No PC4 Upast 50 l
- "; i Astusosa 17 Case C - Reener Trop Wish Cooldown and PC4 Upest 30 1
Safeguaeds Asmaamen i j 18 Caneet Red Deep Case A "C4 Upsme 30 i if 19 CanenA Red Deep Case 5 PC4 Upset u I ) 30 Ceneral Red Deep. Case C PC 2 Usest 30 } 21 Inadverwie Sadeguards Assuansa PC4 Upest 10 t ~~-- g f.1 Parcel Less of RC Plow PC 3 Upeus 40 3 l 23 Inadve tone ACS E;.- PC 3 U ost 15 P 34 Caso n. Umbeella Case PC 3 Upset 15 j 33 Case O. Inadvenene Pnesunser Sysey PC4 Upset 15 36 Esemaswo Pendwaam Pleur PC4 Upast 3D = ar seen tans of Connant Amadent PC4 E m m y nny s a seen sena. Line smak PC4 ameegner s 29 smed Feedweest Line Amak PC4 EmmynsF S 30 Semesn Genweest Tidae Rupeuse PC4 Emergaar S 31 Inadvenant Ausdiary Spesy PC4 Emergosr S 3: Renas,Casient Pipe e eak(L y toCA: PC-s Possue t a tasy smam Line sunk PC4 Pommes
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l 1 i = l i .o ~ } x._ , l= \\ 1 1-i m 4 I e m = = .m
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Reactor Trip w/Cooldown & No Safeguards Actuation j d W kl% en f I. I tas i l \\ Ise e se se m = = m a m w. Reactor Trip w/Cooldown & No Safeguards Actuation
,_-,_m-.__ a --- -, - - -4 -mw.mam-*-wi=m .m m..ar m 4m m _.m -celi.,g. AAm " -= h__A ( O 90 i l e d 4 s I t t t l 4 1 i i k I 4 s 4 'I 4 f e i I a l, i a 4 e= * ' - - w .,%_,7,
i AP600 SGS-020 $sa massoNsa sPGCTRA.X l 1 4 i !) 's t N / x. es' / t i AP600 SGS-020 sSa asSPONSa SPECTRA. Y I t ime IJ d' ( l .i 1 Vi ( y w .s 'e! t i i = AP600 SGS-020 Sea amp 0000 SPECTRA E IJ -' i l t ..m I i'/\\ i y I I es ( e El i G W M d hponse Spectra Frequency (Hs) vs. Acederation yd P
l t " " *
- 888a sist ou t seen a,e,,,,,,3,
v. .. m,w. u. 4 ?' I i l-4 i ' q_ a n u.. ,y-1 Main Feed Isolation Valve Closure Peak Force Location 5 sules rg ita m a ag C NOC$$ $$sg 33]E y g g,gggg gggy,gggg ggg gggg I Y Y d s" aosat iso E f' TI'M',$'" 8'if # l J L J a 1 1 ? i i,. I I,.. 1 1 e ?* a. a.m e secea Bubble Collapse Peak Force I.acation 5 f
'e APso0 rCCDLINC BREAK /CV CLOSURE LOOP O 1005 P0eCR 10ms 007 PIPC SCGWCNT 1
- ses i
e e se6... esses !!000 - 19999 see. O l 3...e l w lett ln "*9 *F9} N1}} Ll L LLlaLD( i 3848 0 89 4 1 6 3 33 Time (sec) Feed Line BrealdCheck Valve Oosure t wh 1 AP600 FEEDLINE BREAK /CV CLOSURE LOOP O 1005 POWER 10ms 80T PlPE SEGMEhT 2 vvatut 3 e e cetsum sages 50000 40000 a lette a sneen U a w issee ln Fqpp
- *F M
n g i.w iw LL iU LU D 19008 i.s' s e.s 2.s Time (sec) Feed Line Broek/ Check Valve coeure Escation 2
Maximum Internal Pressure on the Main Feedwater Line for the Three Water Hammer Events t Events P(initial). psia P(max). osia Check valve closure following 900 1200 4 Usi h0?w U'N ~ a feedline break (g, -(C ni h,'t h ' I J p [Corf \\ Isolation valve closure 900 1150 Vapor pocket / bubble collapse 14.7 200 2m.sw. ..m m.m . m.
ASME Class 2/ Class 3 Strees Evaluation Loading Cominnanoa Node ASME Seems Stress Code Ratio (Condition #) Equation Actual Limit (Equation) l P + DW + CK VLV 2004 9F M000 3375n 0.aiotio g e, r, l (330) (Smauer of 2.255h.1.s e t 2020 27136 5y) o aios P + DW + BUBBLE 2004 9F 24325 33750 0.721 (331) ($mauer of 2.255h. l.s { Sy) P + DW + CTRL VLV 2004 90 22463 27000 0.666 (332) (5mauer of 1.85k. l.5 i l Sy) l P + DW + SSE 2004 9F 30450 43000 04778 p,b. =? 41 4 .ame + .] latemie
- ione.
I..i nc = w N + A-g E "? .? =t "? "? =+ 3..;.. g..3...g....g...g...g...g...g...g...; Late P PE Distan;(se.) Comparison of the Two Dimensional Finite Element Model with the Design Configuration Demonstrating Strees Attenuation Along the tength of the Pipe
4 l l AP600 FEEDWATER NOZZLE SECTION 1 AXIAL S 50 s...g. 4"'* a. 4 40 ,, " A.. " a.. i 4, "- A ey y ..,,,,, a....... - ap O a o w go O O ..~ o i C O o O 0 1 10 0 O 0.2 0.4 0.6 THROUGH WALL THICKNESS (INCH) UNITLOADING WATERHAMMER Sd .. 6... o. Typical Through the wall sensees at the Nosale to 1Gbow WeW
-.ad#w .*4.e2m-heem.4-4+4. . 4 h e ss .m,er.Ap4------wig--- 6-. --'-wme-6=m.--.w-m=r-------s- -2._- 4 4 30 8 $j i i 4 i .d 1 l 9 s 1 I l l l d 1 i l l e d 0 1 1 i i i i d i i 1 J ( l. 1 (. i 4i 5 d I. _w
Sumanary of Main Feedweest Design Transients Plas# Orwenng Numanof NS Deep Tranenent Condeslen Condamene C;_.. 1 Crut loades Senreen Zero and 15% of Full Power PC l Normal 500 2 L' rut Unioedeg Senvan Zero and 15% of Futt PC 1 Norena 400 Power la L*rus Loades et 5% of Full Power /Wune s100%) PC 1 Normat 19 300 36 L* rue Loades at 5% of Fd PowerrWues t15-100%) PC 1 Normal 300 l I Unst Unionding at 5% of Pd Power /Manuse PC l Normal 19.300 li i t50100%) / 4h Urut Unlandeg at 5% of Pd Power /huse PC 1 Normal 500 1 (15 100 %) [' 5 Seep Lead facienee of 10% of Pd Power PC 1 Normal 3000 6 5 esp Load Decrease of 10% of Fd Power PC l Normal 3000 F tarse Seep Load Decrease With Seena Dwnp PC l Normal 200 8 Cove Liiusune Emeansaan PC 1 Normal 40 9 Feedweeme Heatore Out of 5senes PC 1 Normal too 10 $seendary Lenhage Test PC 1 Normal 30 f il Law of Lead PC 2 Upon 30 i 12 Less of Power PC 3 Upest 30 j 1 l 13 Reeceer Tny Prem liedused Power PC4 Upast 130 j 14 Reener Trip Pseen Pd Power PC 3 Upeut 130 I 15 Case A. Renner Tny Wish No inadeereen PC4 Upeut 50 Coeidswa 16 Case 8 - Renner Tety Widi Comidswa and No PC4 Upest 50 I " 'M Asneseen li 17 Case C - Renner Tsty Witt Cesidewn asA PC4 Upast 30 t Safeguards Anuamen 18 Censral Red Deep. Case A PC4 Upset 30 19 Ceneral Red Deep. Case O PC4 Upeut 30 20 Ceneral Red Does. Case C PC4 Usest 30 21 Inadvenant Sadaymards Asnaaman PC 2 Upast 10 22 Parmal Leme of RC Plow PC 3 Upest to 1 25 laadvenant RCS 4 -- r PC 3 Ilysse 15 34 Case A Umbr=Ee Case PC 3 Upon 15 35 Case 8. Inadvenant Proesunast sprey PC4 U ost 15 P as Ensumene Passweier Flow PC4 Upeut 30 27 Small Lams of Comient Aondent PC4 Emergency 5 t 30 $maa 5seen Lane treek PC4 Emergunsy 5 { 29 5 mall Poodweest Lane treek PC4 Emergency 5 30 5esam Genernese Tube Rupswo PC4 ?- 5
- r__,
31 Inadvenant Ateniliary Spesy PC4 E-_.,_., 5 l 32 Renner Coolare Pipe Greek (Large LOCA) PC4 Peeland I li I l
- s targe Se m Lane areek PC4 Poulsed 1
1 l
=
- i Table 7.4-1 Fatigue Crack Growth of Circumferential Cracka of Various Depths Crack Crack Depth (in.) after i
l Initial Depth to l Crack Thickness Depth (in) Ratio 10 Years 2C Years 30 Years 40 Years 50 Years 60 Years .050 0.066 .0500 .0501 .0502 .0502 .0502 .0503 .100 0.131 .1002 .1004 .1005 .1008 .1010 .1012 .150 0.199 .1503 .1507 .1510 .1514 .1517 .1521 .200 0.262 .2007 .2014 .2021 .2029 .2036 .2044 .300 0.393 3019 .3041 .3060 .3082 .3102 3124 .400 0.525 .4033 .4070 .4105 .4143 .4179 .4219 l .500 0.656 .5060 .5126 .5191 .5262 .5331 .5408 l .600 0.787 .6085 .6178 .6268 .6367 .6464 .6569 i Table 7.4-2 Fatigue Crack Growth of Longitudinal (Axial) Cracks of Various Depths summmmmmmmmmma Crack Crack Depth (in.) after Initial Depth to Crack Thickness l Depth (in) Ratio 10 Years 20 Years 30 Years 40 Years 50 Years 60 Years l l .050 0.066 .0500 .0501 .0501 .0502 .0502 .0503 .100 0.131 .1004 .1007 .1011 .1015 .1019 .1023 .150 0.197 .1512 .1524 .1535 .1545 .1555 .1564 .200 0.262 .2013 .2027 .2040 .2054 .2068 .2081 .300 0.393 3023 3045 .3068 .3092 3116 .3140 .400 0.525 .4036 .4071 .4107 .4144 .4182 .4220 0.656 .5054 .5107 .5161 .5217 .5275 .5332 .600 0.787 .6075 .6150 .6226 .6306 .6389 .6472
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e4 4 9 e esenuman ,y
- tam e
9 1 k 1 ) e,i.at, _ tes. ge l u g ) f l Peer %emusori ersenaeums
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- ames==res
= ) g P 1 8herasterigGee L E C'eskseus as a 18'k % i 3 Imeduserone 8'abately i I + ' r--- .-n A .h 3 ,m r e M l PEApea M 3 -_ I Imme tasknoe 4 L_ e I gElDulgdens 7 4M I g a = g -+ 1 4 4 e dcompo b d Analysis of ReHabluty W a Cive, weld g,e eg,, 4 k J 1 1 b i
1 ] Leadings Applied at intervals of Ten Years for which Probabilistic Evaluations Were Made Load Type' No. of Cycles Peak Stresses (ksif i Worst Case Water Hammer 4 21.042 Safe Shutdown Earthquake 10 16.717 4 3 Water Hammer (reflective wave)' 6 12.204 Small Earthquake 63 5.573 i j "These are ordered accordmg to the peak stresses values. j h stresses are superimposed on the existing stresses when the event is assumed to occur. 1 7he reflective wave of the worst case water hammer. j i j i 4 1 1 j Probability of Pipe Leakage and Pipe Rupture Given the Events Occur i j Probability of Leakage 4 Probability of Pipe I Leading 1 gym 3 gym Rupture J Based Failure Criteda Worst Case Water Hammer 3.0 x 17' 4.4 x 10* 5.8 x 10* Safe Shutdown Earthquake 2.9 x 10* 6.5 x 10' 7.8 x 17" Water Hammer (reflective wave) 7.2 x 10* 2.2x1@ 9.9 x 17" Small Earthquake 1.9xIP 8.2 x 17" 2.0 x 1&" Design Transients Only 4.0 x 1&" 2.2 x It" 5.7 x 1 7 " Plow Strees Failure Criteria Worst Case Water Hammer 3.2 x 10
- 23 x 17" 7.7x17" Safe Shutdown Earthquake 3.2 x 1&"
23 x 17" 1.9 x 1758 Water Hammer (reflective wave) 3.2 x 10 " 23 x 17" 9.8 x 17 " Small Earthquake 3.2x17" 23 x 17" 33 x 17" Design Transients Only 3.2 x It " 2.3 x IC" 2 5 x 17"
's l !b 1 J l J I i Probability of Leakage and Pipe Rupture for Water Hammer Occurrence in the Feedwater Line and Overall Feedwater Line Reliability j ummmmmmmm w i mammmmmmmmmmusammma Probability of Leakage { Loading Condition Probability of j Assumed to Occur 1 gym 3 gym Pipe Rupture One Combined Worst Case Water 3.1 x 10# i 4.6 x 10* 5.9 x 10* Hammer Five Combined Worst Case Water 1.5 x 104 2.3 x 10# 2.9 x 108 Hammer 4 4 Five Combir.e4 Worst Case Water 1.57 x 104 2.4 x 10# 3.0 x 10* Hammers, One SSE and Five SmEs l All Design Transients N O T 1 l O e
L of ) l I 8. Conclusions 4 I
l The conclusions applicable to the main feedwater lines of the AP600 are: The SA335 P11 material and associated weld are very tough. Considering the over three thousand years of service, the fifty water hammer events occumng in Westinghouse-type PWRs is a number to be concerned about but should not be unduly alarming. The steam generator water hammers are criticality dated; no steam generator water hammer has occurred in any plant becoming critical after 1975. "Isssons learned" in design fixes and operating procedures suggest steam generator water hammers should not occur in a new plant such as the AP600. Of the 54 Westinghouse type PWRs,3 out of 4 plants have not experienced a feedwater line water hammer,5 out of 6 have not expenenced a steam generator water hammer and 2 out of 3 have experienced neither a feedwater line water hammer nor a steam generator water hammer. In most cases, the damage caused by water hammer is limited to suppoit or snubber damage. No or minor damage is often reported. In only two cases has there been a breach of the pressure boundary by leakage through a crack. In a review of severe water hammer mechanism versus the AP600 design,it is concluded that all water hammers are precluded except possibly in the instance of a valve failure. A mechamstic probability of a water hammer occurring based on historical data l suggest for water hammers of known causes, the probability of occurrence is very small. For historical water hammers of unknown origin, the mechanistic probability is quite l low, the difficulty being in mitigating an unknown cause. A probabilistic pipe rupture evaluation showed the worst case water hammer to be dominant exhibiting a probability of pipe rupture of 5.9 x 10'should the event occur. The over plant probability of pipe rupture for the assumed occurrence of earthquakes (1 SSE,5 SmE) and water hammers (5 worst case water hammers) is 3.0 x 10. 8 1 i
~ PRIMARY CONCLUSION The occurrence of a water hammer in the main feedwater line and steam generator of the AP600 has a very low probability, (8.6x10'6) The probability of pipe rupture in the main feedwater lines of the AP600 is extremely low, (3x10"). l LBB can be applied to the main feedwater piping inside containment l l i 1 i l i 20w 6.w.a l {}}