ML20027E515
| ML20027E515 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 11/08/1982 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Linder F DAIRYLAND POWER COOPERATIVE |
| Shared Package | |
| ML20027E516 | List: |
| References | |
| TASK-03-05.A, TASK-RR LSO5-82-11-021, NUDOCS 8211150454 | |
| Download: ML20027E515 (16) | |
Text
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g November 8,1982 Docket No. 50-409 LS05-82-11-021 Nr. Frank Linder General Manager Dairyland Poser-Cooperative 2615 East Avenue South Lacrosse, Wisconsin 54601
Dear Mr. Linder:
SUBJECT:
SEP TOPIC III-5.A. EFFECTS OF PIPE BREAK ON STRUCTURES, SYSTEMS AND COMPONENTS INSIDE CONTAINMENT LACROSSE BOILING WATER REACTOR In your letter dated February 24,1982 (LAC-8113), you subinitted a safety assessment report on the above topic. We have completed our evaluation which is enclosed. We conclude that the plant is adequately protected from the dynamic effects of pipe break inside containment subject to resolution of the following in the Integrated Plant Safety Assessment.
1.
Clarification concerning the effects of jet impingement and pipe whip motion on mitigating systens.
2.
Confinnation that the portion of the steel vessel not protected by the 9" concrete rould not be damaged by any postulated high energy line l
breaks.
3.
Installation of a valve on decay heat cooling 3 system blowdown line to the main condenser and administrative controls to maintain it in a l
closed position during power operation.
Acceptability of damage to control rod drive mechanisms from postulated 4.
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Resolution of postulated breaks in boron injection system piping damag ing the containment ventilation exhaust damper operators.
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Justificationofthedesignadequacyofanchorholtsfortheexistingg,hgy 6.
pipe whip restraints in the Alternate Core Spray (ACS) lines.
8211150454 821108 PDR ADOCK 05000409 P
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suauwe) onep OFFICIAL RECORD COPY sceo. mi-u ao Nac roau m oo-m nacu om
I Mr. Frank Linder,
The need to actually implement changes as a result of these items will be detemined during the integrated safety assessment. This safety evaluation may be revised in the future if your facility design is c changed or if HRC critetta relating to this topic are modified before the integrated assessment is completed.
Sincerely, Gr.inniSi""'dD7' Dennis M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing
Enclosure:
As stated cc w/ enclosure:
See next page SEPB 4
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D6cket No. 50-409 LaCrasse Rtvis:d 8/82 Mr. Frank Linder CC Fritz Schubert, Esquire U. S. Environmental Protection Staff Attorney Agency Dairyland Power Cooperative Federal Activities Branch.
2615 East Avenue South Region V Office La Crosse, Wisconsin 54601 ATTN: Regional Radiation Representative 230 South Dearborn Street O. S. Heistand, Jr., Esquire Chicago, Illinois 60604' Morgan, Lewis & Bockius 1800 M Street, N. W.
James G. Keppler, Regional Administrator Washington, D. C.
20036 Nuclear Regulatory Commission, Region III 799 Roosevelt Road Mr. John Parkyn Glen Ellyn, Illinois 60137 La Crosse Boiling Water Reactor Dairyland Power Cooperative Mr. Ralph S. Decker P. O. Box 275 Route 4, Box 1900 Genoa, Wisconsin 54632 Cambridge, Maryland 21613 Mr. George R. Nygaard Charles Bechhoefer, Esq., Chairman Coulee Region Energy Coalition Atomic Safety and Licensing Board 2307 East Avenue U. S. Nuclear Regulatory Commission La Crosse, Wisconsin 54601 Washington, D. C.
20555 Dr. Lawrence R. Quarles Dr. George C. Anderson Kendal at Longwood, Apt. 51 Departnent of Oceanography Kenneth Square, Pennsylvania 19348 University of Washington Seattle, Washington 98195 U. S. Nuclear Regulatory Commission Reside *nt Inspectors Office Rural Route #1, Box 276 Genoa, Wisconsin 54632 Town Chairman Town of Genoa Route 1 Genoa, Wisconsin 54632 i
Chairman, Public Service' Commission l
of Wisconsin l
Hill Farms State Office Building l
Madison, Wisconsin 53702 9
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TABLE OF CONTENTS 1.
INTRODUCTION II. REVIEW CRITERIA III. RELATED SAFETY TOPICS AND INTERFACES IV. REVIEW GUIDELINES V.
EVALUATION A.
BACKGROUND B.
APPROACH AND CRITERIA C.
INTERACTION EVALUATION VI. CONCLUSION VII. REFERENCES 9
I a
SYSTEMATIC EVALUATION PROGRAM TOPIC III-5. A LACROSSE BOILING WATER REACTOR TOPIC:
III-5.A. Effects of Pipe Break on Structures, Systems and Components Inside Containment I.
INTRODUCTION The safety objective of Systematic Evaluation Program (SEF) Topic III-5.A, " Effects of Pipe Break on Structures, Systems and Components Inside Containment," is to assure that pipe breaks would not cause the loss of required functions of " safety-related" structures, systems and components and to assure that the plant can be safely shutdown in the event of such breaks. The required functions of " safety-related" systems are those functions required to mitigate the effects of the pipe break and safely shutdown the plant.
II.
REVIEW CRITERIA General Design Criterion 4 (Appendix A to 10 CFR 50) requires in' part' ~ '
~
that structures, systems and components 'important to safetyle a~ppro-priately protected against dynamic effects, such as pipe whip and discharging fluids, that may result from equipment failures.
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III. RELATED SAFETY TOPICS AND INTERFACES 1.
This review complements that of SEP Topic VII-3, " Systems Required for Safe Shutdown."
2.
The environmental effects of pressure, temperature, humidity, and flooding due to postulated pipe breaks are evaluated under USI A-24,
" Environmental Qualification of Safety-Related Equipment,"
3.
The effects of potential missiles generated by fluid system ruptures and rotating machinery are evaluated under SEP Topic III-4.C,
" Internally Generated Missiles."
4.
The effects of containment pressurization are evaluated under SEP Topic VI-2.D, " Mass and Energy Release for Possible Pipe Break Inside Containment."
5.
The original plant design criteria in the areas of seismic input, analysis, and design criteria are evaluated unde'r SEP Topic I11-6,
" Seismic Design Considerations."
6.
The effects of core cooling are evaluated under SEP Topic XV-19
" Loss of Coolant Accidents Resulting from Spectrum of Postulated Piping Breaks Within the Reactor Coolant Pressure Boundary."
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. IV.
REVIEW GUIDELINES The current criteria for review of pipe breaks inside containment are contained in Standard Review Plan 3.6.2, "Detennination of Break Locations and Dynamic Effects Associated with the Postulated Rupture of Piping," including its attached Branch Technical Position, Mechanical Engineering Branch 3-1 (BTP MEB 3-1).
The licensee's break location criteria and methods of analysis for evaluating postulated breaks in high energy pfping systems inside containment have been compared with the currently accepted review criteria as described in Section II above. The review relied upon infonnation submitted by the licensee, Dairyland Power Cooperative, in Reference 1.
The scope of review under this topic was limited to avoid duplication of effort since some aspects of the topic were previously reviewed by the staff or are included under other SEP topics (see III above).
When differences from the review criteria are identified, engineering judgement is utilized to evaluate the consequences of postulatcd pipe break and to assure that pipe break would not cause the loss of required
-function of " safety-related" structures, systems and components and to assure that the plant can be safely shutdown in the event of such break.
V.
EVALUATION A.
Background
On July 20, 1978, the SEP Branch sent a letter (Reference 2) to KMC, Inc. requesting an analysis of the effects of postulated pipe breaks on structures, systems and components inside containment.
In that letter, the staff included a position that stated three approaches were appropriate for postulating breaks in high energy piping systems (either P_>275 psig or T>200 F). The approaches are:
1.
Mechanistic 2.
Simplified Mechanistic 3.
Effects Oriented The staff further stated that combinations of the three approaches could be utilized if justified.
In response to our letter, the licensee submitted Reference ;
concerning postulated high energy pipe rupture inside containment.
. B.
APPROACH AND CRITERIA The licensee has utilized the effects-oriented approach in its high energy line break (HELB) study (Reference 1). Breaks were postu-lated at teminal ends and points of closest approach to components of essential equipment to detennine the effects of pipe whip or jet impingement. This method of approach has been approved for the SEP review of high energy pipe break analysis. The Itcensee has identified the following essential systems inside the containment:
1.
High Pressure Core Spray - both pumps and associated piping 2.
Alternate Core Spray - piping and check valves 3.
Boron Injection System - boric acid storage tank and associated piping 4.
Manual Depressurization System - valves, piping and the shutdown condenser 5.
Control Rod Drive Hydraulic Scram Accumulators 6.
Essential Instrumentation - reactor vessel water level and reactor vessel. pressure The licensee has classified high energy fluid systems as those that are maintained under conditions where either or both the maximum operating temperature and pressure exceed 200'F and 275 psig. This is consistent with current MEB criteria. Using this criteria, the licensee has identified systems inside containment that meet the criteria for high energy for at least part of the piping as follows:
1.
forced circulation 2.
main steam 3.
feedwater 4.
alternate core spray 5.
seal injection system 7.
control rod drive hydraulic system 8.
control rod drive effluent system 9.
shutdown condenser
- 10. boron injection
- 11. decay heat 12.
purification Based on a review of Reference 1 and further discussion with the licensee, we have determined that the licensee has not adequately addressed the effects of jet impingement and pipe whip motion on the other piping l
systems.
In addition, in determining the damage criteria for target i
piping, the licensee has utilized the assumption'that the effect of pipe l
whip and jet impingement will only damage smaller diameter piping. The staff concurs the effects of pipe whip will not damage equal diameter or larger piping with equal or greater wall thickness.
However, in accordance I
with staff positions transmitted on January 4,1980 (Reference 3), the effects of jet impingement should be considered and evaluated regardless of the ratio of impinged and postulated broken pipe sizes.
In a discussion with the licensee, the licensee stated that the effects of jet impingement from the broken ACS line directly on the HPCS line is the most limiting case.from the standpoint of energy level of fluid issuing from the broken
4 pipe, the extreme proximity of the two lines, and the potential for adverse consequences if both the ACS and HPCS are affected.
However, the HPCS line was demonstrated not to be damaged by this particular break location. The licensee should verify that there are no other high energy lines or break locations which could damage both the HPCS and the ACS lines considering the damage criteria discussed above.
C.
INTERACTION EVALUATIONS Using the effects-oriented approach, the licensee evaluated the effects of the postulated pipe breaks on a system by system basis. Each system has been analyzed for the effect that postulated pipe breaks would have on the ability to safely shutdown shut the plant down or to stay shut-down. The results of potential interactions for each postulated pipe break were sunnarized in Table 2 of Reference 1.
It is noted that the only targets addressed in Table 2 by the licensee were safety-related equipment. A discussion with the licensee.concerning the additional targets such as the containment wall, the biological shield, etc., re-vealed that the largest and the most energetic high energy fluid system line inside containment that could conceivably impact the containment wall and the biological shield following pipe rupture is the 10"/8" main steam line to the shutdown condenser. The licensee stated that the inside surface of the 1.16" thick steel containment ~ vessel is protected by 9" of concrete and the damage to the containment boundary by main steam pipe whip should not be of concern. The staff agrees with the licenseets conclusion. However, the licensee should confirm that the portion of the steel vessel not protected by the 9"' concrete would not be damaged by any postulated ~high energy line-breaks.
Break locations in the main steam and decay heat cooling piping were identified that could affect a containment isolation valve.
This valve is on the 2"' blowdown line from the decay heat cooling system to the main condenser. The licensee stated in Reference 1 that a manual valve will be installed in the turbine building reheater area which will be closed by procedure following a high energy line break.
The staff considers that installation of a manual valve will resolve this interaction provided the valve is administratively maintained in a closed position during power operation. This will minimize the possibility of the blowdown line to the condenser as a release path following a postulated rupture of the reactor coolant pressure boundary.
In Table 2 of Reference 1, the licensee indicated that no safety-related equipment could be affected by the postulated breaks in the Alternate Core Spray (ACS) lines because the lines were restrained. Further dis-cussion with the licensee concerning the design of the restraints and cursory review of Reference 4 revealed that the allowable maximum pull out and shear loads, the load combination and the effect of base plate flexibiltty for the assessment of anchor bolts do not meet current criteria. The licensee ts requested to justify the design adequacy of anchor bolts for the existing pipe whip restraints.
Breaks in boron injection system (BIS) piping could affect safety-related equipment. The licensee has noted that this piping is included in the inservice inspection program for Class 1 sysrtems (ASME Section XIl and that the welds have been examined in accordance with the augmented ISI program.
4.
One of the postulated breaks in BIS could damage the containment ventilation exhaust damper operators.
Failure to close of the damper would result in a loss of containment integrity following the loss of coolant accident. The licensee should do one of the following:
1.
Demonstrate that the consequences of this scenario are acceptable, 2.
Provide protection for the operators; or 3.
Use the attached staff guidance to demonstrate that the postulated rupture will not occur.
Another postulated break in the BIS could damage the reactor waMr level instrumentation. A postulated break in the purification system sould have a similar effect. These breaks constitute below-core LOCA's.
For these breaks, inventory loss from the primary system will continue until the vessel water level equalizes with the containment level.
Damage to the water level instrumentation would result in a low level reading which would cause the ECCS to come on automatically. 'With a
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low level indication, the operator would not terminate ECCS. Containment water level instruments could then be used.
Therefore, the staff concludes that damage to the reactor vessel water level instrumentation will not prevent reaching a safe shutdown condition.
A break in the high pressure core spray system could result in loss of the transmitters for both rea,ctor safety channels of reactor pressure.
These channels would not be needed to perform their high pressure scram function, and a physically separated transmitter would be available for monitoring.
Three break locations (seal injection, main steam and control rod effluent) were identified that could cause damage to control rod drive (CRD) mechanisms.
Damage could result in partial failure to insert control rods.
The boron injectiun system has been designed with sufficient capacity to place the core in a shutdown condition with all control rods removed.
Operator action would be required to realign the system from its high pressure core spray mode (following the pipe break) to the boron injection mode. Acceptability of impairment of the CRD mechanisms will be addressed in the Integrated Plant Safety Assessment.
. VI.
CONCLUSION Based on the information submitted by the lice' 1e, we have reviewed the criteria pertaining to the locations, types, as effect of postulated pipe breaks in high energy piping systems inside containment. We have concluded that the criteria used to define the break locations, and types are in accordance with currently accepted standards. We have also detennined that it is acceptable under current SEP criteria to use the interaction study to evaluate the effects of postulated pipe breaks and to detennine the acceptability of plant response to pipe breaks.
However, we have found that the following aspects should be considered for the Integrated Assessment:
1.
Clarification concerning the effects of jet imp'ingement and pipe whip motion on mitigating systems.
2.
Confinnation that the portion of the steel vessel not protected by the 9" concrete would not be damaged by any postulated high energy line breaks.
3.
Installation of a valve on decay heat cooling system blowdown lines to the main condenser, and administrative controls to maintain it in a closed position during power operation.
4.
Acceptability of damage to control rod drive mechanisms from postulated high energy line breaks.'
5.
Resolution of postulated breaks in boron injection system piping damaging the containment ventilation exhaust damper operators.
6.
Justification of the design adequacy of anchor bolts for the existing pipe whip restraints in the Alternate Core Spray lines.
VII.
REFERENCES 1.
Report, "SEP TOPIC III-5.A, EFFECTS OF PIPE BREAK ON STRUCTURES, SYSTEMS AND COMPONENTS INSIDE CONTAINMENT - LACROSSE BOILING WATER REACTOR," Dairyland Power Cooperative (DPC), dated February 24, 1982.
2.
Letter, D. Davis (NRC) to J. McEwen (KMC, Inc.), " ASSESSMENT OF-POSTULATED PIPE BREAKS INSIDE CONTAINMENT FOR SEP PLANTS," dated July 20,1978.
3.
Letter, D. Ziemann (NRC) to F. Linder (DPC), " EVALUATION OF PIPE WHIP IMPACT AND JET IMPINGEMENT EFFECTS OF POSTULATED PIPE BREAKS FOR SEP TOPICS III-5.A AND III-5.B," dated January 4, 1980.
4.
Letter, J.P. Madgett (DPC), to Director of NRR (NRC), Enclosure TR-14, dated July 21, 1976.
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GUIDANCE FOR RESOLUTION OF HIGH -
1
~ ENERGY PIPE BREAK LOCAT10N5 WHERE REMEDIAL MODIFICATIONS ARE IMPRACTICAL From the results of reviews conducted to date, the staff has concluded that the relocation of equipment or other modifications to mitigate the consequences of some postulated pipe breaks may be impractical due to physical plant configura-tions or other considerations. Therefore, the staff has determined that for specific locations where relocation of equipment or other modifications to mitigate consequences of pipe breaks are shewn to be impractical. fracture mechanics evaluation of the piping should be performed to determine if unstable ruptures could occur in piping that contained service induced large undetected flaws.
The intent of the guidance provided by the staff is to provide reasonable assurance that the mitigation of pipe breaks are addressed. The approach taken is to provide assessment that condition which could lead to a double ended pipe rupture do not exist thereby making it unecessary for high energy pipe break considerations to mitigate effects of a guillotine rupture. Tyis would be accomplished using a defense in depth approach that is a combination of augmented inservice inspection (ISI), local leak detection and fracture mech-Augmented inservice inspections would be performedpith the anics evaluations.
goal of detecting and limiting any service induced flaws to limits prescribed Should the flaws by the ASME B&PY Code.Section XI, approximately 10'. thru wall.
go undetected, a local leak detection system would be provided with the requisite sensitivity to identify leakage from a through crack, either longitudinal or circumferential, of a length of twice the wall thickness for minimum flow rates associated with normal (Level A) operating conditions. Fracture mechanics evaluations would be performed to determine that for a circumferential or longitudinal through crack of four wall thickness subjected to maximum ASME design code loads (Level D) that:
(1) substantial crack growth does not occur'.
(2) local or general plastic collapse (instability) does not occur.
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(3) flow through the crack or the effects of a jet from the crack does not impair safe system shutdown.
To provide assurance that a double ended rupture could not occur by unantici-pated loads being applied to a large undetected crack, a fracture mechanics evaluation would be performed to demgnstrate that a through crack of a length total circumferential length, or a ' larger of four times the wall thickness 90 crack if justified for system service experie.nce would remain stable for local e
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fully plastic large deformation bending conditions. The basis for performance of this more conservative fracture mechanics evaluation to assure a double ended pipe rupture would not occur is as follows:
(1 ) operating experience has shown that unanticipated and undefined loads in access of design can and do occur in piping systems, i.e.. water hamer events have failed piping system supports.
(2) uncertainty in:
(a) current analysis methods to accurately predict piping loads analysis and (b) prediction of the energy and frequency content of earthquakes and their effect on piping loads.
(3) SEP criteria for evaluation of structures and system resistance to postulated earthquake loads depend on global structural ductility.
This assumption is based on the ability to have load redistributions occur. For unflawed piping. the necessary local ductility is cer-tainly provided. However, for flawed sections of piping the. ability to sustain fully plastic behavior without crack instability is required to assure pmdently that local ductility is preserved.
.-r The details of the guidance for the combined augmented ISI. leak detection and fracture mechanics evaluations are appended as Appendix 1.
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Appendix 1 -
ALTERNATIVE SAFETY ASSESSMENT FOR S LECTED HIGH ENERGY P1FL BRLAK LUGA110N5 AT SEP FACILITIE5 This assessment is required only if a LWR high energy piping system (i.e..
275 psi or higher; or 200 F or higher etc.) is being considered. It is only required, if a postulated double ended pipe break would impair safe system shutdown hy pipe whip (lacking pipe whip constraints) consequences, or hy the consequences of the implied leakage or its jet action. The following guidance is for a safety aLsessment that may be permitted as an alternative to other system modifications or alterations for locations where the mitiga-tion of the consequences of high energy pipe break (or leakage) have been shown to be impractical.
Guidance for Alternate Safety Assessment The suggested guidance are as follows:
A.
Detectability Recuirements
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Provide a leak detection system to detect through-cracks of a length of twice the wall thickness for minimum flow rates associated with norzal (Level A) ASME B&PV Code sperating condition.
Both circumferentilil anh '
longitudinal cracks must be considered for all critical break 'or leak.__ __:-_-
locations. Methods for estimation of crack opening areas are attached in Appendix 2. Surface roughness of the crack should be considered.
B.
Integrity Recuirements (1) Loads for Which Level D is Specified (a) Show that circumferential or longitudinal through-cracks of four wall thicknesses in length sub'jected to maximum Level D loading conditions do not exhibit substantial monotonic load-7c y plastic L
ing crack growth (e.g., staying below Jyp b
or K zone corrected lineap7 elastic fracture Mchanics methods or a suitable alternative-'.
Also assure that local or general plastic instability does not occur for these loading conditions and crack sizes.
1/For 4t flaws that are calculated to be greater than X rJ sideration will be given to; (1) flaw growth argumentkC (2);ho. con-stulation of small flaws sizes than 4t if justified by leak detection sensitivity.
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a (5) Under conditions in "B.(1)" show that the flow through the crack and the action of the jet through the crack will not impair safe shutdown of the system.
Acceptable methodology for the estimation of crack opening area for a circumferential through crack in a pipe in tension cnd bending and for longitudina.1 cracks subject to internal pressure are attached.
(2) Extreme Conditions to Preclude a Double-Ended Pipe Break Using elastic-plastic fracture-mechanics or suitable alternative show that circumferential through-cracks will remain stable for local fully plastic large-deformation bending conditions under the following addi-tional conditions:
(a) Fully plastic bending of the cracked section is to be assumed, unless other load limiting local conditions (such as elbow collapse) dictate maximum bending loads, for all critical locations.
(b) Assume all system anchors are effective. To simplify-the analysis, supports may conservatively be considered inoperative.
If supports are included, consideration should be given to the adequacy of the support to resist large loads.
,,7 (c) Other as built displacement limits or constr'aints"may be assumed
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as especially justified (such as displacement limits of a pipe running through a hole in a sufficiently strong concrete wall or floor, etc.).
o (d) Assume a through-crack size of 4t or 90 total circumferential length whichever is greater; or a larger crack Enly if especially
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I (e) Assume large deformations means de' formations proceeding to as built displacement limits or other especially justified limits.
(3) Material Properties
' Conservative material properties should be used in the analyses.
Sufficient justification must be provided for the properties, both weldment and base metal, used in the analyses.
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C.
Suberitical Crack Development Consideration should be given to the types of subcritical cracks which may be developed at all locations associated with this type of analysis.
From prior experience ano. r direct analysis it should be shown that:
(1) there is a positive tendency to develop through-wall cracks.
(2) if there is a tendency to develop long surface cracks in addition to through-wall cracks, then it should be further demonstrated that the long surface crack will remain sufficiently shallow.
D.
Augmented Inservice Inspection Piping system locations for which corrective measures are not practicable should be inspected volumetrically in accordance with ASME Code,Section XI for a Class 1 system regardless of actual system classification.
Acknowledgement Assistance in developing this guidance have been provided by Dr. Paul C.-Paris.
Del Research Corporation (and Washington' University, St. Louis, MO) under sub-contract X-8195 in support of technical assistance provided by Idaho National Engineering Laboratory. Idaho Falls, Idaho (FIN A-6456).
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