ML19305C752
| ML19305C752 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 03/07/1980 |
| From: | Hannon J Office of Nuclear Reactor Regulation |
| To: | Ippolito T Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8004080113 | |
| Download: ML19305C752 (16) | |
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UNITED STATES
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1980 Docket No. 50-293 MEMORANDUM FOR:
T. A. Ippolito, Chief, Operating Reactors Branch #3, D0R FROM:
J. N. Hannon, Project Manager, Operating Reactors Branch #3, D0R
SUBJECT:
MEETING
SUMMARY
A meeting was held with representatives from BECo (the licensee) and GE in Bethesda, Maryland on February 29, 1980. The purpose of the meeting was to discuss the recently discovered Pilgrim Core Spray Sparger cracks, associated a.lalysis, and plans for resuming power operation at the Pilgrim Station after the current refueling outage. A list of meeting attendees, agenda, and slides used during the' presentation are enclosed.
The preliminary conclusion of GE and BECc, is that the observed cracks are most probably caused by intergrannular stress corrosion. GE/BECo believe that the cracks could affect the sparger flow distribution, but that structural integrity should be maintained such that water delivery would not be compro-mised. Therefore, BECo is planning to operate the next cycle with no credit being taken for the core spray distribution (i.e., core spray heat transfer),
only for core spray reflood. This will require a revised ECCS analysis, which has been initiated.
It is anticipated that the ECCS analysis, with no credit for core spray heat transfer, may result in a MAPLHGR limit reduction.
BEco stated that concerns in the following areas motivated their decision to preceed with the ECCS reanalysis, rather than some other course of action:
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Outage Economics (procurement, lead times)
Available Technology for Sparger Replacement (hardware, tools, etc.)
Radiation Exposure The staff stated that if the ECCS reanalysis course is pursued, the reanalysis sF ild reflect the current plant status, and address other phenomena that may c:.;ge as a result of the loss of core spray heat transfer.
In addition, the question of fragmentation needs to be developed further, with particular emphasis on the potential for flow blockage, nozzle breakage, and loose parts monitoring during reactor operation.
The meeting was concluded with BECo proposing another meeting in March to discuss further details as they an developed. The current outage schedule was not firm, although the return to power operation for Pilgrim Station is expected to be delayed.
J. N. Hannon, project Manager Operating Reactors Brinch #3 Division of Operatino Reactors 01 N Enclo v ;
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pMEIq UNITED STATES
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WASHINGTON, D. C. 20555
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Mr. G. Carl Andognini l
Boston Edison Ccmpany M/C NUCLEAR 800 Boylston Street Boston, MA 02199 i
Mr. Paul J. McGuire Pilgrim Station Acting Manager Doston Edison Company i
i RFD #1, Rocky Hill Road Plymouth, Massachusetts 02360 l
Anthony Z. Roisman Natural Resources Defense Council 91715th Street, N. W. ~
l Washington, D. C.
20005 Henr;> Herrmann, Esquire Massachusetts Wildlife Federation 151 Tremont Street Boston, Massachusetts 02111 Plymouth Public Library North Street Plymouth, Massachusetts 02360
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Docket File V. Noonan NRC POR G. Knighton Local PDR D. Ziemann ORB!3 Rdg P. Check NRR Rdg.
G. Lainas H. Denton D Crutchfield E. Case F. Pagano D. Eisenhut-R. Clark
- 8. Grimes OELD W. Gamill OI&E(3)
R. Yollmer S. Sheppard L. Shao Project Manacer J. Miller ACRS (16)
T. Ipoolite
- NRC Particicar.ts R. Reid kTMA7 A. Schwencer J. R. Euchanan
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MEETING WITH BOSTON EDISON COMPANY RE: C/S SPARGER February 29, 1980 NRC GE John Hannon, DOR /0RB#3 E H. Oates Bill Mills, IE/ROI J. P. Higgins Robert Aelmann, IE/R0I J. F. Kil ty S. D. Reyvolds, Region I, NRC R. G. Furgeson Phil Grant, DOR /EEB L. M. Zull George Knighton, DOR /EEB Robert E. Legate, Engineer C. P. Woodhead, NRC/0 ELD F. B. Lotton, DSS /SEPB JCP&L Co.
T. A. Ippolito, 00R/0RB#3 Jim Knubel K. P. Roberts, NRC Resident Inspector Pilgrim T. M. Crimmins, Jr.
D. 'V. Kehoe, NRC, Projsct Inspectoi
' grim-R. W. Klecker, NRC/ DOR /EB BOSTON EDISON H. Walker, NRC/ DOR /EB Jack Fulton H. F. Conrad, NRC/MTEB/ DSS G. Carl Andognini S. J. Norwicki, DOR /0RB#2
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BOSTON EDISON CO.
PILGRIM STATION CORE SPRAY AGENDA I.
INTRODUCTION JACK FULTON, BECO e
REASON FOR MEETING e
BECO ATTENDEES e
GE ATTENDEES II.
PILGRIM CORE SPRAY INSPECTION
SUMMARY
JACK FULTON III.
PILGRIM SPARGER B0B LEGATE, GE e
DESIGN & FABRICATION e
INSTALLATION HISTORY e
PERFORMANCE HISTORY IV.
POTENTIAL CAUSES OF CRACKS PAT HIGGINS, GE V.
PILGRIM SPARGER STRUCTURAL INTEGRITY WITH CRACKS B0B LEGATE, GE VI.
PILGRIM LOCA ANALYSIS LARRY ZULL, GE VII.
CONCLUSIONS CARL AND0GN.INI, BECO t
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CORE SPRAY SPARGER ELEVATtON VIEW SHROUD UPPER SPAR 6ER 3 gy 7 aum
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CORE SPRAY SPARGERS f
HEADER ARMS 3 1/2" SCH 40 - TYPE 304 STAINLESS STEEL T-B0X 5" SCH 40 - TYPE 304 STAltiLESS STEEL N0ZZLES 1" HALF COUPLINGS 2 EACH 1" 90 S.R. ELB0WS INTERNAL CLOSE NIPPLE /0RIFICE ALTERNATING N0ZZLE OPENINGS (1) OPEN ELB0W (2) 1HH12 90 N0ZZLES TOTAL N0ZZLES = 112 PER SPARGER FITTING MATERIALS ALL TYPE 304 STAINLESS STEEL
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L FABRICATION HISTORY ~
4 COLD FORMED BEND RADIUS 941/4 INCH (APPR0XIMATELY 2.1% STRAIN)
N0 SOLUTION HEAT TREAT COLD SPRUNG (ASSUMED)
TOTAL > 2.1% STRAIN 6
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SPARGER MOUNTING T-BOX WELDED TO UPPER SHROUD
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EACH ARM SUPPORTED BY 3 BRACKETS BRACKETS WELDED TO SHROUD SPARGER PIPE TO BRACKET CLEARANCE FOR DIFFERENTIAL-THERMAL EXPANSION O
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PERFORMANCE HISTORY FIRST CRITICAL - JUNE 72 NO INADVERTANT CORE SPRAY INJECTIONS PLANT NORMAL OPERAIION
, STRESSES NEGLIGABLE CONSIDERED IMPINGEMENT - FLOW PAST SPARGERS SEISMIC - RIDGID STRUCTURE
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INSTALLATION - RADIAL MISMATCH-PRESSURE THERMAL MISMATCH WEIGHT FLOW INDUCED VIBRATION CORE SPRAY MAINTENANCE FLOW DURING EACH REFUELING MAX A T = 130 F FOUND INDICATIONS ON-INNER BEND RADIUS FEB,180 1
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PILGRIM CORE SPRAY SPARGER CRACKIflG EVALUATION o
POSSIBLE CAUSES HIGH CYCLE FATIGUE LOW CYCLE FATIGUE OVERLOAD STRESS CORROSION-o' OPERA' TION SERVICE STRESSES ARE LOW
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FATIGUE USAGE VERY L0ll CRACK OBSERVATIONS SIMILAR TO IGSCC IN 304 PIPING.
o FABRICATION / INSTALLATION COLD FORMING ( > 2% STRAIN)
WELDING TO TEE B0X PROBABLE ADDITIONAL STRAIN DURING INSTALLATION o
MATERIAL SUSCEPTIBILITY SENSITIZATION + UELD RESIDUAL STRESS HIGH LEVEL OF COLD DEFORMATION MOST PROBABLE CAUSE OF CRACKING
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CRACK DETECTION-e CRACK INITIATION / GROWTH INNER SPARGER BEND RADIUS IN HIGH LEVEL OF RESIDUAL TENSION THEREFORE, CRACKS MOST LIKELY AT INNER SPARGER BEND SURFACES IGSCC IN TYPE 304 STAINLESS STEEL PIPE WELD HAZ's HAVE TYPICAL LENGTH TO DEPTH RATIOS OF 5:1 FOR THIN WALLED PILGRIM SPARGER -
CRACKS > 2-INCH (EVEN IF I.D. INITIATED)
SHOULD BE VISUALLY DETECTABLE e
WELD HAZ OF SPARGER TO TEE BOX JOINT MOST LIKELY LOCATION S
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STRUCTURAL INTEGRITY OF A SPARGER WITH CRACKS STRESSES LITTLE AFFECTED FOR NORMAL PLANT OPERATION EXCEPT - SECONDARY BENDING STRESSES DUE TO INSTALLATION RADIAL MISMATCH WILL INCREASE WITH DECREASE IN SECTION MODULUS--
BUT IS DEFLECTION LIMITED.
SPARGERS SECURELY ATTACHED TO SHROUD EXCEPT - SPARGER ENDS (APPR0X.) 11/2" OUTSIDE END BRACKET.
NOT A LOSSE PART CONCERN STRESSES LOW FOR CORE SPRAY INJECTION EVENT AXIAL LOAD FROM P & BRACKET FRICTION SECONDARYBENDfNGFROMCHANGEINBEND RADIUS TORSION DUE TO' N0ZZLE FLOW WEIGHT-FULL OF WATER 9
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CONCLUSIONS 4
SPARGER FLOW DISTRIBUTION MAY BE AFFECTED BUT 4
CORE SPRAY WATER WILL BE DELIVERED TO SHROUD INTERIOR
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SPARGER SHOULD RETAlti STRUCTURAL CONTINUITY-j<,
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EFFECT OF CORE SPRAY SPARGER CRACKS ON PILGRIM LOCA ANALYSIS
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e CURRENT LICENSING BASIS e
MAPLHGR DETERMINED BY LIMITING LARGE BREAK ACCIDENT 2
4.34 FT BREAK SIZE LOCATION - RECIRCULATION SUCTION LINE SINGLE FAILURE - LPCI INJECTION VALUE SYSTEMS REMAINING - ADS, HPCI, 2 CORE SPRAY e'
FULL CORE SPRAY HEAT TRANSFER ASSUMED IN ANALYSIS e
DEGRADED CORE SPRAY e
CRACKS IN CORE SPRAY SPARGER COULD RESULT IN DEGRADATION OF CORE SPPAY DISTRIBUTION e
ALL ASSEMBLIES MAY NOT RECEIVE RATED SPRAY e
CORE SPRAY HEAT TRANSFER EFFECTIVENESS WOULD BE REDUCED e
WORSE CASE e
NO CORE SPRAY HEAT TRANSFER CREDIT e
CORE SPRAY SYSTEM WATER ENTERS SHROUD AND ADDED TO WATER INVENTORY IN VESSEL e
RESULT - APPR0XIMATELY 10% MAPUiGR REDUCTION SMALL BREAK WILL ALSO BE ANALYZED - EXPECTED'TO'BE LESS e
LIMITING THAN LARGE BREAK e
FOR ALL ACCIDENTS, SPRAY DISTRIBUTION IS NOT REQUIRED FOR LONG-TERM CORE COOLING
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