ML20042A601
| ML20042A601 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 02/19/1982 |
| From: | Chaudhary S, Lester Tripp NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20042A591 | List: |
| References | |
| 50-289-M81-246, IEB-79-02, IEB-79-2, NUDOCS 8203230597 | |
| Download: ML20042A601 (12) | |
Text
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i U. S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT Region I Report No. M81-246 Docket No. 50-289 License No. DPR-50 Priority Category C
C Licensee:
GPU Nucleat orporation P. O. Box 480 Middletown, Pennsylvania 17057 Facility Name: Three Mile Island Generating Station, Unit 1 Meeting At:
King of Prussia, Pennsylvania Meeting Conducted:
December 15, 1981 Reporting Inspector:
S Y. C[eMaw 2/i4/g 2 S
date signed
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.K. Chaudhary, Reactorf Inspector 8 7k2
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fh4 Approved By:
6L. E. Tripp, Chief, Materials and Processes ddte' signed
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Section, EIB Meeting Summary:
Areas Discussed:
A meeting was held at the request of the licensee to discuss the steps taken by the licensee to resolve the concerns expressed by NRC regarding licensee actions pursuant to IE Bulletin 79-02.
Results: The licensee presented additional information regarding the grouted base plates, and factors of safety against SSE.
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DETAILS 1.
Meeting Attendees Met-Ed/GPU-Nuclear D. R. Croneberger, Director, Engineering and Design J. Delezinski, Licensing J. K. Gulati, Supervisor, Engineering Projects R. Miranda, Project Engineer Gilbert / Commonwealth J. C. Herr, Supervisor, Speciality Projects K. E. Nodla.id, Project Engineering Manager R. M. Rogers, Project Manager U. S. Nuclear Regulatory Commission T. T. Martin, Director, Division of Engineering and Technical Programs S. D. Ebneter, Chief, Engineering Inspection Branch R. R. Keimig, Chief, Projects Branch #2, Division of Project and Resident Programs L. E. Tripp, Chief, M&PS, EIB S. K. Chaudhary, Reactor Inspector, M&PS, EIB J. R. Fair, Mechanical Engineer, IE:HQ 2.
Meeting Scope On December 15, 1981, a meeting was convened at the request of the licensee at the NRC Region I offices at King of Prussia, Pennsylvania. The purpose of this meeting was to discuss the steps taken by the licensee pursuant to NRC concerns expressed durir.g a meeting on October 6, 1981 in regards to IE Bulletin 79-02.
3.
Areas Discussed The licensee and licensee contractor presented additional information for resolving the NRC concerns expressed in the earlier meeting with the licensee. A copy of the information used in this presentation is attached.
The presentations and resultant discussions are summarized below.
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The grouted base plates were used for simple installations only.
In attempts to disassemble grouted base plates, bonding of bolts to shell by grout resulted in four (4) bolt shank failures.
Due to the destructive nature of bolt removal, an engineering judgement was made to implement a sequential screening program.
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3 b.
The qualification tests for bolt pull-out capacity did not show any steel failure, all failures were in concrete.
In attempted in place disassembly, no anchor shells were pulled out, only the belts failed.
The loads at failure, therefore, were considered to be in excess of that experienced during the qualification test program.
c.
The sequential screening program for the grouted base plates for 84 supports revealed that:
12 supports had no tension loads.
34 supports had negligible tension and/or shear loads; (F.S >
16 against OBE).
10 supports had anchor bolt factors of safety greater than 10 against OBE and/or 5 against SSE.
7 supports were installed for maintenance purposes, were evaluated with adjacent nozzle taking all loads (supports removed from system), and were found acceptable.
21 remaining supports were redesigned for other reasons, and would be modified before the restart.
d.
The systems with anchor bolt population greater,than 300 were randomly sampled in accordance with IE Bulletin 79-02. A total of 19 systems were investigated.
16 systems by one anchor per plate (Method A).
3 systems by random sampling (Method B).
e.
For anchor failures in random sampling, the sample size was increased to maintain a 95% confidence level of less than 5% defective anchors in each system.
f.
All supports having factor of safety against SSE of less than 2 would be modified such that the minimum F.S. against SSE would be at least 2 before the restart.
4.
The NRC position was summarized by Mr. T. T. Martin as follows:
a.
The investigation and supporting engineering rationale for grouted base plai.e acceptance were technically adequate and acceptable to NRC.
b.
he minimum factor of safety of 2 against SSE for all supports before the restart is also acceptable to NRC for interim operations of the plant. The factor of safety requirements of the bulletin, however, must be met for long term operation of the plant.
ENCLOSURE:
Copy of Material Used in Presentation
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- o GPUNC/GAI TMI-1 79-02 PROGRAM UPDATE
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INTRODUCTION II.
79-02 OPEN ITEMS FOR RESTART III.
COMMITMENTS FOR RESTART
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INTRODUCTION e
MEETING IS IN RESPONSE TO I & E INSPECTION 81-25 AND GPUNC/NRC MEETING - 10/6/81 - ON IEB 79-02 e
NRC EXPRESSED CONCERN OVER EARTHQUAKE
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LOADINGS USED TO EVALUTE ANCHOR BOLTS e
TMI-1 FSAR:
= 0.06G 2 OBE = SSE = DBE = 0.12G e
RESOLUTION OF NRC QUESTIONS CONCERNING:
GROUTED BASED PLATES SAMPLING IECHNIQUES COMMITMENTS FOR RESTART e
NRC CONCURRENCE OF OUR RESTART COMMITMENTS 1
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'.<0UTED BASE PLATES GROUTED PLATES USED ONLY FOR SIMPLE FLOOR INSTALLATION AS SHOWN IN SKETCHES ATTEMPT TO DISASSEMBLE BOLT FROM GROUTED BASED PLATE FOR DIMENSIONAL CHECKS BONDING OF BOLTS TO SHELL BY GROUT RESULTED IN 4 BOLT SHANK FAILURES (IN TORSION) DURING ATTEMPTED INSPECTION ENGINEERING JUDGMENT TO PROCEED WITH ALTERNATE EVALUA-TION PROGRAM DUE TO DESTRUCTIVE NATURE OF BOLT REMOVAL (FAILED BOLTS, CHIPPED GROUT, ETC.)
SEQUENTIAL SCREENING PROGRAM DEVELOPED.
QUALIFICATION PULLOUT CAPACITY TESTS DONE AT THE INITIATION OF 79-02 PROGRAM SHOWED NO INSTANCES OF
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STEEL FAILURE - CONCRETE WAS THE FAILURE MODE (SEE PHOTO)
FOR GROUTED BASED PLATES "Q ANCHOR SHELL PULLOUT d
PROJECTED, ONLY BOLT FAILURE DUE TO BONDING.
THEREFORE, THE LOAD AT FAILURE DURING DISASSEMBLY WOULD HAVE BEEN IN EXCESS OF THAT EXPERIENCED DURING THE QUALIFICATION PROGRAM.
BECAUSE 0F THE INABILITY TO INSPECT ANCHOR BOLTS WITH GROUTED PLATES, THE FOLLOWING SEQUENTIAL SCREENING PROGRAM WAS IMPLEMENTED:
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$1NGLE ANCHOR-TYPICAL TENSION TEST FAILURE CONE i
SEQUENTIAL SCREENING PROGRAM (84 SUPPORTS' s
TYPICAL DETAIL (SEE SKETCH)
GROUTED BASE PLATES ON FLOORS ONLY NO DEVIATIONS OBSERVED FROM EXTERNAL APPEARANCES SITE INSPECTION RESULTS INDICATES FLOOR INSTALLED ANCHORS (WITHOUT GP.0UT) TENDED TO MEET ACCEPTANCE CRITERIA e
TENSION ON ANCHOR BOLTS 12 SUPPORTS HAD NO TENSION OR SHEAR LOADS 34 SUPPORTS HAD NEGLIGIBLE TENSION AND/OR SHEAR LOADS F.S 716 (0BE) 46 SUPPORTS JUDGED ACCEPTABLE e
ANCHOR BOLT FACTOR OF SAFETY F. S.? 10 (OBE) 7 SC5'E) 10 SUPPORTS JUDGED ACCEPTABLE e
EQUIPMENT N0ZZLE LOAD SUPPORT INSTALLED FOR MAINTENANCE PURPOSE SYSTEM EVALUATED WITH ADJACENT N0ZZLE TAKING ALL LOADS (SUPPORT REMOVED FROM SYSTEM) AND FOUND ACCEPTABLE.
7 SUPPORTS - CONSIDERED ACCEPTABLE e
REDESIGNS REMAINING 21 SUPPORTS REDESIGNED FOR OTHER REASONS AND (40DIFIED PRIOR TO RESTART (BROKEN BOLTS, LOAD l
INCREASE DUE TO 79-14) l
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SAMPLING TECH!!IOUES COMPLIED WITH IE BULLETIN 79-02 APP. A GUIDELINES.
SYSTEMS WITH ANCHOR BOLT POPLUATIONS GREATER THAN 300 ANCHORS WERE RANDOM SAMPLED.
19 SYSTEMS INVESTIGATED 16 SYSTEMS BY ONE ANCHOR PER PLATE (METHOD A) 3 SYSTEMS BY RANDOM SAMPLING (METHOD B)
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ANCHOR FAILURES 1.
FOR ANCHOR FAILURES IDENTIFIED IN RANDOM SAMPLING, THE. SAMPLE SIZE WAS INCREASED TO MAINTAIN 957 CONFIDENCE LEVEL OF LESS THAN 5% DEFECTIVE ANCHORS IN SYSTEM.
2.
FOR ANCHOR FAILURES IDENTIFIED IN ONE PER PLATE INSPECTION, ALL ANCHORS ON PLATE WERE TESTED.
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79-02 DESIGN CRITERIA ElRTHQUAKE BULLETIN COMPONENT LOADING ACCEPTANCE CRITERIA COMMITMENT RE0. DESIGN CRITERIA 1
M DIFY PRIOR TO CONCRETE SSE IF FS =
<2 Vo RESTART EXPANSION Io
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7ggn ANCHOR BOLTS SO THAT F.S.> 2 (RESTART MODIFICATIONS {
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= ULTIMATE TENSION CAPACITY OF AN ANCHOR
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= SHEAR FORCE INDUCED INTO AN ANCHOR O
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= ULTIMATE SHEAR CAPACITY OF AN ANCHOR A
- ULTIMATE TENSILE AND SHEAR CAPACITIES WERE BASED ON THE MANUFACTURER'S ANCHOR CAPACITY DATA.
HOWEVER, SOME EVALUATIONS HAD.THE ADVANTAGE OF LARGER ULTIMATE
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TENSILE PULLOUT CAPACITIES, OBTAINED FROM THE ON-SITE TESTING PROGRAM ONCE THE f
DATA BECAME AVAILABLE.
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III.
COMMITMENTS F,lR PESTART
- f TOTAL # OF PRE 79-02 y
SEISMIC l SUPPORTS
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INSPECTED / EVALUATED
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2685 4
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- OF SUPPORTS
- OF SUPPORTS
- OF SUPPORTS
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WITHOUT ANCHOR WITH ANCHOR DELETED
- BOLTS BOLTS 30 1402 1253 I
- OF SUPPORTS REQ.
- OF SUPPORTS HAVING A NO MODIFICATION FOR F.S.<.2 (FOR SSE) BEFORE RESTART BECAUSE MODIFICATIONS F.S.E 2 (FOR SSE)
NOTE:
ALL EXISTING AND E SUPPORTS W:TH CONCRETE EXPANSION ANCHOR BOLTS WILL HAVE A F.S. 2 2 (FOR SSE) PRIOR TO RESTART.
- SUPPORTS WERE DELETED DUE TO VARIOUS DESIGN MODIFICATION (I.E.
NEW ADJACENT SUPPORTS, REPLACEMENT BY LARGER SUPPORTS, ETC.)
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