IR 05000329/1980005
| ML19309D336 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 03/11/1980 |
| From: | Erb C, Knop R, Vandel T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML19309D329 | List: |
| References | |
| 50-329-80-05, 50-329-80-5, 50-330-80-05, 50-330-80-5, NUDOCS 8004100267 | |
| Download: ML19309D336 (7) | |
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U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT
REGION III
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Report No. 50-329/80-05; 50-330/80-05 Docket No. 50-329; 50-330 License No. CPPR-81; CPPR-82 Licensee:
Consumers Power Company 1945 West Parnall Road Jackson, MI 49201 Facility Name: Midland Nuclear Power Plant Units 1 and 2 Inspection At: Midland Site, Midland, MI and Southern Bolt Company, Shreveport, LA Inspection Conducted:
Febrsary 4-5 and 14, 1980
$4fct Inspectors:
T. E. Vandel 8-//-[6
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deu bg J-// ef4 Approved By:
R. C. Knop, Chief
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Project Section 1
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Inspection Summary
_ Inspection on February 4-5 and 14, 1980 (Report No. 50-329/80-05;
$0-330/80-05)
Areas Inspected: This inspection waa 9 special inspection conducted to review the Units 1 and 2 reactor pressure vessel anchor bolts records and fabrication information gathered by the licensee, and observe a meeting conducted at Southern Bolt Company regarding the acceptability of the bc1ts supplied. The inspection involved a total of 43 inspec-tor-hours by two NRC inspectors.
Results: No items of noncompliance were identified.
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s DETAILS Persons Contacted at Midland Site
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Consumers Power Company
- J. L. Corley, Section Head IE & TV B. H. Peck, Construction Supervisor
- D. R. Keating, QA Group Supervisor
- H. W. Slager, Staf f Engineer, Project Engineering Services
- R.
M. Wheeler, PM0 - Civil Section
- J. L. Wood, QA Group Supervisor Bechtel Power Corporation
- A. J. Boos, Project Field Engineer
- L. A. Dreisbach, Project QA Engineer
- P. Goguen, Field Engineer
- R. E. Sevo, QA Engineer E. M. Hughes, Assistant Project Engineer
- Denotes those present at the exit meeting held on February 5, 1980.
Persons Contacted at the Southern Bolt and Fastener Corporation Meeting Consumers Power Company H. W. Slager, Engineer, Project Engineering Services R. Wheeler, Field Civil Engineer J. L. Wood, QA Group Supervisor Bechtel Power Corporation (Bechtel)
C. Boyak, Project Engineer P. Goguen, Field Engineer E. Hughes, Assistant Project Engineer M. Elgaaly, Project Engineer W. Keyser, Materials Southern Bolt and Fastener Corporation E. Nelson, President R. Alexander, Vice President W. Gow, Metallurgist D. Sibley, Quality Assurance T. Goin, Sales B. Mathias, Sales J. Wisby, Sales
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Mississippi Valley Structural Steel (MVSS)
J. Pantukhoff, Vice President N. Cohn, Engineer
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Review of 10 CFR 50.55(e) Reported Deficiency The licensee reported to the NRC RIII office on September 14, 1979 the discovery of a broken reactor pressure vessel holddown stud.
Following is the review of this reportable deficiency:
1.
Inspection at Midland Plant 50.55(e) Item a.
Unit 1 Studs The inspectors visited the site to review information regarding the two broken holddown studs. Failed stud No. 3 was located in the inner ring of studs and was of heat 0 while failed stud 36 was located in the outer ring and also was of heat 0.
While inspecting the RPV holddown bolts of the outer ring, one of the NRC inspectors noticed that stud No. 35 (heat 000) in the outer ring and adjacent to stud 36 was off its seat about an inch. Examination revealed that it had also fractured sometime between December 14, 1979 and February 5, 1980.
It had not been removed yet at the time of writing. Teledyne Engineering Services (TES) had been contracted to investigate the failure of first failed stud 3 and had also been given stud 36 for examination.
In conjunction with the investigation of the two failed studs they had made hardness tests on the exposed ends of all 94 bolts in Unit 1.
Hardness checks were made by TES using a French portable hard-ness tester. Testing was done on the ground end of each stud from the edge to the center. Some bolts showed a decided drop-off in hardness at the center while others were quite uniform from edge to center. This reveals a non-uniformity in the heat treat, which could arise for reasons such as shielding of the stud top by the holding nut and fixture or lack of hardenabil-ity in the 4140 steel.
Edge hardness readings were taken and correlated by heat number in the TES study with the following results:
Heat No.
No Studs L - Converted to Rockwell C.
55 (including 2 failed studs) above 38 RC
9
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6 38 or under.
000 21 (including I failed stud)
42 RC or above-3-
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s Heat numbers for five studs are missing, apparently because the heat number could not be ascerti ' ed from the exposed end.
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(Only one end was stamped). Bechtel specification 7220C-233(Q)
was used to procure the studs, and it referenced ASTM-A 354 Grade BD for the material. A Rockwell "C" hardness of 92-38 was required by that standard. A minimum tensile of 150,000 psi and a minimum yield strength of 130,000 psi was required from specimens machined from mid-radius of 2\\~ test bars. A minimum elongation of 14% and minimum reduction of area of 35% was also required.
Charpy V notch (CVN) tests were re-quired at 40'F at the radius of the bar but were for in-formation only.
The Standard Pressed Steel (SPS) Company tested six Charpy specimens and Rex tested two tensiles from each heat of mater-ial after heat treatment. The results were as follows:
Red.
Lateral No.
Tensile Yield Elong. Area Deform.
Ft. Lbs.
Heat Tyge psi psi
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mils (CVN)
4140 166,000 135,000 16.0 55.8 5.5, 4.5 11.5,10.0,16.0 8.5 171,800 133,800 16.0 56.2 7.5, 5.5 15.0,15.0,14.5 6.0
4145 163,000 138,800 17.0 56.8 5.5, 1.5 16.5, 9.5,13.5 4.5 173,200 151,800 16.0 52.4 5.0, 5.5 12.0, 13.0, 17.0 8.5 000 4140 167,800 135,200 14.0 50.4 9.0, 5.5 16.0, 12.5, 11.0 3.4 163,000 131,800 17.0 56.8 2.5, 1.5 8.5, 6.0, 6.0 6.0 The hardness results for the above tests were in 36-33 RC range and thus met the specification requirements. The tensiles and yield results were also satisfactory, but the CVNs indicated brittle material.
Since the CVNs were for information only, no action was taken except to provide the results. An explana-tion for the above satisfactory tensile, yield, elongation and reduction of area results means that tensiles machined from the mid-radius ef bars with a high hardness gradient would indicate much lower hardness, lower tensiles and higher elongation than material near the edge of the stud.
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Unit 2 Studs The Unit 2 studs were also checked for hardness by TES with the following results:
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Code and Type No. Bolts Hardness X
4340
39 and above X
38 and below
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XX 4340
39 RC XX
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38 and below From the above, it is plain that many more of the studs meet the 38 RC and below criteria than in Unit 1.
However, 19 of the bolts in Unit 2 are above the 38 RC level.
These studs were made from 4340 steel which should have responded with a more uniform hardness across the section and were tempered between 925 F and 1005 F.
However, the suitability for use of the hard studs in Unit 2 remains to be established.
2.
Trip to Southern Bolt and Fastener The inspectors went to Southern Bolt Plant and met, together with the personnel indicated under Persons Contacted, with Southern Bolt and Mississippi Valley Structural Steel management.
Bechtel and Consumer Power Company had prepared questions for the meeting.
The gist of certain answers are given below:
a.
The round bars were received by Southern Bolt in 2-1/2" dia-meter because the preferred 2-3/4" stock was unavailable due to tightness of supply. Visual examination and magnetic test revealed longitudinal indications due to dirty steel.
Grind-ing was used by Southern Bolt to remove the MT indications and permission was asked from Bechtel to accept bolts if the shank size were 2.257" or above.
Four heats (0,4140),
(00,4145),(000,4140) and (0000,4140) of bars were received by Southern Bolt with all 0000 material finally scrapped.
Approximately 200 bars that were started through the process-ing cycle, only 97 bolts were accepted after heat treatment
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and a final magnetic particle inspection.
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l The heat treatment was performed at the J. W. Rex Company in l
Philadelphia, Pa.
MT was performed after heat treatment by Peabody Company and all the bolts were rejected.
Subsequently, after further surface grinding and Maguetic Test at Southern
Bolt, 97 bolts were shipped.
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No record exists that the bolts were normalized prior to the austenitize and quench. The bolts were hung approximately 10 at a time vertically from a fixture in a furnace using a nut on threaded end to hold each piece. The quench was made using the same fixture into an agitated oil bath tank. Ha rddbss surveys by Teledyne of the installed bolts in Unit 1 indicated a wide hardness gradient from center to outside of the bolts for about 50% of the bolts. This indicates uneven quenching poss-ibly affected to some degree by the nut and holding fixture holding each bolt at the top end. The tempering temperature was 850 F minimum by ASTM specification A354-66 which is refer-enced by Bechtel procurement specification 7220-C-233 Q Revision 3.
Forty bolts were processed in each tempering batch.
Bolts were distributed between 3 heats as follows:
Code Heat No.
Material No. Studs
654N136 4140
00 54980 4145
000 655N051 4140
18 bolts from heat 00 were given an additional temper at The,F, but the remaining 78 bolte from Heats 0, and 000 saw 925 only the 850"F.
Exit Interview An exit interview was conducted with the licensee representatives denoted in the Persons Contacted paragraph at the conclusion of the inspection at the Midland site on February 5,1980. The inspectors expressed their appreciation for the efforts of the licensee to provide the inspectors with the information obtained to date regarding the adequacy of holddown studs for both Unit 1 and Unit 2 vessels.
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RIII REPORT / LETTER TRAVELER g
Lic;n: e b Location:
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Fccility(s):
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Liccn:2 No(s): hM //#f cf / M, 7,1 Docket No(s):
3 -f,R9 ' SD -33 8 s
Date(c) of Inspection:
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Currcnt Category:
- Priority:
- Change to Category:
- Priority:
Xmxt Scheduled Inspection Date:
LETTER AND REPORT Date Accomplished By
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Subn i t t e d f o r D ra f t 1 n g.................................
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Drciting Completed.....................................
3 - T-90 dw, Subnitted for Review...................................
3-T-Po M o M-
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Ravicv2d...............................................
3, 7.- M
- C,C4 Subnitted for Final Typing.............................
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%f Finsl Typing Completed.................................
f 31 c p s t c h e d t o Li c e n s e e.................................
( NAR 2 01880 hk.
S i c p e t c h e d t o 11Q...... '.................................
1{1\\h LO/S)
Received:
hply Due:
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hply: Adequate or Inadequate (Circle One)
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Inspector:
(initials)
(Date)
Senior Staff:
(initials)
(Date)
\\cknovicdgement Letter Dispatched......................
In2p;ction Package to Local PDR, etc.
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) ATE DUE FOR FINAL TYPING:
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LEASON FOR NOT HEETING DUE DATE:
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6/77 j I:ter*pla Inspectiona Only
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