ML19338G270
| ML19338G270 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 09/24/1980 |
| From: | Jordan E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | Cobb L NRC OFFICE OF MANAGEMENT AND PROGRAM ANALYSIS (MPA) |
| References | |
| REF-SSINS-1210 NUDOCS 8010280711 | |
| Download: ML19338G270 (4) | |
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.SN SSINS 1210 SEP p.4 1980 MEMORANDlR; FOR:
L. I. Cobb, Executive Officer for Management and Analysis FROM:
E. L. Jordan, Assistant Director for Technical Programs,
._ Division.of. Reactor Operations. Inspection.'...__
~3RdCNTRACT.05-80-251-PARAMETERINC.'~_'...;~:.j~;f;
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SUBJECT:
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Enclosed is Task. Order No. ~ 5. requested under the above contract for a metallurgical analysis of a cracking problem recently: encountered-In_the.:
steaim generator support bolting at Prairie : Island Wnits 1 and 2. -........,
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It:is essential.ibat the cause-of the cracking be determined so_that ari
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assessment of the generic-implications can_b_e made We have discussed the scope of work with Parameter Inc., pending task order authorization by Division.of Contracts I have. assigned R. Hermann technical cre~;. neef
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responsibility for the task efforts;. - - --
-7 Edward L. Jordan Assistant. Director for Technical Programs,
. Division of Reactor Operation.s Inspection
Enclosure:
TMk Order >No.--
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cc:w/ enclosure N. C. Moseley, IE H. D. Rose (V. Tolson), IE W. J. Collins, IE R. A. Hennann, IE CONTACT:
R. A. Hermann, IE W..J. Collins, IE a49 28480-1 T
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- " TECHNICAL ASSISTANCE TO SUPPORT NRC IE PERSONNEL IN INVESTIGATIONS OR INCIDENTS" OIE 80-251
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J.-Collins H. Rose (V. Tolson)'
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PARAMETER INC..
NRC IE CONTRACT - NRC 05-80-251 TASK ORDER NO.
1.
Scope of Work Provide NRC-IE assistance and services in the independent metallurgical analysis of cracked bolts as outlined in the statement of work below.
2.
Backoround On September 4,1980, the NRC staff was informed by the Northern States Pon e Company that extensive cracking of the bolting for the steam generator supports attached to bottom of the steam generators had occurred. The licensee initially discovered the bolting problem when two bolts failed during dete.nsion.ing...The. licensee..was attempting to remove the pre-load on the bolting (specified at..]A00 ft.-lbs) to minimize the h tential for stress corrosion cracking of-the.high strength 1-1/2 inch diameter 250 ksi maraging steel bolting (Vascomax 250.)..
Ultrasonic examination of the support bolting revealed cracks or breaks in 47 of 48 support bolts for the two steam generators at the Prairie Island Unit 1 facility. The licensee. subsequently shut down the Prairie Island Unit 2 facility and performet ultrasonic examinations of the same steam generator support bolting, that failed on Unit 1.
The results of the UT examinations revealed cracks in three of the 48 steam generators support bolts. The licensee attempted to. remove the cracked. bolts from the steam generator supports. Two. cracked bolts were successfully removed while the third failed during removal. Two bolts that were judged as defect free by the ultrasonic examination were also removed.
Magnetic' particle examinations c
confirmed the results of the ultrastnic examinations on the bolts which were removed. As part of the short term corrective actions taken, the licensee
,, has unloaded and retensioned the bolting at approximately 50 to 100 ft.-lbs.
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3.
Statement of Work Theactuallabo'r'aIo'ryanalysisandevaluationshallconsistofthefollowing:
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(1) Photograph.the "as received" bolts to document the physical. condition and to provide references for the location of sections removed for analysis.
(2) Perform optical metallographic examinations at appropriate magnification of the fracture face to characterize the macro topology of the fracture, i
identify crack initiation. sites, and of the bolt surfacer to identify cracks or other discontinuities that may be present. Document the examination result _s with representative photomicrographs.
(3)
Perform optical metallography of selected specimen sections containing j
cracks to determine if the mode of cracking is trans or intergranular.
I Provide an evaluation of the. material structure'to. determine if the.
I structure is representative for the material.
Provide representative photomicrographs which document the structure, cracking mode, and any anomalies observed.
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Parameter Inc.
'~2-(4) Conduct scanning electron metallography (SEM) studies and EDAX
' analysis of the. fracture surface (s). Provide an appropriately documented evaluation of the following:
(a) Characterization of fracture surfaces - initiation sites, fracture morpholegy with respect to mode of failure, i.e.,
fatigue, stress corrosion, stress overload, etc.
(b) Analysis of identified. deposits on thread and crack surfaces, and qualitative correlation with chemical analysis of base materia-l.
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i (5) Perform mechanical test of the bolt material. including. tensile strength,: yield strength,. elongation and reduction of. area.to.
characterize the mechanical properties and verify conformance~with; + :
specification. limits.
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(6)
Perfor hardness survey of crack' areas and a standard hardness test to determine.pf mechanical properties of the bolt meets. specification.
(7)
Perfonn quantitative chemical analysis.of bolt by the most appropr.iate method to suitably characterize the. stud material and determine-conformar,ce to spec.ification limits.
4.
Report Requirements,
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Upon recept of the bolt sample at the designated laboratory for-analysis, the following reports are required:
(1)
Results of laboratory analysis and evaluation as the work progresses shall be verbally. communicated to the IE Headquarters Project.0fficer.
on a weekly basis.
-~(2) A preliininary report on the complete analysis and evaluation shall
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be submitted within 20 days for the Project Officer';s. review.~ ':
(3)
Forty (copies) of a written final report shall be submitted to the IE Project Officer within 45 days.
5.
Special Instructions
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The NRC shall reimburse. the: contractor as invoiced for. 2llowable costs.:. 5.
incurred in' shipment of the bolt samples to the designated laboratory for analysis.
All unconsumed portions of the bolts are to be properly identified and returned to the licensee upon completion of the analysis and evaluation. -
6.
Place of Performance
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Parameter Inc.
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(2) Technimet Inc.
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Cost Ceiling
$6,500
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