IR 05000289/1971007
| ML19262A455 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 01/12/1972 |
| From: | Folsom S, Howard E, Varela A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML19262A452 | List: |
| References | |
| 50-289-71-07, 50-289-71-7, NUDOCS 7910290800 | |
| Download: ML19262A455 (6) | |
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U. S. ATOMIC ENERGY COMMISSION
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DIVISION OF COMPLIANCE
REGION I
CO Inspection-Report No.
50-289/71-07 Subject:
Metropolitan Edison Company
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Three Mile Island Unit 1 License No.
CPPR-40 Location:
Three Mile Island (near Middletown) '
Priority Pennsylvania Category B
Type of Licens2e:
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Type of Inspection:
Special, Unannounced
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Dates of Inspection:
December 16-17, 1971
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Dates of Previous Inspection:
November 16, 1971 Prini:ipal Inspector: S. A. Folsom, Reactor Inspector Date
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///)/ 7F Accc:npanying Inspectors:
(Inspection & Report by) A. A. Varela, Reactof Inspector (Const.)
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Date Other Accompanying Personnel:
NONE
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Date
/2(prZ< b
/--/2 '/2, Reviewed By: t
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E. M. Rovard, Senior Reactor Inspector Date Proprietary Information:
NCNE
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7910290[OO 1480 350
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SECTICM I Enforcement Action Moist cure of freshly placed concrete on containment buildinh dome is in nonconformance to job specifications and stated em=niements in the FSAR.
(Section II, Paragraph 8)
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Licensee Act'.on on Previously Identified Enforcement Matters Repair is continuing on the ring girder concrete voids in accordance with proposals submitted to DRL. This item is not considered re-solved.
(Section II, Paragraph 8)
Unresolved Items
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Not applicable.
Status of Presiously Reported Unresolved Items Not applicable.
w Design Changes j
Not applicable.
Unusual Occurrences
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Not applicable.
Persons Contacted Metropolitan Edison Company /GPU
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B. G. Avers, QA Manager *
M. J. Stromberg, OA Engineer *
J. H. Wright, Resident Civil Engineer *
R. E. Neidig, Assistant Resident Civil Engineer J.' Connelly, Civil QA Engineer
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- Attended Management Interview
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1480 351
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Management Interview al 5j The following subject was discussed:
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Centainment building dome concrete placed Tuesday, December 14, 1971, i
was observed on Thursday afternoon, December 16, to be lacking moist
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cure and therefore was in nonconformance with job specification and
- j construction procedure, which require uninterrupted continuous moist q
cure for seven days, i
The licensee sr.ated that they asked sE&C constructors for a full report on this occurrence, and expecting a letter from CO on the s
matter, they would have a reply at that time.
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'N-4-SECTION II Additional Sub_' ets Inspected, Not Identified In Section I, Where No
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Deficiencies or Unresolved Items Were Found
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1.
General
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The primary purpose of this inspection was to ascertain the status
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of Ring Girder 180 North; repair of concrete, rebar, and tendon
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ducts where-honeycombing and voiding had occurred in the placement i
of March 30, 1971.
This information was needed for apprising DRL on status for a meeting with the licensee cn December 28, 1971.
2.
Status of Concrete Excavation
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All Segement I questionable concrete had been excavated back to apparent sound concrete and Segment II concrete is presently being removed.
Segment III unsound concrete surrounding the double layer of dome trumplates, dome ducts, and vertical ducts is yet to be removed. Total excavation is estimated by Met Ed
to be 35% complete and, presently working two shifts, Met Ed estimates six week's time before Segment I is ready for concrete re-placement.
3.
Status of Rebar Replacement
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No rebar replacement by butt welding or cadwelding has been under-taken in any segnent. The licensee estimates that Segment I rebar replacement is expected to be complete within six weeks.
4.
Status of Tendon Duct Reolacement
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Segnent I dome tendon ducts, where damaged in concrete excavation,
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have been repaired or replaced using " Dresser" clamps for patches and splices, and acceptance tested per original installation pro-cedure, but repair of the thinner vertical tendon sheaths damaged in concrete removal, has been delayed for lack of criteria for acceptance. The licensee stated Segments II and III tendon duct repair has not started yet.
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1480 353
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5.
Status ur Cure Drilling Investigation of Sound concrete Eleven one-inch horizontal cores out of 36 total planned have been taken by Pittsburgh Testing Laboratory crews. These were taken in Segment I below the dome trumplate and after excavation to sound concrete.
PTL has not submitted a report on their core evaluation and borescope survey. However, inspection by CO of two cores and audit of UE&C inspection reports on borescope survey indicates concrete is sound to the maximum of 31-1/2" drilled at D 218 SE trumplate and 36" drilled at D 220 SE trumplate.
6.
Status of Indented (Notched) Rebar/ Tensile Strength Investigation The licensee informed the inspector that PTL has continued their testing on rebar damaged in concrete removal beyond that spoken of in the December 3, 1971 report by Met Ed to DRL, and it has been
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concluded that 3/32" is now the acceptable scximum dent. Although most damaged rebar has already been removed, the remaining stubs will be checked by a Go-NoGO gage for acceptance.
7.
Status of Rebar Butt 'i / Heat Effects on Concrete
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The licensee inform,1 tt inspector that rebar replacement will use cadweld splices except in close areas where butt welding new rebar to short dowels (stubs) will be done.
Recent weld tests have been conducted to determine minimum length of rebar stubs and effects of pre-heat and welding temperature on concrete.
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Details of Subjects Discussed In Section.I 8.
Description of Nonconformance Iten i
The FSAR, Volume 2, Section 5.2.2.1, " Concrete", states in part,
"Otructurst concrete work has been performed in accordance with
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Specifications for Structural Concrete for Buildings, ACI 301-66 l
modified as necessary for the more exacting recuirements of the Reactor Building."
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Section 1405 of ACI 301-66 states in part, "The forms and exposed concrete shall be kept continuously wet for at least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after placing."
Contrary to the' above, it was foand that, prior to completion of the 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> initial drying phase, the upper half of the
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fourth 666 ment of the containment dome concrete was uncovered, and was cool and dry to the hand while the lower half was covered with moist burlap and was warm to the hand, b.
Section 1201 of ACI 301-66 states in part, "Lamediately following the initial curing and before the concrete has dried, additional curing shall be accomplished by one of the following materials or methods:
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Continuing the method used in initial curing.
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Waterproof paper conforming to ASTM C-171.
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Other moisture-retaining, coverings as approved."
Contrary to the above, the upper half of Segment 4 of the -
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containment dome concrete mass p.ar was found to have. been dry precluding the continuance of additional curing.
9.
Procedure for Removal of Unsound Concrete and Evaluation of Excavn-tion Depth m
Removal of unsound concrete is being executed as spoken of in Para-graph 2, by UE&C craf tsmen under craf t supervision and engineering direction starting from vertical exterior face of ring girder.
Depth of excavation was tested by probes and various means of investiga-tion identified in the December 3, 1971 report to DRL.
F. valuation that depth of concrete excavated is adequate is the responsibility of a task force composed of two UE&C engineers, two Gilbert Associ-ates engineers, and three Met Ed/GPU engineers.
Evaluation of each
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segment (extent of concrete excavation) is made.by the task force after core drilling and borescope examination is performed by PTL.
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1480 355
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