ML19220C381
| ML19220C381 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 03/24/1978 |
| From: | Sheumaker NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Silver H Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7905010038 | |
| Download: ML19220C381 (3) | |
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De NOT use this form as a RECORD of approvals, eencurreocs,
disapprovals, clearances, and similar actions.
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STATUS OF INVESTIGATION RFuATED TO ALLEGATI0ft OF IMPROPER CONSTRUC IGN PRACTICES AT THREE MILE ISLAND, UNIT 2 Allecation That rebar had been cut without authorization and 1 1/4 inch diameter extensions had been welded to 3/4 inch diameter studs for attachment of an anchor plate (core flood tank support) without approved procedures.
(This was alleged to be an isolated case.)
Investication Discussions with the. alleger and observation of the indicated area resulted in identification of thre.e anchor plates on the secondary shield wall as probable areas for f urther investigat. ion.
These plates served as anchors for the structural support of the core flood tank CF-T-13.
The wall rebar is not accessible and only one end of each stud is accessible.
UT examination of the studs for these anchor plates showed indications in 5 of the 6 studs holding one plate at Elevation 315'-9".
The indications were evaluated as showing welded joints in the studs.
Based on the length and diameter of the 1 1/4 inch expansion anchors, it is considered probable that some rebar was cut during anchor installa-tion.
No documentation was available to show engineering authorization or QC control of this work.
Conclusion The allegation is considered to be substantiated. '
Corrective Action The licensee has requested that his Architect-Engineer, Burns and Roe, Inc.:(1) evaluate the effect of cutting the rebar on the structural integrity of the snield wall and (2) provide the design loads imposed on the stuas.
Evaluation of the rebar assumed to be cut has not been received.
The licenseg has stated that Burns and Roe provided 1500 # as the design load (tension) on each stud.
The licensee decided to test the studs at 2000 # (which is equivalent to a torque of 50 ft.-lbs. on the stud nut).
The studs were torqued to 50 ft.-lbs. on 3/21 with no motion and then up to 70 ft.-lbs. where tortuing was disccntinued.
No movement was observed.
The licensee considers that the studs are acceptable.
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2 Preliminary Findincs Region I has not yet reviewed the licensee's stud loading evaluation and test results but believes that the licensee's testing, if verified to be as stated, will show the existing studs exceed their design require-ments. Also, Region I doubts that the rebar cutting has degraded the secondaiy shiel) wall structural integrity below structural requirements.
Tnese opinions are not conclusions. Onsite verification is scheduled for later this week.
This information is transmitted at this time because of its potential relationship to tha Three Mile Island U iit 2 hearing process and will be updated basec upon ensite inspection.
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