IR 05000269/1981020
| ML15224A461 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 10/15/1981 |
| From: | Ang W, Herdt A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML15224A460 | List: |
| References | |
| 50-269-81-20, 50-270-81-20, 50-287-81-20, NUDOCS 8111130633 | |
| Download: ML15224A461 (6) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTA ST., N.W., SUITE 3100 ATLANTA, GEORG[A 30303 Report Nos. 50-269/81-20, 50-270/81-20, 50-287/81-20 Licensee:
Duke Power Company P. 0. Box 2178 Charlotte, North Carolina 28242 Facility Name:
Oconee Nuclear Station Docket No. 50-269, 50-270, 50-287 License Nos. DPR-38, DPR-47, DPR-55 Inspection at Duke Power Company Engineering Office, Charlotte, North Carolina Inspector:
L
__.____O_/
__-8
_
Wo W. P. ATM Date Signed Approved by:
_'_______
/1-76
$
41 A lA H
,Section Chi Date Signed Engn ring Inspect'
anch Engineering and echnical Inspection Division SUMMARY Inspection on September 30, 1981 to October 2, 1981 Areas Inspected This routine, announced inspection involved 22 inspector-hours on site in the areas of pipe support baseplate designs using concrete expansion anchor bolts (IE Bulletin 79-02) and seismic analysis for as-built safety-related piping systems (IEB 79-14).
Results Of the areas inspected, no violations or deviations were identifie (8111130633 811019 PDR ADOCK 05000269 PDR
REPORT DETAILS 1. Persons Contacted Licensee Employees
- S. B. Hager, Chief Engineer, CE Division
- R. B. Priory, Principal Engineer, Project Management Division
- D. L. Rehn, Senior Engineer, CE Division
- T. A. Matthews, Senior Engineer, Project Management Division
- M. S. Sills, Design Engineer, CE Division
- Attended exit interview Exit Interview The inspection scope and findings were summarized on October 2, 1981 with those persons indicated in paragraph 1 abov The inspector described the areas inspected and discussed in detail the results of the inspection. The licensee committed to provide a final response for IE Bulletins 79-02 and 79-14 to further clarify previous responses and to provide a schedule for completion of corrective action resulting from the bulletin requirements for Units 1 and. Licensee Action on Previous Inspection Findings Not inspecte. Unresolved Items Unresolved items were not identified during this inspectio. Pipe Support Baseplate Designs Using Concrete Expansion Anchor Bolts - IE Bulletin 79-02 On July 29, 1980, the licensee submitted a revised reponse to IEB 79-02. A follow-on inspection to those documented on IE Report Numbers 50-269/80-2, 50-270/80-1, 50-287/80-1, 50-269/79-39, 50-270/79-36, 50-269/79-27, 50-270/79-25, 50-287/79-27, 50-269/79-22, 50-270/79-20, 50-287/79-22, 50-287/79-16, 50-269/79-17, and 50-287/79-13 was performed to verify licensee compliance with commitments and bulletin requirement The response and the results of the licensee inspections and tests for Units 1 and 2 were reviewed and discussed with the licensee. Baseplate analysis and concrete expansion anchor safety factor calculations for Unit 1 High Pressure Injection System and Unit 2 Steam Generator Flush Systems were reviewe As noted on the licensee's response to item 4 of the bulletin some supports were determined to be inaccessible for inspection and-testing due to their being located in high radiation areas. The licensee estimated that roughly four percent of the Unit 1 concrete expansion anchors and.about two percent of the Unit 2 concrete expansion anchors were in this categor IE Report Numbers 50-269/79-22, 50-270/79-20 and 50-287/79-22 noted that the licensee would evaluate further appropriate action require for concrete expansion anchors found with excessive shoulder to plug measurements. The licensee subsequently determined that upon passing a 1/4 ultimate pull test, the anchor could be allowed a reduced capacity equivalent to 80 percent of the Teledyne Shear Tension Interaction Curves. The review of baseplate and concrete expansion anchor calculations confirmed this. However, the review of inspection records revealed that some of the concrete expansion anchors with high shoulder to plug measurements failed the 1/4 ultimate pull tes The records further indicated that a significant number of concrete expansion anchors with high shoulder to plug measurements were not pull tested due to mechanical interference IE Report Numbers 50-269/79-22, 50-270/79-20 and 50-287/79-22 noted a concern regarding licensee inspection of baseplates with threaded rod type concrete expansion anchor installation The review of Units 1 and 2 inspection records and subsequent discussions with the licensee revealed that the noted threaded rod type installations were considered inaccessible for visual and dimensional inspections due to grout that was normally under the baseplate. The licensee elected to remove grout around one threaded rod per baseplate and performed a 1/4 ultimate pull test on i The test records revealed that approximately 20 percent of the threaded rod installations in Unit 1 and 7 percent in Unit 2, failed the pull test. The test records further revealed that 20 percent of the Unit 1 and Unit 2 threaded rod installations were considered inaccessible for testing and inspectio The licensee was informed of the requirements of IE Bulletin 79-02 Revision 2 page 4 which stated that "Justification for omitting certain bolts from sample testing which are in high radiation areas during an outage must be based on other testing or analysis which substantiates operability of the affected system." The licensee committed to revise the response to the bulletin and identify the concrete expansion anchors that considered inaccessible and not inspected or tested due to high radiation area location, mechanical interference for the untested high shoulder to plug concrete expansion anchors, and grout and mechanical interference for the untested threaded rod type concrete expansion anchor analysi The licensee further committed to perform a failure analysis on the concrete expansion anchors, baseplates, pipe supports and piping systems as applicable for all concrete expansion anchors considered to be inaccessible for inspection or testing for Units 1, 2, and Pending licensee completion of IEB 79-02 requirements, and licensee commitments, the bulletin shall remain ope No violations or deviations were identifie. Seismic Analysis for As-Built Safety Related Piping System - IE Bulletin 79-14 On June 11, 1980 the licensee provided a final update of information provided on previous responses to IEB 79-1 A follow-on inspection to those documented on IE Report Numbers 50-269/79-27, 50-270/79-25, 50-287/79-27, 50-269/80-2, 50-270/80-1, 50-287/80-1, 50-269/79-39, and 50-270/74-36 was performed. The bulletin responses were discussed with the license Piping stress analysis problems 1-07A-1, 1-53-1 and 1-53-2 were selected and reviewed for compliance with IEB 79-14 requirement Problems 1-53-1 and 1-53-2 were modelled using an overlap modelling technique rather than using anchors for the problem ends. Discussions with the licensee revealed that all Oconee piping seismic analysis were reperformed during IEB 79-14 wor The licensee estimated that approximately 12 percent of all the analysis were modelled using the overlapping techniqu In March, 1981, NUREG/CR-1980 BNL-NUREG 51357RM was publishe The NUREG concluded that:
a. There is no general way of assessing the accuracy of the structural overlap method other than comparing the results of the full system anchor-to-anchor analysis to those of the individual subsytem analyses for a particular proble There will be differences between an analysis which uses the overlap method and an analysis of the full syste The differences could be magnified when periodic excitation is impose Appropriate requirements on the overlap region can keep the differences small enough so that, even if magnified, they still remain negligible. This is especially important where time histories of responses are obtained in load combination problem c. The structural overlap method should not generally be applied in lieu of a standard substructure or complete anchor-to-anchor analysis of the full system. However, if a sufficiently stiff (high natural frequency)
property is associated with the overlap region, or if the overlap region is extensive, acceptable results could be obtaine Its use appears to be adequate only for extremely large problems for which case the standard substructure method of analysis is preferabl For those situations where this method is used the following specific criteria should be applied:
(1) The overlap region should have enough rigid restraints and include enough bends in three directions to prevent the transmission of motion due to modal excitation from one end to the other and to reduce to a negligible level the sensitivity of the structure to the direction of excitation. Specifically, there should be at least four rigid restraints in each of three mutually perpendicular directions in the overlap region (including the
ends).
For axial restraints only this requirements may be relaxed to a single restraint in any straight segmen (2)
For cases where multiple spectra are involved at the different anchor points the spectrum to be used for each subsystem analysis is dependent on the rigidity of the overlap regio If the fundamental natural frequency of the overlap region is demonstrated to be at least 25 percent higher than the highest significant forcing frequency then the envelope spectrum of the spectra associated with the boundaries of each separate subsystem is acceptabl If the rigidity of the overlap region is not demonstrated or its frequency characteristics do not meet the criterion stated above the full system.
(3) The envelope of the support forces should be increased by 10% for design purpose The licensee had a copy of the NUREG but had not yet compared the Oconee piping analysis with the conclusions of the NURE Discussions with the licensee and a review of the previously noted piping analysis problems revealed that the overlap modelling technique used for Oconee differed from the NUREG criteria as follows:
a. The Oconee overlap problems did not necessarily contain four rigid restraints in each of the three perpendicular directions in the overlap region. The licensee indicated that a majority of the Oconee piping analysis contained more than the NUREG specified restraints in the overlap region, some problems did not meet this criteri b. The Oconee overlap problems did not overlap the response spectra for the both subsystems involved but enveloped the response spectra for the individual subsystems in each problem. The rigidity of the overlap region was not necessarily evaluate c. The support forces were neither enveloped nor increased by ten percen The licensee indicated that the analysis chose one of the two resultant loads that was deemed to be the most realistic for the individual support The licensee committed to provide a revised response to IEB79-14 to include a comparison of the Oconee overlap modelling technique with the NUREG criteri A review of the status of pipe support and restraint modifications resulting from IEB79-02 and IEB79-14 inspections and re-analysis revealed that out of approximately 2600 seismic catetory 1 hangers per unit, approximately 600 per unit required major modifications, approximately 540 per unit required minor modifications and approximately 130 per unit required remova Reanalysis of pipe supports was noted to be approxiamtely 85% complet The licensee was unable to specify, during the inspection, the projected analysis and repair completion status for Unit 1 refuelling outage
completion. The licensee committed to submit this status by October 16, 198 The licensee further committed to provide the same information for Unit 2 by two months prior to the completion of its next scheduled refueling outag Pending completion of IEB79-14 requirements and licensee commitments the bulletin shall remain ope No violations or deviations were identified.