ML20079K310
| ML20079K310 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 11/23/1983 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| Shared Package | |
| ML20079K291 | List: |
| References | |
| NUDOCS 8401240574 | |
| Download: ML20079K310 (6) | |
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_ O'j '"yj gg A g. gember 23, 1983 U.S. Nuclear Regulatory Comission
. Region II Attn:
Mr.. James P. O'Reilly, Regional Administrator 101.Marietta Street, NW, Suite 2900 Atlanta',- Georgia 30303
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Dear Mr. O'Reilly:
-BELLEFONTE NUCLEAR PLANT UNIT 1 - REVISED RESPONSE TO VIOLATIONS 438/83-15-04,.SWITCHGEAR FRAME WELDED ASSEMBLIES 438/83-15-05, BODY TO BONNET VALVE ~ CONNECTION LOOSE DURING. PERFORMANCE OF DHR FLUSH This letter-is in response to the TVA/NRC telecon of September 30, 1983 concerning activities at Bellefonte Nuclear Plant which appeared to have y
_ been. in violation of NRC regulations as discussed. in D. M. Verrelli's letter to 'H. G. Parris dated July 19, 1983 The NRC requested that TVA provide additional information to supplement our initial response as stated in my letter to you dated August 24,1983 Enclosed is a revision to the initial response with supplemental changes -
and/or corrections.
If you have any questions concerning this matter, please get. in touch with R. H. Shell at FTS 858-2688.
' To the best of my knowledge, I declare the stateme-ts contained -herein are complete and true.
Very truly yours, TENNESSEE VALLEY AUTHORITY i-b L. M. Mills,' Manager I
Nuclear Licensing
. Enclosure oc:
Mr. Richard C. DeYoung, Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Comission Washington, D.C.
20555l "ecords Center (Enclosure) 7.natitute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite'1500 Atlanta,' Georgia 30339 8401240574 831215 (DRADOCK 05000438 PDR 1983-TVA SC,(H ANNIVERSARY An Equal Opportunity Employer e
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r ENCLOSURE BELLEFONTE NUCLEAR PLANT UNIT 1 RESPONSE TO SEVERITY LEVEL V VIOLATION
.t 50-438/83-15-04 SWITCHGEAR FRAME WELDED ASSEMBLIES Description of Deficiency 10 CFR 50, Appendix B, ' Criterion IX and VII and the accepted QA program (TVA-TR-75-1 A, Rev. 5) Sections 17.1 A.9 and 17.1 A.7 respectively require that measures shall be established to assure that welding is controlled and accomplished in accordance with applicable codes and specifications. In addition, measures shall be established to assure that purchased services conform to the procurement documents.
Contrary to the above, on May 24, 1983, activities afrecting quality were not accomplished in accordance with vendor's specifications in that numerous vendor made welds used to assemble the 6.9kV medium voltage switchgear were de ficient.
(Unit 1) 4 TVA Response Admission or Denial-of the Alleged Violation TVA denies the alleged violation.
Reasons for Denial Codes
. At the time the contract was awarded, there was not an applicable welding c od e.
The contract was awarded December 18, 1974. ANSI /AWS Standard D1.3 was first issued in 1978 as " Specification for Welding Sheet Steel in Structures."
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Specifications It is charged that welding as a.special process must satisfy Criterion IX of i
10 CFR 50, Appendix B, which requires that measures be established to assure i
that special processes are performed by qualified personnel using qualified procedures in accordance with applicable codes and specifications, and.
l Criterion VII which requires that measures be establ*.shed to assure that l
purchased equipment conform to the procurement documents.
It was not TVA's intention to define special processes or to prescribe manufacturing methods or processes for this type equipment which has seen many years of proven reliable service and in many cares thousands of
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operations, often in high vibration locations such as coal handling facilities in fossil generating stations. Rather, TVA specifies the required I-performance (including seismic qualification) and conformance to industry standards (requiring proof testing of functional performance and mechanical l
- life as bases for rating) for this type equipment. To require i
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c vendor to d;viat2 fro:n his proven manufacturing methods would tend to introducs unknown offsets in.th3 quality of tha equipment.~ Further, for equipment of this type, TVA requires as a basis of bid that a prospective 1
Vendor provide experience data relative to equipment of similar type,,s, cope,.
and complexity in operation in similar applications, and places high value on '
this documentation (which is confirmed). The welding of the basic structure
'has not been considered by TVA to be a special process unless the vender so identifies it on the 'basia of the criteria-of. Section 9,' Control of Special Processes, of IEEE Standard 467-1980, Quality Assurance-Program Requirements' for the Design of Class 1E Instrumentation and Electric Equipment for Nuclear' Power Generating Stations (NPGS).-
Sw'itchgear welding is defined on standard-manufacturing drawings used exclusively in' shop fabrication (i.e., they are not procurement drawings).
The type of sales order (S0): drawings which are furnished to TVA normally do not show welding symbols. The majority of the switchgear welds (95 percent) are spotwelds. The ITE factory procedures require that spotweld " set ups" are checked by'spotwelding two samples of the same gauge metal as in the switchgear and performing a tensile-pull test to prove the acceptability of the actual switchgear production spotwelds. Records of these test inspec-ltions are maintained. 'Section 3.9.4.1 of the vendor's QA manual points out
- that since the welding machine and operator are qualified by a sample
' demonstration test at time of any change of shift or change of set up, neither criterion for identification as a special process is met because (1) quality is not then dependent on operator skill' and (2) the end quality (of the weld) can be readily determined by inspection and by the pretest. The
. vendor's QA manual, furnished to and approved by TVA as a condition for contract award, discusses only spotwelding.
It is important to note, however, that the welding of concern to the NRC inspector is the are welds appearing in the 8-inch extension added to the front of the switchgear to permit use of a full-height door. The 8-inch extension consists of two side plates, a top plate, and an assembled floor.
The complete extension is assembled and then secured structurally to the main frame by bolting at the rear flar.ges of the side pieces. The top has a lip at the~ sides which is arc welded only to the sides and serves only to maintain' the proper dimensional relationship. The floor is preassembled by t
spotwelding from three pieces so as to match the floor thickness and the breaker guide rails of the main frame floor. The floor is are welded to the sides by lap welds and is butt welded to the main frame floor to assure a plane surface for rolling the drawout breakers and to establish dimensional relationships. The structural strength of the extension to the bauic frarse is ' established by the above-mentioned bolting, not arc welding. The floor sill to which the entire assembly (main frame plus extension) is anchored is beneath the main frame, not beneath the extension. The 8-inch er. tension was a part of the seismic test specimen.
Structural strength of this class switchgear is achieved with structure configuration using spotwelded attachments in the basic frame. Arc welds are typically used only for special device mounting or for added features suon as the extra-depth front enclosure. There are no arc welds picced in the basic frame configuration duc ' to inaccessibility of the spotwelding machine.
Additionally, at the Brown Boveri Electric plant in Chalfont, Pennsylvania, where this ITE switchgear was manufactured, there is no requirement for are welds (tacking) to hold pieces in place until spotwelded.
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- Although tha valvo in qusstion did have a loors connection, the deficicnt
- , condition had not progressed to the point where valve integrity had been lost. Further, had this condition remained unidentified by the inspector, TVA would have been able to identify and correct the deficiency during ' system hydrostatic testing in the event valve integrity was lost. Any gasket leakage detected during the system test would have been promptly corrected by retorquing in accordance with procadures. Any unacceptable leakage discovered after system transfer ta TVA's Division of Nuclear Power is corrected by the maintenance group based on requests by power operations.
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BELLEFONTE NUCLEAR PLANT UNIT 1 RESPONSE TO SEVERITY LEVEL V VIOLATION s
50-438/83-15-05 BODY TO BONNET VALVE CONNECTION LOOSE DURING PERFORMANCE OF DHR FLUSH s
Description of Deficiency 10 CFR 50, Appendix B, Criterion V and the accepted QA program (TVA-Tn75-1A, Rev. 5) Section 171 A.5 requires that activities affecting quality be accomplished in accordance with procedures.
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ANSI N45.2.8, ' paragraph 3.1 states that-the follcwing: Prior to the actual installation of mechanical items, there are certain preliminary inspection, checks and similar activities that shall be completed to verify that the item and the installation area conform to specified requirements and the necessary resources are available to assure that the quality of the mechanical item will be maintained as the installation proceeds.
Contrary to the above, activities affecting quality were found not to be in accordance with. procedures and drawings in that a Decay Heat Removal valve had a loose body to bonnet joint. This became a generic problem in that approximately 464 valves were involved.
TVA Response
' Admission or Denial of the Alleged Violation TVA denies the alleged violation.
Reasons for Denial TVA denies the violation as stated based upon the position that a program deficiency does not exist. TVA aintains that its program which ensures proper mechanical joint integrity adequately addresses this concern. The criteria established by ANSI N45.2.8 referenced in report 50-438/83-15, 50-439/83-15 addresses only five conditions for pre-installation verification, one of them being section 3.1 " General," referenced in the report. These requirements covering preinstallation have been implemented through site-generated Quality Control Procedure 1.1 " Receiving Inspection." The remaining paragraph referenced in the Linspection report from ANSI is 4.4, " Inspection" which identifies controls that are to be established during installation processes. These activities are implemented through Quality Control Procedure 6.9, " Valves," and Construction Test Procedure 7.6, " Hydrostatic Testing." Based on the requirements established by these documents, no violation of criteria in ANSI N45.2.8 was found.
TVA agrees that a technical problem did exist, as identified by NCR 1686, and investigation revealed that the manufacturer had in part used inadequate torque values for assembly of body to bonnet valve connections. New values were established by the manufacturer, and TVA committed to increasing torque values of these connections for 'all affected valves. This completed corrective actions necessary and any concern associated with the manufacturer's requirement to ensure the mechanical joint integrity.
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.In summary, thcre are no hidden ctructural tro welds in the switchgcar, and s
the are welds inspected et thb sito by the NRC inspector do not ssrve a structural function but rather to maintain dimensional relationships.
a At the time the switchgear fbr this contract was manufactured the spotwsiding procedures and welding personnel were qualified. Similar equipment constructed by the same production facilities has been subjected to seismic testing at levels substantially higher than that of the Bellefonte Plant without any weld failures. Both the vendor and TVA continue to maintain that this equipment is acceptable for Class 1E use as is and is fully qualified for the life of the plant.
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