IR 05000269/1991025
| ML16148A561 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 10/04/1991 |
| From: | Blake J, Economos N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML16148A562 | List: |
| References | |
| 50-269-91-25, 50-270-91-25, 50-287-91-25, NUDOCS 9110290137 | |
| Download: ML16148A561 (7) | |
Text
1REq UNITED STATES
.
o NUCLEAR REGULATORYCOMMISSION
REGION II
101 MARIETTA STREET, ATLANTA, GEORGIA 30323 Report Nos.:
50-269/91-25, 50-270/91-25, and 50-287/91-25 Licensee:
Duke Power Company 422 South Church Street Charlotte, NC 28242 Docket Nos.:
50-269, 50-270, License Nos.:
DPR-38, DPR-47 and 50-287 DPR-55 Facility Name:
Oconee 1, 2, and 3 Inspection Cond ted:
September 3-6, 1991 Inspector:-
<
N.Date Signed Approved by: CeDate Signed M ter als and Processes Section ng eering Branch ivision of Reactor Safety SUMMARY Scope:
This routine, unannounced inspection was conducted in the area of Unit 1 inservice activities with emphasis on once through steam generator (OTSG) tube plugging. repairs, components cooling check valve replacement and associated welding, boric acid corrosion prevention programs, evaluation of primary loop indication identified by ultrasonic examination during this outag Results:
By observation, interviews and a review of records and procedures, the inspector ascertained that plugging of the cracked welded plugs.installed in previous outages was being done with prototype equipment developed for this project. Engineers and technicians directing and/or performing this task were found to be well trained and exercised conservatism in their decisions. Record keeping of work activities was satisfactor In the areas inspected, violations or deviations were not identifie PDR ADOCK 05000269 G
REPORT DETAILS 1. Persons Contacted Licensee Employees
- H. B. Baron, Station Manager
- J. Batton, Nuclear Production Engineer B. W. Carney, Mechanical Technical Support Engineer
- W., W. Foster, Maintenance Superintendent
- W. T. McClure, Tech Support, QA
- B. Millsaps, Maintenance Services Manager
- R. A. Morgan, QA Director Other licensee employees contacted during this inspection included technical support, QA,.and administrative personne Other Organizations B&W Nuclear Services Company M. M. Munsterman, Welding. Foreman B. Stallings, Project Manager NRC Resident Inspectors P. Harmon, Senior Resident Inspector
- B. B. Desai, Resident Inspector W.. Poertner, Resident Inspector
- Attended exit interview Inservice Inspection Unit 1 This inspection was conducted as a follow-up to that documented in Report N /91-20 for the purpose of observing the welding of plugs on previously explosively plugged tube This action became necessary when it was discovered that the explosive plugs had exhibited crackin. Welding (55050)
a. Once Through Steam Generator (OTSG) Welded Plug Repair, Unit 1 The eddy current (EC)
inspection of welded plugs in OTSGs "lA" and
"lB" disclosed evidence of crack indications and the licensee concluded that corrective action would be necessary prior to returning the unit to servic The number of tubes with plugs requiring repair was as follows:
S/G 1A S/G 1B Cold Leg
--
Lower Tube Sheet
25 Hot Leg
--
Upper Tube Sheet
.104 B&W Nuclear Service Company (B&W) was contracted to provide technical support and manpower for this tas ASME Code Section XI, 1989 Edition IWB-4230, (Code) was invoked as the controlling document for this repair. Because this edition of the Code has-not been approved by the Commission, the licensee requested and received permission from NRR to proceed with the repair under the rules of the. subject Code edition (see Region II Report N for further details on this matter). As discussed in the -aforementioned report, the repair plugs were welded to the tubes using the automatic gas tungsten.arc process (TIG)
with NiCr-3 Inconel filler metal wir The actual welding was done by remote control to minimize exposure to radiatio The welding equipment was developed specifically for this repair by Welding Services of Atlanta, GA,. while the milling machine and plug handling equipment used to weld-prep. (spot-face)
the tube ends, and to transport the repair plugs were-developed by B&W., Because the milling and handling equipment were prototypes,.B&W encountered a number of mechanical problems, which included metal cutting, handling and locating the plugs in the tube end However, as the repair progressed, these difficulties were resolved and the -job was completed satisfactoril The repair plugs were made from Inconel 690 material produced from heat number NX6977HK, Lot number 1 The material was provided by INCO Alloys to B&W under QA Package 23-1200823-00. Certificate(s) of conformance and certified material test reports on the subject plugs were reviewed and found. in orde The repair activity was controlled by a Process Traveler entitled Remote Welded Plug Installation, number 50-1203388-00. This document provided detailed work instructions for the project which included hole preparation, remote welded plug installation, remote welded plug repair and line item documentation of work performe Completed welds were visually inspected per VT-1 procedure, Visual Examination of S/G Tube Plug Welds, Re, written to comply with ASME Code Section XI (86W86), IWA-2000 and Section V, Article 9, 1986 Editio Third party inspect-ion (ANI) was provided by Hartford Boiler Compan The inspector reviewed technical support documents and quality records including personnel qualifications, materials receipt inspection reports, certifications,.inspection results, noncon formance reports and QA/QC inspections of completed welds. Following is a list of tubes where some of the aforementioned problems were incurre Tube N OTSG Problem Resolution
- 87-126
"B" Tungsten Electrode Corrected by welding stuck repair 147-11
"A" Weld imperfection Corrected by welding
"fish eye" repair 73-1
"A" Incomplete weld Repositioned equipment due to weld head and completed join positio *98-126
"B" Arcing because of Corrected by welding equipment problem repair
- Nonconformance reports were written on these tubes to document multiple repair In addition to the above, the inspector noted that in the upper tube sheet of OTSG/"B",
a' small 'section of the clad, along with three tubes85-125, 85-126 and 86-126, sustained some damage during the spot-facing/machining operation. The licensee stated that the damag incurred because of an indexing problem with the milling machin This caused the. machine to cut at an angle of approximately 28 degrees off the vertica The licensee's follow-up inspection and evaluation disclosed that a section of tube '85-125 was machined down to the clad/tube-sheet interface location which exposed a small area (0.027")
of the alloy. steel tube-shee Damage to the other two tubes,85-126 and 86-126, was relatively mino Following the close of this inspection, the inspector ascertained that the.licensee took the following remedial actions on the subjec tubes:
85-125 Drill hole in existing explosive plug; reroll tube and install a roll plu Drill hole in existing explosive plug and install a rolled plug with stabilize No remedial action require In reference to the exposed alloy steel material on the upper tube sheet of OTSG "B", the licensee stated that an engineering evaluation had been performed which determined that it was.acceptable to leave the affected -area. in. the as is condition for one fuel cycle. A repair procedure to correct the damage will be developed and implemented at the next refueling outag It is the inspector's understanding that the licensee contacted NRR by.memorandum to apprise them of the use of ASME Code Section XI,.1989 Edition and the
aforementioned damage to the tube-sheet. Through discussions with NRR staff, the inspector ascertained that NRR has concurred with the licensee's position on the use of the 1989 Edition of the Code and that the proposed remedial action(s) are under evaluatio Within the areas inspected, no violations or deviations were identifie b. Check Valve.Replacement Discussions with Maintenance Services management disclosed that replacement of problem swing check valves was scheduled for.this outage. For the most part, the problem was related to accelerated degradation of valve internals which resulted in their failure to perform their design function or to pass required testin 'The majority of these check valves were found in the feedwater system, component cooling and circulating water system The. valves ranged in size from three to ten inches in diameter. Four check valves from the component system were selected for a.review and evaluation of material, installation and testing records. The subject replacement valves were identified as follows:
Valve #
Size Type QA Tag ICC-20 6-inch dia Swing Soft Seat 62401 ICC-24 6-inch dia Swing Soft Seat 62401 ICC-76 2-1/2 inch dia Swing Soft Seat 62404 ICC-77 2-1/2 inch dia Swing Soft Seat 62404 These replacements were performed on work requests 54053 through 54055, respectivel Maintenance procedures used in this task included:
MP/0/A/1800/001 Process Record (tools and materials inventory)
MP/0/A/1810/014 Valves and piping -
Welded -
Removals and Replacement -
Class A-F MP/0/B/1810/015, Change 11 Process record of procedure reviewed MP/0/A/1720 Change 17 System hydro The controlling code of record for welding and testing was USAS Power Piping Code B31.1. The welds were classified as Duke Class F and as such were visually inspected following weld completio The replacement valves were purchased to meet ASME Code Section III, Class 3 (89W89) requirements, delineated in on Duke's purchase orders
A12669-77-003 and-004 and the applicable specificatio The inspector reviewed quality records including work travelers, code data reports, material certifications, certificates of compliance and receipt inspection reports for the subject valves and associated replacement pipin The new welds were fabricated with a combination gas, tungsten arc/shielded metal arc (TIG/SMAW)
weld procedure qualified to ASME Code Section IX requirement The inspector reviewed procedure qualification records and performance records for welders who fabricated the replacement welds. These welders were. identified by stencil number W91, 455 and 58 Within the areas inspected, violations or deviations were not identifie. Boric Acid Corrosion Prevention Program Units 1 and 2 (62001)
Discussions were held with the licensee's cognizant engineer.to ascertain whether the essential elements of Generic Letter 88-05,
"Boric Acid Corrosion of Carbon Steel Reactor Pressure Boundary Components in PWR Plants," were being implemented. These elements were to include, but not be limited to, a documented program, approved working procedures providing clear guidance for performing activities specified by the program and objective evidence to verify implementation of programmatic requirement Administrative controls for this task is provided. through Operations Management Procedure (OPMN)
1-6, Rev. 5, and Maintenance Directive 5.37, Conducting and Documenting Reactor Building Boron Inspections. Inspection records spanning a period of three years were reviewe These records documented observations and corrective actions taken as require Based on this work effort, the inspector concluded that the licensee has adequately responded to Generic Letter 88-05 requirements through a'
comprehensive inspection program that provides for identification of problem areas and the mechanism to take appropriate corrective action as require Within the areas inspected, violations or deviations were not identifie. 'Review and Evaluation of ISI Records Unit 1.(73755)
In the previous inspection, documented by Report No. 91-20, the inspector reported that a code rejectable indication had been identified in a imary loop piping weld No 1P1B15, figure number B09.011.03 The indication was discovered during a scheduled inservice inspection by ultrasonic examination. A problem investigation report, #1-091-0085, was issued and following an evaluation by the licensee's Level III examiner to confirm its validity, the licensee expanded the weld population by adding
.eleven more welds to the inspection plan as required by the Cod During this inspection, the inspector reviewed the weld selection and inspection results which identified no further problems. Since.the close of this inspection, the inspector ascertained that the licensee performed a fracture analysis and determined that the indication in the weld did not compromise weld integrit This analysis will be. reviewed by this inspector on a future inspectio Within the areas inspected, violations or deviations were not identifie. Exit Interview The inspection scope and results were summarized on September.6, 1991, with those persons indicated in paragraph 1. The inspector described the areas inspected and. discussed in detail the inspection result Dissenting comments were not received from-the licensee.