IR 05000259/1979032
| ML14358A389 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 11/07/1979 |
| From: | Herdt A, Van Doorn P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML14358A388 | List: |
| References | |
| 50-259-79-32, 50-260-79-32, 50-296-79-32, NUDOCS 7912210218 | |
| Download: ML14358A389 (4) | |
Text
SoUNITED STATES NUCLEAR REGULATORY COMMISSION REGION il 101 MARIETTA ST., N.W., SUITE 3100 ATLANTA, GEORGIA 30303 NOV
- 91979 Report Nos. 50-259/79-32, 50-260/79-32 and 50-296/79-32 Licensee:
Tennessee Valley Authority 500A Chestnut Street Chattanooga, Tennessee 37401 Facility Name:
Browns Ferry Nuclear Plant Docket Nos.50-259, 50-260 and 50-296 License Nos. DPR-33, DPR-52 and DPR-68 Inspection at Browns Ferry Site near Decatur, Alabama Inspector:
""
d Y'. VanDoo Date Signed Approved by:
-
-3-/.cy 1 <y cr
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/4e A. rdt, Section Chief, RC&ES Branch Date Signed SUMIMARY Inspection on October 16-18, 1979 Areas Inspected This routine announced inspection involved 20 inspector-hours on site in the areas of inservice inspection work activities and records (Unit 3); followup inspection of feedwater pump shaft failures (Units 1, 2 and 3); and followup inspection of actions taken concerning damages caused by dropping of an RHR heat exchanger tube bundle (Unit 3).
Results Of the three areas inspected, no items of noncomplience or deviations were identifie DETAILS Persons Contacted Licensee Employees
- H. L. Abercombie, Plant Superintendent
- J. E. Swindell, Assistant Outage Director
- D. E. Harvey, ISI Coordinator T. L. Hale, ISI Coordinator C. E. Anderson, Turbine Maintenance Group Engineer M. W. Haney, Mechanical Maintenance Supervisor Other Organization Lambert, MacGill and Thomas, Inc. (LMT)
E. L. Thomas, Level III Inspector/Supervisor NRC Resident Inspector
- R. F. Sullivan
- Attended exit intervie.
Exit Interview The inspection scope and findings were summarized on October 18, 1979, with those persons indicated in Paragraph 1 abov.
Licensee Action on Previous Inspection Findings Not inspecte.
Unresolved Items Unresolved items were not identified during this inspectio.
Independent Inspection Effort Unit 3 Recirculation System Inlet Nozzles The inspector reviewed ultrasonic test (UT) records for inspection of the thermal sleeve attachment welds for recirculation system inlet nozzle No N2B, N2D, N2F, N2H, and N2K. This was a special inspection conducted to ascertain if cracking emanated from the attachment weld. TVA has now completed the UT inspection of these welds for all recirculation system inlet nozzles for all Browns Ferry Units. TVA volunteered to perform this inspection since some design similarities were noted to Iowa Electric Light and Power Company's Duane Arnold Nuclear Facility where severe cracking had
-2 been experienced. Scan 4 (vessel toward weld) showed 3600 indications greater than 100% DAC which are typical geometric indications caused by the external sloped configuration of the safe-end. Geometric indications were also noted from the more meaningful Scan 3 (toward vessel).
These were 3600 and ranged from 25% to 50% DAC. Therefore, no significant indications have been found in recirculation system inlet nozzles at Browns Ferr No items of noncompliance or deviations were identifie.
Followup Inspection of Feedwater Pump Shaft Failures (Units 1, 2 and 3)
The inspector reviewed status and actions taken by the licensee regarding feedwater pump shaft fatigue cracking experienced in pumps 1A and 3 It should be noted that the feedwater pumps are non-safety-related components at Browns Ferry. This inspection was conducted to determine possible generic implications. TVA has determined that the problem is a generic one involving Dresser Industries, Pacific Pump Division pumps which were manu factured prior to 1972. No other pumps are affected at Browns Ferr A similar material problem was reported to TVA by Westinghouse Electric Corporation concerning safety-related Centrifugal Charging Safety Injection Pumps at the Sequoyah Nuclear Facility. These shafts were replaced with improved material. TVA is determining how many shafts are affected in all systems at all TVA sites and will systematically replace the original shafts. Original shafts were Type 414 stainless steel and were found to have low impact test values. TVA intends to replace shafts with improved Type 17-4PH stainless steel. These new shafts are expected to be available at Browns Ferry by January 198 Shafts for pumps 1A, IB, 3A, 3B and 3C have -been replaced on an interim base However, these shafts are not the new Type 17-4PH shafts. Catostrophic failure is not expected since experience has shown that vibration is experienced prior to total failure. The pumps are instrumented to detect the vibration. The Browns Ferry pumps have also experienced impellor errosion from a cavitation problem caused by unequal flow to the two suction heads induced by the inlet piping configuratio TVA has modified a suction head support strut on pump 3A to attempt to improve flow characteristics. Other pumps may also be modified if improve ment is realized on pump 3A. TVA also intends to change impellors to an improved material to better resist errosio If these actions do not improve impellor errosion, modifications to piping will be evaluate Further evaluation is being conducted by NRC concerning the pump shaft generic proble No items of noncompliance or deviations were identifie.
Followup Inspection of Actions Taken Concerning Damages Caused by Dropping of an RHR Exchanger Tube Bundle (Unit 3)
On October 7, 1979, an RHR heat exchanger tube bundle weighing approxi mately 11.5 tons was dropped approximately 20 feet back into the heat exchanger shell. No personnel injuries were sustained. It was subse quently determined that a rigging chain link weld had failed. Preliminary metallurgical evaluation showed 50% to 70% lack of weld bond on the broken
- e
-3 link. Preliminary evaluation of damages showed damages to concrete at support locations, displacement of supports as much as three inches and tube denting for at least the first two outer rows of tubes. At the time of this inspection intended actions by the licensee included the following:
providing a temporary support structure under the heat exchanger shell prior to attempting removal of the tube bundle; removing the tube bundle with a new lifting rig, load testing the chain of the new lifting rig, and load testing the complete rig just prior to performing the new lift; taking precautions to prevent overload (load cells and strain gages); taking precautions to prevent twisting of chain during the second lift (it is possible that twisting of chain occurred during the first lift); accom plishing a full evaluation of damages and induced stresses once the tube bundle is removed; and analyzing and inspecting of piping and supports based on assessment of stress caused by the accident. On October 17, 1979 the inspector questioned whether nondestructive examination could be per formed on the chain link weld It was determined that magnetic particle inspection (MT) might be possible using a direct current coil method and that radiography could be used as a tool to verify MT results. The licensee agreed to attempt these inspections prior to the new lift being performe The licensee also informed the inspector that further metallurgical evalua tion would be performed on the chain which faile No items of noncompliance or deviations were identifie.
Inservice Inspection - Observation of Work and Work Activities (Unit 3)
The applicable Code is the ASME Boiler and Pressure Vessel Code,Section XI, 1974 Edition plus addenda through Summer 1975. The inspector observed ultrasonic inspection to determine whether NRC, Code and procedure require ments were being met. The inspector observed portions of 600 shear wave inspection of recirculation system inlet nozzle to reactor vessel welds for nozzles N2B and N2D and 700 shear wave inspecton of the inner radius of feedwater system nozzle N4E. The ISI program was being followed, personnel were properly qualified, approved procedures were available, personnel were familiar with equipment and methods being employed, results were appropriately recorded and procedure technical attributes were being followed for each inspectio No items of noncompliance or deviations were identified.