IR 05000338/1982027
| ML20027A968 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 08/18/1982 |
| From: | Economos N, York J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML20027A954 | List: |
| References | |
| 50-338-82-27, 50-339-82-27, NUDOCS 8209160229 | |
| Download: ML20027A968 (6) | |
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O Escog UNITED STATES NUCLEAR REGULATORY COMMISSION E
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101 MARIETTA ST, N.W., SUfTE 3100
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Report Nos. 50-338/82-27 and 50-339/82-27 Licensee:
Virginia Electric and Power Company Richmond, VA 23262 Facility Name: North Anna Docket Nos. 50-338 and 50-339 License Nos. NPF-4 and NPF-7 Inspection at North Anna site near Mineral, VA Inspector:
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J. W. Yorkf y
' Dat6 Signed Approved by:
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V N. Ecoli5'mos, Acting Section Chief
/Datefigned Engineering Inspection Branch
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Division of Engineering and Technical Programs
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SUMMARY Inspection on July 27-30, 1982 Areas Inspected This special announced inspection involved 23 inspector-hours on site in the areas of thermal sleeve removal, flow splitter removal, peening damage to steam generator tube sheets and tube lane blocking device fasteners cracking.
Results In the areas inspected no violations or deviations were identified.
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8209160229 820819 PDR ADOCK 05000338 G
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REPORT DETAILS 1.
Persons Contacted Licensee Employees
- W. Cartwright, Station Manager
- J. Hanson, Jr., Superintendent of Technical Services
- M.
Fellows, Staff Assistant J. McAvoy, Senior Staff Engineer Q. Parker, Engineering Supervisor, Project Other licensee employees contacted included construction craftsmen, technicians, and office personnel.
NRC Resident Inspector
- D. Johnson M. Shymlock
- Attended exit interview 2.
Exit Interview The inspection scope and findings were summarized on July 30, 1982, with those persons indicated in paragraph I above. The licensee acknowledged the inspection findings.
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Licensee Action on Previous Enforcement Matters Not inspected.
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Unresolved Items Unresolved items were not identified during this inspection.
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Independent Inspection Effort (92706)
Currently'both Units 1 and 2 at the North Anna site are in an outage. The scheduled return to power dates are August 9 for Unit 2 and mid September for Unit 1.
The inspector reviewed the following activities that were being planned or were underway for this outage (a) thermal sleeve removal, (b) flow splitter removal, (c) problem with nuts on tube lane blocking device, and (d) problem with tube sheet damage caused by locking nut from control rod guide tube support pin. Following are the results of the inspections in these areas:
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(a) Removal of Thermal Sleeves - Units 1 and 2 IE Information Notice No. 82-30, " Loss of Thermal Sleeves in Reactor Coolant System Piping at Certain Westinghouse PWR Power Plants," states that Westinghouse has recommended that a nondestructive examination be performed to assess thermal sleeve conditions of affected systems at the next extended plant outage. As a result of this recommendation, the licensee radiographed the following nozzles in both Unit Nos. 1 and 2 to determine the condition of the thermal sleeves:
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2 inch diameter loop fill nozzle, loop A
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2 inch diameter loop fill nozzle, loop B
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2 inch diameter loop fill nozzle, loop C
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3 inch diameter charging nozzle, loop B
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6 inch diameter safety injection nozzle, loop A
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6 inch diameter safety injection nozzle, loop B
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6 inch diameter safety injection nozzle, loop C
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12 inch diameter accumulator discharge nozzle, loop A
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12 inch diameter accumulator discharge nozzle, loop B
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12 inch diameter accumulator discharge nozzle, loop C
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14 inch diameter pressurizer surge line nozzle The nozzles were radiographed to determine if the thermal sleeves were in their correct positions, along the length of the nozzle and in the correct position with regard to the circumferential direction.
Two fillet welds approximately 7/8 inch in length and located approximately opposite from each other hold the thermal sleeve in position. These welds were included in the radiographic evaluation.
The following problem areas were found:
Unit 1
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3 inch diameter charging nozzle in loop B - welds cracked
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6 inch diameter safety injection nozzle in loop A - sleeve not located in nozzle length to header Unit 2
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3 inch diameter charging nozzle in loop B - welds cracked and sleeve rotated 40
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6 inch diameter safety injection nozzle in loop C - weld cracked and sleeve rotated 5
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12 inch diameter accumulator discharge nozzle in loop B - welds cracked and sleeve dropped approximately 4 inches
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12 inch diameter accumulator discharge nozzle in loop C - welds cracked and sleeve dropped. approximately 1/8 inch. The licensee has decided to remove the displaced cracked thermal sleeves. The four thermal sleeves in Unit 2 will be removed first, before removing the two in Unit 1.
The thermal sleeve of the 6 inch diameter safety. injection nozzle in loop A of Unit 1 was not discernable in the radiographs The bottom of the reactor vessel was being video scanned for loose parts and the missing thermal sleeve.
The licensee's repair plans were not complete, but current planning indicates that the lines will be cut and the weld areas ground and examined. The pipe sections made accessible by the cut, will also be examined to determine if the thermal sleeves could have moved into the piping.
The two (2) thermal sleeves in loop C were being removed during this inspection. To remove each thermal sleeve the pipe was cut in two places and then prepared for rewelding.
The inspector observed the machining of a weld preparation on one end of the 6 inch diameter line and on one end of the 12 inch diameter line.
The inspector reviewed portions of Design Change No. 82-S16B,
" Reactor Coolant Thermal Sleeve Removal," which provides instruc-tions and sign off sheets for QC hold points.
The licensee visually inspected the two welds that held the thermal sleeve in the nozzle, after the cutting operation. When the thermal sleeve in the 6 inch diameter safety injection nozzle was visually inspected, one of the two welds appeared cracked, but when the thermal sleeve in the 12 inch diameter accumulator discharge nozzle was visually examined before removal, no cracking was evident in either weld although radiography indicated cracking.
Within the areas inspected, no violations or deviations were identified.
j (b) Removal of Flow Splitters Unit 1 During plant pre-start up at Unit 2 a crack was found in the reactor coolant pump suction elbow splitter on one.of the loops. The licensee decided to remove the flow splitter from this' elbow on all three loops and committed to inspecting and monitoring the flow splitters in Unit 1.
As a result of this monitoring program on Unit 1, one side of.
the flow splitter in the A loop was found to have ultrasonic testing (UT) indications that have increased in length by 15.5 inches from the October, 1981 inspection to the June, 1982, inspection. There are now UT indications of varying degrees along approximately 63 percent of the length of the weld plate interface.
The licensee has scheduled the removal of the flow splitter plate in this loop during the current outage. The plate will be removed using underwater plasma cutting torch which will be guided by a track and
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monitored by an underwater camera. The plate will be removed through the disassembled reactor coolant pump.
Before removal through' the-pump, the plate will be cut into four or five pieces using the under-water plasma torch. A protrusion of approximately 3 to 3h inches will remain on each side of the elbow after cutting. A milling machine will be set up to mill underwater approximately 1h" from these pro-trusions. An ultrasonic test will then be performed from the outside diameter of the elbow to assure that all of the defects have been removed.
The schedule of these events is as follows:
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Underwater plasma cutting of flow splitter plate-August 11
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Sectioning of splitter plate - August 12 to 13
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Milling of protrusions - August 16 to 18
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Ultrasonic testing - August 21 The licensee has not determined whether to remove either of the other two flow splitters during this outage and stated that Westinghouse was performing a thermohydraulic evaluation with several combinations i.e.,
with one flow splitter out and two remaining etc.
Within the areas inspected, no violations or deviations were identi-fied.
(c) Control Rod Drive Guide Tube Support Pin Failure - Unit 1 During May, 1982, North Anna 1 had a pin failure. The lock nut of a support pin was found in steam generator A and a smaller piece of the support pin was found in steam generator C.
Approximately 75 percent of the tube ends sustained some degree of damage. The greatest damage was on the tube ends nearest the partition plate and nearest the edges of the chamber.
Westinghouse is conducting a fracture mechanics evaluation for tube and tube welds.
The licensee stated also that several approaches are being evaluated for restoring the tube diameter in order to be able to perform ISI eddy current testing.
The following options were considered for solving the guide tube pin problem.
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Install a new set of upper internals
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Install new guide tubes
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Replace only the pins At the time of the inspection installing all new guide tubes was the chosen option. At the time the old guide tubes are removed and the guide tube pins are inspected the licensee stated that the option could be modified. Unit 2 had properly heat treated pins installed before initial criticality.
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Within the areas inspected, no violations or deviations were identi-fied.
(d) Nuts on Tube Lane Blocking Device - Unit 2 The licensee broke loose one of the locking / tensioning nuts in the sleeve area, when removing the tube lane blocking devices from Unit 2.
Each sleeve has two nuts welded to the top of the sleeve and one to the bottom. A bolt is inserted through the nut and the hole in the sleeve and rests against the steam generator inspection port wall.
The licensee examined the other sleeves and found that these three nuts had a number of cracks. The licensee repaired the components and dye penetrant inspected the welded nuts to insure the absence of cracks.
The licensee committed to requesting additional information from Westinghouse on this matter, i.e., material specification for nuts, if the flow in this area is sufficient to cause a loose nut to move into the tube lane area, etc.
Within the areas inspected, no violation or deviations were identified.