IR 05000313/1987017
| ML20215A215 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 06/09/1987 |
| From: | Hunnicutt D, Kerch H, Westerman T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML20215A192 | List: |
| References | |
| 50-313-87-17, 50-368-87-17, NUDOCS 8706160562 | |
| Download: ML20215A215 (12) | |
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APPENDIX U.S. NUCLEAR REGULATORY COMMISSION
REGION IV
NRC Inspection Report:
50-313/87-17 Licenses:
DPR-51-50-368/87-17 NPF-6
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Dockets: 50-313
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50-368 Licensee: Arkansas Power & Light Company (AP&L)
P. O. Box 551 Little Rock, Arkansas 72203 Facility Name: Arkansas Nuclear One (AN0)
Inspection At:
Russellville, Arkansas, and Region IV Offices, Arlington, Texas Inspection Conducted: May 10-26, 1987 Inspectors:
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//7/77 D. M. Hunnicutt, Chief, Operations Section ITate/
h b 1 ST H. W. Kerch, NRC, Region I, Lead Reactor Ddte/
Engineer Approved:
8.M/l 9/[7 T. F. Westerman, Chief,' Reactor Safety Date Branch Inspection Summary Inspection Conducted May 10-26, 1987 (Report 50-313/87-17)
Areas Inspected: -No inspection of Unit 1 was conducted.
Results: Not applicable.
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DETAILS'
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! Persons' Contacted'
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ANO.
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- D. B..Lomax,; Plant Licensing Supervisor
- E.'C. Ewing,1 General Manager, Plant ~ Support
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- P. Michalk, Pla'nt Licensing Supervisor
.*D. Provencher,;QA Supervisor
- D.' Howard,-Special Project: Manager.
- R.-Lane',' Manage'r, Engineering _
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- L.~Humphrey,.. General Manager, Nuclear' Quality-
- J.-Taylor-Brown', QC Superintendent.
.#B. Bakeri Operations'. Manager-
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- L. Taylor,-Plant Licensing Engineer.-
NRC
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- E. H.-' Johnson, Director, Division of Reactor _ Safety.and Projects
- C.:C. Harbuck, Resident Inspector
- D' M 1Hunnicutt Chief, Operations Section
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- H. W.'Kerch,- Lead Reactor-Engineer, Region I
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- - DenotesLattendance at-the May 14, 1987, exit interview.
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- Denotes' attendance at the May 15, 1987,' exit interview.
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The NRC inspectors also held discussions ~with other station and contractor personnel
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Identification'of Pressurizer Leakage
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~ On April 22, 1987, an entry was made into-ANO-2 containment to assess a l
possible'~small leak on'one of the safety injection tanks.
During the
'walkdown, leakage in the" area of the pressurizer was detected.
Entries L
into the ANO-2 containment were made on April 23 and 24,.1987, to further'
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evaluate.the leakage in the vicinity'of the pressurizer.- Two.small leaks were detected..0ne from the high point vent above the pressurizer (about 100 drops per minute) and the'second leak was from the area of the.
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pressurizer lower head (about 60 drops per minute or about 0.002 gallon L
p Eper minute).
ANO-2 was shut down on_ April 24, 1987,- as required by the
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- Technical Specifications.
The licensee issued a 10 CFR Part 50.72 report
.Lon the_ assumption that the leakage from the lower head area was through
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-The licensee removed the insulation from the-lower head area and
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1 determined that the leakage source was from the pressurizer heater sleeve
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in position XI. The' licensee attempted unsuccessfully to remove the
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heater element from the X1 sleeve.
The heater element in position T4 l.
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could not be removed. The upper head pressurizer manway was then opened for visual-inspection of the pressurizer heaters.
Visual inspection-revealed that these two heater elements had ruptured.
The rupture of heater. element in position X1 had caused damage to_the heater sleeve that.resulted in leakage.through the sleeve to the outside of the pressurizer.
Rupture of the heater element in position T4 had not damaged the sleeve and no leakage had occurred.
3.
. Pressurizer Repair Procedure-
.The licensee requested NRC approval to utilize the temper bead weld repair technique as described ~in paragraph NB-4622.9 of the Winter 1985 Addenda-of _ the ~1983 Edition of Section III of the ASME B&PV Code for temporary repair of the~ANO-2 pressurizer.
Permanent repair to the pressurizer as specified_in 10 CFR Part 50.55a, with current tooling limitations, would require excessive' radiation exposure to workers, a prolonged outage (estimated up to 22 weeks), and other related problems.
The proposed pressurizer repair technique was described in a meeting between the licensee and NRC staffs.on May 8, 1987.
The proposed repairs consisted of cutting and boring out the damaged sleeves (positions X1 and T4), verifying by nondestructive testing (NDE) that flaws were removed, mapping each-cavity and fabricating a carbon steel plug of compatible SA-533, Gr. B, C1.1 (P3) material, and completing a weld repair with pre-heat and post-heat treatment.
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4.
Full Scale Mockup for Personnel and Material Qualification
~The licensee prepared a full scale mockup to qualify personnel, procedures, and equipment.
The mockup consisted of a plate of carbon steel (C/S) (P3 material) approximately 4 inches thick and 30 inches in diameter.
This C/S plate was fitted into a confined area with dimensions similar to those encountered in the pressurizer lower head area.
This mockup area was constructed of light gage metal formed into an area approximately 9 feet in diameter.
The 4-inch thick, 30-inch diameter C/S
_ plate with heater extension tubes on centerlines and other related obstructions found below the pressurizer was installed into the full scale mockup.
The mockup was very similar to the conditions experienced under-the pressurizer as related to confined spaces, heater tube extensions, and physical obstructions.
The physical obstructions in the mockup area were in place to. impair the welders ability to perform; thus simulating conditions similar to those encountered by welders and NDE personnel-during welding and NDE examinations under the pressurizer.
The mockup for qualification of personnel required the following actions:
Welders were originally qualified to the procedure prior to
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qualifying at the mockup assembly.
Welders were fully dressed in protective clothing and respirators as
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required by the radiation work permit (RWP) for the repairs during welder qualification on the mockup.
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-Welding was performed.according to. weld procedure (DWPS SMA-3.3-914)
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irequirements, including preheat conditions of 350*F for the C/S plate and:the plug.
- The' temperature recording instrumentation was calibrated in
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accordance with the procedure.
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- The temperatures were~ monitored at eight locations during preheat,
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welding, interpass waiting periods, post weld heat treatment (PWHT),
and controlled cooldown during welding operations on the mockup.
Four locations were monitored during welding operations on Linstallation of plugs in locations:X1 and T4 on the Unit 2
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ipressurizer.. Four positi'ons. adequately monitored welding operations at.the--X1 and T4 positions.
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' Magnetic particle (MT) examinations were performed on the base metal
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Lweld joint, the temper bead layer (second weld bead layer), and each
. succeeding layer.of we.ld metal, including the finished weld surface.
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~ Welder qualification as required by ASME B&PV Code.
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- Weld procedure qualification test assembly to 'be same material (P3),
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pre-heat and PWHT:at: equivalent time:and temperature as the pressurizer. material (P3).
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Dimensional requirements of weld procedure qualification test-
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assembly,..includin'g depth of cavity.
Minimum 4-hour PWHT~ holding time for P3 material after veld repair.
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NDE and visual examinations verified' sound weld deposit metal in the
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X1 and T4 heater positions and in the pressurizer shell near the X1 heater' position.
' Remote visual examination of the heater diameter and area immediately
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above -the heater '(pressurizer inside diameter) including-the nozzle
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- cladding,' and seal weld area could be accomplished with the.
boroscope/ video; remote dye penetrant-(PT) could be done and
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The NRC inspectors observed portions of the above procedure'and personnel qualifications.
No violations or' deviations were identified.
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Welder Qualification The. welders were qualified at the mockup in accordance with ASME
.B&PV Code,Section III, 1983 Edition with Addenda through Winter 1985, c
Sections NB-4300, NB-3337.3, and paragraph N8-4622.9(g) and Section XI, paragraph IWB-4322.2. The full scale mockup demonstrations by each welder
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. determine that these welders were fully qualified to ASME B&PV Code, Sections III and XI, and the appropriate licensee procedures. The NRC inspectors observed portions of the procedure and welder qualifications at
'the. mockup on May 10-13, 1987.
No violations or deviations were identified.
6.
Remote PT Examinations Th'e licensee requested Babcock and Wilcox (B&W) to develop a technique for remote PT examination of the pressurizer heater channels and the inside diameter regions of the pressurizer shell in and near the X1 and T4 positions. The procedure (B&W ISI-246) and personnel were qualified on the mockup.- The procedure was approved for use prior to start of the pressurizer. repairs by the-AP&L staff.
The NRC inspector questioned the inservice inspection (ISI) requirements for the repairs to the X1'and T4 channel areas. The licensee requested Combustion Engineering (CE) to establish an ultrasonic (UT) baseline and applicable.ISI requirements. The completed temporary repairs will be monitored by AP&L staff members until permanent repairs are affected.
These actions and consnitments answered the NRC questions.
The' NRC-inspector discussed the weld repair procedure, NDE procedures, personnel qualifications, and ASME B&PV Code requirements with the Authorized Nuclear Inspector (ANI). The ANI approved these procedures subsequent to qualification and prior to start of repairs on the pressurizer.
. No violations or deviations were identified.
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NRC Review of Licensee and Licensee Contractor Procedures
' Procedure Title of.
Revision Date Number Procedure Number Approved 99770078-007-Engineering Requirements
05/10/87 for Removal and Reinstalla-tion of Heaters at ANO-2 9977078-003 Engineering Requirements
05/10/87
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for Repair of X1 Penetration at AN0-2 1000.12 Control of Site Contractors
12/05/86 1009.003 Contract Administration
11/05/86 Procedure
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.'ISI Program Requirements ~
07/14/86-1032.016/.
Field. Change Notice -
05/12/87
~202F20-
-Pressurizer. Heater #T-4
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Repair Modifications 11000.23-
. Quality Control Program 9:
~10/28/86 fct x
Dwg.-WOB-3898E Pressurizer Heater A
06/19/82:
-St.!No...'
"PressurizeriHeater T-4:
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05/12/87
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99779150-007 Penetration Repair l-
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9977078-008
/Eng'ineering R'equirements for
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. Repair'of-T-4_ Penetration at
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- ANO One,fUnit 2.
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.DWPS...
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- Welding Procedure' Specification
05/08/87 SMA-3.3-914-
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Welder Performance Qualifica-
05/12/87
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tion for the X-1 and:T-4 x
Heater Penetration Repairs to
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the ANO Unit 2 Pressurizer
-;99770078-004-C.E. Mockup Engineering-
05/12/87 Requirements DCP.#87-2044AJ Design Change ALARA Review
05/12/87-
- Checklist i DCP #87-2044A S&W ISI Procedure 246, " Remote
05/14/87
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Dwg!(Contract. Heater Sleeve-Elevation'
05/07/87 73370)~
Arkansas Pressurizer 99770077 STD-CFS-089~. Set-up and Operation of Heat
Treat Equipment
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C-E Manual.
Combustion Engineering.
09/78-No.' 73370-Pressurizer Instruction
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Manual
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DSG-87-096 Evaluation of Loose N/A 05/03/87-
~ Heater Parts in ANO-1, Unit 2 Pressurizer 2CAN058704 ANO-2 Pressurizer Heater N/A 05/12/87 Repair-10 CFR 50.55a(2)(3)
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Request and Attachments A and B s
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-8-The NRC inspectors l determined that the above referenced procedures contain'ed the information required to perform the stated functions.
No violations or deviations were identified.
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NRC Inspector Review of Combustion Engineering Operating Manual
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Section Revision Date Procedure Title-
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Number Number Approved Job Site Indoctrination and OP-1.1 6'
09/01/86 Training Requirements QA/QC Interface with' Authorized OP-2.1
02/16/87 Inspection Agency Procurement Control
- OP-4.1
09/01/86 Approved Products Procedure OP-4.2
02/16/87-QC Review and Preparation of OP-5.3
02/16/87-Quality Documentation Drawing and Document Control 0P-6.1
02/16/87 General Housekeeping for OP-8.2
09/01/86 Construction Work at Nuclear Power Plants'
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Personnel ~and Material OP-8.3
09/01/86 Accountability for Controlled Access Areas Visual Examination.for Completed OP-9.1
09/01/86 Weld Surfaces
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Magnetic Particle Examination OP-9.2
09/01/86 Liquid Penetrant Examination OP-9.4
09/01/86 Visual Examination Defined as OP-9.5
09/01/86-VT-1,-VT-2, VT-3 Welder Performance Testing 0P-9.7
02/16/87-Procedure
Heat Treating OP-9.9
09/01/86 Weld Inspection Records OP-10.4
02/16/87
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" Hydrostatic Test OP-11.1 6'
09/01/86 JControl of_ Measuring and Test OP-12.1
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Equipment.-
v Quality Assurance Records Control OP-17.1=
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02/16/87
.1-The'NRC inspector review determined that the above referenced procedures contained the required elements for appropriate completion of repair work on the pressurizer heater channels.
No violations or deviations were identified.
9.
Repairs to Channels X1 and T4~
The plugs installed in the pressurizer heater channels and the surfaces repaired in positions XI and.T4 are non-clad SA-533, Grade B, C1. 1, carbon steel (P3) material.: The corrosion effect for the remainder of the
' current fuel cycle (unti1*approximately. March 1988) was assessed..These evaluations considered aerated.and deaerated operating and shutdown-conditions.1 The-evaluations determined that corrosion effects were within acceptable; limits and no1 deleterious effects were identified.
Stress. corrosion cracking-and hydrogen embrittlement were evaluated by AP&L_and their contractor personnel. The results of these evaluations
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should not contribute,to weld failure' at either of these locations during the remainder of the current fuel cycle.
.10.
Postulated Failure Identification Safeguards The licensee has installed a temporary sampling line to the containment atmosphere monitor (CAM) to continuously; sample the area immediately above the pressurizer. The CAM system continuously monitors airborne particulate and gaseous radioactive isotopes using an air particulate detector.(APD)anda:radioactivegasdetector.
A containment entry will be made for the specific purpose of leak detection and assessment on a once-per-month schedule..
- Refresher training of the reactor operators for a small break LOCA will be completed prior to restart of Unit 2.
The licensee will continue to be alert for parameter changes that could indicate-primary leakage (example: higher than normal' makeup rate to the safety injection tanks)..
No violations or deviations were identified.
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Pressurizer Shell Repairs
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The licensee removed the heater sleeve frem heater position T4.
No damage to the pressurizer heater channel was observed.
A plug was machined to the dimensions (1.181-inch diameter) of the final heater channel diameter, buttered in accordance with the repair procedure, and installed in the channel in accordance with the weld procedure.
NDE examination verified that the weld was acceptable.
The licensee removed the heater sleeve from heater position X1.
An area about 1/4-inch wide and 1/2-inch long on the downhill side of the channel indicated slight surface damage'from either steam cutting or boric acid corrosion. This area was easily blended out to clean metal.
No repairs were required to the inside of the pressurizer heater channel.
A plug was machined to the final hole diameter (1.188-inch) and installed as described for heater channel T4.
The NDE-examination verified that the weld was acceptable.
An area near the X1 heater channel indicated a boric acid wastage (corroded /erroded) volume about 1 1/2-inch in diameter and about 3/4-inch deep in the pressurizer shell.
This volume was ground out to clean metal.
The ground out volume was approximately 1 1/2-inch in diameter and 1 inch in depth.
The pressurizer shell in the vicinity of the ground out area to be repaired was examined by NDE methods and verified to be free from deleterious defects.
The void was repaired in accordance with the welding procedure.
NDE examination verified that the weld repair was acceptable.
The welders had been qualified on the mockup, using the approved repair weld procedure.
The NDE procedure and NDE personnel had been qualified on the mockup prior to examination of the pressurizer shell repairs.
No violations or deviations were identified.
12.
Pressurizer Heater Removal and Replacement The licensee determined that the root cause of the through wall pressurizer leak (60 drops per minute or about 0.002 gallons per minute)
was a failure through the sleeve at heater position X1.
The root cause of the sleeve degradations at heater positions X1 and T4 was related to two Watlow heaters that had ruptured sometime subsequent to the installation of these heaters in 1982.
In 1982, 23 out of the 96 originally installed General Electric design pressurizer heaters were replaced with unannealed Inconel, 600 Watlow design heaters.
During this outage 21 of these Watlow heaters were removed without problems.
Visual inspection by licensee personnel determined that no apparent failure or damage to any of these 21 heaters had occurred during service.
Six spare General Electric design pressurizer heaters were installed in selected positions.
Fifteen pressurizer channels were plugged in accordance with qualified and approved procedures.
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revealed that two General Electric designed heaters had failed with open
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These two heaters were removed from the respective pressurizer channels.
The channels were plugged in accordance with the qualified and approved procedures, previously implemented in the plugging of the 15 other channels.
At startup on May 27, 1987, subsequent to completion of removal, repair, and replacement of pressurizer heaters, there were 77 operable pressurizer heaters.
This number of pressurizer heaters is greater than the minimum number of pressurizer heaters required by the Technical Specifications for control of plant transients, natural circulation cooldown, and safety requirements.
No violations or deviations were identified.
13.
Inspection of Pressurizer Lower Head Area Licensee personnel completed an inspection of the pressurizer lower head area following completion of pressurizer heater repairs.
The pressurizer heater cables were found to be in good condition.
During the inspection, no visual evidence of damage from steam, boric acid, or physical abuse during welding and/or inspection operations was identified.
An NRC inspector was present during selected portions of the pressurizer heater repair activities.
No indications of damage to cables or other components were observed during these inspections.
No violations or deviations were identified.
14.
Loose Pressurizer Heater Parts The licensee completed an evaluation of loose parts in the Unit 2 pressurizer.
The evaluation and analyzed consequences of loose parts from these heaters indicated that no significant damage to components or operating problems will occur through continued operation of the facility with the known loose heater parts in the pressurizer.
The NRC inspector reviewed the evaluation.
No violations or deviations were identified.
15. Metallurgical Examination of Failed Pressurizer Heaters The licensee packaged the two failed pressurizer heaters, T4 and X1, and forwarded one to Combustion Engineering and one to Babcock and Wilcox metallurgical laboratories for detailed examination.
The results of these metallurgical examinations will be reviewed by the NRC inspector when these examinations have been complete,
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Exit Interviews-The NRC inspectors held an exit interview with licensee personnel-designated in paragraph 1 on May 14, 1987.
A second exit interview was held on May 15,_1987; The resident inspector. attended the exit interview on May 15, 1987.
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