IR 05000249/1988010
| ML17201J315 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 06/28/1988 |
| From: | Danielson D, Schapker J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML17201J314 | List: |
| References | |
| FRN-59FR979 50-249-88-10, AC93-1-030, AC93-1-30, NUDOCS 8807050430 | |
| Download: ML17201J315 (13) | |
Text
U.S. NUCLEAR REGULATORY COMMISSION
REGION III
Report No. 50-249/88010(DRS)
Docket No. 50-249 Licensee:
Commonwealth Edison Company P. 0. Box 767 Chicago, IL 60690 F~cility Name:
Dresden Station, Unit 3 Inspection At:
Dresden Site; Morris, Illinois License No. DPR-25 Inspection Conducted:
April 4-7, May 3-5, 16-18, and June 13-14, 21-22, 1988
~
Inspecto~. F. Schapker
~~
Date'
Approved By:
D. H. Danielson, Chief Materials and Processes Section Dat~
/
Inspection Surrnnary Ins ection on A ril 4-7, Ma 3-5, 16-18, and June 13-14, 21-22, 1988 Re ort No. 50-249/88010 DRS Areas Ins ected:
Routine unannounced inspection of inservtce inspection
!SI activities including review of program (73051), procedures (73052),
observation of work and work activities (73053), of data review and evaluation (73055); of the inspection for verification of Mark 1 BWR Drywell Vacuum Breaker Modifications (37828)(TI 2515/96); of IE Infonnation Notices (92704);
of plant modifications (37702); and of inspection of the Drywell containment for degradation (GL-87-05) (92703).
Results:
!SI activities were accomplished within the guidelines of ASME Section XI and Generic Letter (GL) 84-11 requirement The licensee has received GL 88-01 and is in process of revising the !SI program to implement the augmented requirements withi Plant modification welding and nondestructive examinations were perfonned to the applicable code requirement Implementation of modifications were adequately controlled by QA, QC requirement Licensee's actions taken on Generic Letters and Information notice was adequate to assure safety was not compromise * *
DETAILS Persons Contacted Commonwealth Edison Company (CECo)
- E. Eenigenburg, Station Manager E. Armstrong, Regulatory Assurance Supervisor C. Schroeder, Services superintendent
- R. Geier, QC Supervisor
- K. Peterman, Regulatory Assurance Supervisor
- J. Achterberg, Technical Staff Supervisor *
- J. Williams, Regulatory Assurance
-
- D. Van Pelt, Assistant Superintendent Maintenance
- J. WuJciga, Production superintendent
- J. Brunner, Assistant superintendent Technical Services R. Falbo, Regulatory Assurance M. Harbaczewski, Technical Staff !SI R. Dyer, Technical Staff Assistant Modification Group Leader L. Luna, Technical Staff Engineer Modification Group K. Knudson, Technical Staff Engineer Modification Group D. Fischer, Technical Staff Engineer Modification Group General Electric Co. (GE)
B. Newell, Level III T. Kimball, Level u*
V. Krueger, Level II P. Wright, Level II T. Bordenet, Level I Hartford Steam Boiler Inspection (HSB)
K. Kilmer, ANII U.S. Nuclear Regulatory Commission S. Dupont, Senior Res i-dent Inspector P. Kaufman, Senior Resident Inspector The NRC inspector also contacted and interviewed other licensee and contractor employee *Denoted those present at the final exit meeting June 22, 198.
Licensee Action Taken on Information Notices (Closed) Information Notice 88-03 (88900-01) Cracks in Shroud Support Access Hole Cover Weld Background Jet pump BWRs are designed with access holes in the shroud support plate which is located at the bottom of the annulus between the core shroud and the reactor vessel wal Each reactor vessel has two such holes which are located 180 degrees apar These holes are used for access during construction and are subsequently closed by welding a plate over the hol The covers and shroud support ledge are Inconel Alloy 600 materia The connecting weld material is also Inconel 600 (Alloy 182 or 82).
The high residual stresses resulting from welding, along with a possible crevice geometry of the weld, when. combined with less than ideal water quality, present a condition conducive to intergranular stress corrosion cracking (ISGCC).
This has been recognized by General Electric and, as a result, they have developed a remotely operated ultrasonic testing capability for detecting cracks in the cover plate weld The first use of this custom ultrasonic testing fixture was at Peach Bottom Unit On January 21, 1988, intermittent short cracks were found in. the weld heat-affected zone around the entire circumference of the covers at Peach Bottom Unit It is estimated that cracking exists over 50% to 60% of the circumference with cusps as deep as 70% through the wal It is believed that cover plate welds have not been inspected previously on any other BW It is possible that the cracking is generic and may, therefore, affect all BWRs with jet pump *
Licensee Action The licensee employed the services of GE to examine the welds utilizing ultrasonic examination of the cover plate weld During the examination of *the cover plate welds no-indications associated with IGSCC were recorded with the 11Smart UT 11 (SUT) system utilizing 45° shear wave and 55° refracted longwave (RL) search unit The 11Smart UT 11 system did record non-relevant indications, root geometry and shear redirect with the 45° shear wave search uni With the 55° RL search unit the SUT system.recorded root geometr The examination was*
performed from the access cover side of the weld, inspecting both the weld material and heat affected zon The examination was conduct~d remotely with a specialized access hole cover scanning fixture designed by GE utilizing the immersion techniqu The UT examination provides adequate assurance that the access cover plate welds and heat affected zones have not degraded and will not compromised the safety of the operation of the reacto.
Inspection For Verification of Mark I BWR Drywell Vacuum Breaker Modifications (Closed) SIMS MPA-D20 (TI 2515/96)
Objective To inspect those plants that have modified their drywell vacuum breakers in response to NRR Generic Letter 83-08, and to allow close out of this action item, under Multi-Plant Action Item D-2 Background In December 1979, General Electric issued SIL No. 321 informing customers of unanticipated cycling and damage to drywell vacuum breakers during LOCA tests in a prototype Mark I containmen To assure that drywell vacuum breakers would be capable of withstanding chugging and condensation oscillation loads, the staff issued Generic Letter 83-08 requesting licensees of Mark I containments to perform plant-unique calculations to determine the structural adequacy of the drywell vacuum breaker The staff has received responses to the Generic Letter and has issued Safety Evaluation Some licensees, in their response, determined that vacuum breaker modifications were required, whereas others determined that no modifications were neede The need for modifications is identified in the Safety Evaluation Repor Inspection The NRC inspector reviewed the licensee 1 s Technical Evaluation Report for the structural evaluation of the Vacuum Breakers and the Safety Evaluation by NR In each of the Dresden 2 and 3 Mark I Containments, there are twelve 18
external type vacuum breakers made by Atwood - Morrill mounted on six exterior headers connecting the suppression chamber and the vent line exterior of th~ wetwel Loadings on Mark I structures and vacuum breakers are based on the General Electric Company Report, NED0-21888, 11Mark I Containment program Load Definition Report, 11 Revision 2, dated November, 198 For vacuum breakers, the loadings. included are gravity, seismic, and hydrodynamic load The hydrodynamic forcing functions were developed by Continuum Dynamics, In by using a dynamic model of a Mark I pressure suppression system and the full scale test facility dat The system model was capable of predicting pressure transients at specific locations in the vent syste Loading across the vacuum breaker disc caused by pressure differentials based on test data was thus quantified as a function of tim This issue was reviewed and approved by NRC on December 24, 198 Loadings were combined according to the FSAR commitment To determine the structural integrity of the vacuum breakers, results from a finite element model and ANSYS program analyses were compared with design limits specified in the ASME Boiler and Pressure Vessel Code,Section III, Revision I, Subsection NC, 1977.Edition and Addenda up to
- Summer 197 It was found that the hydrodynamic chugging force in Dresden 2 and 3 will not significantly increase the impact velocity on vacuum breakers to cause any additional loadin Since the original design margin does not need improvement, the licensee decided that no modifications were needed on the construction of its vacuum breaker The licensee, however, did replace the original aluminum cast discs with aluminum plate material for better ductilit The NRC inspector reviewed the licensee's design modification records pertaining to the replacement of the cast aluminum disc to wrought aluminum discs with stainless steel pos The SER review by NRR determined that the structural analysis indicated the existing vacuum breaker design was acceptable and no additional modifications were require Review of vacuum breaker disc modification documentation disclosed completion of the disc replacement had been made with material as required by design change modificatio No violations or deviations were identifie.
Licensee Action Taken on Generic Letter 87-05 Inspection of Unit 3 Drywell Containment Background Significant corrosion was found to have thinned the drywell skin at Oyster Creek Station in November 1986 in a location adjacent to the sand cushio The cushion is located just below the torus vent lines on the outside of the drywell ski The cushion's purpose is to provide a transition from the rigid support at the bottom of the drywell to allow movement of the ski Licensee Action In the Summer of 1987, the licensee inspected the drains to the sand cushions and determined that they were plugge The plugged lines were cleared and the water from the drains were determined to be mildly corrosiv During this outage the licensee initiated an inspection program to measure the thickness of the drywell skin in the sand cushion are Twenty two core drillings in the concrete surface to the drywell liner was mad The core drillings were made at the top and bottom sections of the sand pocket area (11 at the top and 11 at the bottom).
The azimuth sections were selected based on sand pocket location and accessibilit Ultrasonic examinations (UT) of the drywell wall was performe The as designed nominal wall thickness is 1.0625.
The thickness measurements were as follows:
- Identification Measured Location (Azimuth)
Point Report #
Thickness Sector No. 1:
x=5
22.5.1.lA*
CP0-109 1.10 11 Sector No. 1:
x=5
22. 5. 1.18**
CP0-110 1.14 11 Sector No. 1:
x=6
22. 5.1. 2A CP0-110 1.1411 Sector No. 1:
x=6 1 22. 5.1. 28 CP0-112 1.10 11 Sector No. 2:
x=7 1 112. 5.1. lA CPD-107 1.12 11 Sector No. 2:
x=7 1 112. 5.1.18 CPD-119 1.12 11 Sector No. 2:
x=5.5 1 112. 5.1. 2A CPD-108 1.1011 Sector No. 2:
x=5. 5 1 112. 5.1. 28 CPD-119 1. 0811 Sector No. 3:
x=ll
157.5.1.lA CP0-104 1.1411 Sector No. 3:
x=ll 1 157.5.1.18 CP0-105 1.1411 Sector No. 3:
x=9
157. 5.1. 2A CPD-102 1.1411 Sector No. 3:
x=9
157.5.1.28 CP0-103 1.12 11 Sector No. 4:
x=13.5 1 202. 5.1. lA CPD-100 1. 08 11 Sector No. 4:
x=13. 5 1 202. 5.1.18 CPD-101 1. 0811 Sector No. 5:
x=12
292. 5.1. lA CP0-114 1.1811 Sector No. 5:
x=12
292. 5.1.18 CP0-117 1.1211 Sector No. 5:
x=7 1 292. 5.1. 2A CPD-115 1.1211 Sector No. 5:
x=7
292. 5.1. 28 CPD-116 1. 26 11 Sector No. 6:
x=9
337. 5.1. lA CP0-118 1. 20 11 Sector No. 6:
x=9
337.5.1.18 CPD-120 1. 0811 Sector No. 11:
x=ll 337.5.l.2A CP0-106 1.12 11 Sector No. 11:
x=ll 337.5.1.28 CPD-113 1. 24 11
- A = top section of sand pocket
- 8 = bottom section of sand pocket See Attachment 11A11 for sketch of azimuth 1 ocat ion The ultrasonic examinations provides additional assurance that the drywell wall has not degraded due to the trapped water discovered when the plugged drain lines were cleare During the core drilling of the concrete floor to gain access to the drywell wall in the sand pocket areas, the licensee encountered water in the core holes: The licensee took samples of the core hole water and determined the source was hydrolyzing which was performed prior to the core drillin To assure all water was* removed from this process the licensee drilled a well hole in the center of the containment floor to the Drywell wall interfac However no water was recovered at this poin The licensee 1 s investigation as to the source of the water included inspection of the mastic seal at the concrete - drywe 11 wa 11 interface and the concrete floor within the drywe 11. * The mastic sea 1 appeared to be intact however cracks in the concrete floor of the drywe 11 are a 1 i ke ly source for the water from hydrolyzin The licensee sealed the inspection holes and will perform further inspections to assure the drywell wall does not degrade and attempt to find the source of the leakage into the sand pocket area and initiate corrective action.
- The licensee has established that the drywell wall does not exhibit degradation from the water which was trapped in the sand pocket and has initiated a corrective action program which will assure the safety of the containment is not compromise.
Inservice Inspection (IS!) Unit 3 General This was the third outage of the second period in the second ten year pla The licensee contracted with General Electric Corporation (GE) to perform ultrasonic (UT), magnetic particle (MT),
liquid penetrant (PT), and visual examinations (VT).
Examinations were performed in accordance with ASME Section XI, 1977 Edition, Summer 1979 addend The NRC inspector reviewed the !SI inspection second ten year plan, Revision 1, dated, December 1982, ASME Section XI code relief request CR-1 through CR9 and verified the licensee successfully demonstrated the UT calibration blocks attenuation and velocities are representative of the reactor vessel base material as required by relief request CR-b,
!SI Procedure Review The NRC inspector reviewed the following NDE procedure *
CECo, Nondestructive.Testing (Inservice Inspection) OAP 11-8, Revision *
CECo, 11 Preservice and Inservice Ultrasonic Inspection of Similar and Dissimilar Metal Pipe Welds at Nuclear Station,
NDT-C-2, Revision 1 *
GE "Qualification and Certification of Nondestructive Testing Personnel, 11 QC-2 Revision *
GE "Visual Acuity Testing, 11 QC-4 Revision *
. CECo, "Ultrasonic Inspection of the Vessel Nozzle Inner Radii at Nuclear Stations, 11 NDT-C-10,.Revision 1 *
CECo, "Ultrasonic Inspection of Flange Ligaments Between Threaded Bolt Holes, 11 NDT-C-11, Revision 1 *
CECo, "Ultrasonic Examination of Reactor Vessel Welds to NRC Reg. Guide 1.150 for Boiling Water Reactors, 11 NDT-C-.30-79, Revision *
CECo, "Beam spread and Refracted Angle Determination to NRC Reg. Guide 1.150 for Boiling Water Reactors, 11 NDT-C-31-79, Revision 0.
CECo, 11 Nonaqueous Red Dye Liquid Penetrant Examination for Section XI Class IWB and IWC Components for Nuclear Stations,
NDT-D-2, Revision *
CECo, "Visual Examination - Welds, Pressure Retaining Bolting, and Component Internals, 11 VT-1-1, Revision *
CECo, "Visual Examination - System Hydrostatic and Leak Tests,
VT-2-1, Revision *
CECo, 11 Visual Examination - Component Supports, 11 VT-3-1, Revision *
CECo, "Magnetic Particle Examination for A.S.M.E.Section XI Class IWB and IWC Components for Nuclear Stations, 11 NDT-B-1, Revision No violations or deviations were identifie Review of ISI Data, Material, Equipment and NOE Personnel Certifications The NRC inspector reviewed the following documents and determined that the applicable QA/QC requirements were met:
ISI Data Reports.*
Ultrasonic Instruments, Transducers, and Couplant Certification *
Liquid Penetrant, Cleaner and Developer Certification *
Magnetic Particle materials and Equipmen *
NOE personnel certifications compliance to SNT-TC lA requirement Obs~rvations of Work and Work Activities (ISI)
The NRC inspector observed nondestructive examinations in progress on the following components and pipin *
Ultrasonic. examination of the Reactor Vessel Closure Head circumferential welds D, E, and meridional weld No. *
Magnetic particle examination of Reactor Vessel Head - Flange to head weld. (D)
Ultrasonic examination of Core Spray line No. 1403, piping welds Nos. 10-10, 10-Kll, 10-Kl *
Visual examination of various hangers and supports for damage, wear, proper settings, and weld reinforcement.
The NRC inspector also observed calibrations of ultrasonic equipment prior to and after the examinations referenced above, discussed NOE procedures and examination findings with the Level II and III examination personne Examinations performed by the cognizant personnel were adequate in meeting the safety objectives of the ASME Section XI requirement Augmented Inspection of Intergranular Stress Corrosion Cracking (IGSCC) Susceptible Piping (GL 84-11)
During the Fall 1985/Spring 1986 Recirculation Pipe Replacement outage most of the IGSCC susceptible piping was replaced using IGSCC resistant materia There is some remaining Class 1 stainless steel piping that is susceptible to IGSC There are a total of fifty (50) welds in this category to which twenty-eight (28) were stress improve A total of twelve (12) IGSCC susceptible piping welds were ultrasonicly examined this outage in accordance with the sampling plan which follows the requirements of Generic Letter 84-1 No IGSCC indications were f6und in the examination for the twelve pip*ing weld Examination services were provided by GE using approved Commonwealth Edison Cq. (CECo) procedure CECo NOE personnel were utilized for review and ultimate resolution of the examination result CECo. and GE IGSCC UT examination personnel were qualified at the EPRI NOE Center after September of 198 The NRC inspector reviewed ex.ami nation results and concurred with the UT inspectors evaluation.
Feedwater Regulator Valve Modification Background Feedwater transients occurred at the Dresden Station Unit 3 on July 11, and August 7, 198 Based on results from an investigative team report; the following modifications were initiated for the feedwater system to correct the deficiencies:
. (1)
Replace the 3A feedwater regulating valve with a drag valv (2). The actuator for the 3A feedwater regulating valve was to be changed to an electro-hydraulic actuato (3)
The internals for the 3B feedwater regulating valve were to be replaced with a new type of internals that will provide more stable valve operatio (4)
The feedwater low flow line was increased from six inches diameter to ten inche (5)
The set points of the switches that control the opening of the reactor feed pump minimum flow valves were to be raise.,, Review of Records, Reports and Certification The NRC inspector reviewed the following,documentation items and determined that the applicable requirements of QA/QC commitments have been met:
Fabrication/Installation Traveler and Drawing *
Weld Data Shee *
Stress Relief Temperature Recording Charts
Welder Qualification Record *
Piping and Weld Material Certification *
NOE Personnel Certification *
NOE Procedure *
NOE Report No violations or deviations were identifie Observation of Work Activities The NRC inspector observed the fit-up/welding of p1p1ng, valves, and hanger Inspections of welder certifications, use of certified weld material, weld procedures, stress relief and visual examination of welding in progress were completed throughout*the modificatio The following final radiographs of the pipe to pipe and pipe to valve welds were reviewed:
Weld Map M381-1-2 M381-1-2 M381-1-2
.M381-1-1 M381-1-1 M381-1-1 M381-1-1 M381-1-1 M381-1-1 M381-1-1 Weld N BlG B9 BG B9 BlO B11 BG BS B4 BS No violation or deviations were observe Pipe Diameter
11
11
11
11
11
11
11
11
11
11
' Standby Liquid Control Modification Background This modifications was implemented to allow simultaneous operation of both the Standby Liquid Control system (SLCS) injection pumps, and increase the minimum sodium pentaborate solution concentration to 14 weight percen This modification meets the requirements of 10 CFR 50.62 which states in Paragraph (C)(4)
11 Each boiling water reactor must.have a SLCS with a minimum flow capacity and boron content equivalent in control capacity to 86 gallons per minute of 13 weight percent sodium pentaborate solution.
11 Review Records, Reports, Procedures, and Drawings The NRC inspector reviewed the following documentation/records, and determined the applicable code and NRC regulatory commitments were met:
Modification package Ml2-2(3)-84-119
Design Specification K-4080
Work Request D38684
Drawings:
M384 Revision H M414 Revision H M364 Revision X Mll49 Revision A
Weld procedure*8~8~D Revision 3 (QW 482)
Weld material ER 308/308L, Heats 42554, 09735, 73797
Visual inspection procedure VT-1-1 Revision 2
10 CFR 50.59 review Observation of Work Activities The NRC inspector observed the fit-up, welding of the pipe to pipe and pipe to standby liquid control tank weld Inspections included review of welder certifications, use of certified weld materials, weld procedures, drawing dimensions, and visual inspections of ID and OD of weld '
The standby liquid control modification was adequate to assure the safety objectives as described in 10 CFR 50.62 have been complied wit ir Exit Meeting The NRC Inspector met with the licensee representatives (denoted in Paragraph 1) at the conclusion of the inspection on June 22, 198 The inspector summarized the purpose and findings of the inspectio The licensee representatives acknowledged this informatio The inspector also discussed the likely informational content of the inspection report with regards to documents or processes reviewed during the inspectio the licensee representatives did not identify any such documents/processes as proprietar ',,
THICKNESS MEASUREMENT AZIMUTH 22. s*
202.s*
1s1.s*
1 eo*