IR 05000275/1994025
| ML16343A261 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 11/14/1994 |
| From: | Powers D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML16342C733 | List: |
| References | |
| 50-275-94-25, 50-323-94-25, NUDOCS 9411220016 | |
| Download: ML16343A261 (18) | |
Text
APPENDIX B
U.S.
NUCLEAR REGULATORY COMMISSION REGION IV.
Inspection Report:
50-275/94-25 50-323/94-25 Licenses:
DPR-80 DPR-82 Licensee:
Pacific Gas and Electric Company 77 Beale Street, Room 1451 P.O.
Box 770000 San Francisco, California 94177 Facility Name:
Diablo Canyon Nuclear Power'lant, Units
and
Inspection At:
Diablo Canyon Site, San Luis Obispo County, California Inspection Conducted:
September 26 through October 7 with in-office inspection through October 28, 1994 Inspector:
L.
E. Ellershaw, Reactor Inspector,'aintenance Branch Division of Reactor Safety Approved:
r.
D. A. Powers, C ie
, Maintenance Branc Division of Reactor Safety Date Ins ection Summar Areas Ins ected Unit
No inspection of Unit 1 activities was performed.
Results Unit
Not applicable.
Areas Ins ected Unit 2
Routine, announced inspection of the inservice inspection program.
Plant 0 erations Not applicable during this inspection.
Maintenance The inservice inspection program was well established and administratively controlled.
The licensee appeared to be adhering to 94ii220016 94iii6 PDR ADOCK OS000275
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Haintenance The inservice inspection program was well established and administratively controlled.
The licensee appeared to be adhering to the examination schedule for the current inspection period (third) of the first 10-year inspection interval (Section 2. 1).
The observed nondestructive examinations were performed by knowledgeable, appropriately certified individuals in, accordance with approved procedures.
Calibrations were performed as required (Sections 2.2 and 2.3).
The inservice inspection procedures contained sufficient detail and instructions to perform the applicable nondestructive examinations and were consistent with the requirements of the ASHE code (Section 2.4).
Licensee personnel failed to develop instructions which would adequately provide appropriate measures for controlling or containing excess reactor coolant system water that spilled out of the Loop 1 hot leg subsequent to machining operations (Section 2.5),
Not applicable during this inspection.
Licensee personnel failed to identify and document on an action request, an incident during Refueling Outage 1R6, in which a spill of reactor coolant system water occurred coincidental with machining operations on a Unit 1 hot leg.
Had this incident been documented and evaluated, it may have prevented a reactor coolant system water spill during Refueling Outage 2R6 machining operations on a Unit 2 hot leg (Section 2.5).
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Hang ement Overview Supervision of the inservice inspection program was considered exceptionally strong (Section 2.3).
Summar of Ins ection Findin s:
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Violation 275;323/9425-01 was identified (Section 2.5).
Attachment:
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Attachment Persons Contacted and Exit Heeting
-3-DETAILS
PLANT STATUS During this inspection period, Unit 1 was in Mode 1, while Unit 2 was in Refueling Outage 2R6.
INSERVICE INSPECTION (ISI)
(73753)
The objective of this inspection was to determine whether:
(1) the performance of ISI examinations and any repair or replacement of Class 1,
2, and 3 pressure ret'aining components was accomplished in accordance with the applicable ASME code and (2) the licensee had appropriately satisfied industry initiatives.
2 '
ISI Pro ram The inspector reviewed Revision 4 of the licensee's ISI.program plan for the first 10-year inspection interval for Diablo Canyon Power Plant, Unit 2, dated June 12, 1989.
The NRC's safety evaluation report dated October 25, 1989, documented a review and evaluation which determined that Revision 4 of the ISI program plan was in compliance with 10 CFR 50.55a(g),
Technical Specification 4.0.5; and met the requirements of the 1977 Edition, Summer of 1978 Addenda of Section XI of the ASME code, except that the extent of examinations of Code Class
and 2 pipe welds were determined by the 1974 Edition, Summer 1975 Addenda of Section XI of the ASME code, as required by
CFR 50.55a(b)(2)(iv).
Sections 3.1, 3.2, and 3:3 of the ISI program plan described the ASME Code Class 1,
2, and 3 components subject. to surface, volumetric, and visual examinations, and Section 3.4 included NRC-approved requests for relief for each item where it had been determined that a code-required examination was not practical.
The tables in each of the program plan sections identified the name of the component or system, code class, code category, item number, and general identification.
Also included were the total number of items in the system, the required nondestructive examination (NDE) methods, the amount of items to be examined and the extent of the examinations, the examination period in which the examinations would be conducted, percent of examinations completed to date, and applicable remarks or references to requests for"relief that have been approved.
The inspector's review of examinations completed to date, and the schedule of examinations for this outage, indicated that the licensee was adhering to the examination schedule for-the current inspection period (third)
of the first 10-year inspection interva The licensee had also established provisions for performing NRC-required augmented inspections and NDE including eddy current testing of steam generator tubes, visual and functional testing of all safety-related snubbers, ultrasonic examination of a percentage of containment spray system welds, and ultrasonic and magnetic particle examinations of reactor coolant pump flywheels.
2.2 Observation of NDE The inspector was informed that volumetric and surface examinations consisting of ultrasonic and liquid penetrant examinations had been scheduled during the week of September 26, 1994.
The inspector was also informed that ASHE code repair and replacement activities pertaining to the elimination of the resistance temperature detector bypass piping network which was connected, to the reactor coolant system at-the hot legs, cold legs, and crossover legs, was in-process.
The inspector observed the performance of ultrasonic examinations of the
.
following welds:
Class 2 tube plate to shell girth weld (Wl-2) on Steam Generator 2-1, Class 1 girth weld (Wl-1) on Steam Generator 2-1, automated ultrasonic examination of the feedwater nozzle weld on Steam Generator 2-1, and a Class 1 circumferential pipe to elbow weld (WIB-53) on Safety Injection Line 3844.
The examination of the circumferential pipe weld was conducted with a shear wave mode (45-degree angle beam)
in two directions (perpendicular and parallel to the weld axis) using a transducer
.with a frequency of 2.50 Hz.
The examinations of the steam generator girth welds were performed in two directions using a 0-degree longitudinal wave mode, and a 45-and 60-degree shear wave mode.
The inspector verified that designated Procedures N-UT-l,
"Ultrasonic Examination Procedure For Pipe Welds," Revision 7,
and N-UT-4,
"Ultrasonic Examination of Pressure Vessel Welds," Revision 2, had been approved and were being followed.
The inspector also observed the NDE examiners perform a calibration check at the beginning and end of each examination.
Before the ultrasonic examinations were conducted, the inspector observed the system calibration which included both axial and circumferential scans.
The transducer selection, sensitivity calibration, and construction of the distance amplitude correction curve was performed in accordance with each of the procedures.
The inspector also verified, by review of the certified material test report, that the correct calibration blocks were used (i.e.,
similar to the component to be examined in terms of material, diameter, and wall thickness).
I
~ IP
The NDE examiners documented their calibration and examination results on an ultrasonic calibration report and an ultrasonic examination data sheet, respectively.
The reports were numerically identified and contained all pertinent information specified by the procedure.
Recording of identified indications was based on the established distance amplitude correction curve.
The inspector also observed liquid penetrant examinations performed on a
Class 1 pipe-to-elbow weld (WIB-53) on Safety Injection Line 3844, and on two of the completed resistance temperature detector modification thermowell welds (FW1-FC-207 and -209).
These examinations were performed in accordance with Procedures N-PT-1, "Liquid Penetrant Examination," Revision 5,
and GgP 9.7,
"Liquid Penetrant Examinations and Acceptance Standards for Welds, Base Materials, and Cladding," Revision 4, respectively.
The inspector also reviewed the certified material test reports of the 'penetrant, cleaner, and developer materials used, to verify that the chloride and halogen limitations had not been exceeded.
In all cases, the NDE examiners verified that the surface temperature of the welds exceeded the minimum procedural requirements.
Discussions with the examiners performing the ultrasonic and liquid penetrant examinations indicated that they were experienced and knowledgeable NDE personnel.
They were cognizant of the procedural and documentation requirements, and understood the examination techniques.
2.3 Personnel ualifications and Certifications The licensee informed the inspector that the performance of ISI examinations was not contracted out, but rather was performed by NDE examiners who were employed and certified by the licensee.
The inspector reviewed Procedure 2. 1, "qualifications and Certifications of Personnel,"
Revision 7, which was contained in Revision 49 of.the licensee's nondestructive examination manual, to verify that the certification process met the requirements of American Society for Nondestructive Testing's
"Recommended Practice SNT-TC-IA," 1980 Edition.
The inspector then reviewed the applicable qualification files of the four NDE Level I'I examiners and the two Level III examiners.
The files contained the appropriate examinations and certifications for the NDE methods th'at the inspector observed.
The records showed that the personnel had been certified in accordance with the 1980 Edition of SNT-TC-1A.
As required by the ASME code, all of the individuals had received annual near-distance acuity and color vision examinations.
The inspector
'noted that ISI supervision exhibited a high degree of competency, was fully cognizant of ASME code requirements and ISI program commitments, and provided strong leadership to the ISI staf.4 ISI Procedures Review The inspector reviewed the NDE procedures used during the observed examinations to verify that they were consistent with the requirements of Section XI of the ASHE Code, 1977 Edition, Summer 1978 Addenda.
The procedures were found to be well written and contained sufficient detail and instructions to perform the intended examinations.
2.5 Re air and Re lacement Activities Design Change Notice (DCN) DC2-EH-44425, through Revision 2, described a
modification that consisted of replacing the existing single-element resistance temperature detectors (RTDs) with new "fast response" dual-element RTDs.
This included, removing the RTD bypass piping network and associated supports connected to the reactor coolant system at the hot legs, cold legs, and crossover legs; installation of thermowells to house the new RTDs; and adding new cabling to connect the new RTDs to the plant process protection system cabinets.
This DCN was the principal design document, and it addressed work activities, essentially by discipline (i.e., mechanical, electrical, etc.),
and identified each of the applicable sub-DCNs.
During this inspection, the principle, repair, and replacement work activity observed by the inspector dealt with installation of thermowells and caps.
This work had been contracted to PCI 'Energy Services, a wholly owned subsidiary of Westinghouse Electric Corporation, and was being performed under DCN DC2-EP-44425, Revision 0.
The inspector verified that all ASME Code Section XI required tests and examinations had been identified and incorporated into the RTD design change.
This included hydrostatic testing, visual examination, liquid penetrant examination, and radiography.
It appeared that the licensee and PCI Energy Services had properly considered and accounted for ASHE code requirements regarding welding, testing, and examination during development
.of the RTD design modification project.
On October 5, 1994, the inspector observed electrical discharge machining (EDH) operations being performed as part of the RTD modification on the Unit 2, Loop 1 hot leg.
Upon completion of machining (i.e., breaching the wall of the Loop 1 hot leg at the 185 degree position from the top),
and the removal of the machine pendant from the pipe, a large quantity of water (later estimated to be approximately 90 gallons)
flowed out of the Loop 1 hot leg.
The water rapidly filled up and overflowed a drip bag (with drain tube) that had been placed under the pipe to capture and direct the water that had been knowingly introduced into the pipe as part of the EDH process.
It was clear that the amount of water that flowed.out of the pipe was far beyond that expected.
Since the bag and drain, tube capacity was inadequate, the water overflowed to the floor below.
Health physics personnel, who were standing by, reacted promptly in preventing the water from flowing beyond the immediate area, and in cleaning up the spilled water.
Precautions had been taken to
protect personnel from possible contamination caused by the expected outflow of the EDH-injected water.
These precautions included normal anti-contamination clothing, shielding masks, and rubber gloves.
However, one person was slightly contaminated when he attempted to plug the machined hole in the pipe to prevent further outflo'w.
On. October 6, 1994, the licensee initiated Action Request A0352971, in which the afFected groups were specifically requested to review the incident and document the results of their respective evaluations.
Subsequently, on October 13, 1994, the licensee provided the inspector with the results of the evaluations.
Evaluation 01 for the action request was assigned to the system engineer, who provided the mechanical data and bases for the excess reactor coolant system water release.
He determined that while the centerline of the pipes were the same, the diameters were not.
The hot leg had an inside diameter of 29.200 inches whereas the cold leg had an inside diameter of 27.700 inches.
Since the drains were located in the cold legs, a volume of undrained water (approximately 90 gallons)
remained in the reactor vessel and the hot legs after the cold legs were drained.
Nuclear Construction Services-Hechanical, the organization responsible for the planning and execution of the RTD modification project, documented their review in Evaluation 02 for the action request.,
Nuclear Construction Services-Hechanical determined that they did not identify or evaluate the differences in pipe diameters which resulted in having more water to deal with when the EDH pendant was removed.
Since they did not identify this condition, they did not.provide instructions to the radiation protection group to properly establish controls to deal'ith the larger than expected amounts of reactor coolant system water.
Therefore, when the Loop 1 hot leg was breached, the flow of previously undrained water quickly overwhelmed the drip bag arrangement.
In addition, Nuclear Construction Services-Hechanical also identified that they should have provided proper drain adapters to fit on the new reactor coolant system hot leg boss fittings.
As a corrective action subsequent to the overflow, drain adapters were fabricated and successfully employed to properly drain the other reactor coolant hot legs after the EDH pendant was removed.
The failure to develop instructions which would adequately provide appropriate measures for controlling or containing excess reactor coolant system water that spilled out of the Loop 1 hot leg subsequent to machining operations was a violation (275;323/9425-01).
The inspector had learned, after inquiry, that a similar RTD modification had occurred during the last refueling outage for Unit 1 (i.e.,
1R6 during Harch 12 to Hay 7, 1994); therefore, the licensee was asked to determine whether a similar condition regarding spilled water had occurred.,
To document this review, the licensee added an additional action request evaluation to the original Action Request A0352971, noted above.
This action request evaluation was assigned to Nuclear Construction Services-Hechanical, and was completed
t
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and provided to the inspector on October 24, 1994.
The response indicated that, during the removal of the EDH pendant from the Unit 1 reactor coolant system hot leg at the 185 degree location, a similar amount of water was released.
A larger drip bag had been set up under the pipe at that location but, due to the congestion caused by scaffold configuration and tight working space, the drip bag was disturbed during removal of the pendant causing a
The spilled water was cleaned up by radiation protection personnel.
However, the response noted that this condition was not documented, thus, was not identified as-an area for improvement (i.e.,
lessons learned)
during the planning of the RTD modification project for Unit 2.
Subsequent communication with licensee representatives verified that the Unit 1 water spill had not been documented in an action request nor had it been discussed in work debriefs.
Administrative Procedure OH7. IDI requires the documentation of all identified hardware-related or administrative problems relative to nuclear power generation activities, through the initiation of an action request, so that the cause of problems can be identified and actions developed to ensure the problems do not happen, again or to reduce the chance of the problem recurring.
The failure of licensee personnel to identify and document either a
hardware-related problem or an administrative problem was a violation (275;323/9425-01).
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PERSONS CONTACTED ATTACHMENT l. 1 Licensee Personnel
¹ W. Crockett, Manager, Technical and Support Services
¹ C. Dougher'ty, Supervisor, Site equality Assurance
- R. Flohaug, Senior Supervisor, equality Assurance
.
¹*W. Fujimoto, Vice President and Plant Manager, Diablo Canyon Operations
¹ D. Gonzalez, Supervisor, Inservice Inspection
- T. Grebel, Director, Regulatory Compliance
¹ C. Groff, Director, Plant Engineering
¹*K. Hubbard, Engineer, Regulatory Compliance
- R. Oldenkamp, Director, Nuclear Construction Services
¹*J. Portney, System Engineer
- K. Rogers, Construction Planner, Nuclear Construction Services
¹ G. Rueger, Senior Vice President, Nuclear Power Generation Business Unit M. Smith, Design Engineer
¹ J.
Wood, Jr.,
equality Assurance Engineer 1.2 PCI Ener Services T. Grubbs, Manager, equality Assurance M. Petersen, Project Manager 1.3 Hartford Steam Boiler Ins ection 3 Insurance Co.
R. Elnar, Authorized Nuclear Inservice Inspector K. Kim, Authorized Nuclear Inservice Inspector 1.4 NRC Personnel
¹* M. Tschiltz, Resident Inspector In addition to the personnel listed above, the inspector contacted other personnel during this inspection period.
¹Denotes those attending the preliminary exit meeting on October 7, 1994.
- Denotes those attending the telephonic exit meeting on October 28, 1994.
EXIT MEETING A preliminary exit meeting was conducted on October 7, 1994, followed by a
telephonic exit meeting on October 28, 1994.
During this meeting, the inspector reviewed the scope and findings of the report.
The licensee acknowledged the inspection findings documented in this report, and requested that the potential violations be considered as non-cited violations or that the Notice of Violation not require a licensee response.
The licensee did not identify as proprietary any information provided to, or reviewed by, the inspector.