IR 05000259/1993038
| ML18037A552 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 10/27/1993 |
| From: | Blake J, Coley J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML18037A551 | List: |
| References | |
| 50-259-93-38, 50-260-93-38, 50-296-93-38, NUDOCS 9311160252 | |
| Download: ML18037A552 (12) | |
Text
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+y*y4 UNITED STATES NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIElTASTREET, N.W., SUITE 2900 ATLANTA,GEORGIA 303234199 Report Nos.:
50-259/93-38, 50-260/93-38, and 50-296/93-38 Licensee:
Tennessee Valley Authority 6N 38A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Docket Nos.:
50-259, 50-260 and 50-296 License Nos.:
DPR-33, DPR-52, and DPR-68 Facility Name:
Browns Ferry 1, 2, and
Inspection Cond
October 12-15, 1993 Inspect ey
/a ate sgne Approved by:
J.
.
e,
>e Mat i
s and Processes Section En n
ring Branch Division of Reactor Safety SUMMARY ate lgne Scope:
This routine, announced inspection was conducted in the areas of inservice inspection (ISI), observation of work activities and evaluation of recorded data.
Other areas examined included review of corrective measures taken by TVA for a steam leak in a Unit 2, 4 - inch, weld-o-let to pipe weld on the No.
2 extraction steam line, and review of TYA's preliminary plans to visually re-examine the reactor shroud for all Browns Ferry Units in accordance with GE's Services Information Letter No.
572 Revision l.
Results:
, ~
. In the areas inspected, violations or deviations were not identified.
However, two concerns were identified.
One concern dealt with the wording used to evaluate crack indications in GE's Procedure No. GE-UT-401. 'n October 14, 1993, GE revised procedure GE-UT-401 to modify the statement in question (see paragraph 2).
The second concern dealt with apparent erosion/
corrosion in an extraction steam line that should not have seen significant flow.
The licensee will investigate to determine the cause and extent of the erosion/corrosion by examining the same lines on Unit 1 (see paragraph 4).
9311160252 931108 PDR ADOCK 05000259
REPORT DETAILS Persons Contacted Licensee Employees
- H. Bajestani, Technical Support Hanager
- S. Bugg, Environmental and Waste Control Hanager
- H. Crisler, Lead Engineer, Site Engineering
- F. Froscello, Supervisor, ISI
- E. Hartwig, Project Hanagement
- H. Hollins, Unit 3, Outage Hanager
- J. Johnson, guality Assurance Hanager
- J. Maddox, Hanager, Nuclear Engineering
- R. Hull, Superintendent Operations
- J. Rupert, Engineering and Hodifications Hanager
- J. Sabados, Chemistry Hanager
- P. Salas, Licensing Hanager
- R. Wells, Compliance Licensing Hanager
- J. Whitaker, ISI Level III Examiner
- 0. Zeringue, Site Vice President Other licensee employees contacted during this inspection included engineers, technicians, and administrative personnel.
Other Organizations
- G. Nelson, Project Hanager, GE Nuclear Energy Services
- R. Seals, GE Project Hanager for GERIS Automatic Ultrasonic Systems NRC Resident Inspectors
- J. Hunday, Resident Inspector
- C. Patterson, Senior Resident Inspector
- G. Schnebli, Resident Inspector
- Attended exit interview Acronyms and initialisms used throughtout this report are listed in the last paragraph.
Inservice Inspection of the Unit-3 Reactor Vessel Background This inspection report covers work activities involved in the examination of the Unit 3 reactor pressure vessel (RPV) from the inside surface of the reactor vessel.
The inspection continues NRC's surveillance of the RPV examination activities.
Previous RPV inspections are documented in Region II, Inspection Reports 50-259, 260,296/92-40, 42, 93-26, and 93-34.
The Unit 3 RPV examinations represent the first attempt by a Region II Boiling Water Reactor (BWR) Owner, to perform ultrasonic examinations in accordance with NRC's new rule for augmentented examination of the
llg
reactor vessel welds.
The rule 50.55a (g) (6) (ii) (A) became effective on September 8,
1992.
I Browns Ferry Unit 3 is presently in an extended shut down, in cycle 5B of the third 40-month period, of the first ten-year interval.
The applicable code for ISI, for Unit 3 is the ASME B&PV Code,Section XI, 1974 Edition with addenda through the Summer 1975 (74S75) for everything except technique.
The applicable code for technique is the ASME BRPV Code Section V and XI, 1986 Edition.
The licensee has contracted General Electric (GE)
Company to conduct the automated ultrasonic (UT) examinations of the RPV welds using the GERIS OD system for the nozzle to vessel welds and the nozzle bore and inner radius examinations.
The ID weld examinations will be performed with the GERIS 2000 Automated Ultrasonic Data Acquisition System.
GE's BWR gA Program is described in their Topical Report NEDO-11209.
On and off site ISI service is covered in the GE Nuclear Projects guality Assurance Manual, (AM-001.
GE's ISI program, plan, and procedures were reviewed in Region II Inspection Report 93-34.
a.
Observation of Invessel RPV Ultrasonic Examination Work Activities (73753)
The licensee scheduled the GE invessel examinations to start on September 15, 1993 and to continue for 17 days.
However, during the first 15 days GE was plagued with electrical, mechanical, and software problems; these problems had not been encountered at the two foreign reactors that GE had inspected previously.
Therefore, GE spent considerable time trouble shooting the system to determine the cause of the failures and taking the appropriate actions.
On October 12, 1993, the inspector arrived at the Browns Ferry facility to observe the GERIS 2000 invessel system, acquire ultrasonic data and determine whether the acquisition, sizing, and evaluation of the data was conducted as delineated in GE's procedures GE-UT-700, GE-UT-701, and GE-ADM-1002.
The inspector observed the examiners set up the system menus in accordance with the GERIS 2000 Scan Plan and observed the acquisition of data for the following vessel examination patches:
Patch No.
Weld Confi uration and Weld No.
BF-024 BF-048 BF-025 BF-027 Circumferential Weld No. C-4-5 Vertical Seam Weld No. D-4-C Circumferential Weld No. C-3-4 Circumferential Weld No. C-3-4 At the conclusion of the inspector's visit on October 15, 1993, the GERIS 2000 system had worked well for the entire week.
During this week the system came out of the water only once (versus 16 times prior to the inspector's visit) for normal preventive maintenance to clean the transducer gimbal connection Within the areas examined, no violation or deviation was identified.
Review of GERIS 2000 Ultrasonic Data and Evaluations (73755)
The inspector reviewed data for the inspection patches listed below to determine if the data was within the acceptance criteria, and whether the recording, evaluating, and dispositioning of findings were in compliance with the applicable nondestructive examination (NDE) procedure.
~atch o.
BF-039 BF-040 BF-041 eld o f't'on a d No.
Vertical Seam No. V-5-A Vertical Seam No. V-5-A Vertical Seam No. V-5-A Documentation for the above examination patches was excellent.
Evaluation and dispositioning of recorded indications by the analyst was also performed satisfactorily.
GERIS OD and GERIS 2000 examiner certification and qualification records were reviewed by the inspector and found to be satisfactory Within the areas examined, no violation or deviation was identified.
Observation of the GERIS OD Ultrasonic System (73052 8 73753)
The licensee had originally scheduled GE to conduct the GERIS OD examinations of the RPV nozzles after the invessel work was
.complete.
However, due to the delays encountered with the GERIS 2000 examinations the licensee decided to work both systems concurrently.
Procedures for this system had not been reviewed previously, therefore, GE's Procedure Nos GE-UT-400 Revision 3, and GE-UT-401 Revision 5 were reviewed by the inspector prior to observing work activities.
During the review of procedure GE-UT-401, (which is GE's procedure for the examination of the nozzle inner radius and bore regions)
the inspector noted that Paragraph 8.2 stated that, in order for an indication to be called a crack, it shall appear at the same nozzle azimuth location and be recorded for both the clockwise and counterclockwise examinations.
The inspector took exception to the word "shall" since the GERIS OD system operates with a low level gate on.
In addition experience at another TVA facility which has cracks in the inner radius and bore region has indicated that at least some of the signals from crack indications are very low level and possibly could not meet this criteria because of the gate settings.
The wording of this paragraph was discussed with TVA and GE and a
GE Field Revision Request (No.
FRR-001)
was issued to modify "shall" to "should".
During the inspector's visit the GERIS OD system experienced some delays and the inspector was only able to verify acquisition data on Nozzle N-4-E during the 0'xamination 8 306 to 242'.
Within the areas examined, no violation or deviation was identified.
Invessel Visual Examination of Reactor Vessel Shroud (IAW GE Services Information Letter No.
572 Revision I)
All Units (73753)
Background In October 1990, GE's RICSIL No. 054 reported that cracking was found near the circumferential seam weld at the core beltline area of the shroud in a BWR/4 located outside the United States.
The crack indications, initially observed at three locations on the inside surface of the shroud are confined to the heat affected zone (HAZ) of a circumferential seam weld.
The GE RICSIL provided interim recommendations.
All owners of GE BWR plants were requested to review fabrication records for the type of material used in their shrouds and determine the locations of the welds.
For plants with high carbon 304 stainless steel shrouds, GE recommended visual examinations of the accessible areas of the seam welds and HAZ on the inside and outside surfaces of the shroud at the next scheduled ou'tage.
In July 1993, while conducting the invessel visual examinations IAW GE's RICSIL No. 054, cracking was found in a stainless steel shroud of a GE BWR/4 located in the United States.
A 360'ircumferential crack was confirmed near the top guide support ring weld at this plant.
An enhanced visual examination, which used a I mil wire as a calibration reference, precleaned areas to be examined, and utilized improved lighting and camera resolution techniques, was found to be necessary by the utility involved in order to accurately detect and characterize the crack indications.
As a result, additional cracks were found elsewhere
'in the shroud.
Host of these other indications are associated with welds.
Metallurgical evaluation of cracked shroud samples indicate that the cracking is associated with weld sensitization in the HAZs, neutron fluence, and material conditions.
Because of the susceptibility factors present, GE concluded that similar cracking could exist at other GE BWR plants; therefore, GE issued RICSIL No. 054 Revision I, which recommended that owners of all GE BWRs perform visual examinations of accessible areas of the seam welds and associated HAZs on the inside and outside surfaces of the weld.
Based on the shroud crack observations to date, GE issued SIL No.
572 Revision I to provide an overview of the situation and recommendations on suitable inspection techniques and inspection frequency to detect cracking that could lead to structural integrity concern As a result of the above actions, the inspector held discussions with managers, engineers, and ISI Level III examiners of the licensee to determine what actions TVA has taken to date on this issue and what actions are scheduled for each Unit.
These discussions revealed the following:
TVA has sent representatives to the utility in the U.S. which first reported the cracking in the shroud.
The trip was made to determine the similarities between the Units and to observe the enhanced methods use by the utility to detect and characterize the crack indications.
TVA representatives found this trip very beneficial.
- TVA also intends to send representatives to a second utility which has reported cracking in the core region of the shroud.
This utility's shroud was fabricated by the same vendor as the three units at Browns Ferry.
TVA is in the process of reviewing drawings, fabrication and material records, and plant chemistry and operation records for all
~ three units at Browns Ferry to determine similarities and differences between the plants with reported cracks and the TVA units.
- TVA tentatively intends to examine Unit 3 in December of 1993, followed then by Unit 1,. If the examinations on Units 1 and 3 are satisfactory, TVA intends to seek an exception from GE on Unit 2 in order to operate an additional outage.
The exception will be based on the Unit 1 and 3 inspection results, operational time on the unit, materials of construction, and plant chemistry history for the unit.
Within the areas examined, no violation or deviation was identified.
4.
Review of Actions Taken by TVA for Reported Steam Leak In a 4" Extraction Steam Line
- Unit 2 (49001)
On October 6, 1993, TVA notified NRC that they had experienced a steam leak in a weld joining a weld-o-let to a 4" drain line.
The line runs off the 24",
No.
2 extraction steam line.
Steam was leaking from what appeared to be a 1/8" hole in the weld.
The line ran to a strainer, then through a steam trap and then to a 2" header pipe to the condenser.
The line. normally did not see flow since it was supposed to be only in operation from startup to 15% power.
Since the 4" line was spraying steam and the radiation levels were high on Unit 2, the licensee tentatively planned to ultrasonically examine the same fittings on Unit 1 and 3 to determine whether erosion/corrosion was the mechanism for the failure.
The licensee also stated that hole would be sealed using a mechanical clamp and liquid sealant.
On October 14, 1993, the inspector held discussions and reviewed documentation with the manager and engineers responsible for the erosion
corrosion program at Browns Ferry.
As a result of the reviews and discussions the inspector discovered that the licensee had ultrasonically examined the Unit 2 pipe and had found thin - wall areas in the pipe which indicated that erosion/corrosion was occurring in this pipe.
However, the ultrasonic readings also indicated that, in this area of the pipe sufficient material remained to make erosion/corrosion not the likely cause of the failure.
The inspector's review of the erosion/corrosion program for the 24" extraction steam lines revealed the pipe and fittings upstream and downstream of the weld-o-let were well covered by the program and the results of these examinations indicated that erosion/corrosion was not a problem in these lines.
However, since the licensee considered the drain line to have low flow it was not included in the program.
Further review by the inspector revealed that the licensee already had a liquid sealant can on the 2 - inch pipe down-stream of the strainer, and that the licensee intended to replace all of the piping from the weld-o-let on the No.2 and 3 extraction steam lines to the condenser during the next outage.
Based on the fact that the above lines already have two liquid sealant cans installed on them on Unit 2, the licensee was questioned about the adequacy of their assumption that the lines had only seen low flow.
In addition, the inspector questioned if other similar conditions might exist.
As'a result of the above discussions, the licensee decided to ultrasonically investigate the piping on Unit l.
Unit I was chosen because it has the same pipe configuration, operational time, and worse chemistry.
This investigation should determine whether these lines and other similar lines should be in the erosion/corrosion program and whether there are other areas on Unit 2 that should be examined and corrective measures taken to prevent another failure.
Within the areas examined, no violation or deviation was identified.
Licensee Actions on Previous Inspection Findings (92702)
A.
(Closed) Severity Level IV Violation 50-296/92-43-01,
" Failure to Implement Weld Overlay Specification Requirements
"
B.
(Closed) Severity Level IV Violation 50-259,260,296/93-26-01,
"
Failure of licensee to Take Adequate Corrective Action for a Previously Identified Vendor Welding Program Nonconformance
"
Corrective measures addressed in the licensee's letter of response dated September 9,
1993 were verified on site by the inspector.
These corrective measures were complete and thorough, and should prevent the re-occurrence of the discrepancies reported in A and B above.
Within the areas examined, no violation or deviation was identifie.
Exit Interview
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The inspection scope and results were summarized on October 15, 1993, with those persons indicated in paragraph 1.
The inspector described the areas inspected and discussed in detail the inspection results.
Although reviewed during this inspection, proprietary information is not contained in this report.
Dissenting comments were not received from the licensee.
7.
Acronyms and Initialisms ASME B&PV BF BWR FRR GE GERIS-IAW ID ISI NDE No.
NRC OD gA (AM RICSIL-RPV SIL TVA US UT American Society of Mechanical Engineers Boiler and Pressure Vessel Browns Ferry Boiling Water Reactor Field Revision Request General Electric Company General Electric Remote Inspection System In-Accordance-With Inside Diameter Inservice Inspection Nondestructive Examination Number Nuclear Regulatory Commission-Outside Diameter guality Assurance guality Assurance Manual Rapid Information Communication Services Information Letter Reactor Pressure Vessel Service Information Letter Tennessee Valley Authority United States Ultrasonic