IR 05000259/1986023
| ML20212A653 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 07/16/1986 |
| From: | Blake J, Coley J, Coley J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML20212A625 | List: |
| References | |
| 50-259-86-23, 50-260-86-23, 50-296-86-23, GL-84-07, GL-84-11, GL-84-7, TAC-55590, TAC-55591, TAC-55592, NUDOCS 8607290094 | |
| Download: ML20212A653 (6) | |
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A MC UNITED STATES o -
NUCLEAR REGULATORY COMMISSION
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REGION ti n
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,j 101 MARIETTA STREET, N.W.
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ATLANTA, GEORGI A 30323
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Report Nos.: 50-259/86-23, 50-260/86-23, and 50-296/86-23~
Licensee:
Tennessee Valley Authority 6N38 A Lookout Place 1101 Market Str6et Chattanooga, TN 37402-2801
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Docket Nos.: 50-259, 50-260 and 50-296
.' License Nos. : DPR-33, DPR-52, and DPR-68 Facility Name: Browns Ferry
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Inspection Conducted: June 23-25, 1986 '
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Inspector: \\.N.
14A h 5b IN, 98$
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Q Signed
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Approved by:
Af Bf4 J.
Yake, Section Chief
'Oge'Siined n
eering Branch D ision of Reactor Safety
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SUMMARY Scope:
This routine, unannounced inspection was in the area of ultrasonic examination of the reactor vessel nozzle thermal sleeve welds utilizing TVA's automated ultrasonic system (Intraspect-98).
Results:
No violations or deviations were identified.
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REPORT DETAILS I
1.
Persons Contacted Licensee Employees
- R. L. Lewis, Plant Manager, Browns Ferry Nuclear Plant (BFNP)
- E. A. Grimm, Assistant to Plant Manager, BFNP
- W. Thomison, Supervisor, Technical Services, BFNP
- J. Savage, Compliance Engineer, BFNP
- G. Minton, Inservice Inspection (ISI) Supervisor, Office of Engineering -
Service (OES)
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- F.
S. Leonard, ISI-Level III Examiner, OES Other licensee employees contacted included engineers, technicians, and office personnel.
NRC Resident Inspector
- G.
L. Paulk, Senior Resident Inspector
- Attended exit interview 2.
Exit Interview The inspection scope and findings were summarized on June 25, 1986, with those persons indicated in paragraph 1 above.
The inspector described the areas inspected and discussed in detail the inspection findings.
No dissenting comments were received from the licensee. The licensee did not identify as proprietary any of the materials provided to or reviewed by the inspector during this inspection.
3.
Licensee Action on Previous Enforcement Matters This subject was not addressed in the inspection.
4.
Unresolved Items Unresolved items were not identified during the inspection.
5.
Ultrasonic Examination Of The Reactor Vessel Nozzle Thermal Sleeve Welds Utilizing TVA's Automated Ultrasonic System (Intraspect-98)
In July of 1984 the Philadelphia Electric Company (PECO) reported that indications of cracks had been identified in the 12-inch jet pump inlet riser (recirculation) safe ends during pipe replacement activities at the Peach Bottom 2 plant.
Liquid penetrant examination of three of the safe ends revealed circumferential indications in the safe end near the thermal
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sleeve attachment weld in two of the nozzles.
Subsequent ultrasonic examinations of the ten jet pump inlet riser safe ends and both 28-inch recirculation suction safe ends revealed that there were 14 shallow circumferential indications in five riser safe ends, i
Metallurgical examination of a boat sample taken from the effected area showed that the indications were intergranular stress corrosion cracking (IGSCC), both on the noncreviced side and creviced side of the weld.
In addition, the cracking on the noncreviced side of the weld was associated with a surface that had been upset or cold worked.
It was confirmed that the material was Type 316L, low carbon stainless steel.
The event discussed above raised a concern that may prove to have generic l
implications for the following reasons:
a.
The cracks were in low carbon stainless steel both in creviced and noncreviced locations.
b.
This represented the first field experience where cracking had occurred in a low carbon grade austenitic stainless steel, t
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The design configJration at the safe end/ thermal sleeve weld location
required the use of special ultrasonic equipment and techniques.
d.
Laboratory test data had shown that cracks could occur at creviced or cold worked locations in low carbon grades of austenitic stainless steel.
As a result of the above finding, NRC Information Notice No. 84-89 was issued to alert other boiling water reactor licensee of this potentially significant problem.
L On June 4, 1986, TVA notified the inspector that the jet pump inlet riser t
safe end to the thermal sleeve weld examinations would start on June 17, 1986 and that TVA's newly design automated ultrasonic system (Intraspect-98)
would be used to perform these examinations.
This was to be the first official examinations performed utilizing the Intraspect-98. High radiation levels near the reactor vessel nozzles however, made the automated ultrasonic examination of these welds the preferred method of examination.
On June 23, 1986, the inspector arrived at the Browns Ferry Nuclear Plant to perform an assessment of TVA's automated system by observing the system perform the reactor vessel nozzle thermal sleeve weld examinations on Unit 2.
The inspector examined the Intraspect-98 examination procedure, observed the examination activities indicated below including calibrations, reviewed the recorded examination data, and verified examiner qualifica-tion / certification records to determine whether the nondestructive examinations were being conducted in accordance with the applicable procedure, regulatory requirements and licensee commitments. The applicable codes for the examinations delineated below are ASME,Section XI, 74S75 for i
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the extent of examinations and ASME, Section X1, 77578 for inspection
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technique and defect evaluation.
a.
Review of Procedure (730528)
The inspector reviewed TVA's procedure No. N-UT-38, " Ultrasonic
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Examination of Safe End Crevice Regions Using the Intraspect-98 Automated System," to determine the tecnnical adequacy of the procedure
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in the following areas: Type of apparatus used; extent of coverage of
weldments; calibration requirements; search units; beam angles; reference level for monitoring discontinuities; method for demonst-rating penetration; limits for evaluating and recording indications and; acceptance limits. The inspector concluded that TVA's procedure
was well written and covered all pertinent ASME Code, and regulatory
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requirements.
b.
Observation of Nondestructive Examination (NDE) Work Activities -
Unit 2 (73753)
The inspector observed the in process ultrasonic examinations, including calibration activities, for the weld listed below.
The
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observations were compared with the applicable procedure in the following acsas:
availability of and compliance with approved procedure; use of knowledgeable NDE personnel; use of NDE personnel qualified to the proper level; type of apparatus used; extent of coverage of weld; instrument calibration requirements; search units; beam angles; reference level for monitoring discontinuities; method of demonstrating penetration; limits of evaluating and recording indica-tions; continuous observation of scanning pattern to achieve 100s coverage of welds and base metal section designated for examination; continuous recording of meaningful and reproducible data with accurate j
orientation to the reference points and; initial unit calibration, examination block calibration, and subsequent calibrations are performed in accordance with the NDE procedure.
The following examinations were observed:
Weld Identification Process Observed N2CTSC Calibration & Examination N2GTSC Calibration & Examination The Intraspect-98 system demonstrated an excellent capability to acquire examination data with minimum restriction due to geometric conditions. The system also appeared to be very durable experiencing only minor problems during this initial field trial, i
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c.
Evaluation of Recorded Data (737558) Unit 2 Recorded data was reviewed by the inspector to ascertain whether the method, extent, and technique of examination complied with the licensee's NDE procedure; the examination data was within the acceptance criteria as outlined in the applicable NDE procedure and; the ultrasonic methods used for the examination was sufficient to determine the full extent of indications or acceptance.
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Since each weld examination required three separate series of system calibrations TVA elected to perform one series of examinations on all of the welds before recalibrating the system and performing the second or third series of examinations. This method saves time when gathering examination data, but it prevents the evaluation of a single weld until nearly all the welds have been completed. Therefore, the data reviewed by the inspector was not complete and final conclusions as to the acceptability of the weld could not be established. Partial examina-tion data was reviewed for the following welds:
Weld Identification Process
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N2ATSC Data Evaluation N2BTSC Data Evaluation
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Preliminary data taken by the system revealed indications in the area of interest for both weld.
Plots depicting the location of geometric conditions on the inside surface of the nozzle safe end and of the suspected indications were easily made from the data presented on the screen.
However, additional scans in various directions will be required before final disposition of the data can be made.
d.
Qualification / Certification of Examiners The inspector reviewed the certification records for the below listed examiners to determine the extent of each examiners certification and to insure that only examiners qualified to a specific function were
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i performing that function. The following examiners certifications were reviewed:
Examiner Level of Certification H.E.Q.
UTA-Level IIA Data Acquisitionist/
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Analyst (Limited)
C.A.
UTA-Level IIA Data Acquisitionist/
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Analyst (Unlimited)
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UTA-Level IIA Data Acquisitionist E.W.S.
UTA-Level IIA Data Acquisitionist i
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D.I.H.
UTA-Level IIA Data'Acquisitionist/
Analyst (Unlimited)
In addition to reviewing the certification records of the above examiners the inspector observed the performance of each examiner and
. concluded that the examiners were well qualified within the area of their certification.
Within the areas examined, no violation or deviation was identified.
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