ML16161A898
| ML16161A898 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 10/14/1987 |
| From: | Blake J, Coley J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML16161A899 | List: |
| References | |
| 50-269-87-37, 50-270-87-37, 50-287-87-37, NUDOCS 8710270003 | |
| Download: ML16161A898 (8) | |
See also: IR 05000269/1987037
Text
V REG
UNITED STATES
o
NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTA STREET, N.W.
)@
ATLANTA, GEORGIA 30323
Report Nos.:
50-269/87-37, 50-270/87-37, and 50-287/87-37
Licensee:
Duke Power Company
422 South Church Street
Charlotte, NC 28242
Docket Nos.: 50-269, 50-270,
License Nos.: DPR-38, DPR-47, and
and 50-287
Facility Name:
Oconee 1, 2, and 3
Inspection Conducted:
September 18 and September 21-24, 1987
Inspector:
)c -ii- P7
J.
Date Signed
Approved by:
M
,o
q'2
J J. lake, Chief
Date Signed
at ials and Processes Section
Division of Reactor Safety
SUMMARY
Scope:
This routine, announced inspection was in the areas of inservice
inspection - observation of the ultrasonic examination of the reactor vessel
flange-to-shell weld, and review of the first interval hydrostatic testing
program for Unit 1 and, IE Bulletin 83-06.
Results:
No violations or deviations were identified.
8710270003 871016
ADOCK 05000269
REPORT DETAILS
1. Persons Contacted
Licensee Employees
M. S. Tuckman, Station Manager
- L. V. Wilkie, Acting Station Manager
- T. C. Mathews, Regulatory Compliance Specialist
- D. W. Denard, Performance Engineer
- A. J. Hogge, Jr., General Office - QA
Other licensee employees contacted included construction craftsmen,
engineers, technicians, operators, mechanics, security force members, and
office personnel.
Other Organization
- M. Hacker, B&W -
Level III
NRC Resident Inspector
- J. Bryant, Senior Resident Inspector
- Attended exit interview
2. Exit Interview
The inspection scope and findings were summarized on September 24, 1987,
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
following new item was identified during this inspection:
(Open)
Unresolved Item 50-269/87-37-01, Hydrostatic Test Boundaries
Uncertain -
paragraph 6.
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.
2
4. Unresolved Items
Unresolved Items are matters about which more information is required to
determine whether .they
are acceptable or may involve violations or
deviations.
One unresolved item identified during this inspection is
discussed in paragraph 6.
5. Ultrasonic Examination of the Oconee Unit 1 Reactor Vessel Flange-to-Shell
Weld (57080)
During the 1986 outage of Oconee Unit 1, an ultrasonic examination of the
reactor vessel flange-to-shell weld was conducted from the flange face. A
total of 22 indications were recorded.
These indications appeared at
several elevations within the area of interest for the weld and all were
recorded from the clad side of the flange.
These indications were
evaluated as subsurface flaws for the purpose of disposition and were
acceptable to the requirements of either IWB-3500 or IWB-3600 of the ASME
Code.
Since these indications were not detected by any previous
examinations and they were not detected from the unclad side of the flange
when using the unclad calibration, there was speculation that they may not
indicate a flaw condition.
Subsequent investigations on a similar weld joint located at the B&W
Mr. Vernon facility indicated that it
was possible to obtain false
indications of similar magnitude to the Oconee indications when examining
through the clad surface of the flange face. The results of these efforts
have been previously documented
(B&W
Document
No.
1163186A-0).
An
improved ultrasonic examination procedure (ISI-187, Rev. 0) was developed
to minimize the occurrence of false indications. This procedure was used
at Oconee Unit 2 during 1986 and resulted in no false indications being
recorded.
The intent of this inspection was to properly characterize the previously
recorded indications on the Unit 1 reactor vessel flange-to-shell weld and
to provide a baseline for future inspections from the flange face.
The ultrasonic (UT)
instrument used during the 1986 examination was the
Krautkramer Model USIP-11. The reliability of the Krautkramer USIP-11 UT
instrument had been a problem for the contractor (B&W)
when used in an
environment where the instrument must be sealed to prevent contamination.
To eliminate the problem, a different UT instrument was used this outage.
The
Panametric Digital
instrument
Model
EPOCH-2002
and the
Krautkramer-Branson, Inc., Model USD-10 were evaluated and compared to the
USIP-11 by B&W and the EPOCH-2002 was selected as the instrument best
suited for the examination.
As stated above, the examination of the flange-to-shell weld had two major
objectives.
The first was to establish a more accurate representation of
the actual condition of the flange-to-shell weld. this was to serve as a
baseline for future examinations.
The second objective was to properly
disposition the 22 indications recorded during the previous outage.
3
Since the examination was
on critical path,
two inspection teams,
designated as Teams A and B, were used for the examination.
Team A
performed the full 360 examination of the flange excluding the previously
recorded indications.
This examination was performed per the requirement
of ISI-187.
The results of this inspection and that performed by Team B
established the new baseline.
Team B was dedicated to the resolution of
the 22 previously recorded indications.
The objective was to duplicate as
closely as possible the examination performed in 1986 utilizing B&W
Procedure ISI-130.
Next, Procedure ISI-187 was used to acquire as much
data as possible using selected transducers of different size, frequency,
and a combination of straight beam and angle beam inspections where access
permitted.
The calibration block used for the examination was block #50304 which was
the same block used in the 1986 examination of Unit 1 and the examination
of Unit 2.
The following calibration setups were used to conduct the
examinations:
CALIBRATION SET-UPS
CALIBRATION BLOCK 50304
Calibration
Calibration
Number
Transducer
Surface
- 1
1" Dia. 0 -
Degree
Full Clad
2.25 mHz
(as welded)
- 2
1" Dia. 0 -
Degree
Clad Patch
2.25 mHz
(machined)
- 3
1.5" Dia. 0 -
Degree
Clad Patch
5.0 mHz
(machined)
- 4
1" Dia. 5 - Degree
Unclad
2.25 mHz
- 5
1" Dia. 10 -
Degree
Unclad
2.25 mHz
- 6
1" Dia. 15 -
Degree
Unclad
2.25 mHz
- 7
1.5" Dia. 0 -
Degree
Full Clad
5.0 mHz
(as welded)
Note calibration #7 was added by the licensee when the inspector noted
that the calibration setup for the 1.5 Dia., 5.0 mHz did not evaluate the
reflectors at the same sensitivity as the 1986 examinations. The setup in
the inspection plan was using the machined clad patch as the surface for
calibration in lieu of the "as welded" full clad surface.
The difference
between these surfaces represents approximately a 30 decibel drop with the
'@
4
as welded full clad calibration being the more sensitive examination.
In
NRC's safety evaluation report for Unit 1, NRC informed the licensee to
treat the reflectors in the weld as real cracks in reactor vessel and that
the issue could not be resolved by simply reducing the instrument gain
such that the flaws indications were no longer recordable by ASME
Section XI criteria.
Calibration #3 in the B&W plan did exactly that for
the evaluations using a 1.5 Dia., 5 mHz transducer. After the inspector
discussed the situation with the licensee's corporate QA technical
supervisor, the licensee decided to add calibration #7.
The inspector observed the UT calibrations, the examinations of the
vessel-flange weld,
and portions of each evaluation process.
The
examination process started approximately 1:00 a.m.,
on September 22,
1987, and completed at approximately 9:00 p.m., the same night. A break
of approximately four hours was taken when one examiner who was recording
data was overcome by the heat in the canal.
Prior to leaving the site on September 24,
1987, the inspector reviewed
B&W's preliminary examination data.
The re-examination of the flange
using the same techniques as the 1986 examinations were basically
representative of the previous examination with one exception where one
indication representing 500 DAC during the 1986 examination was less than
20 DAC during the present outage.
In this case, the examiner apparently
was not in the correct position; however, calibration #7 recorded the
indication at 70 DAC which is approximately the expected amplitude using
the larger transducer with a higher frequency to reduce the sound beam
spread. During the 1986 inspections, there was only one team of examiners
and they had to wear respirators which inhibited their ability to
communicate. This probably would account for the differences noted in the
recorded data. Calibration #7 still recorded five of the 22 reflectors;
however, their size and amplitude were reduced from that previously
recorded and angle beam calibrations (#4, #5, and #6) from the unclad
surface of the flange did not detect any of the five reflectors.
Calibrations #2 and #3, which include the new baseline, did not detect any
indication over 50% DAC.
B&W's preliminary evaluation of the data was that the reflectors are
caused by the geometry of the forged flange and the examination of the
flange in the 1986 examinations had been at too high a sensitivity level
to obtain meaningful results.
Although, the preliminary data appears to
support B&W's position, the inspector advised the licensee to be very
conservative in their evaluation approach to the five reflectors recorded
in the #7 calibration examinations.
The licensee informed the inspector that a final disposition of the
recorded indications would be available for NRC review within two weeks.
Within the area examined, no violations or deviations were identified.
4
5
6.
Review of First Interval Hydrostatic Testing Program - Unit 1 (73755)
The Duke Power Company (DPC)
inservice inspection (ISI)
program for the
first interval examinations and testing of components and piping was
conducted in accordance with the requirements of Section XI of the ASME
Code, 74S75 Edition and Addendas.
Section XI requires that piping and components of boiling and pressurized
water reactor plants be examined and pressure tested for the 40 year
service lifetime of the plant.
These examinations and tests are to be
completed during each of four ten-year intervals.
These ten-year
intervals are calculated from the start date of commercial operation of
the facility.
Oconee Unit 1 started commercial operation on July 15,
1973,
so the first interval examinations and testing should have been
completed in 1983.
However, since Section XI of the ASME Boiler and
Pressure Vessel Code allows extension of the interval of up to one year so
that the interval can be made to correspond to a plant's outage schedule,
the final completion date allowed by the Code for the first interval
examination and testing on Unit 1 would have been July 15, 1984.
The inspector reviewed select test procedures and quality records for the
first interval inspections to determine the adequacy and completeness of
the tests, the test procedures, and the records.
In order to obtain a clear perspective of hydrostatic testing with a
minimum sample, the inspector selected a test procedure from each code
class.
In addition, the sample selected represented two systems that the
inspector had found at other facilities to be susceptible to testing
errors. The following systems were chosen for this review:
System
Test Procedure
Class
Emergency Core Cooling
TT/1/A/450/25
1
Reactor Building Spray
TT/1/A/450/15
2
Reactor Building Cooling
TT/1/A/450/11
3
During the inspector's review of the emergency core cooling system, the
inspector noted isolation valves on instrumentation lines were not listed
in the test procedure valve alignment enclosure.
Failure to list the
position of these valves would normally indicate hydrostatic test boundary
uncertainty.
However, the drawings used by the inspector to perform the
review were updated OFD drawings and all modifications to the system were
incorporated.
The first interval hydrostatic tests were inspected to
marked up PO drawings that were kept in the Charlotte Corporate QA office.
The
licensee's cognizant performance engineer felt that the
instrumentation valves in question,
1RC-34, 1RC-35, and 1RC-84, were new modifications as a result of TMI, and
therefore,
would not have been listed in the test procedure valve
enclosure verification list. In addition to the instrumentation isolation
boundary valves, valve 1RC-46 was also not on the valve list for the test.
6
This valve should have isolated an instrument line and the reactor
building component drain header during the test.
The licensee felt that
this line may not have been a new modification; however, to resolve these
issues, the marked up PO drawings will have to be sent to the site for the
inspector's review. The inspector reported this item as Unresolved Item
50-269/87-37-01, Procedure Hydrostatic Boundaries Uncertain.
Within the areas examined, no violations or deviations were identified.
7.
IE Bulletin -
Units 1, 2 & 3 (92701)
(Closed)
83-BU-06:
Nonconforming Materials by Tube-Line Corporation
Facilities at Long Island City,
and Carol
Stream, Illinois.
By memoranda
dated November 18
and
December 9, 1983,
the licensee
responded to the action items requested by this Bulletin.
The response
stated that the only Tube-Line (T-L)
material supplied. to Oconee was
installed in the Unit 3 Auxiliary Feedwater System.
The material in
question involved weld-neck flanges, end caps and reducing tees - all of
which were made of carbon steel material.
Tests performed on a sample of
SA-234 WPB material produced from the same heat as the caps and tees, in
Oconee 3, showed the material properties equaled or exceeded the ASME Code
requirement. However, in the case of the three inch (3") weld-neck raised
face flanges, which are located on the risers that lead to the Auxiliary
Feedwater Steam Generator Nozzles, laboratory tests conducted by Babcock
and Wilcox (B&W), and T-L indicated that the material properties did not
meet B&W's purchase specification requirements. Specifically, the yield
and ultimate strength properties were below the
standards.
The Code of Record, the 1967 USAS B 31.1 Code,
does not
require a specific flange analysis.
However,
it
does require that the
material meet ASTM and B 16.5 standards. The laboratory test results were
essentially identical to the material properties for materials which are
acceptable per ANSI B 16.5 for Oconee.
The reported test results and
Code/ANSI standard requirements are as follows:
Yield KSI at
Tensile KSI at
Ambient To
Ambient To
36
70
SA-105
USAS, B31.1/B 16.5 Required
Material Properties
ASTM A-105Gr.1
30
60
Flange Material
31.1
59.8
Properties
4
7
On the basis of these results, the licensee concluded the material meets
B31.1 Code requirements for ASTM A-105 Gr.1 but not ASTM A-105 Gr-11/ASME
SA-105 as specified.
Results of a rigorous analysis used to evaluate the subject flanges,
caused the licensee to conclude that one of the 12 installed flanges did
not meet Code stress allowables for the flange stresses and flange bolt
stresses during operating conditions.
However, the licensee concluded
that, on the basis of these evaluations, Unit 3 could return to power
until the spring 1984 Refueling Outage.
During that outage all the
flanges were visually inspected and checked for hardness.
All material
except one flange was found acceptable and the one that failed was
replaced.
This bulletin remained open,
however, because the licensee
could not provide stress analysis calculations for the inspector's review
and a description of the general concerns as expressed in paragraph 4 of
the bulletin, i.e., short-term and long-term corrective actions as
applicable was not included in the licensee's response.
Supplement
information was provided to the inspector during this inspection and
reviewed by cognizant inspector and this matter is considered closed.