ML17156B360
| ML17156B360 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 09/19/1989 |
| From: | Kaplan H, Oliveri M, Strosnider J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML17156B358 | List: |
| References | |
| 50-387-89-26, NUDOCS 8909260114 | |
| Download: ML17156B360 (7) | |
See also: IR 05000387/1989026
Text
U.S.
NUCLEAR REGULATORY COMMISSION
REGION I
Report
No.
50-387/89-26
Docket No.
50-387
License
No.
Licensee:
Penns
lvania Power
and Li ht
Com an
2 North Ninth Street
Allentown
Penns
1 vania
18101
Facility Name:
Sus
uehanna
Steam Electric Station Unit
1
Inspection At:
Berwick
Penns
lvania
I
C
d:.~A7-8
89
Inspectors
J.
Kaplan,
Reactor
Engineer
date
. Oliveri,
NDE Technician
7 /i/H
date
Approved by:
trosnider,
Chief,
MPS,
EB,
date
Ins ection
Summar
Announced Ins ection
on Au ust 7-8
1989
Re ort No.
50-387/89-26
Areas Ins ected:
Review of chronology of events
and reasons
that led to plant
start
up with potentially unacceptable
ISI ultrasonic indications in the
vicinity of a longitudinal
seam weld in the reactor vessel.
Results:
The inspectors
determined that the plant was started
up with potentially
unacceptable
ultrasonic indications in the reactor vessel
because
of inadequate
procedural
controls regarding
the disposition
and evaluation of ISI ultrasonic
indications.
The problem
stemmed
from the lack of timely evaluation resulting
fr'om poor communication
between
the licensee
and the ISI subcontractor.
The
licensee failed to maintain appropriate
surveillance of the subcontractor's
activities and the latter failed to formally notify the licensee of the final
disposition of a complex pattern of ultrasonic indications in a timely manner.
Subsequently (after startup),
the licensee's
ISI and
NDE Level III concurred
8e09260114
":9091
PbR
ADOCK 0~000387
9
with GE's evaluation;
however,
the licensee
determined that additional informa-
tion from Engineering
was necessary
to verify the acceptability of the indi-
cations.
The indications were ultimately attributed to segregated
streaks
of
nonmetallic inclusions,
which are not considered
relevant
by ASME Section XI/V.
Also, the licensee
had
a fracture mechanics
analysis
performed of two groups of
indications which potentially could be construed
to be rejectable.
The analysis
indicated these
indications are acceptable
by code
and should not experience
significant crack growth or challenge
reactor vessel integrity.
DETAILS
1.0
Persons
Contacted
Penns
lvania
Power
and Li ht
David S.
Borge, ISI Engineer
Ross A. Beckley,
QC Supervisor
George J.
Kuczynske,
Technical
Supervisor
Robert A. Baker,
NDE Level III
James J.
Graham,
Operations Assistant
Manager
D.
F.
McAnn, Compliance
Engineer
S.
L. Denson,
Outage Supervisor
T.
C. Dalpiaz,
Maintenance
Outage Supervisor
T.
K. Stiengass,
ISI Supervisor
Dale
R. Roth,
SR Compliance
Engineer
Jerry Blakeslee,
Asst. Superintendent
of Plant
Genie Stanley,
Asst. Superintendent
of Outages
General Electric Nuclear Ener
ZB
Michael
Stamm,
Project Manager
K.
R. Loll, Site .Services
Manager
~Back round
On April 22,
1989,
General Electric completed inservice inspection of weld
BA in the reactor vessel utilizing an automatic ultrasonic
system.
The
presence
of numerous indications led to
a series of events
as
shown in
the chronological tabulation in Exhibit A regarding the evaluation
and
final disposition of the subject indications.
The details of these
events
are discussed
below.
Weld BA is
a longitudinal
seam located in
the lower shell
course
(Ring ¹1).
The shell, (6.44" thick) was
fabricated
from SA-533 Gr B, Class
I rolled plate.
3.0
~Findin
a
During the recent Inservice Inspection of the reactor
vessel
General
Electric, the ISI subcontractor,
found ninety six (96) ultrasonic
indications in the vicinity of Weld BA, using the
GERIS automatic
system.
Thirty-four indications were recorded
in this area during the preservice
inspection
(PSI).
On April 4,
1989, the
GE technician questioned
the
significance of these indications because
of their complexity and
number
in terms of ASME XI flaw characterizations
requirements.
The indications
appeared
to be confined to the heat affected
zone of Weld BA and adjacent
base metal.
The raw data
was submitted to GE,
San Jose for evaluation
without notifying the licensee.
After the grouped indications were
bounded
in a rectangle
and characterized,
preliminary analysis of the data
indicated
two possible flaws, identified as ¹32 and ¹73.
Upon reanalysis,.
flaw ¹73, originally considered
to be
a rejectable
planar flaw, was
evaluated
as
an acceptable
laminar flaw.
Flaw ¹32 which consisted
of
fourteen (14) individual indications
was initially characterized
as
a
rejectable
laminar flaw because it exceeded
the
maximum area
requirements
of Section XI.
Upon final analysis
both ¹32 and ¹73 flaws were judged to
be irrelevant as permitted by Section
XI and Section
V since they were
considered
to be due to segregated
streaks
of nonmetallic inclusions which
are usually found in plate of this grade
and thickness.
This conclusion
which was subsequently
concurred
in by the licensee's
metallurgist,
was
supported
by the following facts:
(1) the indications found by straight
beam technique
were oriented in a parallel direction relative to the
length of the plate; (2) the indications
were located in the center of the
plate thickness
and extended
approximately
5" outboard
from the weld; (3)
angle
beam examination did not reveal
any indications associated
with
these
laminar oriented indications;
and,
(4) no reduction in back reflec-
tion was found associated
with indications.
The increase
in the
number of
indications
between
the ISI and
PSI data
was attributed to the implementa-
tion of Regulatory Guide
1. 150 which resulted
in an increased
search unit
overlap (.2" maximum step
size
used in the ISI vs.
.75" maximum step size
used in the PSI).
On July 24,
1989,
subsequent
to plant restart
on June
10,
GE formally
submitted their final report
+o the licensee,
but failed to provide an
independent
review of the subject indications,
On receipt of report the
licensee's
NDE Level III concurred with GE's evaluation
and,
per procedure,
forwarded the report to Engineering for their concurrence.
Licensee's
management
decided to treat flaw ¹32 as
a rejectable
flaw and requested
that Engineering
perform
a fracture analysis.
Flaw ¹73 was classified
as
laminar and determined to be acceptable;
however,
the fracture mechanics
analysis conservatively
bounded flaw ¹73 as well as ¹32.
NRC was notified
of the problem on July 28,
1989.
On August 11,
1989
NRC received the
fracture mechanics
report that concluded
flaw ¹32 (a worst case)
did not
exceed
the crack growth and fracture criteria of ASME XI.
The licensee
provided the inspector with a certified mill test report for
the subject shell plate (Lukens Steel
Heat C0814).
Although the test
report did not include ultrasonic results,
the licensee
reported that the
shell plate
had
been ultrasonically inspected
by Chicago Bridge 5 Iron
before field fabrication, followed by ultrasonic inspection of the weld
after completion with acceptable
results.
Licensee
review of nonconfor-
mance records
indicated
a problem during welding of the upper portion of
the weld at the 3/4" thickness
level in which preheat
was inadvertently
dropped.
No problem was reported at the mid-level, the location of the
ultrasonic indications.
The licensee
indicated that they will continue to
search
CBKI's process
sheets
for additional information regarding fabrica-
tion of the vessel.
The licensee
also reported that they possess
a nozzle
dropout which they
may use to determine
the quality of the subject plate
particularly with respect
to the type and severity of the nonmetallic
inclusions.
4. 0
~Summa r
The licensee's
actions
subsequent
to being informed of indications ¹32
and ¹73 were appropriate.
However, these actions
should
have
been
completed prior to returning the plant. to service.
Returning the plant
to service without appropriate
evaluation
and review of potentially code
rejectable
indications is
a serious
concern.
The inspector determined that the basic
reason for the licensee starting
up the plant with potentially rejectable
ultrasonic flaws in the reactor
- vessel
was due to inadequate
procedural
controls,
both within the licensee's
and ISI subcontractor'
organization.
The under lying fault appears
to be
due to the licensee's
failure to maintain appropriate
surveillance of the
subcontractor's
inspection activities
and subsequent
evaluation
process
to
assure
conformance to ASME XI requirements.
Fai lur'e to provide adequate
control of ISI activities is a violation of 10
CFR Appendix B, Criterion IX
(50-387/89"26-01).
I
0
Although the preponderance
of evidence
including metallurgical
and
ultras. nic factors
supported
the licensee'
and subcontractor'
opinion
that the indications were due to segregated
streaks
of nonmetallic inclu-
sions in the plate material,
the licensee
opted to take
a conservative
approach
and treat the two groups of indications
as significant flaws.
The flaws were subjected
to
a Section
XI fracture mechanics
analysis
and
found to be acceptable.
The licensee
indicated that they will reinspect
Weld BA and adjoining plate in the next outage
and will keep
NRC informed
of their ongoing search of fabrication records
and the results of any
metallurigcal
studies
regarding the subject plate.
5.0
Exit Interview
An exit interview was held
on August 8,
1989 with members of the
licensee's
staff noted in Paragraph
1.
The inspector discussed
the
scope
and findings of the inspection.
At no time during this inspection
was
written material
provided to the licensee
by the inspector.
Time Line
UT Inspection of weld "BA" completed
GE technician
questions
indications,
PP&L not notified
GE summary
sheet
prepared,
weld "BA" acceptable
but no independent
review performed
and
PP&L not notified
Plant start
up
GE issues final report evaluating
weld "BA" indications acceptable
PP&L issues
ISI notification form 54 (INF) sent to
NDE Level III to
receive his concurrence.
After'concurring INF 54 sent to plant
engineering for their concurrence
Engineering replies
"May take
some time to concur with INF 54"
NCR 89-0459 issued
by ISI supervisor - requests
more information to
characterize
indications ¹32 and ¹73
Management notified, Engineering notified to treat indications
as
valid flaws for conservatism - initiate fracture analysis
NRC notified
Results of fracture mechanics
analysis
indicate indications ¹32 and
¹73 acceptable
by code.
0