ML14191B106
| ML14191B106 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 04/06/1989 |
| From: | Dance H, Garner L, Jury K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML14191B103 | List: |
| References | |
| 50-261-89-07, NUDOCS 8904200180 | |
| Download: ML14191B106 (9) | |
See also: IR 05000261/1989007
Text
\\
p REGo
UNITED STATES
NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTA STREET, N.W.
ATLANTA, GEORGIA 30323
Report No.:
50-261/89-07
Licensee:
Carolina Power and Light Company
P. 0. Box 1551
Raleigh, NC
27602
Docket No.:
50-261
License No.: DPR-23
Facility Name: H. B. Robinson
Inspection Conducted: February 11 -
March 10, 1989
Inspector:
A_____
__
__
__________
k
L. W. Garner, Senior Resident Inspector
ate Signed
K. R. Jury, Resident Inspector
Date Signed
Approved by: 9'
C 4
-
-'--4-4/
H. C. Dance, Section Chief
Date Signed
Division of Reactor Projects
SUMMARY
Scope:
This routine announced inspection was conducted in the areas of opera
tional safety verification, surveillance observation, maintenance observation,
ESF system walkdown, onsite followup of events at operating power reactors, and
onsite review committee.
Results:
The unit experienced a high steam flow coincident with Low Tavg SI
induced reactor trip from 30% power due to a personnel
error.
While
troubleshooting a EH power supply an I & C technician inadvertently connected a
current meter into the control circuit. The resultant short circuit closed two
governor valves, thereby, initiating the transient.
A violation was identified concerning procedure usage. Procedure steps were
signed off certifying that safety related valves operated properly before the
post-maintenance tests were actually performed, paragraph 4.
An operator was observed manipulating a valve without first verifying valve
identification, resulting in the wrong valve being manipulated.
This poor
practice is discussed in paragraph 3.
The licensee demonstrated a conservative approach to safety, in that, plant
operation has been voluntarily limited to 9 months as a result of the A loop
hot leg RTD thermowell cracking issue described in paragraph 6.
,i,,904200 1808946
p~ D
VCK 05000261
PIc
REPORT DETAILS
1. Licensee Employees Contacted
R. Barnett, Maintenance Supervisor, Electrical
C. Bethea, Manager, Training
R. Chambers, Engineering Supervisor, Performance
- D. Crook, Senior Specialist,.Regulatory Compliance
- J. Curley, Director, Regulatory Compliance
- C. Dietz, Manager, Robinson Nuclear Project Department
R. Femal, Shift Foreman, Operations
W. Flanagan, Manager, Design Engineering
W. Gainey, Support Supervisor, Operations
- E. Harris, Director, Onsite Nuclear Safety
- R. Johnson, Manager, Control and Administration
D. Knight, Shift Foreman, Operations
D. McCaskill, Shift Foreman, Operations
R. Moore, Shift Foreman, Operations
- R. Morgan, Plant General Manager
0. Nelson, Maintenance Supervisor, Mechanical
M. Page, Acting Manager, Technical Spport
D.
Quick, Manager, Maintenance
F.
Seagle, Shift Foreman, Operations
J. Sheppard, Manager, Operations
R. Steele, Acting Operating Supervisor, Operations
- H. Young, Director, Quality Assurance/Quality Control
Other licensee employees contacted included technicians, operators,
mechanics, security force members, and office personnel.
- Attended exit interview on March 12, 1989.
Acronyms and initialisms used throughout this report are listed in the
last paragraph.
2. Operational Safety Verification (71707)
The inspectors observed licensee activities to confirm that the facility
was being operated safely, in conformance with regulatory requirements,
and that the
licensee management control
system was effectively
discharging its responsibilities for continued safe operation.
These
activities were confirmed by: direct observations, tours of the facility,
interviews and discussions with licensee management and personnel,
independent verifications of safety system status and limiting conditions
for operation, and reviews of facility records.
2
Periodically, the inspectors reviewed shift logs, operations records, data
sheets, instrument traces, and records of equipment malfunctions to verify
operability of safety-related equipment and compliance with TS. Specific
items reviewed include control room logs,
maintenance work requests,
auxiliary logs,
operating orders,
standing orders,
jumper logs,
and
equipment tagout records.
Through periodic observations of work in
progress and discussions with operations staff members,
the inspectors
verified that the staff was knowledgeable of plant conditions; responded
properly to alarm conditions; adhered to procedures and applicable
administrative controls; and was
aware of equipment out of service,
surveillance testing, and maintenance activities in progress.
The
inspectors routinely observed shift changes to verify that continuity of
system status was maintained and that proper control
room staffing
existed. The inspectors also observed that access to the control room was
controlled and operations personnel were carrying out their assigned
duties in an attentive and professional manner.
The control room was
observed to be free of unnecessary distractions. The inspectors performed
channel checks, reviewed component status and safety related parameters,
including SPDS information, to verify conformance with the TS.
During this reporting interval, the inspectors verified compliance with
selected LCOs. This verification was accomplished by direct observation
of monitoring instrumentation, valve positions, switch positions,
and
review of completed logs and records.
Plant tours were conducted to verify the operability of standby equipment;
assess the general
condition of plant equipment;
and verify that
radiological controls, fire protection controls, and equipment tag out
procedures were properly implemented. These tours verified the following:
the absence of unusual fluid leaks; the lack of visual degradation of
pipe, conduit and seismic supports; the proper positions and indications
of important valves and circuit breakers; the lack of conditions of which
could invalidate EQ; the operability of safety-related instrumentation;
the calibration of safety-related and control instrumentation including
area radiation monitors, friskers and portal monitors; the operability of
fire suppression and fire fighting equipment;
and the operability of
emergency lighting equipment.
The
inspectors also verified that
housekeeping was adequate and areas were free of unnecessary fire hazards
and combustible materials.
In the course of the monthly activities, the inspectors included a review
of the licensee's physical security and radiological control programs.
The inspectors verified by general observation and perimeter walkdowns
that measures taken to assure the physical protection of the facility met
current requirements. The inspectors randomly verified that radiological
controls were being adhered to by station personnel.
No violations or deviations were identified within the areas inspected.
0II
3
3. Monthly Surveillance Observation (61726)
The inspectors observed certain surveillance related activities of
safety-related systems and components to ascertain that these activities
were conducted in accordance with license requirements.
For the
surveillance test procedures listed below, the inspectors determined that
precautions and LCOs were met,
the tests were completed at the required
frequency, the tests conformed to TS requirements, the required adminis
trative approvals and tagouts were obtained prior to initiating the tests,
the testing was accomplished by qualified personnel in accordance with an
approved test procedure,
and the required test instrumentation
was
properly calibrated.
Upon completion of the testing, the inspectors
observed that the recorded test data was accurate, complete and met TS
requirements,
and that test discrepancies were properly rectified.
The
inspectors independently verified that the systems were properly returned
to service. Specifically, the inspectors witnessed/reviewed portions of
the following test activities:
a. OST-202 (revision 16) Steam Driven Auxiliary Feedwater System
Component Test
The test implements surveillance requirements of ASME Section XI and
The inspectors witnessed the performance of section 7.2
which tests the SDAFW pump.
The test was performed in order to
declare the SDAFW pump operable after adjustments of the Masoneilan
pressure controller were completed. The adjustments were necessary
as the required flow rate had not been obtained during the
performance of OST-206. The inspectors verified that the acceptance
criteria concerning pump speed, differential pressure, vibration, and
feed-steam differential pressure were met.
b. OST-206 (revision 9) Steam Driven Auxiliary Feedwater Pump Flow Test
The procedure implements test requirements of ASME Section XI.
On
February 24,
1989,
the SDAFW pump developed approximately 300 gpm
instead of the anticipated 600 gpm during the test performance.
During troubleshooting activities, the operator was observed to
manipulate an instrument air valve without first reading the valve
tag. This resulted in manipulation of the air regulator valve to the
Masoneilan pressure controller instead of the controller's air
isolation valve. This had no safety significance in that the SDAFW
pump was already inoperable. However, the inspectors have observed a
tendency by operations personnel to not alway verify valve identifi
cation prior to operating valves. This is considered a poor work
practice. The inspectors acknowledge that there is no requirement to
verify a valve tag prior to operating equipment.
However,
the
licensee is required to identify equipment in
some manner
and
4
implement procedures adequately.
In the context of equipment
identification established by the licensee (i.e., valve tags), the
failure to habitually use the established system (i.e.,
read valve
tags) is considered a weakness. This issue was discussed with the
Operations
Manager.
The
inspectors observed
adjustment of the
pressure controller by I&C, and the subsequent successful completion
of OST-206.
No violations or deviations were identified within the areas inspected.
4. Monthly Maintenance Observation (62703)
The
inspectors observed several maintenance related activities of
safety-related systems and components to ascertain that these activities
were conducted in accordance with approved procedures, TS, and appropriate
industry codes and standards.
The inspectors determined that these
activities did not violate LCOs,
and that redundant components were
The
inspectors
also
determined that
activities were
accomplished by
qualified
personnel
using
approved
procedures,
appropriate ignition and fire prevention controls were implemented,
and
the affected equipment was properly tested before being returned to
service.
In particular, the inspectors observed/ reviewed the following
maintenance activities:
o
CM-111
(revision
5); Limitorque Limit Switch and Torque Switch
Maintenance
o
WR/JO 89-ACUM1; Weld repair of A SWBP PI-1601A pressure indicator
sensing line.
o
WR/JO 89-ACXW1; Repair of B EDG air compressor.
On February 15, 1989, while reviewing implementation of CM-111 associated
with WR/JO 89-ACMK1 and 89-ACML1, the inspectors identified a procedure
usage problem.
The WRs involved inspection of V2-14A (89-ACMK1)
and
V2-14C
(89-ACML1),
the SDAFW pump discharge valves to S/Gs A and C,
respectively. Step 7.6.4 of CM-111 requires verification of proper motor
operator function when the valves are electrically cycled fully open
and closed.
This verification is to be initialed on the associated
attachment 8.1.
The inspectors identified that this verification was
initialed as having been completed before the valve operators were
completely reassembled.
Upon discussion of this situation with the maintenance personnel performing
the work,
the inspectors were told that they had every intention of
completing the procedure, and that they had just signed the verification
step in advance. This situation is identified as a violation: Initialing
Procedure Steps Prior to Performing Work (89-07-01).
One violation was identified within the areas inspected.
5
5. ESF System Walkdown (71710)
The inspectors performed a field walkdown of parts of the CS andthe SI
sub-systems shown on drawings 5379-1082 sheets 1, 2 and 3, and the MDAFW
sub-system shown on drawing G-190197 sheet 4. Specifically, the
inspectors examined the system components located in the CS tank room, the
SI pump room,
the CCW room,
and the MDAFW pump
room.
Items examined
included pumps,
valves, piping, pipe supports,
instrument tubing and
their supports, and valve tagging. The inspectors verified that all major
valves were in their correct position,
manual valves were locked as
required, instrumentation was valved into service, and power was available
to MOVs as indicated by the RTGB indicators and MCC breaker positions.
No conditions which could render these sub-systems incapable of performing
the safety function were observed.
No violations or deviations were identified within the areas inspected.
6. Onsite Followup of Events at Operating Power Reactors (93702)
a.
Failure of the A Loop RTD Hot Leg Thermowells
On February 9, 1989,
while at rated temperature and pressure in
preparation for taking the reactor critical
after refueling
number 12, the licensee observed an abnormal downscale indication on
the A loop TAVG instrument. On February 11, the licensee discovered
that a small plume of steam was being emitted from one of the loop A
hot leg RTD thermowells.
The reactor system was returned to cold
shutdown and the thermowell was removed. Liquid penetrative examina
tion at the Harris Energy and Environmental Center revealed a 200
degree crack at the transition area between the threaded area and the
shank of the thermowell.
Subsequent destructive testing revealed
that the crack was a fatique failure at a stress riser. The cracking
resulted from stresses due to high flow induced vibrations and
amplified by a very small radius of curvature in the transition area
(approximately 5 mils radii).
Removal of the other two A loop hot
leg
thermowells
revealed non-throughwall cracking.
In one
instance the crack was in the same location as the one discussed
above.
The radius of curvature was found to be
15 mils.
The
specified radius of curvature was 30 plus or minus 10 mils.
The
other thermowell was cracked in between the first and second threads.
In this instance the crack initiated at a manufacturing defect.
In
summary, the cracking was attributed to higher than anticipated flow
induced stresses, compounded with either stress risers due to either
a small radius of curvature or a manufacturing flaw.
The licensee has performed a safety analysis which indicates that
total failure of a hot leg RTD thermowell (i.e., complete separation)
is bound by existing analysis for loose parts and would not result in
6
coolant inventory loss in excess of the normal makeup capability.
The largest leak from one completely severed thermowell is limited to
that which would occur from a one fourth inch diameter hole.
One
charging pump can make up the leakage from a three-eighths inch
diameter hole. Consequently, failure of the three A loop hot leg
RTD thermowells would not render the safeguards system inoperable.
The licensee, with the assistance of Westinghouse (the RTD Thermcwell
supplier) and Weed Instrument Company (the RTD manufacturer), modified
the design of the replacement A loop hot leg RTD thermowells.
The
changes included a shorter thermowell (i.e.,
a 3.5 inch instead
of 4.5 inch emersion depth); increased transition area radius of
curvature
(machining);
increased compressive stresses in the
transition area (shot peening); and reduced thermowell to coolant
pipe wall gap (chrome plating).
Reduction of the gap limits the
allowable deflection of the thermowell. This limits the amplitude of
vibration and hence limits the maximum stress in the transition area.
The licensee's engineering department performed calculations which
demonstrated a useful life for the replacement RTD thermowells of
9 months. These calculations conseratively assumed that the vibration
amplitude could be as large as 16 mils, the thermowell to coolant
pipe wall gap. The licensee has authorized plant operation for up to
nine months while a permanent solution is found.
The licensee is
pursuing redesign of the A loop hot leg RTD thermowells and develop
ment of more realistic analytical models. This issue is identified
as an IFI: Review Permanent Solution to RTD Thermowell
Cracking
Phenomena (89-07-02).
The unit was placed on line at 9:47 a.m.,
on February 25,
1989.
Subsequent inspection and channel checks of the RTGB TAVG indicators
have revealed no unusual indications from the A loop hot leg RTDs.
b.
Reactor Trip and NOUE
On February 27, 1989, at 4:17 p.m., the unit experienced a SI signal
reactor trip from 30% full power.
The plant was brought to stable
conditions in accordance with EOP PATH-1 and end path procedure
EPP-7,
revision 6, SI Termination.
All ESF systems performed as
expected. Plant Emergency Procedure,
PEP-101,
revision 8, Initial
Emergency Actions, describes conditions
requiring entry
into
emergency classification.
Item 1.b of
PEP-101,
Attachment
9.1
requires an unusual event be declared for an "Automatic (non-spurious)
S-signal"; where an S-signal is a SI signal.
The licensee declared a
NOUE at 4:22 p.m.,
and after the plant was stabilized, the NOUE was
terminated at 4:51 p.m.
The inspectors entered the control
room approximately 15 minutes
after the trip. The inspectors verified that timely notifications
were made to the state and to the NRC. The inspectors also witnessed
7
successful completion of EPP-7. A post scram review determined that
the trip had occurred as a result of a personnel error.
While
troubleshooting an EH power supply trouble alarm,
an I&C technician
inadvertently shorted out part of the control circuit during the
installation of a meter into the circuit.
The meter can serve as
either a voltmeter or ammeter depending upon a switch position . The
technician had intended to measure voltage, but had the meter set to
the ammeter mode. The resultant shorting of the circuit caused two
of the turbine governor valves to go closed. The subsequent loss of
load caused three steam dumps to open.
The I&C technician, sensing
something was amiss because of relay actuations, proceeded to remove
the meter from the circuit.
This action caused the two governor
valves to reopen. With the three steams dumps also open,
a high
steam flow and over cooling of the primary resulted (i.e.,
TAVG
decreased rapidly).
The resultant high steam flow coincident with
low TAVG, conditions indictative of a steam line break, initiated the
SI signal and reactor trip.
The inspectors reviewed the draft post trip review report and have no
further concerns at this time. The EH power supply was repaired and
the unit was returned to service on February 28, 1989.
No violations or deviations were identified within the areas inspected.
7. Onsite Review Committee (40700)
The inspectors evaluated certain activities of the PNSC to determine
whether the onsite review functions were conducted in accordance with TS
and other regulatory requirements. In particular, the inspectors attended
the special PNSC meetings on February 18 and 22, 1989, concerning the RTD
thermowell replacements prior to plant
startup.
In addition, the
inspectors also attended the monthly scheduled PNSC meeting on
February 15,
it
was ascertained that provisions of the TS dealing with
membership, review process, frequency, and qualifications were satisfied.
No violations or deviations were identified within the areas.inspected.
8. Exit Interview (30703)
The inspection scope and findings were summarized on March 12, 1989, with
those persons indicated in paragraph 1.
The inspectors described the
areas inspected and discussed in detail the inspection findings listed
below and those addressed in the report summary. Dissenting comments were
not received from the licensee.
Proprietary information is not contained
in this report.
Item Number
Status
Description/Reference Paragraph
89-07-01
Open
VIO - Initialing Procedure Step Prior
to Performing Work, paragraph 4.
88-07-02
Open
IFI - Review Permanent Solution For RTD
Thermowell Cracking Issue, paragraph 6.
8
9. Acronyms and Initialisms
American Society of Mechanical Engineers
Component Cooling Water
Corrective Maintenance
EH
Electro-hydraulic
Emergency Operating Procedures
End Path Procedures
Environmental Qualifications
Engineered Safety Feature
Instrumentation & Control
IFI
Inspector Followup Item
LCO
Limiting Condition for Operation
Motor Control Center
Motor Driven Auxiliary Feedwater
Motor Operated Valve
Maintenance Surveillance Test
Notice of Unusual Event
NRC
Nuclear Regulatory Commission
OST
Operations Surveillance Test
PEP
Plant Emergency Procedure
PNSC
Plant Nuclear Safety Committee
Radiation Control Area
Resistence Temperature Detector
Reactor Turbine Generator Board
Radiation Work Permit
System Driven Auxiliary Feedwater
S/G
Safety Injection
Safety Parameter Display System
SWBP
Service Water Booster Pump
TAVG
Temperature, Average
TS
Technical Specification
Violation
Work Request
WR/JO
Work Request/Job Order
0II