ML14181A770
| ML14181A770 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 09/18/1995 |
| From: | William Orders, Verrelli D NRC Office of Inspection & Enforcement (IE Region II) |
| To: | Carolina Power & Light Co |
| Shared Package | |
| ML14181A768 | List: |
| References | |
| 50-261-95-23, NUDOCS 9509280240 | |
| Download: ML14181A770 (10) | |
See also: IR 05000261/1995023
Text
C,"pkREG114.9
UNITED STATES
NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTA STREET, N.W., SUITE 2900
ATLANTA, GEORGIA 30323-0199
Report No.:
50-261/95-23
Licensee:
Carolina Power & Light Company
P. 0. Box 1551
Raleigh, NC 27602
Docket No.:
50-261
License No.:
Facility Name: H. B. Robinson Unit 2
Inspection Conducte
1
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</26, 1995
Lead Inspector:
OrW
,
dent Inspector
ate Signed
Other Inspectors: R. McWhorter, Senior Resident Inspector, North Anna
.Oge, Resident Inspector, Robinson
Approved by:
4
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u
V'd9
--
Davd M. Verrlli, Chief
Date S-.gned
Reactor Projects Branch 1A
Division of Reactor Projects
SUMMARY
SCOPE:
This routine, resident inspection was conducted in the areas of plant
operations, and maintenance activities.
RESULTS:
One violation with two examples was identified concerning an inadequate
operating procedure and an operator's failure to communicate intended plant
configuration changes.
[Paragraph 3]
Based on the results of this inspection, the licensee effectively implemented
the maintenance program during this evaluation period.
[Paragraph 4]
9509280240 950918
PDR ADOCK 05000261
G
REPORT DETAILS
1.
PERSONS CONTACTED
Licensee Employees:
- B. Baum, Manager, Human Resources
- P. Cafarella, Superintendent, Mechanical Systems
- A. Carley, Manager, Site Communications
B. Clark, Manager, Maintenance
T. Cleary, Manager, Mechanical Maintenance
- D. Crook, Licensing/Regulatory Compliance
D. Gudger, Senior Specialist, Licensing/Regulatory Programs
- C. Hinnant, Vice President, Robinson Nuclear Plant
P. Jenny, Manager, Emergency Preparedness
J. Kozyra, Licensing/Regulatory Programs
- R. Krich, Manager, Regulatory Affairs
B. Meyer, Manager, Operations
- G. Miller, Manager, Robinson Engineering Support Services
- J. Moyer, Manager, Nuclear Assessment Section
B. Steele, Manager, Shift Operations
D. Stoddard, Manager, Operating Experience Assessment
- D. Taylor, Plant Controller
R. Warden, Manager, Plant Support Nuclear Assessment Section
W. Whelan, Industrial Health and Safety Representative
D. Whitehead, Manager, Plant Support Services
T. Wilkerson, Manager, Environmental Control
- D. Young, Plant General Manager
Other licensee employees contacted included technicians, operators,
engineers, mechanics, security force members, and office personnel.
NRC Personnel:
- W. Orders, Senior Resident Inspector
R. McWhorter, Senior Resident Inspector, North Anna
C. Ogle, Resident Inspector
- Attended exit interview
Acronyms and initialisms used throughout this report are listed in the
last paragraph.
2.
PLANT STATUS AND ACTIVITIES
a.
Operating Status
The unit operated at or near full power for the entire report
period.
b.
Other NRC Inspections and Meetings
Rick McWhorter, RII, Senior Resident Inspector, North Anna, was on
site during the week of August 7 -
11, 1995. His inspection
efforts included a review of the technical specification bases
2
supporting the requirement for the pressurizer spray valves.
Results of this inspection are contained in paragraph 3 of this
report.
3. OPERATIONS
Plant Operations (71707)
The inspectors evaluated licensee activities to determine if the
facility was being operated safely and in conformance with regulatory
requirements. These activities were assessed through direct observation
of ongoing activities, facility tours, discussions with licensee
personnel, evaluation of equipment status, and review of facility
records. The inspectors evaluated the operating staff to determine if
they were knowledgeable of plant conditions, responded properly to
alarms, and adhered to procedures. Selected shift changes were observed
to determine that system status continuity was maintained and that
proper control room staffing existed.
Routine plant tours were conducted to evaluate equipment operability,
assess the general condition of plant equipment, and to verify that
radiological controls, fire protection controls, physical protection
controls, and equipment tagging procedures were properly implemented.
Pressurizer Spray Valve Failure
At 5:55 a.m., on August 5, 1995, operators identified that RCS pressure
was oscillating slightly. After observing the oscillations for several
hours, at approximately 8:00 a.m., operators energized the pressurizer
backup heaters in an attempt to stop the oscillations. When no effect
was observed, operators returned the backup heaters to automatic.
Shortly thereafter at 8:27 a.m., pressure was noted to be decreasing
despite the fact that all heaters had automatically come on.
Further
investigations revealed that pressurizer spray valve PCV-455A indicated
approximately ten percent open with its controller in automatic.
Operators shifted the controller to manual and attempted to close the
valve, but the valve remained slightly open. During this time, pressure
dropped very slowly at approximately one psig per minute. Operators
entered AOP-19, Malfunction of RCS Pressure Control, and initiated
troubleshooting activities. At approximately 10:39 a.m., technicians
entered containment and shut the spray valve by isolating its air
supplies, and RCS pressure returned to normal.
The lowest pressure
observed during the transient was approximately 2152 psig.
Later on the
same day, technicians entered containment again to adjust the valve's
pneumatic positioner and reconnect the valve's air supplies. The valve
was returned to service, but operators kept the valve shut and its
controller in manual to avoid any possible future problems. On
August 9, technicians entered containment and removed the pneumatic
positioner and booster relay from the valve for further troubleshooting
and maintenance. This action fully disabled the A spray valve.
3
The inspectors reviewed the licensee's actions in response to the failed
spray valve to ascertain if operator response was proper and if TS
requirements were met. TS 3.1.1.3.b required the licensee to maintain
the "pressurizer, including necessary spray and heater control systems"
operable. The TS basis for this specification stated, "The pressurizer
is necessary to maintain acceptable system pressure during normal plant
operation, including surges that may result following anticipated
The inspectors questioned the licensee concerning how this
specification could be met with only one spray valve operable. The
licensee referred the inspectors to their Expert Operability Analysis,
serial RNP/95-0328, completed on August 7, which concluded that only one
spray valve was required. The inspectors reviewed the analysis and
discussed its basis in detail with licensee engineers. The licensee's
conclusion was based primarily on two interpretations:
1) "normal plant
operation" meant steady state operation, for which one spray valve was
fully capable of working with pressurizer heaters to control pressure,
and 2) "surges following anticipated transients" referred to transients
addressed by the UFSAR chapter 15 accident analyses, in which no credit
was taken for pressurizer spray valve operation. In addition to the TS
basis, the documents discussed in the analysis which provided additional
information were the licensee's RCS DBD and a vendor design basis
review, WCAP-12735.
The inspectors reviewed the DBD and WCAP-12735 and found that the sizing
of the pressurizer spray valves was based on ensuring that they had the
capacity for controlling pressure without opening a pressurizer PORV
during a step change in power from 100 to 90 percent. To accomplish
this, a capacity of at least 420 gpm was listed as the minimum required
with a note stating that the requirement had been revised to 600 gpm.
Since the actual spray valve capacity was 300 gpm each, proper design
response would require two spray valves. The inspectors discussed with
licensee engineers the fact that the system's design basis inferred that
"normal operation," as referred to in the TS basis, appeared to include
response to a 100 to 90 percent power change, which would require two
operating spray valves. The engineers disagreed with this position
because this was not a safety-related function as referred in the UFSAR.
The inspectors also noted that step 3.a of the Expert Operability
Analysis included implementing a compensatory action for the Manager
Operations to issue a night order notifying all personnel of the
unavailability of PCV-455A. On August 9, the inspectors reviewed the
night order book in the control room and found that no such night order
had been issued. During the control room review the inspectors noted
that the unavailability of PCV-455A was denoted for operators by a red
sticker on the controller which had been installed earlier that same
date when the valve's actuator parts had been removed.
The inspectors
informed the licensee of this finding. Additionally, the inspectors
discussed with the licensee questions concerning the requirements for
maintaining emergency power available to the remaining spray valve as
required by TS definitions for operability. This issue was not
addressed by the analysis.
4
The inspectors concluded that the licensee's Expert Operability Analysis
did not fully justify operation with only one spray valve.
Specifically, the analysis did not address the fact that the system
design basis required two spray valves for controlling pressure during a
100 to 90 percent load reduction. Additionally, the analysis did not
address operability power requirements for the remaining spray valve.
Pending further action to resolve whether one or two spray valves are
required to meet the requirements of TS, this item is identified as
Unresolved Item URI 50-261/95-23-01, Inadequate Justification For Plant
Operation With One Pressurizer Spray Valve Inoperable.
In response to the inspectors' concerns, on August 11, the licensee
completed a more detailed review. The inspectors had not received a
copy of the results of this review by the end of the report period.
The inspectors also reviewed operator response to the transient. The
inspectors learned that operators had experienced difficulty in applying
AOP-19 to the situation. Specifically, when operators reached AOP-19,
step 7 RNO, they had performed the first sub-step to place the spray
valve controller in manual and attempted to shut the valve, but they
stopped their actions at the second sub-step. The second sub-step
required operators to reduce reactor power and stop a RCP if the spray
valve could not be closed. With the concurrence of senior station
managers who were present in the control room, the operators stopped the
procedure at that point, in order to take additional actions (entering
containment to remove air from the valve) to close the valve.
The inspectors inquired how this deviation from the procedure was
allowed.
Licensee managers responded that they believed that the
actions taken were consistent with the intent of the procedure step,
since the pressure decrease was very slow and time was available for
further corrective actions to shut the valve. The inspectors agreed
that it was prudent to defer the power reduction while repair attempts
continued, but questioned how this stopping in the middle of the
procedure was administratively controlled. Licensee management
responded that the shift supervisor had the authority to make such a
decision, and that senior manager concurrence was also present in this
situation. The inspectors agreed that the action and approval authority
was appropriate, but concluded that the procedure deviation should have
been more formally controlled. Even in urgent situations, maintaining
formal control of procedure deviations was necessary to reduce the
opportunity for errors. The inspectors reviewed the licensee
requirements for procedure use and found that OMM-001, Operations
Conduct of Operations, step 5.9.1.3, allowed operators to deviate from
procedures in cases where adherence could cause a worsened condition,
but stated that a procedure change or deviation should be made.
Administratively, the inspectors concluded that the decision to stop in
the middle of the procedure should have been documented by a procedure
change or deviation, such as described in OMM-001, in order to maintain
the preferred formality.
5
Unusual Event, RCS Leakage
At 3:33 p.m., on July 24, 1995, the licensee declared an Unusual Event
due to RCS leakage in excess of 10 gpm. The leakage was coming from
valve CVC-283A, the relief valve on the discharge of the "C" charging
pump, and a piping crack where relief valve CVC-283C is mounted to the
discharge of the "A" charging pump.
The leak was caused by operators closing valves in the flow path of the
running positive displacement charging pump which resulted in system
over-pressurization.
Ultimately, the leaks were isolated and the Unusual Event was terminated
at 4:39 p.m.
The Robinson CVC system includes three, variable speed, three piston,
positive displacement pumps. The pumps have a flow capacity raging from
approximately 25 gpm at minimum speed, to about 77 gpm at maximum speed.
At the time of the event, the "A" charging pump was operating at minimum
speed supplying approximately 25 - 30 gpm to the RCS, split between the
seals and the normal charging flowpath.
The Shift Supervisor had elected to remove the normal letdown flowpath
from service and place excess letdown in service to accommodate
scheduled work on valve LCV-115A. When excess letdown was placed in
service, the "A" charging pump, which was aligned for automatic
pressurizer level control, slowed to minimum speed. The control room
SRO noted that RCP seal differential pressure was lower than normal and
had an AO check seal injection flow using local gauges. The AO reported
that seal injection flow was 6, 0, and 7 gpm respectively for the three
RCP's. Desired seal injection flow is 8 -
13 gpm. The control room SRO
directed the RO to throttle charging flow control valve HCV-121 to force
more flow to the seals. Valve HCV-121 was adjusted to 80 - 85 percent
demand on the controller. This increased seal injection flow to 9 - 11
gpm to all three pumps. Unbeknownst to the operators, their action had
completely closed HCV-121, diverting all charging flow to the seals.
Noting that pressurizer level was still increasing very slowly, the RO,
of his own volition, and without communicating his intended actions,
directed an AO to adjust RCP seal flow to 8 gpm for each pump. This is
done by adjusting manual valves CVC-297 A, B, and C, in the charging
pump room. As the AO was adjusting seal flow, relief valve CVC-283A
lifted and failed to reseat. The AO had throttled the seal injection
valves such that the positive displacement charging pump had
insufficient flow path.
The operator's failure to communicate his
intended actions to the operating crew is one of two examples which
collectively constitute Violation VIO 50-261/95-23-02, Operator Fails To
Follow OMM-001, Procedure OP-301 Inadequate. This point is significant
because a number of very similar events have occurred. In each of these
6
previous events, the operating crews were made aware of the
circumstances of the incidents. Had the reactor operator announced his
intended actions as required, another member of the operating crew may
have been able to pre-empt the event based on previous experience.
The AO exited the charging pump room to use the P. A. system to .
inform the control room of the situation.
Based on this information and
confirmatory observations of plant parameters the control room SRO
directed the entry into Abnormal Operating Procedure AOP-16, Excessive
Primary Plant Leakage. The RO instructed the AO to check charging pump
discharge pressure. As the AO re-entered the charging pump room, he
noted a small leak on the flange of the A charging pump discharge relief
valve.
He immediately exited the room to inform the control room of
this new observation. The RO directed the AO to close valves CVC-286
and CVC-287, the discharge valves from the C charging pump.
At 3:19 p.m., the idle "B" charging pump was started and the "A"
charging pump was stopped.
By 3:20 p.m., the AO had closed valve CVC
286 and was closing valve CVC-287 when an HP directed the AO to evacuate
the room due to deteriorating conditions associated with the leak on the
piping of the "A" charging pump. As the AO left the room, he noted that
the leak on the "A" charging pump was much worse.
At about 3:26 p.m., the SRO directed another AO to close valves CVC-290
and CVC-291, the discharge valves on the "A" charging pump.
At 3:33 p.m., the SS declared an Unusual Event due to RCS leakage of
greater than 10 gpm after the leak rate was determined to be
approximately 14 gpm based on VCT level profile.
By 3:50 p.m., letdown divert valve LCV-115A was returned to service,
normal letdown was re-established, and excess letdown was isolated.
At 4:20 p.m., an AO entered the charging pump room to complete the
isolation of the "C" charging pump.
At 4:39 p.m., the Unusual Event was terminated after a confirmatory RCS
leak rate determination.
It was subsequently determined that the relief valves for the "A" and
"C" charging pumps had lifted. Both valves revealed severe
internal
damage when disassembled. The valve vendor attributed the damage to
"severe chatter," caused by the valves cycling with each piston stroke
of the positive displacement pump.
Both valves were replaced the
following day. The piping crack was repaired by replacing the section
of piping affected. The licensee determined that the crack was due to
the vibration stresses associated with the relief valves rapidly opening
and closing.
The resident inspectors responded to the control room at the initiation
of the event, reviewed plant parameters, discussed the plant status with
operations personnel, and notified NRC Region II management. The
7
inspectors monitored the event until the leak had been terminated,
normal charging had been established, and a normal leak rate calculated.
Pressurizer level remained relatively stable throughout the event.
The inspectors reviewed the procedures in use at the time of the event,
assessed operator performance, and evaluated the transient to assess
equipment performance. OP-301, Chemical And Volume Control System, was
used by the operators to place excess letdown in service. After
performing a thorough review of the procedure and its contribution to
the event, the inspectors concluded that OP-301 was inadequate. The
procedure contained no specific guidance concerning the manipulation of
the charging and seal injection valves while on excess letdown and the
associated possibility of over-pressurizing the system. This is despite
the fact that the procedure had been used during two very similar events
on November 9 and November 11, 1993, during which the system was over
pressurized. Adverse Condition Report 93-276 documents the licensee's
investigation of those two events and lists OP-301 as the procedure
employed by the operators to remove normal letdown from service and
place excess letdown in service, yet no changes were made to OP-301.
The inadequacy of OP-301 constitutes the second of two examples of
procedure compliance which collectively comprise Violation VIO 50-261/
95-23-02, Operator Fails To Follow OMM-001, Procedure OP-301 Inadequate.
It should be noted that although the licensee recognized during their
associated Event Review, that the operator had failed to follow
procedures and that procedure OP-301 was inadequate, the NRC cannot
exercise enforcement discretion because it is the NRC's opinion that
comprehensive corrective action to the 1993 events could have prevented
this incident.
It should also be noted that the inspector's review of the licensee's
initial set of prompt corrective actions, which included a revision to
OP-301, "Real Time" operator training, and an Operations Night Order,
revealed that OP-301 still did not entail detailed specific operator
guidance in the aforementioned critical areas. The inspectors notified
licensee management of this observation. A subsequent, more detailed
revision to OP-301 was generated. This example of corrective action is
considered marginal and indicative of a minimalistic approach to
corrective actions.
Notice of Enforcement Discretion
On July 21, 1995, the licensee documented a request for the NRC to
exercise enforcement discretion. The combined leakage from the
Penetration Pressurization System (PPS) exceeded the allowable limit of
1.57 SCFM required to meet containment integrity. The Resident Staff
will address the root cause that led to the need for the NOED during a
future inspection. This will be known as Unresolved Item URI 50-261/95
23-03, NOED: PPS Exceeded the Allowable Limit.
8
4.
MAINTENANCE
a.
Maintenance Observation (62703)
The inspectors reviewed selected safety-related maintenance
activities to determine if the activities were conducted in
accordance with regulatory requirements, approved procedures, and
appropriate industry codes and standards.
The inspectors reviewed
associated administrative, material, testing, radiological, and
fire prevention controls requirements to determine licensee
compliance.
b.
Surveillance Observation (61726)
The inspectors evaluated selected safety-related surveillance
activities to determine if these activities were conducted in
accordance with license requirements. The inspectors analyzed the
associated administrative controls, the qualifications of the
personnel, procedure compliance, test instrumentation calibration,
and the required test frequency.
Surveillance activities evaluated included but were not limited to
the following:
OST-010
Power Range Calorimetric During Power Operations
OST-924
Radiation Monitor Quarterly Test (R-3)
OST-051
Reactor Coolant Leakage Evaluation
OST-201
Motor Driven Auxiliary Feedwater System
Component test
OST-750
Control Room Emergency Ventilation System
Based on the results of this inspection, the licensee's programs
were successfully implemented in this functional area.
5.
EXIT INTERVIEW
The inspectors met with licensee representatives (denoted in
paragraph 1) at the conclusion of the inspection on August 29, 1995.
During this meeting, the inspectors summarized the scope and findings of
the inspection as they are detailed in this report. The licensee
representatives acknowledged the inspector's comments and did not
identify as proprietary any of the materials provided to or reviewed by
the inspectors during this inspection. No dissenting comments from the
licensee were received.
Item Number
Status
Description/Reference Paragraph
URI 95-23-01
Opened
Inadequate Justification For Plant
Operation With One Pressurizer Spray
Valve Inoperable, paragraph 3.
9
VIO 95-23-02
Opened
Operator Fails To Follow OMM-001,
Procedure OP-301 Inadequate,
paragraph 3.
URI 95-23-03
Opened
NOED:
PPS Exceeded the Allowable
Limit, paragraph 3.
6.
ACRONYMS AND INITIALISMS
Auxiliary Operator
Abnormal Operating Procedure
CVC
Chemical and Volume Control
Design Basis Documentation
gpm
Gallons Per Minute
Hand Control Valve
HE&E
Harris Environmental & Engineering
Health Physicist
Level Control Valve
LCO
Limiting Condition for Operation
LDV
Letdown Divert Valve
OP
Operating Procedure
P.A.
Public Announcement
Pressure Control Valve
Power Operated Relief Valve
psi
Pounds Per Square Inch
psig
pounds Per Square Inch - Gage
Quality Control
Reactor Coolant Pump
Robinson Nuclear Plant
Reactor Operator
Senior Reactor Operator
Shift Supervisor
TS
Technical Specification
Updated Final Safety Analysis Report
Unresolved Item
Volume Control Tank
Violation
Westinghouse Corporate Atomic Power