ML14178A484
| ML14178A484 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 05/09/1994 |
| From: | Casto C, Girard E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML14178A483 | List: |
| References | |
| 50-261-94-06, 50-261-94-6, GL-89-10, NUDOCS 9405160209 | |
| Download: ML14178A484 (20) | |
See also: IR 05000261/1994006
Text
,pt REG
UNITED STATES
NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTA STREET, N.W., SUITE 2900
ATLANTA, GEORGIA 30323-0199
Report No.:
50-261/94-06
Licensee:
Carolina Power and Light Company
P. 0. Box 1551
Raleigh, NC 27602
Docket No.:
50-261
License No.:
Facility Name:
H. B. Robinson
Inspection Conducted:
March 28 - April 1, 1994
Lead Inspector:
C
.
O<
E. Girard
Date Signed
Other Inspectors: M. Hunt
M. Miller
Other Personnel:
R. Cain, Consultant (EG&G Idaho, Incorporated)
Approved by:
5/
p
9
C. Casto, Chibf
Date Signed
Test Programs Section
Engineering Branch
Division of Reactor Safety
SUMMARY
Scope:
This special, announced inspection examined the implementation of the
licensee's motor-operated valve (MOV) program to meet commitments in response
to Generic Letter (GL) 89-10, "Safety-Related Motor-Operated Valve Testing and
Surveillance."
The inspectors utilized the guidance provided in Temporary
Instruction (TI) 2515/109 (Part 2), "Inspection Requirements for Generic
Letter 89-10, Safety-Related Motor-Operated Valve Testing and Surveillance."
As delineated in Part 2 of TI 2515/109, this inspection was the initial review
of the licensee's MOV program implementation in response to GL 89-10.
The inspectors reviewed the GL 89-10 design calculations, test packages, and
diagnostic signature traces for a selected sample of 14 MOVs. They also
examined the licensee's actions in response to related previously identified
open items and a violation.
9405160209 940510
ADOCK 05000261
0
2
Results:
Based on the evaluation completed, the inspectors concluded the licensee was
implementing a satisfactory GL 89-10 MOV program. However, program
implementation had not been completed and additional NRC evaluation will be
required. The inspection described in this report identified the following
inspector followup items (IFIs) that require further evaluation:
(Open)
IFI 50-261/94-06-01, Margin for Load Sensitive Behavior.
(Section 2.2)
(Open)
IFI 50-261/94-06-02, Correction of Maximum Settings for Torque
Switch Repeatability. (Section 2.2)
(Open)
IFI 50-261/94-06-03, Actions to Ensure Capabilities of RHR-744
Valves. (Section 2.2)
(Open)
IFI 50-261/94-06-04, Revision of Design Criteria Assumptions
Based on Test Data. (Section 2.3)
(Open)
IFI 50-261/94-06-05, Adequacy of Periodic Verification Methods.
(Section 2.4)
(Open)
IFI 50-261/94-06-06, MOV Post Maintenance Testing. (Section
2.3)
(Open)
IFI 50-261/94-06-07, Mispositioning. (Section 2.10.c)
(Open)
IFI 50-261/94-06-08, Setting Closed-to-Open Bypass Switch
Limit. (Section 2.10.e)
A previously identified violation and ten other open items were closed.
(Closed) Violation 50-261/92-19-01, Inadequate Design Control Involving
Unverified Assumptions Related to DP for Valves FW-2V-6A, B,
and C. (Section 2.10.a)
(Closed) Open Item 50-261/91-201-01, Determination of Design Basis Flow
Rate. (Section 2.10.b)
(Closed) Open Item 50-261/91-201-02, Failure to Review Mispositionable
Valves. (Section 2.10.c)
(Closed) Open Item 50-261/91-201-03, Undersized Actuators for Valves FW
V2-6A, 6B, and 6C. (Section 2.10.d)
(Closed) Open Item 50-261/91-201-04, Setting of Closed-to-Open Bypass
Limit. (Section 2.10.e)
(Closed) Open Item 50-261/91-201-05, Procedures for Controlling Design
Basis Testing. (Section 2.10.f)
3
(Closed) Open Item 50-261/91-201-06, Periodic Verification of MOV
Operability. (Section 2.10.g)
(Closed) Open Item 50-261/91-201-07, Inadequate Documentation and
Corrective Action for MOV Deficiencies. (Section 2.10.h)
(Closed) Open Item 50-261/91-201-08, MOV Setpoint Document Control of
Switch Settings. (Section 2.10.i)
(Closed) Open Item 50-261/91-201-09, MOV Post Maintenance Testing.
(Section 2.10.j)
(Closed) Open Item 50-261/91-201-10, Failure to Periodically Test
Thermal Overloads. (Section 2.10.k)
Strengths
The following strengths were noted during the inspection:
Trending program
All valves practicable to test were tested in accordance with GL 89-10
Tests were well-documented
No violations or deviations were identified in this inspection.
SII
REPORT DETAILS
1.0
Persons Contacted
- A. Canterbury, Manager, Component Engineering
W. Clark, Manager, Maintenance
- S. Farmer, Manager, Inservice Inspection
- D. Gudger, Regulatory Affairs
C. Hinnant, Vice President, Robinson Plant
G. Hoffman, Clerk
- K. Jury, Manager, Licensing/Regulatory Programs
- R. Krich, Manager, Regulatory Affairs
- S. McCutcheon, MOV Component Specialist
M. McDaniel, MOV Mechanical Engineer (NED)
W. McGoun, Senior Engineer (NED)
M. Murdock, MOV Engineer (NED)
B. Nauhria, MDV Engineer (RNP NED)
A. Nguyen, Component Engineer
C. Olexik, Manager, Plant Assessment Section
M. Page, Manager, Mechanical Engineering (RNP NED)
E. Paine, Mechanical Evaluation and Analysis Subunit
M. Pearson, Plant Manager
A. Redpath, Engineer, Harris Engineering Support Section
S. Roberts, MDV Electrical Engineer (NED)
R. Steele, Manager, Maintenance Programs
R. Wehage, Manager, Mechani-cal Subunit -(RNP NED)
- R.. Williamson, MOV Component Specialist
NRC Personnel
- W Orders, Senior Resident Inspector
- B. Mozafari, Project Manager, Office of Nuclear Reactor Regulation
- Denotes personnel that attended the exit meeting.
Acronyms and initialisms used throughout this report are listed in the
last paragraph.
2.0 GENERIC LETTER (GL) 89-10 "SAFETY-RELATED MOTOR-OPERATED VALVE [MDVI
TESTING AND SURVEILLANCE"
(2515/109)
On June 28, 1989, the NRC issued GL 89-10, which requested licen sees and
construction permit holders to establish a program to ensure that switch
settings for safety-related MOVs were selected, set, and maintained
properly. Subsequently, six supplements to the GL have been issued.
NRC
inspections of licensee actions implementing commitments to GL 89-10 and
its supplements have been conducted based on guidance provided in
Temporary Instruction (TI) 2515/109, "Inspection Requirements for Generic
Letter 89-10, Safety-Related Motor-Operated Valve Testing and
Surveillance."
TI 2515/109 is divided into Part 1, "Program Review," and
Part 2, "Verification of Program Implementation.
2
The current inspection is the initial TI 2515/109 Part 2 program
implementation inspection. The TI 2515/109 Part 1 program review for
Robinson was conducted June 10 through 14, 1991, and was documented in
NRC Inspection Report 50-261/91-201, dated July 25, 1991.
The principal focus of this inspection was to evaluate in depth the
implementation of GL 89-10 for a sample of MOVs selected from the
licensee's program. The MOV sample was chosen from a list of valves that
had received differential pressure (DP) testing. The majority of the
valves selected were gate valves with high design-basis DP (DBDP)
operating requirements. The MOVs in the sample were as follows:
Valve No.
MOV Function, Size, and Type
AFW-V2-14A
SDAFW Pump Discharge Valve to Steam Generator A
4 inch double disc gate
AFW-V2-16A
AFW Header Discharge Valve to Steam Generator A
4 inch double disc gate
CC-749B
RHR Heat Exchanger B Cooling Water Isolation Valve
16 inch solid wedge gate
FW-V2-6A
Feedwater Header Section Valve
16 inch solid wedge gate
MS-V1-8A
Steam Admission Valve to SDAFW Turbine
2 inch double disc gate
RHR-744A
RHR Loop to RCS Cold Leg Valve
10 inch flex wedge gate
RHR-744B
RHR Loop to RCS Cold Leg Valve
10 inch flex wedge gate
RHR-759B
RHR HX B Outlet Isolation Valve
10 inch solid wedge gate
SI-845B
CV Spray Additive Tank Discharge Valve
2 inch globe
SI-866A
Loop 3 Hot Leg Injection Valve
2 inch globe
SI-869
Loop 2 and 3 Hot Leg Injection Shutoff Valve
3 inch double disc gate
SI-870A
Boron Injection Tank Outlet Isolation Valve
3 inch double disc gate
SI-880C
CV Spray Pump B Discharge Isolation Valve
6 inch double disc gate
3
V6-16B
SW to Turbine Building Isolation Valve
16 inch butterfly
This inspection also evaluated actions which the licensee had taken to
correct a related violation and weaknesses identified in previous
inspections, as described in Section 3.0 of this report.
Based on the evaluation completed during this inspection, the inspectors
concluded that the licensee was implementing an acceptable MOV program in
response to GL 89-10. Additional NRC evaluation is planned to complete
the evaluation of some areas and to address specific findings identified
as followup items below. Details of the inspection and the findings are
provided in the following sections of this report.
2.1 Design-Basis Reviews
The inspectors reviewed the licensee's Design Basis Differential Pressure
Reports and their referenced documentation together with applicable
operational procedures, system flow drawings, pump curves, the System
Description Procedure, and the Design-Basis Documents and verified that
the maximum flow and differential pressure were determined. The
calculations of differential pressure, electrical degraded grid voltage,
flow, and temperature were reviewed and verified to be complete and
correct. Calculations of thrust and torque were verified to use
appropriate inputs of design DP, degraded voltage, and temperature
corrected motor torque capabilities. The inspectors verified that the
licensee completed the DBDP Reports for all the safety-related systems
and addressed flow. The design-basis fluid flow rate was included in the
"Assumptions Section" of the thrust calculations for each MOV. These
thrust calculations were titled "Mechanical Analysis and Calculation for
[Valve No]."
The licensee had been notified of the effects of elevated temperature on
motor torque through a Potential 10 CFR Part 21 Notice dated May 13, 1993
and Technical Update 93-03 (March 1993) issued by Limitorque Corporation.
The inspectors examined Design Guide DG-V.67, "Electrical Evaluation of
AC Powered Motor-Operated Valves," and Calculation EE107-CS-58, "AC MOV
Calculated Available Torques for Various Voltage Scenarios," and verified
that the effects of elevated temperature were properly addressed for the
licensee's MOVs.
The inspectors concluded the licensee had adequately implemented the
design-basis recommendations of GL 89-10 for design-basis reviews.
2.2 MOV .Sizing and Switch Setting
The inspectors reviewed the licensee's Design Guide DG-I.11, "Design
Guide for Limitorque Motor-Operated Valve Mechanical Evaluations,"
Revision 6, dated July 27, 1993, which specified the use of a standard
industry equation for calculating thrust for gate and globe valves.
Except in the case of valves provided by Westinghouse, the licensee used
a valve factor of 0.40 for gate valves and 1.10 for globe valves for
4
development of the initial thrust setting window. For Westinghouse
valves, the licensee used data provided by the valve manufacturer, where
available, or assumed a valve factor of 0.55 in the opening and closing
direction. The valve's mean seat diameter was used to calculate the
valve disc seat area.
Further, a stem friction coefficient of 0.20 was
used to calculate the minimum required torque. The minimum required
thrust was increased for diagnostic equipment inaccuracies and torque
switch repeatability by adding the values of these error factors.
During review of the licensee's thrust calculations, it was noted that a
margin was not included for load sensitive behavior (also known as "rate
of loading").
Licensee personnel stated that their evaluation of test
data did not indicate an appropriate amount of margin to be set aside for
load sensitive behavior. They stated that the previously mentioned
additions of the diagnostic and torque switch repeatability accuracies
(rather than using the square root of the sum of the squares method) to
the calculated minimum thrust requirement increased the conservatism of
their minimum required thrust settings and would account for load
sensitive behavior. The licensee's justification that this margin will
be adequate for MOVs that cannot be tested at or near design-basis
differential pressure is to be evaluated in a-subsequent NRC inspection
and is identified as Inspector Followup Item 50-261/94-06-01, Margin for
Load Sensitive Behavior.
The inspectors noted that the calculated maximum thrust limit was not
reduced for torque switch repeatability. However, the limit did include
a 10 percent safety margin. This margin would be adequate to address
torque switch repeatability except at numerical switch settings of 1,
where the repeatability error may be as great as 20 percent (Reference
Limitorque Maintenance Update 92-2 for repeatability error). At the end
of this inspection, the licensee initiated a procedural change to provide
for the repeatability error. The matter will be evaluated further in a
subsequent NRC inspection and is identified as Inspector Followup Item
50-261/94-06-02, Correction of Maximum Settings for Torque Switch
Repeatability.
In reviewing the licensee's calculations, the inspectors found that the
motor torque provided for valves RHR-744A and B was marginal and that
744A had recently failed to open during a surveillance test. When the
licensee had re-evaluated motor torque as a result the Part 21 report and
Limitorque Technical Update referred to in Section 2.1 above, they
initially determined that RHR-744A and B did not have adequate torque in
the opening direction. The licensee recalculated the minimum available
torque for the opening stroke per Limitorque Technical Update 93-03 and
found the torque marginally adequate under degraded voltage conditions.
A check of Adverse Condition Reports (ACRs) by the inspectors found that
valve RHR-744A had failed to open during surveillance test OST-252,
conducted February 1, 1994, during a plant outage. The inspectors
reviewed the licensee's identification and disposition of this event
documented in ACR 94-00249.
The operators on shift during the event had
attempted to reset the breaker and thermal overloads before an
investigation of the failure, possibly removing evidence of the root
0I
cause. The shift log indicated the valve was actuated and correctly
opened following the resetting. The valve operated properly in
troubleshooting performed following the failure and documented on Work
Request 94-ACMG1 completed February 7, 1994. The cause was not
identified in the ACR. The inspectors were informed that the open torque
switch setting had been found at a setting that had been acceptable
previously, but that no longer applied. The setting was raised to the
current requirement, which was the maximum allowed by the limiter plate,
as specified in the Electronic Database System (EDBS).
The inspectors
verified that the EDBS specified this setting and that Work Request 94
ACMG1 documented this as-left setting. Considering the failure
experienced on valve RHR-744A and the marginal capabilities of both RHR
744 valves, the inspectors questioned whether additional actions were
being taken to ensure the valves remained operable. In response,
licensee personnel provided copies of Plant Improvement Requests 94
019/00 and 93-059/00. The former was for replacement of the motor feeder
cables, which would result in increased motor torque margin. The latter
increased the range of open torque switch bypass, which would aid in
assuring that the maximum actuator torque would be available for opening.
The inspectors considered these appropriate actions. The licensee's
completion of actions to ensure the capabilities of the valves is
identified as Inspector Followup Item 50-261/94-06-03, Actions to Ensure
Capabilities of RHR-744 Valves.
From the evaluation completed, the inspectors concluded that the licensee
had satisfactorily implemented sizing and switch settings for the valves
with diagnostic thrust measured near DBDP. The adequacy of sizing and
switch settings for other valves will be determined after the licensee
has completed program implementation. Two followup items (-01 and -02)
were identified which appeared to represent weaknesses in the licensee's
sizing and switch setting criteria and require further evaluation. A
third followup item was identified for confirmation of the licensee's
action to correct the marginal capabilities of valves RHR-744A and B.
2.3 Design-Basis Capability
The licensee had identified 64 MOVs within its GL 89-10 program. The
inspectors were informed that all of the valves had been set and design
basis DP tests had been performed for those valves where it was
practicable (48 valves).
The inspectors reviewed the licensee's test procedures, completed test
packages, and VOTES diagnostic static and dynamic test traces for the
MOVs listed in Section 2.0, except valves CC-749B, RHR-744B, and SI-880C.
Independent calculations were performed by the inspectors, using the
licensee's test results, to assess MOV capabilities and determine if the
licensee's assumptions were justified. The results of these reviews are
discussed in the following paragraphs.
Valve factors obtained from the test data were examined by the
inspectors. The closing gate valve factors ranged up to 0.7 (Valve MS
V1-8A).
Based on this, the valve factor assumptions which the licensee
- 0I6
used in calculating thrust settings for gate valves was not always
bounding. In the initial valve setups a valve factor of 0.40 had often
been used by the licensee. The inspectors' review suggested this was too
low. Licensee personnel agreed that a valve factor greater than 0.40
would be appropriate if an initial setup was required in the future for a
new valve or replacement. It was the inspectors' understanding that
Design Guideline DG-I.11 would be revised to include the best available
data for valve factors. The inspectors considered the feedback of best
available data for valve factor into the licensee's Design Guideline
important and identified this as Inspector Followup Item 50-261/94-06-04,
Revision of Design Criteria Assumptions Based on Test Data.
The inspectors verified that the operability reviews were performed on
MOVs prior to returning them to service after differential pressure
testing. The review requirement was documented in TMM-035, Attachment
6.1, "Analysis of MOV Diagnostic Data."
In accordance with the
procedure, site engineering personnel determined the valve stem thrust at
flow cut-off (adjusted for running loads) from diagnostic test results
and calculated a valve factor. This valve factor was used to calculate
design-basis thrust requirements. The design-basis thrust requirements
were then compared to the thrust measured at torque switch trip to verify
a satisfactory margin and confirm operability. At a later date valve
factor, load sensitive behavior, and stem factor were calculated by the
licensee's Nuclear Engineering Department (NED) and then compiled into a
complete package for each tested MOV.
In examining the operability reviews described in the previous paragraph
the inspectors found that design-basis thrust in the open direction had
not been determined for valves AFW-V2-14A, RHR-759B, and MS-V1-8A, which
had active safety functions in the opening and closing directions.
Calculations of opening requirements performed by the inspectors using
the licensee's data demonstrated that these valves had adequate opening
capabilities for design-basis conditions and that there was no
operability concern. Further, the inspectors noted that adequate post
return to service determinations were performed later by NED which
adequately evaluated design-basis performance in the open direction. To
ensure that any future site operability reviews of diagnostic test
results included valve opening requirements, the licensee initiated a
change to their procedure TMM-035. The inspectors reviewed the revised
procedure (Rev. 6) and found that it appeared adequate.
Summary information on all valves in the licensee's test program
indicated that adequate diagnostic thrust measurements could not be
obtained for 13 of the 48 valves dynamically tested. The tests on these
13 valves were performed at or near design-basis differential pressure.
Licensee personnel indicated they were developing justifications for
setup of these valves as-well-as for the MOVs that were not practicable
to test at or near design-basis DP. The justifications will be addressed
in a subsequent NRC inspection of the licensee's program implementation.
The justifications will be addressed in a subsequent NRC inspection of
the licensee's program implementation. The licensee's prompt analysis
and feedback of the results of testing to ensure the operability of
07
valves that could not be adequately tested will be evaluated in that
inspection.
Based on the review and evaluation completed, the inspectors concluded
that the licensee had adequately implemented design-basis testing in
accordance with GL 89-10. A followup item (-04) was identified to verify
that the licensee appropriately revises the valve factors assumed in its
design criteria, based on testing results. Additional NRC evaluation of
the licensee's implementation of actions to assure the design-basis
capabilities of MOVs is planned. The evaluation will include actions for
valves that could not be adequately tested to demonstrate design-basis
capabilities, such as valves that were not practicable to test at or near
full DP and valves that that were tested at less than DBDP without thrust
measurements.
2.4
Periodic Verification of MOV Capability
Recommended action "d" of the generic letter requests the preparation or
revision of procedures to ensure that adequate MOV switch settings are
determined and maintained throughout the life of the plant. Section "j"
of the generic letter recommends surveillance to confirm the adequacy of
the settings. The interval of the surveillance was to be based on the
safety importance of the MOV as well as its maintenance and performance
history, but was recommended not to exceed five years or three refueling
outages. Further, GL 89-10 recommended that the capability of the MOV be
verified if the MOV was replaced, modified, or overhauled to an extent
that the existing test results are not representative of the MOV.
The licensee's MOV coordinator stated that static diagnostic tests were
to be used to periodically verify MOV capabilities as follows:
The periodic verification is to begin Refueling Outage (RFO) 16
(one outage following completion of all design-basis differential
pressure testing).
Scheduling is controlled through the licensee's AMMS database, with
the static diagnostic test to be performed in association with
Preventive Maintenance Procedure PM-423 (electrical inspection).
The period between verifications is now set at two RFOs but may be
changed.
Capabilities of valves that cannot be statically diagnostic tested
due to sensor problems (e.g., reversal) will be verified by partial
diagnostic testing using the calibrator as auxiliary sensor and
measuring motor current. For Accumulator discharge MOVs even the
calibrators cannot be practically mounted and only motor current
will be checked (Note: Removal of these valves from the program is
being evaluated by the licensee).
The capabilities of only a portion of the valves will be verified
during RFO 16.
The remaining valves will be verified either RFO 17
8
or 18.
The valves to be verified during each of these outages has
not been fully established.
The inspectors viewed the AMMS for valve AFW-V2-16A and confirmed that
this GL 89-10 MOV was scheduled for static diagnostic testing as
preventive maintenance at a two RFO frequency. They informed the
licensee that the adequacy of static diagnostic testing and other methods
involving less than design-basis conditions for periodic verification of
MOV capabilities had not been established but is an industry issue
recognized by the NRC. The adequacy of the methods used by the licensee
for periodic verification of valve capabilities is identified as
Inspector Followup Item 50-261/94-06-05, Adequacy of Periodic
Verification Methods.
The inspectors reviewed the requirements that would apply to maintenance
operations, which were specified in Appendix A of Procedure MMM-003,
Rev. 39, Maintenance Work Requests. The inspectors found that static
diagnostic testing was specified to verify required thrust following
limit switch removal or replacement (for limit closed rising stem
valves), operator overhaul, packing maintenance, and valve overhaul or
replacement.
The inspectors indicated the adequacy of static testing to
verify thrust was not adequately justified for valve replacement or
overhaul.
The inspectors were informed that the licensee plans to revise
MMM-003, Appendix A. The licensee was informed that the adequacy of the
revisions to post maintenance testing requirements would be identified as
Inspector Followup Item 50-261/94-06-06, MOV Post Maintenance Testing.
The inspectors were informed that post modification testing would be
specified for a given modification consistent with post maintenance test
requirements. They reviewed the requirements-specified by the licensee's
Nuclear Plant Modification Program, Rev. 4, and found that it contained
rather general criteria for testing all components.
Licensee personnel
stated that proper post modification testing would be assured by
requiring that the Nuclear Engineering Department MOV group review
significant design changes involving safety-related MOVs. The inspectors
verified that a memo, dated February 16, 1993, had been issued to clarify
that the MOV group was to review design changes that could effect MOV
capabilities. The memo specifically referenced the licensee's commitment
to establishing and maintaining a design basis meeting GL 89-10
recommendations.
The licensee's implementation of GL 89-10 recommendations in this area
will require further evaluation to assure adequate post maintenance
testing is specified and to assure that the methodology specified for
periodic verification is adequate. The issues will be examined in a
subsequent inspection and are identified above as inspector followup
items.
.
2.5 MOV Failures, Corrective Actions, and Trending
Recommended action "h" of the generic letter requests that licensees
analyze and justify each MOV failure and corrective action. The
9
documentation should include the results and history of each as-found
deteriorated condition, malfunction, test, inspection, analysis, repair,
or alteration. All documentation should be retained and reported in
accordance with plant requirements. It is also suggested that the
material be periodically examined (every two years or after each
refueling outage after program implementation) as part of the monitoring
and feedback effort to establish trends of MOV operability.
The inspectors reviewed the four Adverse Condition Reports (ACR) related
to MOV problems listed below:
ACR No.
CONDITION 93-168
During DP Test SP 1181, SI-866A failed to close against SI pump
pressure. SI-866A is required to open to perform its safety
function.
Corrective Action: A burr was found in the yoke area of the
anti-rotation device and removed. The anti-rotation device was
replaced. The MOV was retested and met all test requirements.93-175
When SI-845B was tested after refueling maintenance had been
performed, the valve would not operate due to a locked motor.
Corrective Action:
Residue grease from the original greases
used in the operators had leaked into the motor due to a
cracked bearing seal.
The motor was replaced and the valve
tested. The corrective actions were satisfactory.93-194
An operability determination concern related to RHR-744A was
not processed properly by operations personnel.
Corrective Action:
There was no fuel in the vessel at the time
and no operability determination was-required at the time. A
review of this ACR was conducted with the personnel involved,
stressing the importance of communication and followup.93-290
Feedwater block valves had dual indication when they were
tested per the Special Procedure 1178 (DP Testing of V2-6A, B,
& C. The valves did not completely close even though they were
set per the calculated values.
Corrective Action:
Due to the effects of an increased valve
factor caused by "rate of loading", the valves only closed to
95 percent. To overcome this condition the torque switch
bypass in the close direction was installed to assure closure
under design conditions.
The inspector reviewed four MOV Failure Trending Reports that covered the
period from January 1, 1991, to December 31, 1993.
The reports were
developed from information contained in Work Requests and were intended
to identify common mode MOV failures and provide tracking information for
future MOV performance evaluations. These reports divided information
regarding the identified MOV failures into coded failure categories. The
reports included tables and charts that provided information for
10
comparison of failures of MOVs included in the GL 89-10 program to those
that are not part of the program.
The program for trending appeared to be a thorough well planned effort
that providing useful information to support the GL 89-10 program. The
trending program was considered a strength.
Based on the documents reviewed and discussions with the personnel
involved in activities that support corrective actions and trending, the
inspectors concluded that the licensee has an acceptable method for
correcting and tracking MOV failures and deficiencies.
2.6 Schedule
In GL 89-10, the NRC requested that licensees complete all design-basis
reviews, analyses, verifications, tests, and inspections that were
initiated in order to satisfy the generic letter recommendations by
June 28, 1994, or three refueling outages after December 28, 1989,
whichever is later. The licensee committed to the generic letter
schedule and, as three refueling outages have already occurred, the
June 28, 1994, completion date applies.
The licensee identified 48 valves in the GL 89-10 program that were
determined practicable to DP test. The inspectors were informed that all
of these valves had been tested, that preliminary analyses of all test
results had been performed, and that remaining final analyses were in
process. The completion of testing and preliminary analyses was verified
by the inspectors for their selected sample of MOVs. Based on their
review for the sample and their discussions with licensee personnel, the
inspectors believe the licensee is progressing satisfactorily to meet the
specified completion schedule.
2.7 Pressure Locking and Thermal Binding
The Office for Analysis and Evaluation of Operational Data has completed
a study of pressure locking and thermal binding of gate valves. It
concluded that licensees have not taken sufficient action to provide
assurance that pressure locking and thermal binding will not prevent a
gate valve from performing its safety function. The NRC regulations
require that licensees design safety-related systems to provide assurance
that those systems can perform their safety functions. In GL 89-10, the
staff requested licensees to review the design basis of their safety
related MOVs.
The licensee submitted a Licensee Event Report 82-011 which identified
the pressure locking phenomenon which occurred August 11, 1982 during RHR
System Component tests. Motor-operated valve SI-861A would not fully
open. Valves SI 861-A and B were modified by drilling a 3/8 inch hole in
the high pressure discs as directed by Modification No. 677. A study
that followed identified 12 other valves that required modifications to
prevent disc warpage caused by the effect of pressure locking. These
modifications were performed during the steam generator replacement
outage under Modification No. 792.
Thermal binding was identified on three feedwater block valves in the
late 1980s. Operating procedures were changed to require the manual
cycling of these valves during cool down of the system. The licensee
reports that no further problems with thermal binding have been
experienced.
The licensee's evaluation of INPO SOER 84-07 determined that the
modifications to the Safety Injection valves to overcome pressure locking
agreed with the INPO recommendation.
Review of Information Notice 92-016
by the licensee determined that no further corrective actions were
required. The NRC will issue additional recommendations regarding
pressure locking and thermal binding in the future.
2.8 Motor Brakes
The licensee had identified ten MOVs that were equipped with brake
mechanisms. The engineering evaluations (EEs) for the continued operation
of these MOVs was reviewed by the inspectors. These engineering
evaluation reports are listed as follows:
EE No.
Valve No.93-160
SI-865A, B, and C, Safety Injection Accumulator A, B, and C
Discharge Isolation Valves93-161
SI-880A, B, C, and D Containment Spray Pump A and B Discharge
Isolation Valves93-162
CC-716 A and B RC Pump Cooling Water Inlet Isolation Valves,
and CC-730 RC Pump Cooling Water Return Isolation Valve
In EE-93-160 valves SI-865A, B, and C were determined to be capable of
performing their intended safety function based on the fact that the
valves are open under normal operating conditions and are therefore ready
to allow the accumulators to discharge into the RC system if needed.
EE-93-161 and EE-93-162 contained the necessary evaluations to determine
that the brakes will function after a seismic event and are electrically
acceptable for operation at degraded voltages. The degraded voltage
operation acceptance was based partly on the testing performed at
Northeast Utilities, Millstone Unit One.
The inspectors found that the above evaluations appeared to be complete
in that all aspects of the brake mechanism were considered and evaluated
for possible failure modes and the impact the failure would have on the
operation of the MOV.
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2.9 Quality Assurance Program Implementation
The inspectors reviewed MOV Program Assessment Report No. R-SP-92-08
which was performed during April 20-23, 1992, which was an assessment of
the effectiveness of the MOV program. The assessment result indicated
aneed for increased management commitment and attention to the MOV
program. These findings were based on the incomplete resolution of nine
weaknesses identified during the NRC Part 1 inspection.
Engineering and Technical Support Assessment Report No. R-ES-93-01
conducted September 15-27, 1993, identified two weaknesses regarding the
MOV program with regard to evaluation of test data prior to returning
valves to service and independent verification causing delays in MOV
testing. This report also included resolution of findings identified in
Report No. R-SP-92-08.
Both reports identified strengths in addition to the weaknesses and
appeared to be in depth audits that were performed by knowledgeable
personnel.
The audits addressed the weaknesses to the organizations
responsible to bring attention to the finding and get the proper
solutions. The inspectors concluded that the assessments were adequate
and a contributor to the MOV program improvement.
.
2.10 Followup of Previous Inspection Findings
The inspectors reviewed the status of open findings identified in the
previous GL 89-10, Part 1 inspections. These findings included a
violation and 10 "open items".
The licensee had provided written
responses to the violation and open items in letters to the NRC dated
August 20, 1992, and September 23, 1991, respectively. The results of
the inspectors' review are described below:
a.
(Closed) Violation 50-261/92-19-01, Inadequate Design Control
Involving Unverified Assumptions Related to DP for Valves FW-2V-6A,
B, and C.
The licensee's August 20, 1992, letter acknowledged the violation,
described the corrective actions taken, and stated the steps taken
to avoid further violations. The inspectors verified that new
thrust values had been calculated as the result of the identified
higher differential pressures and that the torque switch setting had
been increased to meet the high thrust requirements. The inspectors
reviewed differential pressure calculations and examined the
assumptions used to determine the DP values.
New larger electrical
cables were installed which resulted in a higher motor torque.
These valves were identified as being subject to thermal binding as
discussed in Section 2.7 of this report. General Procedure GP-007,
Plant Cooldown From Hot Shutdown to Cold Shutdown, directs that
these valves be cycled at three different intervals during cool down
of the plant. The licensee has taken adequate corrective actions
for this violation. This item is closed.
13
b.
(Closed) Item 50-261/91-201-01, Determination of Design Basis Flow
Rate.
This item identified the licensee's failure to consider the effects
of flow in either the design-basis review or the in the testing.
GL 89-10 recommended the evaluation of factors such as flow.
In its September 23, 1991, letter responding this item, the licensee
indicated that design flow was not an important consideration, since
it did not have a quantifiable effect. The inspectors agreed that
there was no currently quantifiable effect but noted that flow has
been observed to effect required thrust and should be considered in
testing and evaluations. In particular, it is important to have
significant flow to simulate design-basis conditions adequately in
the testing. The inspectors' current review found that the licensee
had determined and added the design-basis flow rate to the
assumption Section of the "Mechanical Analysis and Calculation" in
the thrust calculation package for each MOV. Additionally, the
licensee had used substantial system flows in the MOV tests.
The
inspectors concluded that this adequately addressed the issue.
c.
(Closed) Item 50-261/91-201-02, Failure to Review Mispositionable
Valves.
This item identified that the licensee had determined that it was
not necessary to review the capability of mispositioned valves to be
repositioned to their safety position, if redundant valves or
systems existed. This was contrary to a recommendation of GL 89-10.
As indicated in its response letter, the licensee's determination is
consistent with an owner's group position. The matter is currently
under.evaluation by the NRC and, pending an NRC decision, this issue
remains open. The original open item will be closed and re
identified as Inspector Followup Item 50-261/94-06-07,
Mispositioning, for tracking by NRC Region II.
d.
(Closed) Item 50-261/91-201-03, Undersized Actuators for Valves FW
V2-6A, 6B, and 6C.
This item is closed based on the information reviewed by NRC
inspectors during the close out of Violation 50-261/92-19-01.
e.
(Closed) Item 50-261/91-201-04, Setting of Closed-to-Open Bypass
Limit.
This item questioned the licensee's practice of setting closed-to
open torque bypass limit switches at 5 percent of the valve opening
stroke, as this might not adequately encompass the unseating of some
valves. Additionally, concern was expressed regarding the
licensee's failure to balance torque switches (to assure actuation
at similar opening and closing torques) and its use of torque
wrenches for setting the torque switches.
14
The licensee's response to this finding indicated that diagnostic
data obtained during MOV testing would be reviewed to ensure the
open torque switch bypass limit was set appropriately to allow
proper functioning of the valve. It further stated that new
installations would require torque switch balancing and that the
need for routine balancing would be considered.
The inspectors found that the licensee had issued Plant Improvement
Request 93-059100 (dated April 30, 1993) which recommended
increasing the closed-to-open bypass from 5 percent to 95 percent.
Therefore, the torque switch would be bypassed for 95 percent of the
valve's opening stroke and be placed back into the circuit for the
remaining 5 percent of the opening stroke. This change in open
torque switch control was not fully implemented.
The inspectors had previously observed a demonstration of the
licensee's use of torque wrenches to set torque switches at the
licensee's Harris facility. The practice applied by the licensee
was found to be acceptable.
Further NRC review of the licensee's torque bypass changes and
torque switch balancing practices will be conducted in a subsequent
inspection. The original open item will be closed and re-opened as
Inspector Followup Item 50-261/94-06-08, Setting Closed-to-Open
Bypass Switch Limit, for tracking by NRC Region II.
f.
(Closed) Item 50-261/91-201-05, Procedures for Controlling Design
Basis Testing.
This item identified the following apparent deficiencies in the
procedures used to control design-basis testing:
(1) Dynamic diagnostic testing had been performed without
accompanying static testing.
(2) Test results had not been fully assessed almost three months
after the tests had been completed.
(3) Test flow and differential pressure were not recorded in a way
that was readily available to the test results evaluator.
In their review of design-basis testing during this inspection the
inspectors determined that the apparent deficiencies identified
through this open item had been adequately addressed by the
licensee. Timely operability reviews had been documented, static
diagnostic testing accompanied dynamic testing, and recorded test
parameters were readily available. This item is closed.
15
g.
(Closed) Item 50-261/91-201-06, Periodic Verification of MOV
Operability.
This item questioned the licensee's planned lubrication and cleaning
of MOVs before periodic testing.
This practice would preclude
evaluation of the as-found valve condition.
The licensee's response letter stated that Preventive Maintenance
Procedure PM-420 had been revised to require lubrication only prior
to baseline testing. Additionally, the inspectors were informed
that the AMMS database which initiates the lubrication requires that
the MOV coordinator be contacted to assure that testing is performed
prior to the lubrication and cleaning. The inspectors verified the
above corrective actions through a review of PM-420, Rev. 9, and the
AMMS database requirement for the lubrication.
The issue is
resolved.
h.
(Closed) Item 50-261/91-201-07, Inadequate Documentation and
Corrective Action for MOV Deficiencies.
This item identified two cases in which deficient conditions
appeared inadequately documented and evaluated. The first case
involved tightening the packing of valve RHR-744B from 46 to 138
foot pounds without an engineering review or post modification test
and failing to adequately evaluate the reported movement of this
valve during actuation. The second case involved inadequate
evaluation of stem galling on valve V2-6A.
The licensee's response letter stated that Maintenance Work Request
91-AIDQ1 provided testing (June 14, 1991) that verified the packing
adjustment on valve RHR-744B had not significantly increased
actuator loading. In addition, the response stated that the valve
had been observed during stroking and did not exhibit any abnormal
movement. The inspectors reviewed and verified the above Work
Request, which contained the results of current traces performed on
the valve.
They also interviewed the licensee's MOV coordinator,
who indicated that he had observed the valve in operation and saw no
abnormal movement. Finally, the inspectors verified that the
licensee had conducted design-basis DP testing of the valve and
found that it operated satisfactorily. On this basis the original
finding is considered closed. However, this valve and valve RHR
744A, were identified as marginal valves as described in Section 2.2
above and further licensee actions to ensure that these valves
perform satisfactorily are to be verified in a subsequent NRC
inspection.
SII
16
i.
(Closed) Item 50-261/91-201-08, MOV Setpoint Document Control of
Switch Settings.
This item identified that procedure CM-111 did not provide torque
switch, limit switch, or thrust settings for numerous MOVs. The
technicians who set MOVs were obtaining the values to be used
verbally from the MOV coordinator.
The licensee's response stated that MOV switch settings and thrust
values would be controlled through its automated Equipment Database
System (EDBS), eliminating the need for the verbal transfer of
information.
The inspectors verified that the EDBS contained the
setting entries and that procedure CM-111, Rev. 21, directed use of
the EDBS for the settings. This resolves the finding.
j. (Closed) Item 50-261/91-201-09, MOV Post Maintenance Testing.
The licensee's procedure did not require that thrust margin be
verified following maintenance that could affect MOV performance.
The licensee's response letter indicated that using thrust data to
verify performance was under review. In the current inspection the
inspectors found that post maintenance testing requirement guidance
was specified by Appendix A of procedure MMM-003, Rev. 9. Thrust
verification appeared satisfactorily controlled except where
significant valve maintenance was performed.
For example, static
(no DP) thrust testing was specified following packing maintenance,
valve overhaul or replacement, and operator overhaul.
For valve
overhaul or replacement use of static testing may not be adequate.
As discussed in Section 2.4 above, the adequacy of post maintenance
testing will require further NRC review and has been designated
Inspector Followup Item 50-261/94-06-06, replacing Open Item 50
261/91-201-09.
k.
(Closed) Item 50-261/91-201-10, Failure to Periodically Test Thermal
Overloads.
This item identified that there was no periodic testing to verify
proper setting of the thermal overloads on MOV circuits.
The licensee's response letter indicated this issue was under
advisement.
The licensee tested all the TOLRs for 94 safety related MOVs.
The
TOLRs for six MOVs were replaced due to failures. Three of the
failures were determined to be opening at a value .greater than the
range of the TOLR. Three others were borderline when the tolerance
was taken into account could have been out of range. These were
replaced as a conservative action. The licensee had not determined
the interval that will be used for TOLR testing but plans some form
of testing in the future.
17
3.0
EXIT INTERVIEW
The inspection scope and findings were summarized on April 1, 1994, with
those persons indicated in Section 1. The inspectors described the areas
inspected and discussed in detail the inspection results. Proprietary
information is not contained in this report. No dissenting comments were
received from the licensee. Eight inspector followup items were
identified. These items are listed in the summary at the beginning of
this report, which gives the status of all items inspected.
4.0 ACRONYMS AND INITIALISMS
Alternating Current
ACR
Adverse Condition Report
AMMS
Automated Maintenance Management System
Component Cooling System
CFR
Code of Federal Regulations
Charging System
Control Switch Trip
CV
Containment Volume
DBDP
Design Basis Differential Pressure
DP
Differential Pressure
EDBS
Electronic Database System
EE
Engineering Evaluation
GL
Generic Letter
Heat Exchanger
IFI
Inspector Followup Item
Institute for Nuclear Power Operations
Motor-Operated Valve
MS
Main Steam System
NED
Nuclear Engineering Department
NRC
Nuclear Regulatory Commission
RC
Refueling Outage
Residual Heat Removal System
Robinson Nuclear Plant
Steam Driven Auxiliary Feedwater (Turbine)
Safety Injection
Significant Operating Event Report
TI
Temporary Instruction
TOLR
Thermal Overload Relay
VOTES
Valve Operation Test and Evaluation System
Soeo eea euain