ML062420513
| ML062420513 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 08/30/2006 |
| From: | Howell A NRC/RGN-IV/DRP |
| To: | Venable J Entergy Operations |
| References | |
| EA-06-136 IR-06-009 | |
| Download: ML062420513 (33) | |
See also: IR 05000382/2006009
Text
August 30, 2006
Joseph E. Venable
Vice President Operations
Waterford 3
Entergy Operations, Inc.
17265 River Road
Killona, LA 70066-0751
SUBJECT: WATERFORD STEAM ELECTRIC STATION, UNIT 3 - NRC INSPECTION
REPORT 05000382/2006009 AND NOTICE OF VIOLATION
Dear Mr. Venable:
On August 9, 2006, the NRC completed an inspection at your Waterford Steam Electric Station,
Unit 3. The enclosed report documents the inspection findings which were preliminarily
discussed on May 11, 2006, with Mr. Kevin Walsh and other members of your staff. A followup
call concerning the disposition of the related enforcement activities was conducted with you and
other members of your staff on June 23, 2006, and a final telephonic exit meeting was
conducted on August 9, 2006.
This inspection examined activities conducted under your license as they relate to safety and
compliance with the Commissions rules and regulations and with the conditions of your license.
Within these areas, the inspection consisted of selected examination of procedures and
representative records, observations of activities, and interviews with personnel.
The report documents one violation of 10 CFR 50.9, with two examples, for reporting inaccurate
information to the NRC associated with the NRCs Safety System Unavailability (High Pressure
Injection and Residual Heat Removal) Performance Indicators. The performance indicator
information was inaccurate because your staff improperly concluded that the Train B high
pressure safety injection and Train B containment spray systems were still available for the full
range of potential accidents during an extended period when the containment safety injection
sump suction valve was partially open during the period of November 11, 2003 to September 9,
2004. If this data had been accurately reported, then the High Pressure Injection Performance
Indicator should have been Red and the Residual Heat Removal Performance Indicator should
have been Yellow up until the point that the safety system unavailability performance indicators
were replaced by the mitigating systems performance index (MSPI) on April 1, 2006.
The Enforcement Policy, Supplement VII, specifies that issues such as reporting inaccurate
performance indicator data that would have caused a performance indicator to change color
from Green to Yellow or Red would be a Severity Level III violation. However, the NRC has
determined that a Severity Level IV violation was more appropriate in this particular
circumstance. This determination was made primarily on the basis that the risk significance
Entergy Operations, Inc.
-2-
associated with the valve being mis-positioned was determined to be very low (Green) as
documented in NRC Inspection Report 05000382/2004005. Additionally, under the NRCs
recently implemented MSPI program, which replaced the safety system unavailability
performance indicator program on April 1, 2006, a similar set of circumstances would have
resulted in a Green outcome because of the differences in the way fault exposure is treated
under the former safety system unavailability performance indicator program and the current
MSPI program. While the overall risk significance of the underlying performance deficiency
was low, the failure to provide accurate information calls into question the ability to effectively
and consistently implement the performance indicator program, particularly for circumstances in
which the performance indicator outcome may result in a degradation of the cornerstone safety
objective.
The Severity Level IV violation is being cited because not all the criteria specified in Section
VI.A.1 of the NRC Enforcement Policy for a noncited violation were satisfied. Specifically,
Entergy failed to restore compliance and report corrected or accurate performance indicator
information, or otherwise notify NRC that the data reported in the past was not accurate, within
a reasonable time after the potential violation was initially identified. For the purposes of this
criterion, you were notified of the violation during the May 11, 2006, exit debrief meeting. Even
though the safety system unavailability performance indicators were superceded by MSPI
before the date of the exit meeting, the failure to accurately report the data was still material
because the NRC used the information to determine its level of oversight of Waterford 3.
Additionally, as stated in the Enforcement Policy, 10 CFR 50.9 violations are not evaluated
under the Significance Determination Process because violations of this nature impact the
ability of the NRC to properly regulate its licensees. You are required to respond to this letter
and should follow the instructions specified in the enclosed Notice when preparing your
response. The NRC will review your response, in part, to determine whether further
enforcement action is necessary to ensure compliance with regulatory requirements.
The NRC Action Matrix is described in NRC Inspection Manual Chapter 0305, Operating
Reactor Assessment Program. In accordance with the Action Matrix, one Red and one Yellow
performance indicator input would have placed your facility in the Multiple/Repetitive Degraded
Cornerstone, column. This would have required the implementation of Inspection Procedure 95003, Supplemental Inspection for Repetitive Degraded Cornerstone, Multiple Degraded
Cornerstones, Multiple Yellow inputs, or One Red Input, at your facility, as well as a number of
additional regulatory actions. For the same reasons as those specified for categorizing the
violation at Severity Level IV, the NRC also determined that a deviation from the NRC Action
Matrix was warranted. In lieu of these actions, we will implement actions as specified in the
Licensee Response column because, in this circumstance, this will provide the appropriate level
of regulatory response. This deviation from the NRC Action Matrix is documented in a
memorandum dated July 25, 2006.
Entergy Operations, Inc.
-3-
In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter, its
enclosures, the July 25, 2006, Action Matrix Deviation Memorandum, and your response will be
made available electronically for public inspection in the NRC Public Document Room or from
the NRCs document system (ADAMS), accessible from the NRC Web site at
http://www.nrc.gov/reading-rm/adams.html. Should you have any questions concerning this
inspection, we will be pleased to discuss them with you.
Sincerely,
/RA/
Authur T. Howell III, Director
Division of Reactor Projects
Docket: 50-382
License: NPF-38
Enclosures:
NRC Inspection Report 050000382/2006009
w/Attachment: Supplemental Information
cc w/Enclosure:
Senior Vice President and
Chief Operating Officer
Entergy Operations, Inc.
P.O. Box 31995
Jackson, MS 39286-1995
Vice President, Operations Support
Entergy Operations, Inc.
P.O. Box 31995
Jackson, MS 39286-1995
Wise, Carter, Child & Caraway
P.O. Box 651
Jackson, MS 39205
General Manager, Plant Operations
Waterford 3 SES
Entergy Operations, Inc.
17265 River Road
Killona, LA 70066-0751
Entergy Operations, Inc.
-4-
Manager - Licensing Manager
Waterford 3 SES
Entergy Operations, Inc.
17265 River Road
Killona, LA 70066-0751
Chairman
Louisiana Public Service Commission
P.O. Box 91154
Baton Rouge, LA 70821-9154
Director, Nuclear Safety &
Regulatory Affairs
Waterford 3 SES
Entergy Operations, Inc.
17265 River Road
Killona, LA 70066-0751
Richard Penrod, Senior Environmental
Scientist
Office of Environmental Services
Northwestern State University
Russsell Hall, Room 201
Natchitoches, LA 71497
Parish President
St. Charles Parish
P.O. Box 302
Hahnville, LA 70057
Winston & Strawn LLP
1700 K Street, N.W.
Washington, DC 20006-3817
Entergy Operations, Inc.
-5-
Electronic distribution by RIV:
Regional Administrator (BSM1)
DRP Director (ATH)
DRS Director (DDC)
DRS Deputy Director (RJC1)
Senior Resident Inspector (MCH)
Branch Chief, DRP/E (DNG)
Senior Project Engineer, DRP/E (VGG)
Team Leader, DRP/TSS (RLN1)
RITS Coordinator (KEG)
OEMAIL
D. Starkey, OE
D. Solorio, OE
J. Luehman, OE
M. Vasquez
M. Haire
Only inspection reports to the following:
J. Lamb, OEDO RIV Coordinator (SCO)
ROPreports
WAT Site Secretary (AHY)
SUNSI Review Completed: __DNG__
ADAMS: / Yes
G No Initials:_DNG____
/ Publicly Available G Non-Publicly Available G Sensitive
/ Non-Sensitive
R:\\REACTORS\\WAT\\2006\\WT2006-09RP-GDR.wpd
RIV:SRI:DRS/EB1
SPE:DRP/D ACES
C:DRP/E
D:DRP
GDReplogle
MAJunge
MCHay
GMVasquez
DNGraves
ATHowell
/RA/
E-GDR
/RA/
/RA/
/RA/
/RA/
6/16/06 & 6/23/06
6/12/06
6/20/06
8/24/06
8/24/06
8/30/06
OFFICIAL RECORD COPY
T=Telephone E=E-mail F=Fax
Enclosure 1
Entergy Operations, Inc.
Docket No. 50-382
Waterford Steam Electric Station
License No. NPF-38
During an NRC inspection conducted on March 6 through May 11, 2006, a violation of NRC
requirements was identified. In accordance with the NRC Enforcement Policy, the violation is
listed below:
10 CFR 50.9 requires, in part; Information provided to the Commission by a licensee
shall be complete and accurate in all material respects.
Contrary to the above, from approximately November 1, 2004, (when the licensee
initially submitted the subject performance indicator information) to May 11, 2006,
information provided to the Commission in the form of system unavailability statistics for
the high pressure safety injection (Train B) and containment spray (Train B) systems
was not complete and accurate in all material respects. The licensee significantly
under-reported the unavailability hours for each train. This was material because the
NRC used the information to determine its response (e.g., inspection) to the data.
This is a Severity Level IV violation (Supplement VII).
Pursuant to the provisions of 10 CFR 2.201, Entergy Operations is hereby required to submit a
written statement or explanation to the U.S. Nuclear Regulatory Commission, ATTN: Document
Control Desk, Washington, DC 20555 with a copy to the Regional Administrator, Region IV, and
a copy to the NRC Resident Inspector at the facility that is the subject of this Notice, within 30
days of the date of the letter transmitting this Notice of Violation (Notice). This reply should be
clearly marked as a "Reply to a Notice of Violation; EA-06-136" and should include: (1) the
reason for the violation, or, if contested, the basis for disputing the violation or severity level,
(2) the corrective steps that have been taken and the results achieved, (3) the corrective steps
that will be taken to avoid further violations, and (4) the date when full compliance will be
achieved. Your response may reference or include previous docketed correspondence, if the
correspondence adequately addresses the required response. If an adequate reply is not
received within the time specified in this Notice, an order or a Demand for Information may be
issued as to why the license should not be modified, suspended, or revoked, or why such other
action as may be proper should not be taken. Where good cause is shown, consideration will
be given to extending the response time.
If you contest this enforcement action, you should also provide a copy of your response, with
the basis for your denial, to the Director, Office of Enforcement, United States Nuclear
Regulatory Commission, Washington, DC 20555-0001.
Because your response will be made available electronically for public inspection in the NRC
Public Document Room or from the NRCs document system (ADAMS), accessible from the
NRC Web site at http://www.nrc.gov/reading-rm/adams.html, to the extent possible, it should
not include any personal privacy, proprietary, or safeguards information so that it can be made
available to the public without redaction. If personal privacy or proprietary information is
necessary to provide an acceptable response, then please provide a bracketed copy of your
-2-
Enclosure 1
response that identifies the information that should be protected and a redacted copy of your
response that deletes such information. If you request withholding of such material, you must
specifically identify the portions of your response that you seek to have withheld and provide in
detail the bases for your claim of withholding (e.g., explain why the disclosure of information will
create an unwarranted invasion of personal privacy or provide the information required by
10 CFR 2.390(b) to support a request for withholding confidential commercial or financial
information). If safeguards information is necessary to provide an acceptable response, please
provide the level of protection described in 10 CFR 73.21.
Dated this 30th day of August, 2006
Enclosure 2
U.S. NUCLEAR REGULATORY COMMISSION
REGION IV
Docket No.:
50-382
License No.:
Report No.:
Licensee:
Entergy Operations, Inc.
Facility:
Waterford Steam Electric Station, Unit 3
Location:
Hwy. 18
Killona, Louisiana
Dates:
March 6 through August 9, 2006
Inspectors:
G. D. Replogle, Senior Reactor Inspector, Division of Reactor Safety
M. A. Junge, Mechanical Engineer, Office of Nuclear Reactor Regulation
Approved By:
Arthur T. Howell III, Director, Division of Reactor Projects
ATTACHMENTS:
Supplemental Information
Enclosure 2
-2-
SUMMARY OF FINDINGS
IR05000382/2006-009; 03/06/2006-08/09/2006; Waterford Steam Electric Station, Unit 3;
Discrepant or Unreported Performance Indicator Data
The report covered a 5 month period of inspection by a Region IV senior reactor inspector and
a mechanical engineer from the NRCs Office of Nuclear Reactor Regulation. The inspector
identified one Severity Level IV violation, which is not subject to the Significance Determination
Process. Findings for which the Significance Determination Process does not apply may be
Green or be assigned a severity level after NRC management review. The NRCs program for
overseeing the safe operation of commercial nuclear power reactors is described in
NUREG-1649, Reactor Oversight Process, Revision 3, dated July, 2000.
A.
NRC-Identified and Self-Revealing Findings
Cornerstone: Mitigating Systems
Severity Level IV. The inspector identified a violation of 10 CFR 50.9, with two
examples, for the failure to provide accurate information to the NRC associated with the
Safety System Unavailably High Pressure Injection and Residual Heat Removal
Performance Indicators. The performance indicator information was inaccurate because
the licensee improperly concluded that the Train B high pressure safety injection and
Train B containment spray systems were still available during an extended period when
the containment safety injection sump suction valve was partially open. The inspector
found that the licensee had underestimated the size of valve (SI 602B) opening when
assessing system availability and failed to address inconsistencies between their field
data, diagnostic test data and their own informal calculations. Further, a second
analysis performed by a contractor (to determine the as-found valve position) was
inadequate, as it contained several errors and inappropriate assumptions. The licensee
also provided inadequate contractor oversight with respect to this effort. The erroneous
valve position determination resulted in the licensee reporting system availability
information that caused the performance indicators to be Green when the High Pressure
Safety Injection System Unavailability Performance Indicator should have been Red and
the Residual Heat Removal System Unavailability Performance Indicator should have
been Yellow.
The failure to provide accurate information to the NRC in accordance with 10 CFR 50.9
requirements was a performance deficiency. The issue had more than minor
significance in that, had the information been accurate, two performance indicators
would have changed color. Per the NRC Enforcement Policy,Section IV.A.3, these
issues are not subject to the Significance Determination Process. The Enforcement
Policy, Supplement VII, specifies that a Severity Level III violation would be appropriate
for these issues. However, considering: 1) the NRCs recently implemented Mitigating
Systems Performance Index program, which would have resulted in the subject
performance indicators returning to the Green threshold; and 2) the risk associated with
Enclosure 2
-3-
the underlying valve performance issue was of very low safety significance (Green), the
NRC determined that a Severity Level IV violation was more appropriate. This finding
had problem identification and resolution crosscutting aspects, in that the
implementation of the licensees Corrective Action Program did not result in a thorough
evaluation of the identified condition such that information reported to the NRC was
verified to be complete and accurate (Section 4OA1).
B.
Licensee-Identified Violations
None.
Enclosure 2
-4-
REPORT DETAILS
4OA1 Discrepant or Unreported Performance Indicator Data (71150)
a. Inspection Scope
The purpose of the inspection was to evaluate the accuracy of performance indicator
information submitted by the licensee for the High Pressure Injection and Residual Heat
Removal Performance Indicators. The accuracy of the performance indicator
information was questioned after an operator found containment safety injection sump
suction Valve SI-602B partially open on September 9, 2004. This condition could have
affected the availability of the Train B high pressure safety injection and Train B
containment spray systems. The licensee determined that the valve had been partially
open since November 11, 2003, when valve technicians incorrectly set one of the
Valve SI-602B limit switches. The partially open valve posed potential challenges to the
availability of the noted trains in response to medium break and large break loss of
coolant accidents. The availability of the high pressure safety injection system affected
the Safety System Unavailability High Pressure Injection Performance Indicator while
availability of the containment spray system affected the Safety System Unavailability
Residual Heat Removal Performance Indicator.
The inspector reviewed the licensees evaluation of the as-found valve position, the root
cause evaluation report and two contractor-furnished analyses. One contractor had
performed an evaluation of system impacts based on different valve positions. The
second contractor performed an analysis to determine the valves as-found position. In
addition, the inspector interviewed plant personnel who were involved with issue
identification and problem evaluation. Finally, the inspector obtained motor-operated
valve drawings and valve test data and performed independent calculations to
determine the valves as-found position.
The underlying valve performance issue was documented as a licensee-identified
violation of very low risk significance (Green) in NRC Inspection
Report 05000382/2004005, Section 4OA7. Therefore, the focus of this inspection dealt
solely with the determination of the accuracy of the data submitted to the NRC regarding
the two subject performance indicators.
b.
Findings
Introduction. The inspector identified a violation of 10 CFR 50.9, with two examples, for
the failure to provide accurate information to the NRC associated with the High Pressure
Safety Injection System Unavailability and Residual Heat Removal System Unavailability
Performance Indicators. The performance indicator information was inaccurate because
the licensee improperly concluded that the Train B high pressure safety injection and
Train B containment spray systems were still available during an extended period when
the containment safety injection sump suction Valve SI-602B, was partially open. The
inspector found that the licensee had underestimated the size of the valve opening when
assessing system availability and failed to address inconsistencies between their field
Enclosure 2
-5-
data, diagnostic test data and their own informal calculations. Furthermore, a second
analysis performed by a contractor to determine the valves position was inadequate, as
it contained several errors and unsupported assumptions. The licensee provided
inadequate contractor oversight with respect to this effort. The erroneous valve position
determination resulted in the licensee reporting system availability information that
caused the two performance indicators to indicate Green when the High Pressure
Injection System Unavailability Performance Indicator should have been Red and the
Residual Heat Removal System Unavailability Performance Indicator should have been
Yellow.
Background: On September 9, 2004, during a system piping integrity test, the test
operator found the containment safety injection sump suction Valve SI-602B partially
open. The valve is a 24 inch Fisher 9200 series butterfly valve driven by an SMB-00
electric actuator through a quarter turn H2BC gear operator. The licensee determined
that the condition had existed since November 11, 2003, when one of the valve limit
switches was set incorrectly and prevented the valve disc from reaching the fully closed
and seated position.
In response to medium and large break loss of coolant accidents that pressurize
containment, the partially open valve posed two potential challenges to system
availability. First, the pressurized containment would force air, steam and water through
the valve and into the system flow streams. Air entrainment can cause excessive pump
vibration and pump air binding which can render the system unavailable. Second, the
system suction lines could be pressurized sufficiently as to force and hold closed the
refueling water storage pool discharge check Valve SI-107B. This would starve the
system pumps of a suction source of water, rendering them unavailable. Depending on
the position of SI-602B, this condition had the potential of rendering the high pressure
safety injection system Train B, low pressure safety injection system Train B, and
containment spray system Train B unavailable. However, in this case, the unavailability
of the Train B low pressure safety injection system would not affect a performance
indicator value.
The licensee performed a detailed analysis to determine the equipments sensitivity to
air entrainment and suction header pressurization. The licensee determined that the
total valve opening could not exceed 0.41 square inches. In addition, the licensee
attempted to replicate the valve position and then took physical gap measurements to
determine the affected valve disc area. The licensee determined that the open area
was 0.25 square inches, which was within the 0.41 square inch acceptance limit. The
licensee then took additional valve measurements and determined that the valves as-
found position was approximately 3.2E open. In response to the NRC questions and
concerns regarding the valves actual as-found position, the licensee contracted with an
industry engineering firm to again determine the as-found valve position.
Summary: The following bullets summarize the inspector observations and findings.
Additional details concerning each identified problem are provided in subsequent
sections of this report.
Enclosure 2
-6-
The licensees evaluation of system impacts, based on different possible valve
positions, was conservative and effective. The evaluation concluded that system
availability could be maintained with a maximum valve opening of 0.41 square
inches. The inspector had no findings of significance related to this evaluation.
The licensees re-creation of the as-found position of Valve SI-602B was
inadequate because it failed to account for direction-dependent differences in
valve performance. Specifically, valve leakage started and stopped at different
handwheel positions depending on whether the valve was being opened or
closed. The licensees re-creation concluded that the valve was 3.2E open.
A subsequent engineering evaluation performed by a contractor was inadequate
because:
The contractors evaluation of the licensees re-creation of the valves as-found
position also failed to account for direction-dependent differences in valve
performance. The licensee had not provided the contractor with the pertinent
test data. This affected one of five contractor valve position assessments.
The contractor inappropriately assumed that the valve was over-traveling past
the 0E position. The contractor provided no objective evidence to support this
assumption and the inspector identified evidence to the contrary. The two
calculations that used this assumption concluded that the valve was 3.4E and
3.5E from the 0E position. However, when the inspector applied correction
factors to these calculations to account for the erroneous assumption, the
calculated valve positions were 5.4E and 5.6E, respectively.
The contractor used an inappropriate value for the Modulus of Rigidity (an
engineering term related to the stiffness of a round bar when torque is applied) in
one calculation. This made two calculations that were based on different values
of handwheel turns (0.55 and 1.0) come to the same final result. This
inappropriate factor was used in one calculation but not the other.
The contractors estimation of valve position based on HBC operator stop nut
measurements was not credible. The data, which was provided by the licensee,
was obtained under informal and uncontrolled conditions, was not specific as to
the conditions under which it was obtained, and was inconsistent with other
information. This affected one contractor calculation.
The licensee reviewed the contractors analysis prior to providing it to the NRC
but they failed to identify the noted problems.
The inspector performed two additional independent calculations and determined
that the valves as-found position was slightly greater than 5E from the zero
position. The licensee had performed similar calculations and had obtained
similar results, but had not formalized these efforts. In addition, the licensee had
Enclosure 2
-7-
not attempted to explain the inconsistencies between these calculations and
other results that they utilized. The licensees evaluation of these issues lacked
sufficient engineering rigor.
A summary of the calculated valve positions, including inspector corrected values and
results from independent NRC calculations, is provided below:
Contractor Calculations and NRC Corrections
Calculation Method/
Referenced Position
Change in Disc
Position from
Referenced Position
Inspector
Corrected
Values
HBC Stop Nut
2.915E
Not Credible,
Inconsistent
Data
Handwheel Closure (one full
handwheel turn)
2.870E
3.9E
Least Accurate
Stroke Time Comparison
3/10/1999 Trace (diagnostic
system traces)
3.363E
5.4E
Reasonable
Approximation
Stroke Time Comparison
11/6/2003 Trace (diagnostic
system traces)
3.549E
5.6E
Reasonable
Approximation
Disc Measurement
3.186E
Inadequate Re-
creation
Average
3.177E
Independent NRC Calculations
Method
Results
Relative
Accuracy
Inservice Stroke Time Tests
5.9E
Reasonable
Approximation
Diagnostic System Test Data
5.5E
Most Accurate
The detailed supporting sections of this report are organized into three main categories:
Assessment of Licensees Initial Evaluation
Assessment of Licensees Contractor Evaluation
Independent NRC Calculations
Enclosure 2
-8-
Assessment of Licensees Initial Evaluation
Licensees First Field Test: The licensee performed field testing to estimate the
valves as-found position.
The first field test was a local leak rate test. The test involved slowly opening the valve
using the manual handwheel in 1/8 turn increments to the 2-1/4 turns open position.
Then an operator closed the valve in 1/8 turn increments until it was fully closed. The
valve operator stated that he did not start counting the handwheel turns until he
obtained resistance. That means that the operator did not count the first part of the
handwheel operation before the handwheel dogs engaged into the drive sleeve slots.
Until the handwheel dogs are engaged, the handwheel would spin freely. The inspector
considered this approach appropriate for counting handwheel turns.
The inspector noted that the apparent positions of the valve when leakage started
(going open) and stopped (going closed) were sensitive to the direction of valve
movement. For example, in the open direction gross leakage initiated between 1-3/8
and 1-1/2 handwheel turns from hard-seat contact. In the closing direction, gross
leakage stopped between 7/8 and 3/4 handwheel turn from hard-seat contact. In
response to inspectors questions, the licensee stated that they had also noticed this
discrepancy but had not attempted to evaluate it.
The inspector reviewed the valves diagnostic testing system torque traces and
determined that the significant difference between the points where leakage started and
stopped was due to gear play. The traces revealed that, when the valve changed
direction, the motor and gears operate for 1.34 seconds before the valve stem started to
move. In the more pertinent part of the trace (from hammer-blow to the initiation of
valve movement) the time delay was 0.8 seconds. This is the more pertinent trace
section because it mimics the valve/actuator response when it is operated with the
handwheel. The delay of 0.8 seconds equates to about 0.6 handwheel turn worth of
motion, which turns out to be the approximate difference in the handwheel positions
noted above.
In reality, for both the opening and closing directions the valve disc was in about the
same position when gross flow initiated and stopped. The indicated position in the open
direction was misleading because the licensee did not account for the gear play
contribution. Accounting for this type of gear play is only necessary when changing the
valves direction and will usually only affect the estimated position (using handwheel
turns) in the open direction.
The table, below, illustrates the affect of gear play on the valve position. In this
example, the valve in question is repositioned from full closed to 1.8 handwheel turns
open. Then the valve is repositioned back to the closed position. For this example, one
full handwheel turn is equal to 5.14E of valve movement.
Enclosure 2
-9-
Opening
Handwheel
turns from
fully
closed,
going open
Actual valve
position in
equivalent
handwheel
turns from
fully closed
Valve
position in
degrees
open
0
0
0E
0.2
0
0E
0.4
0
0E
0.6
0
0E
0.8
0.2
1.0E
1.0
0.4
2.0E
1.2
0.6
3.0E
1.4
0.8
4.1E
1.6
1.0
5.1E
1.8
1.2
6.2E
Closing
Handwheel
turns from
fully closed,
going
closed
Actual valve
position in
equivalent
handwheel
turns from fully
closed
Valve
position in
degrees
open
1.8
1.2
6.2E
1.6
1.2
6.2E
1.4
1.2
6.2E
1.2
1.2
6.2E
1.0
1.0
5.1E
0.8
0.8
4.1E
0.6
0.6
3.0E
0.4
0.4
2.0E
0.2
0.2
1.0E
0
0
0E
As demonstrated above, when the valve is being repositioned in the open direction,
handwheel position is not an accurate indicator of valve position unless the amount of
gear play is known and accounted for. Conversely, moving in the closed direction, once
the valve moves through the gear-play region, the handwheel position is a relatively
accurate indicator of valve position. This fact is important and has direct ramifications
on the licensees evaluation as discussed below.
Licensees Second Field Test: The second field test involved positioning the valve to
the one handwheel turn open position and taking internal gap measurements. The gap
measurements were then used to estimate the approximate valve opening. For clarity,
each major step is discussed separately:
1.
The licensee opened the valve one full handwheel turn, against resistance, and
match-marked the valves position indicator. The indicator is directly aligned with
the valve stem. It is connected to the stem through a splined shaft, which has a
small amount of gear play.
The inspector noted that because of the position error in the opening direction
(due to gear play), the valve was not the equivalent of one full handwheel turn
open (5.12E) but was about 0.4 handwheel turn open (2E).
2.
An operator opened the valve to the 40 percent open position (about 34E).
Enclosure 2
-10-
3.
The operator then closed the valve to align the match-markings that were made
in the first step. The inspector noted that the licensee had not counted the
number of turns back to this position to verify that the valve was actually one
handwheel turn from the seat. Instead, the licensee aligned the valve indicator
to the match marks that corresponded to the 0.4 handwheel (2E) open position.
If there had been no gear play between the indicator and the valve stem, then
the valve would have been only 2E open. This gear play between the indicator
and the valve stem caused the indicator to lead the actual valve position very
slightly. When reversing the valves direction (going in the closed direction) the
gear play would cause the valve to be slightly more open at the match-marked
position than when the match-marks were made. Since this gear play
constituted only a portion of the total gear play in the valve/actuator system, it
was not sufficient to cause the valve to be the equivalent of one full handwheel
turn open (5.12E).
4.
The licensee took gap measurements between the valve disc and body.
5.
The licensee took additional internal measurements and established that the
valve disc was approximately 3.2E open.
6.
The licensee repeated the procedure and calculated the total valve open area at
0.25 square inches (using the larger of the two measurements). The two
measurements were approximately 50% different in magnitude. The licensee
identified small gaps between the Tee-Ring and the seat in one lower quadrant
and in a small section of one upper quadrant, where the Tee-Ring had torn.
The inspector noted that, between the two tests, the licensee had to reposition the valve
to the full closed position in order to start the procedure over for the second set of
measurements. The licensee could have easily verified that the valve was actually one
full handwheel turn from hard-seat contact at this point in their procedure. The licensee
did not perform this verification. If they had done so, then they would have found that
the valve was not one full handwheel turn away from the fully closed position.
Assessment of Licensees Contractor Evaluation
As discussed later in this report, the inspector had performed independent calculations
and determined that the valve was slightly more than 5E open. In response to the
inspector concerns, the licensee hired a contract engineering firm to evaluate the valves
as-found position. The licensee provided the inspectors with the contractors report,
Independent Assessment of Disc Position of SI-602B Between November 3, 2003 and
September 11, 2004, dated May 8, 2006.
The engineering firm determined that the valve was likely at the 3.2E open position,
consistent with the licensees claims. The engineering firm calculated the valves
position using four different methods, five estimations in all. However, the inspector
identified several inappropriate assumptions and errors in the analysis. The following
table summarizes the vendors results as well as the inspector corrected values:
Enclosure 2
-11-
Calculation Method/
Referenced Position
Change in Disc
Position from
Referenced
Position
Inspector
Corrected
Values
HBC Stop Nut
2.915E
Not Credible,
Inconsistent
Data
Handwheel Closure (one
full handwheel turn)
2.870E
3.9E
Stroke Time Comparison
3/10/1999 Trace
(diagnostic system
traces)
3.363E
5.4E
Stroke Time Comparison
11/6/2003 Trace
(diagnostic system
traces)
3.549E
5.6E
Disc Measurement
3.186E
Inadequate
Re-creation
Average
3.177E
The inspector findings are discussed in detail below:
HBC Stop Nut Method: This method is based on gap measurements between one of
the HBC operator stop nuts and the adjacent enclosure wall. The stop nuts are used in
the HBC-2 operator to limit valve travel. While the licensee did not utilize the stop nuts
for this purpose, the gap measurements provided some information with respect to the
as-found valve position. Most importantly, the stop nut is on the same shaft as the
handwheel. Stop nut movement correlates directly with handwheel movement (when
the handwheel is engaged). Since the stop nuts had seven threads per inch, one
handwheel turn equates to 143 mils in stop nut travel.
The licensee had stated that when the valve was checked, after the operator had closed
it, the as-found stop nut gap measurement was 70 mils. After the valve was opened
and closed electrically (with the inappropriate limit switch setting) the gap measurement
was 150 mils. The licensee then adjusted the valve limit switch until the stop nut
measurement was 71 mils. The licensee provided this data to the engineering
contractor.
The contractor calculated that the operator had turned the valve handwheel 0.55 turns
when he found it. Considering stem deflection (based on the torque at the final valve
position being 965 foot-lbs) the contractors calculated as-found valve position was
Enclosure 2
-12-
2.915E open. The contractors report indicated that the 0.55 handwheel turns appeared
inconsistent with the operators statements (that he had closed the valve approximately
one full handwheel turn).
The inspector noted the following problems and inconsistencies with the data and the
contractors assessment.
As noted by the contractor, gap measurements did not correlate with operator
statements. The HBC stop nut movement should correlate exactly with
handwheel movement. The components are on the same shaft. But, the gap
measurements indicated that the operator had only turned the valve 0.55
handwheel turn while the operator had indicated that he had repositioned the
valve approximately 1 full handwheel turn.
The HBC gap measurement taken after the operator closed the valve was
70 mils. The gap measurement taken after the valve limit switch was adjusted
so that the stop nut gap approximated the same position was 71 mils. These
two gap measurements are almost exactly the same. Accordingly, the torque on
the valve stem that coincided with each measurement should have been about
the same. They were not. The torque value after the operator closed the valve
was 965 ft-lbs while the torque value measured after the limit switch was
adjusted was 454 ft-lbs.
The gap measurements were not performed in accordance with procedures and
the existing documentation was unclear with respect to what was measured and
when it was measured. The licensee had stated that they took gap
measurements after each of 15 limit switch adjustments (when they were
attempting to properly adjust the values limit switch on September 11, 2004).
However, no data was apparently recorded for 14 of the gap measurements.
When asked on more that one occasion for any and all documents associated
with these gap measurements, the licensee provided only two documents that
contained gap values. One document, Work Order 51581 stated, in part:
After adjustment 145 mils Desired HW set 70 mils using ETT as AS
switched to sts. gap = 71
The work order contained no steps to take these measurements and the
meaning of some of the terminology was not clear. For example, 145 mils was
obtained after adjustment. The document does not state what adjustment was
made. Additionally, there was no formally controlled record of the 150 mil value
which the contractor used in the calculations (the 145 mil value was not used in
the calculations). The 150 mil value was recorded in the computer system but
not in the hard copy of the work order.
The second document, a print of a computer screen (print date May 5, 2006)
stated, in part:
WO# 51581 150 mils Desired HQ set at 70 mils.
Enclosure 2
-13-
While this document provided some of the same measurement values utilized by
the contractor in their calculations, the 150 mil value was inconsistent with the
value actually documented in the work order (145 mils after adjustment). In
addition, this value was contained in an uncontrolled computer file and was not
subject to any quality controls such that it could have been changed in an
uncontrolled manner.
The results from the stop nut measurements were inconsistent with results that
the inspector obtained from other calculations, such as those based on
diagnostic system torque traces and Inservice Testing stroke times. The time
signature data in the diagnostic system torque traces was of a high quality and
was very accurate with respect to the identification of artifacts and the time they
occurred (provided later in this report).
A representative from Limitorque informed the inspector that the HBC stop nut
threads were 1-1/4 X 7 UNC - coarse. This means, in part, that the stop nut has
7 threads per inch and they are coarse, versus fine or medium grade. The
inspector also noted, while inspecting the threads on a much smaller HBC unit,
that the stop nuts could move slightly from side to side (without any stop nut
rotation). Limitorque had not designed the stop nuts to be used for the purpose
of taking precise measurements for the purpose of estimating valve position.
They were only provided as a means to stop valve movement. Making precise
measurements, to within a few mils, would be very difficult.
Based on the above, the inspector had a low level of confidence in the accuracy of the
HBC stop nut gap measurements and it was not clear that calculations based on these
values provided meaningful results. Compared to the quality of the other available data,
such as the valve torque traces, the HBC stop nut measurements were not credible.
Handwheel Turns: The contractor calculated the as-found valve position based on the
operators statement that he had repositioned the valve approximately one full
handwheel turn. The contractor based this calculation on 1.0 handwheel turn (exactly)
and then deducted the contribution from stem deflection. Stem deflection is the amount
of stem rotation observed without corresponding valve movement (the twisting of the
stem due to torque). This would occur when the operator continued to turn the valves
handwheel after the valve disc had contacted the hard-seat.
The inspector identified that the contractors calculation for stem deflection utilized an
inappropriate factor (torsional stiffness) instead of the standard classical equation that
is used for these purposes. This error affected the calculation sufficiently as to make
the final result (2.9E from the backseat) appear the same as the calculation based on
HBC stop nuts (the contractor had utilized the classical engineering equation in lieu of
the torsional stiffness factor in the HBC stop nut calculation). Getting almost exactly the
same value in the two calculations was unexpected because the stop nut calculation
was based on 0.55 handwheel turn worth of movement while the handwheel turn
calculation was based on 1.0 handwheel turn worth of movement. Since the other
factors should have been the same, the calculations should have produced different
results.
Enclosure 2
-14-
The contractor derived the torsional stiffness factor from a portion of the diagnostic
system torque trace between hard seat contact and motor-cuttoff. The contractor had
performed no validation testing of the torsional stiffness factor to verify that it properly
predicted system deflection. The stem deflection equation used by the contractor was:
Stem Deflection = Torque/Torsional Stiffness
The inspector noted that the torsional stiffness factor included deflection from all of the
actuator/HBC gear trains (including a sliding worm gear in the Limitorque actuator) when
only a much smaller portion of the gear train is in service when operating the valve with
the handwheel. The inspector observed that the use of the torsional stiffness factor, in
lieu of the classical equation, resulted in a higher calculated stem deflection value and a
smaller valve opening for the handwheel calculation.
Calculated as-found position = calculated position - stem deflection
Furthermore, the contractor acknowledged that the torsional stiffness factor was not
linear, as it appeared to change based on the amount of torque applied to the system.
However, the contractor calculated and utilized the value as if it were linear. The
contractor used the one calculated value for all circumstances.
The inspector also observed that the contractor had calculated the torsional stiffness for
three different closing strokes and had obtained three different results, as provided
below:
431 ft-lbs/degree
310 ft-lbs/degree
358 ft-lbs/degree
The relatively large degree of variability in this factor called into question its usefulness
in any of the stem deflection calculations. Any factor used to calculate stem deflection
should demonstrate good repeatability. The contractor chose to use the
310 ft-lbs/degree value, which also provided the most optimistic (lesser degree of valve
opening) results for the handwheel turn calculation. The contractor calculated the
stem deflection to be:
2.273E
The contractor then calculated the amount of valve opening based on this method as:
5.12E - 2.273 E = 2.9E
NOTE: The contractor also used the torsional stiffness term in their stroke time
calculations. The effect of using this term in these calculations makes the
calculated valve position more open, which is conservative. The magnitude of
the adjustment, however, was much smaller, as a much smaller torque
difference was applied. As noted later in this report, the contractor had used a
different inappropriate assumption in these calculations which made the
calculated valve position appear more closed.
Enclosure 2
-15-
Various text and reference books provide a classical equation for calculating the angle
of deflection of a round bar with a given torque (for example, Mechanical Engineering
Design, Fourth Edition, Shigley and Mitchell). Since the stem torque was known (from
a direct measurement on the stem) and the diameter, material and length of the stem
was also known, the contractor should have utilized the standard equation for this
purpose. Considering the configuration of the other components in the affected gear
train, deflection of the other components should be negligible. The equation, along with
applicable values, is provided below:
= Twist Angle in radians = (T*l)/(G*J)
T = Torque (use the torque difference in this case) = 705 ft-lbs
l = Length of Stem = 28 inches
G = Modulus of Rigidity = 11,500,000 psi
J = Polar Moment of Inertia = *d4/32 = 0.92
d = Diameter of Stem = 1.75 inches
The stem deflection based on the above is: 1.27E, compared to the 2.273E used by the
contractor. The difference is:
2.27E - 1.27E = 1.0E
Adjusting the contractors calculation to account for this difference, the valve position
should be:
2.9E + 1.0E = 3.9E position.
In addition to the above, converting this data to the same units as used in the
contractors torsional stiffness factor, the apparent torsional stiffness using the widely
accepted engineering equations would be:
555 ft-lbs/degree, which is substantially greater than the 310 ft-lbs/degree value
used by the contractor.
While the inspector agreed that this calculation provided the valves position based on
the operators recollection, the operator had only estimated the amount of handwheel
movement at approximately, one handwheel turn. The actual amount of travel could
have been a little more or a little less. The inspector considered other calculations,
based on diagnostic system torque traces, for example, to provide a much higher level
of accuracy and confidence.
Stroke Time Measurements: The contractor performed two calculations based on the
timing of artifacts in the diagnostic system torque traces. The contractor referred to
these as stroke time measurements. These were similar to a calculation performed by
the inspector in a later part of this report (Diagnostic System Test Data Method). They
should not be confused, however, with another calculation performed by the inspector
that was based on Inservice Testing stroke time measurements.
Enclosure 2
-16-
The theory behind the position estimation calculation is that by comparing the as-found
(partially open valve) torque trace with a torque trace of the same valve where it did fully
close (to the 0E position), the angle of the valve opening with respect to the 0E degree
position can be calculated. The inspector agreed that this method of analysis should
provide an accurate as-found valve position.
The inspector found that instead of comparing the as-found torque trace to traces where
the valve was at the fully closed position, indicated by the presence of hard seat contact
on the trace, the contractor had compared the as-found torque trace to other valve
traces where the valve did not reach the 0E position. This resulted in significantly under-
estimating the valves position. The contractor used the closing stroke dated March 10,
1999, and the closing stroke dated November 6, 2003, as reference traces.
For the 1999 torque trace, the valve stopped significantly before the 0E position. The
inspector calculated the distance that the 1999 valve stroke was from the hard seat by
utilizing a trace that was known to reach the 0E position, as evidence by a characteristic
shape when the valve reaches the hard seat. Based on this approach, the inspector
determined that the valve in the 1999 trace had stopped at the 1.9E position. The valve
was leaktight but was still not fully seated. The valve vendors drawing indicated that the
valve could be leak tight out to the 3.2E position. To find the actual as-found valve
angle, the inspector added this additional amount of travel to the contractors results.
3.36E + 1.9E = 5.4E
For the November 6, 2003, reference trace, the valve had traveled closer to the valve
seat than in the 1999 reference trace. However, the contractor chose a point
substantially before the valve had stopped moving as the reference point and treated
this point as if it were the 0E position. This reference point was 0.57 seconds short of
hard seat contact. That equates to 2.15E degrees of additional travel. Adding this
amount to the contractors calculation resulted in:
3.549E + 2.15E = 5.6E
NOTE: For the two calculations above, the inspector neglected any additional
adjustment for stem deflection, as the torque in these traces was substantially
smaller than in the handwheel case and any additional adjustment would be very
small. Additionally, the stem deflection would cause the valve to be slightly more
open (making the problem worse, not better).
The inspector determined that the contractor had utilized an inappropriate assumption
when performing these calculations. The contractor had assumed that the valve stop
was not in the correct position, or was absent altogether, and that the valve was over-
traveling past the 0E position. This would make all of the calculated valve opening
angles smaller by the amount of over-travel. The contractors report indicated that the
valve was at the 0E position when it was at the first large torque peak and had further
stated that this information came from the valve vendor. Some torque traces had two
torque peaks (one at the 3.6E position and one at the 2.2E position). The inspector
noted that the contractor had no objective evidence to support this claim. In addition,
the inspector disagreed with this contention for the following reasons:
Enclosure 2
-17-
The inspector called the valve vendor and the vendor did not agree that the 0E
position was at the first large torque peak. In addition, the vendor indicated that
for over-travel to occur, the valve stop set-screw, which is attached to a larger
hard stop, would have to be misadjusted or missing. The vendor stated that the
set-screw was either staked or welded into position at the factory.
The licensee had also informed the inspector that they had measured the gap
between the set-screw stop and the larger hard stop during the past outage and
had verified with the valve vendor that it was the proper size (0.25 inches). This
indicated that the valve stop set-screw was in the correct position.
The inspector reviewed a similar valve trace for the identical valve in Train A,
Valve SI-602A. The inspector noted that the valve displayed the same two
hump-like features as were evident in the Valve SI-602B traces. If
Valve SI-602B was over-traveling past the 0E position, as described by the
contractor, both valves were over-traveling. This was not likely, given the vendor
information regarding set-screw installation.
As a bounding exercise, if the set-screw was totally missing, the valve could only
travel an additional 0.25 inches at the outer edge. That equates to only an
additional 1.2 degrees of valve travel. The inspector calculated the angular
distance between the large hump and the hardseat (without correction for stem
deflection at 3.6E). In other words, the hump was too far from the hard stop for
this theory to be credible.
Independent NRC Calculations
The inspector used the licensees test data and two calculation methods to determine
the as-found position of Safety Injection Valve SI-602B. Based on the calculations, the
inspector determined that the valve was open slightly more than 5E, which was
significantly more than the 3.2E assumed in the licensees analysis. The following table
provides a summary of the results:
Method
Results
Relative Accuracy
Inservice Stroke Time Tests
5.9E
Reasonably Accurate
Diagnostic System Test Data
5.5E
Most Accurate
The calculations are provided below:
NRC Calculation 1: Based on Inservice Stroke Time Tests: Since the
inappropriate limit switch setting also affected the valves stroke time, the
inspector calculated the valve position based on the difference in the recorded
stroke times. The inspector compared the average of the stroke times when the
limit switch was set incorrectly to the average of the stroke times when the limit
switch was set properly.
Enclosure 2
-18-
Stroke Times (Close Direction), Limit Switch set Incorrectly:
11/7/2003
22.2 Seconds
1/6/2004
22.5
3/30/2004
22.5
6/25/2004
22.5
Average = 22.4 Seconds
Stroke Times (Close Direction), Limit Switch set Properly
9/11/2004
23.9
12/7/2004
23.7
3/1/2005
24
5/25/2005
24
6/16/2005
23.9
8/16/2005
23.9
8/17/2005
23.9
11/8/2005
23.8
1/31/2006
24.2
Average = 23.9 Seconds
Calculate Difference in Averages
= 23.9 - 22.4 = 1.5 seconds
Calculate Valve Speed in Degrees per Second (based on 1800 RPM motor
speed)
Given Information:
Limitorque actuator overall ratio (OAR) = 41.0
Limitorque HBC operator ratio = 70
Motor speed = 1800 rpm (based on motor speed curve)
Calculate the time for the valve to rotate 90E:
((41*70) motor rev. per valve rev.)(60 seconds per minute)(90E)
(1800 motor revolutions per min)(360E)
= 23.9 seconds
Determine the valve speed in degrees per second:
= (90E)/(23.9 seconds) = 3.77E/second
Enclosure 2
-19-
Calculate the Difference in Valve Travel (based on valve speed and difference in
= (1.5 seconds) * 3.77E/second = 5.66E open
Calculate Stem Deflection Adjustment (from stem torque traces)
T = Stem Torque Difference, Between As-Found Torque when Partially
Open (285 foot-lbs) and the Torque when Valve Disc Starts to
Move (150 foot-lbs)
= 265 - 150 = 115 foot lbs
l, d, G and J are the same as used in an earlier calculation.
Based on the above,
= (115 foot-lbs * 28 inches * 12 inches/foot)/(11,500,000 psi*.92)
= 0.00365 radians * (180E/ radians) = 0.21E
Calculate Valve Opening Based on the Difference in Inservice Stroke Times
Since stem deflection causes the valve disc to lag slightly, stem deflection affect
causes the valve to be slightly more open.
= 5.66E + 0.21E = 5.87E . 5.9E
The accuracy of this calculation is affected by the method used for measuring
the individual stroke times. When testing the valve, operators used a stop
watch. There is some variability in operator response times when stopping the
watch. This uncertainty is limited to some degree because the calculation uses
the difference in the average stroke times, versus comparing any two points
directly. Considering that the data scatter was very limited, the response times
for the opening and closing tests should approximately cancel each other in the
calculation. Therefore, this calculation should provide a reasonable estimation of
valve position.
Calculation 2: Based on VOTES Torque Traces: This method of
approximation utilizes data taken directly from diagnostic system torque traces.
Diagnostic system torque traces are very accurate when identifying the location
of artifacts in the traces with respect to time. Artifacts such as the start of valve
movement and the point where the valve disc hits the hard seat are easily
identified by commonly known characteristic shapes on the traces. Accordingly,
the timing between artifacts, which is performed in this calculation, is easily
determined and the results are very accurate. When combined with relatively
minor adjustments to account for stem deflection and valve coastdown (the
amount of valve travel after the motor is de-energized), the final calculated valve
position is very accurate when compared to other estimation methods.
Enclosure 2
-20-
The inspector considered this method the most accurate of all of the
approximation methods used in this report.
Given Information:
Limitorque actuator overall ratio (OAR) = 41.0
Limitorque HBC operator ratio = 70
Motor speed = 1800 rpm
Valve Speed = 3.77 degrees/second (calculated earlier)
NOTES:
1.
The calculation assumes that the 1800 rpm motor experiences no
slippage. This is generally a safe assumption considering the applicable
part of the motor curve (torque = less than 1 foot pound). As part of a
sensitivity analysis, however, the inspector also performed a calculation
assuming worst case slippage (the motor rotates at 1775 rpm). This is
considered more than bounding for this problem.
2.
The inspector used data from two motor-operated valve torque traces. In
one trace (2005), the closing limit switch was set properly while in the
other (2003) the limit switch was set short of the target (and is the
genesis of the discrepant PI inspection).
Part A: Determine the size of the valve opening (in degrees) in 2003 when the
limit switch was set incorrectly (based on 1800 revolutions per minute motor
speed).
1.
Determine the valve travel time when the limit switch was set correctly
(information from 2005 MOV torque trace):
Time valve starts moving (from MOV trace) = 1.36 seconds
Time close limit switch opens = 23.55 seconds
Travel time = 23.55 - 1.36 = 22.19 seconds
2.
Calculate the distance traveled (in degrees) when limit switch was set
correctly:
(22.19 sec)(3.77E/second) = 83.7E
Therefore, when the valve was full open, it was 83.7E away from hard
seat contact.
Enclosure 2
-21-
3.
Determine the valve travel time when the limit switches were set
incorrectly (information from 2003 MOV torque trace):
Time valve starts moving (from MOV trace) = 1.34 seconds
Time close limit switch opens = 22.02 seconds
Travel time = 22.02 - 1.34 = 20.7 seconds
4.
Calculate the distance traveled (in degrees) when the limit switch was set
incorrectly:
(20.7 sec)(3.77E/second) = 78.0E
5.
Calculate the valves open angle (in degrees) from the seat when the
closing limit switch opened in 2003:
= total distance traveled in 2005 (from full open to seat) - total distance
traveled in 2003
= 83.7E - 78.0E = 5.7E
6.
Determine the time that the valve continued to move after the closing limit
switch contact opened (2003 trace):
Limit switch opened at 22.02 seconds
Valve stopped moving at 22.22 seconds
Time of additional travel = 22.22-22.02 = 0.2 seconds
The most that the valve could have continued to travel was:
(0.2 seconds)(3.77E) = .75E
Since the valve was not traveling at full speed for the entire time, but was,
instead, slowing to a stop, use 1/2 of the above.
1/2 * .75E = .38E
7.
Determine the 2003 distance from the seat considering additional valve
coasting after the limit switch contact opened:
= 5.7E - .38E = 5.3E
8.
Adjust for Stem Deflection (use same value as in NRC Calculation 1)
5.3E + .21E = 5.5E
Enclosure 2
-22-
Part B (sensitivity case): Determine the size of the valve opening in 2003 when
the valve closing limit switch was set incorrectly (assuming 1775 revolutions per
minute motor speed, maximum slippage).
Part B was completed in exactly the same manner as Part A above, with the
exception that the motor speed was changed from 1800 revolutions per minute
to 1775 revolutions per minute. The resultant valve angle was:
5.3E
The inspector asked the plants engineers if they had performed other calculations
similar to those performed in this report (by the inspector) to determine valve position.
The engineers stated that they had performed similar calculations and that they had
obtained similar results (the valve was approximately 5E open). However, the engineers
did not formalize these calculations or formally address the inconsistencies between
their field data, the diagnostic system data and the calculations.
Performance Indicator Conclusions
During the first 2 years of Reactor Oversight Process implementation, NRC staff and
industry identified problems with the safety system unavailability performance indicators
and worked to implement incremental changes to the indicators. Over the next 4 years,
a working group developed a performance indicator that addressed the identified
problems. This indicator, the Mitigating System Performance Index, was implemented
April 1, 2006, and is addressed in NRC Regulatory Issue Summary 2006-07, Changes
to the Safety System Unavailability Performance Indicators.
Based on a valve opening of approximately 5E, which is a close approxiation of the
degree of valve opening as determined by the NRC, the Train B high pressure safety
injection and both Train B containment spray pumps were unavailable between
November 11, 2003, and September 9, 2004, for a range of medium and large break
loss of coolant accidents. The licensee calculated the maximum tolerable valve opening
area at 0.41 square inches. According to the valve vendor, a valve opening of 5E
corresponded to an opening size of 3.16 square inches, over 7 times the acceptable
opening.
The inspector determined that the High Pressure Injection and Residual Heat Removal
Performance Indicator information provided to the NRC was not accurate. Based on
revised data, the High Pressure Injection Performance Indicator should have been Red
while the Residual Heat Removal Performance Indicator should have been Yellow up
until the point that the safety system unavailability performance indicators were replaced
by MSPI on April 1, 2006. Specifically, revising the reported performance indicator data
to reflect the appropriate system unavailability would have caused the High Pressure
Injection Unavailability Performance Indicator to turn White in the fourth quarter of 2003
with a value of 2.5%, Yellow in the first quarter of 2004 with a value of 6.9%, and Red in
the second quarter of 2004 with a value of 11.2%. The indicator would have remained
Red until the changeover to MSPI on April 1, 2006. The Residual Heat Removal
System Unavailability Performance Indicator, which includes Containment Spray, would
Enclosure 2
-23-
have turned White in the first quarter of 2004 with a value of 3.6%, and Yellow in the
second quarter of 2004 with a value of 5.8%. The Indicator would have remained
Yellow until the changeover to MSPI on April 1, 2006.
Analysis. The failure to provide accurate information to the NRC in accordance with
10 CFR 50.9 requirements was a performance deficiency. The issue had more than
minor significance because, had the information been accurate, two performance
indicators would have changed color. Per the NRC Enforcement Policy,Section IV.A.3,
these issues are not subject to the Significance Determination Process. In determining
the violations severity level, the NRC considered a recent revision to the Mitigating
Systems Performance Indicators. Specifically, under the revised process fault exposure
hours would not be counted and the affected performance indicators would return to the
Green performance level. Additionally, the initial performance deficiency, Valve SI-602B
being left slightly open, had been evaluated under the Significance Determination
Process and found to be of very low safety significance (Green). Following identification
of the mis-positioned valve, the licensee promptly placed the valve in the correct position
which reestablished the functionality of the affected systems. The licensee conducted a
root cause evaluation of the underlying performance deficiency, and took actions to
ensure that the condition was not present on similarly operated valves. Field
verifications were conducted to ensure that similar valves were in fact, fully closed.
Accordingly, the NRC concluded that the concerns are more consistent with a Severity
Level IV violation in lieu of the Severity Level III recommendation made in the
Enforcement Policy (Supplement VII). This finding had problem identification and
resolution crosscutting aspects in that the licensees Corrective Action Program did not
thoroughly evaluate the identified condition such that information reported to NRC was
verified to be complete and accurate.
Enforcement. 10 CFR 50.9 requires, in part, that Information provided to the
Commission... by a licensee... shall be complete and accurate in all material respects.
Contrary to the above, from approximately November 1, 2004 (when the licensee initially
submitted the information) to May 11, 2006, information provided to the Commission in
the form of unavailability statistics, for the Train B high pressure safety injection and
Train B containment spray systems, was not complete and accurate in all material
respects. The licensee significantly under-reported the unavailability hours for each
train. This violation did not qualify for consideration as a noncited violation because the
violation did not meet the Enforcement Policy,Section VI.A.1.a criterion in that the
noncompliance was not corrected within a reasonable time following the identification of
the violation. For the purposes of this criterion, the violation was identified on the
inspection exit debrief date of May 11, 2006. As of the date of this inspection report
issuance, the licensee had not corrected the inaccurate information
Enclosure 2
-24-
4OA6 Meetings, Including Exit
Exit Meeting Summary
On May 11, 2006, the senior reactor inspector presented the inspection results to
Mr. Kevin Walsh, General Manager, Plant Operations and other members of the
licensees staff, who acknowledged the findings. The inspector updated the licensee by
telephone on June 23, 2006, with respect to proposed enforcement conclusions. A final
telephonic exit meeting was conducted on August 9, 2006, with respect to a subsequent
review of additional information provided by the licensee. The conclusions remained the
same. Some proprietary information was reviewed during the inspection but none of the
information was documented in this report.
ATTACHMENT: SUPPLEMENTAL INFORMATION
Attachment
A-1
SUPPLEMENTAL INFORMATION
KEY POINTS OF CONTACT
Licensee Personnel
J. Venable, Vice President, Operations
T. Gaudet, Manager, Quality Assurance
A. Harris, Acting Director, Nuclear Safety Assurance
J. Holman, Manager, Nuclear Engineering
B. Lanka, Supervisor, Engineering Design
T. Mitchell, General Manager Plant Operations, Arkansas Nuclear One
R. Murillo, Manager, Licensing
R. Osborn, Manager, Engineering Programs and Components
K. Peter, Manager, Design Engineering
P. Stanton, Supervisor, Engineering Programs and Components
T. Tankersley, Director, Safety Assurance
K. Walsh, General Manager, Plant Operations
B. Williams, Director, Engineering
ITEMS OPENED, CLOSED, AND DISCUSSED
Opened
Inaccurate Performance Indicator Information
LIST OF DOCUMENTS REVIEWED
Condition Reports
CR-WF3-2004-02847
Drawings
52B8124, 24 body, SMB-00-HBC-1 Actuator Limitorque - 9200 Electric Actuated Control
Valve, Revision B
Various piping and instrumentation diagrams for the safety injection and containment spray
systems
K11131, Cross-Section Adjustable Elastomer Tee Ring in Disc Edge, dated February, 1972
Butterfly Valve Information Sheet, Sheet B-3, dated October 10, 1995
Vendor supplied drawing of valve configuration, no date, title or revision number
Attachment
A-2
Work Orders
51581
55621
66541
50686649
Miscellaneous
MPR draft letter report titled Waterford Unit 3 Safety Injection and Containment Spray
System Air Entrainment Reanalysis for Large and Medium Break LOCA, dated
February 21, 2006.
Licensee document No. 2493C, Rev. 1, Appendix D: Response to NRC Comments of
May 11, 2006
MPR-2758, Waterford 3 Safety Injection and Containment Spray Systems Past
Availability Evaluation, Revision 0
Calculation Number ECM05-007, Waterford 3 Safety Injection and Containment Spray
Systems Past Availability Evaluation for Medium Break LOCA, Revision 0
Calculation Number ECM05-006, Waterford 3 Safety Injection and Containment Spray
Systems Past Availability Evaluation, Revision 0
Root Cause Analysis Report, SI-602 B Not Fully Seated, CR-WF3-2004-2847, Dated
September 9, 2004, Report Date: November 10, 2004.
MPR-2469, Appendix J, Verification of Hydraulic Analysis Program, Revision 0
Various safety injection Valve SI-602A and SI-602B motor-operated valve VOTES
traces, dated November 6, 2003; September 11, 2004; May 5, 2005; May 7, 2005; and
May 12, 2005
White Paper, Standard of Proof for Assessing Past Operability, no date
Limitorque AC Motor Curve, 10 Ft-Pound motor
STI-W3-2005-0004-00. Special Test Instructions (STI): Leak Rate Test of SI-602B,
performed on May 25, 2005
Informal calculation to determine as-found backpressure, assuming 0.25 square inch
opening, no date
Table of trended Inservice Test data for Valve SI-602B, no revision or date
Estimated valve opening areas for 4E and 5E open positions, dated April 4, 2006
Independent Assessment of Disc Position of SI 602B between November 3, 2003, and
September 11, 2004, dated May 8, 2006, Kalsi Engineering