ML100630900
| ML100630900 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 03/04/2010 |
| From: | Chamberlain D NRC/RGN-IV/DRP |
| To: | Matthew Sunseri Wolf Creek |
| References | |
| EA-09-326, IR-09-004 | |
| Download: ML100630900 (9) | |
See also: IR 05000482/2009004
Text
UNITED STATES
NUC LE AR RE G UL AT O RY C O M M I S S I O N
R E GI ON I V
612 EAST LAMAR BLVD , SU I TE 400
AR LI N GTON , TEXAS 76011-4125
March 4, 2010
Matthew W. Sunseri, President and
Chief Executive Officer
Wolf Creek Nuclear Operating Corporation
P.O. Box 411
Burlington, KS 66839
SUBJECT: RESPONSE TO DISPUTED NON-CITED VIOLATIONS IN NRC INSPECTION
REPORT 05000482/2009004 AND WITHDRAWAL OF NONCITED VIOLATION
Dear Mr. Sunseri:
Thank you for your December 9, 2009 letter of reply (WM 09-0065) to our November 10,
2009 inspection report (ML 093140803). Attachments I and II of your reply contained a
request for withdrawal of noncited violations NCV 05000482/2009004-03, Inadequate
Evaluation of Emergency Diesel Generator for Common Cause Failure in the Supporting
Essential Service Water System, and NCV 05000482/2009004-06, Performing Prohibited
Elective Maintenance on Safety Bus NB02 Channel 4 during Emergency Diesel Generator
Maintenance, respectively. Attachment III of your reply contained a request for withdrawal
of two of the three examples of NCV 05000482/2009004-07, Failure to Report Conditions
that Could Have Prevented Fulfillment of a Safety Function.
We have reviewed the denial of the two noncited violations and the two examples from the
third noncited violation. Our comments and conclusions are addressed below as discussed
on March 4, 2010, with Mr. S. Hedges, Site Vice President, and other members of your staff.
NCV 05000482/2009004-03, Inadequate Evaluation of Emergency Diesel Generator for
Common Cause Failure in the Supporting Essential Service Water System:
The referenced report stated, in part:
Technical Specification 3.8.1 Required Actions B.3.1 and B.3.2 require, with one diesel
generator inoperable, to determine that the operable diesel generator is not inoperable due to
common cause failure or else perform SR 3.8.1.2 [run the diesel generator]. Contrary to this
requirement, on June 30, 2009, the licensee failed to demonstrate that Emergency Diesel
Generator A was operable by evaluation of common cause failure or by performing SR 3.8.1.2
while emergency diesel generator B was inoperable due to essential service water piping
corrosion. Specifically, the control room logs exited Required Action B.3.1 stating that EDG B
inoperable due to ESW being inoperable not a common cause failure. No further evaluation
was provided.
Wolf Creek Nuclear Operating Corporation - 2 -
In Attachment I of your reply, you stated that you did not believe a violation of Technical Specification 3.8.1 existed. The reasons that you requested withdrawal of the above noncited
violation were:
- Emergency Diesel Generator B was declared operable prior to the expiration of the
24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Completion Time; and
- A common cause determination was performed, although not required per Generic
Letter 93-05.
The regional staff, in consultation with NRCs Office of Nuclear Reactor Regulation and Office of
Enforcement, has reviewed these reasons and the supporting information. We have concluded
that the original noncited violation is still applicable as described below.
Technical Specification 3.8.1 Required Actions B.3.1 and B.3.2 require, with one diesel
generator inoperable, to determine that the operable diesel generator is not inoperable due to
common cause failure. On June 30, 2009, the Train B emergency diesel generator was
declared inoperable due to a leak in the essential service water system caused by through-wall
corrosion. As stated in your response, the common cause was ruled out on the basis that a
common cause failure did not exist since the inoperability was due to a support system. Your
response further stated that any leaks would have been identified by operators during their
rounds. The staff concluded the lack of reported leakage was not a valid basis to conclude
similar corrosion did not exist in Train A. Consequently, the staff concluded the operators
inappropriately exited Required Action B.3.1 without a valid determination that the operable
diesel generator was not affected by a common cause failure mechanism. As a result, when the
Train B emergency diesel generator was restored to service, operators did not initiate an action
in the plant corrective action program to evaluate the common cause potential as stated in the
Technical Specification Bases for Required Action B.3.1.
The staff recognizes that Technical Specifications have changed over time, particularly with
regard to emergency diesel generator surveillance testing and required actions. While previous
guidance has either included or excluded diesel generator inoperability caused by support
systems, the NRC expects licensees to comply with their stations current Technical
Specifications. As a result, the NRC has concluded the original noncited violation is still
applicable.
NCV 05000482/2009004-06, Performing Prohibited Elective Maintenance on Safety Bus NB02
Channel 4 during Emergency Diesel Generator Maintenance:
The referenced report stated, in part:
Procedure AP 22C-003, Operational Risk Assessment Program, Revision 13, prohibits
elective maintenance within the switchyard that would challenge offsite power during Technical Specification 3.8.1.B.4.2.2. Normally the safety bus NB02 cabinets are protected equipment (no
work allowed) but because this work was planned in advance for the diesel outage, the work
was permitted. In consultation with the Office of Nuclear Reactor Regulation, the inspectors
concluded that Procedure STS IC-208B and power supply replacement was inappropriate
during the 7-day diesel outages because it increased the probability of the loss of offsite power
Wolf Creek Nuclear Operating Corporation - 3 -
to safety equipment that could not be powered by the diesel. Wolf Creek appropriately
restricted access to the portion of the switchyard outside the protected area but did not
appropriately restrict work for offsite power inside the protected area. The inspectors
determined that challenges to offsite power can originate with elective maintenance inside the
protected area. The inspectors found that Wolf Creek assessed risk under 10 CFR 50.65 a(4)
for this evolution, resulting in elevated risk within the Green band during the 7-day diesel
outage. The inspectors also found that Wolf Creek appropriately protected component cooling
water, emergency service water, instrument busses, dc busses, emergency core cooling, the
Train A diesel, and control room ventilation.
Technical Specification 3.8.1, Required Action B.4.2.2, permits one diesel generator to be
inoperable for 7 days provided the limitations articulated in the NRC SER for License
Amendment 163 are met. The NRC SER for License Amendment 163 requires that the offsite
power supply and switchyard conditions be conducive to an extended diesel generator
completion time, which includes ensuring that switchyard access is restricted and no elective
maintenance within the switchyard is performed that would challenge the offsite power
availability. Contrary to the above, on March 24, 2009, Wolf Creek performed elective
maintenance which challenged offsite power availability while emergency diesel generator B
was in the 7-day extended completion time. Specifically the licensee performed maintenance
on the safety bus NB02 degraded and undervoltage voltage relay Channel 4 power supply while
the emergency diesel generator Train B was in an extended outage.
In Attachment II of your reply, you stated you did not believe a violation of Technical Specification 3.8.1, Required Action B.4.2.2 existed because:
- Emergency Diesel Generator B was restored within the 7 day Completion Time of
Required Action B.4.2.2;
- The Safety Evaluation for Amendment 163 prohibits elective testing and maintenance in
the switchyard and the power supply replaced and testing performed were not in the
switchyard; and
- The Work Order and post maintenance test were evaluated as part of a risk assessment
and determined not to yield unacceptable results.
The regional staff, in consultation with NRCs Office of Nuclear Reactor Regulation and Office of
Enforcement, has reviewed these reasons and the supporting information. We have concluded
that the performance deficiency associated with the original noncited violation is more
appropriately characterized as a noncited violation of 10 CFR 50.65(a)(4) involving the failure to
adequately assess and manage the risk associated with maintenance activities. The basis for
this determination is described below.
The staff determined Attachment II of your reply was correct in that the Technical Specification
Required Action statement does not require that the limitations articulated in the NRC Safety
Evaluation for License Amendment No. 163 are met. However, the staff concluded the station
did not comply with the administrative controls specified in the Technical Specification Bases.
As stated in the Technical Specification Bases, the 7-day Completion Time of Required Action
B.4.2.2 is a risk-informed allowed outage time based on a plant-specific risk analysis. The
Wolf Creek Nuclear Operating Corporation - 4 -
reliability of offsite power is an important contributor to the risk analysis for an emergency diesel
generator outage. This importance is reflected in the administrative controls stated in the
Technical Specification Bases during implementation of the 7-day Completion Time, which
include: The offsite power supply and switchyard condition are conducive to an extended DG
Completion Time, which includes ensuring that switchyard access is restricted and no elective
maintenance within the switchyard is performed that would challenge offsite power availability.
Consistent with the Tier 2 controls described in Regulatory Guide 1.177, An Approach for
Plant-Specific Risk-Informed Decisionmaking, this administrative control provides reasonable
assurance that risk significant equipment outage configurations will not occur during the
extended allowed outage time. Section 2.3 of Regulatory Guide 1.177 discusses the need for
maintenance risk assessments during extended allowed outage times, stating The need for
[operational risk assessment] stems from the difficulty of identifying all possible risk-significant
configurations under Tier 2 that will ever be encountered over extended periods of plant
operation.
As stated in your reply, the Probabilistic Safety Assessment group reviewed the power supply
replacement as part of an operational risk assessment which determined the activity would not
render the load shedder and emergency load sequencer unavailable. The staff noted this
evaluation did not address the reduction in reliability of offsite power or the potential for
consequential equipment failures or human error. Specifically, the change in coincidence logic
from 2 out of 4 to 1 out of 3 reduced the reliability of offsite power, in that a single spurious
signal could result in actuation of the trip circuitry. The performance of maintenance activities
inside the cabinets containing the protective circuitry for load shedder and emergency load
sequencer also increased the likelihood of a spurious trip signal, similar to the way that
equipment operation inside the switchyard would increase in the likelihood of spurious trip of
offsite power. Consequently, the risk analysis performed by the station was inadequate in that it
failed to consider that the maintenance activity impacted the reliability of offsite power upon
which the risk analysis to support the extended completion time of Required Action B.4.2.2 was
based, and the activity should have therefore been prohibited while the diesel generator was out
of service.
The staff determined the performance of maintenance activities that reduced the reliability of
offsite power during the extended allowed outage time for the Train B emergency diesel
generator was a performance deficiency. Per NRC management review using Appendix M of
Manual Chapter 0609, Significance Determination Process, the staff determined the finding
was of very low safety significance (Green) since it did not affect both qualified sources of offsite
power and sufficient defense in depth remained.
Title 10 CFR 50.65(a)(4) requires, in part, that licensees shall assess and manage the increase
in risk that may result from proposed maintenance activities. Contrary to the above, on March
24, 2009, the licensee failed to adequately assess and manage the increase in risk from
maintenance activities. Specifically, the licensee failed to ensure the offsite power supply
remained conducive to an extended emergency diesel generator allowed outage time by
performing elective maintenance which challenged the reliability of offsite power while the Train
B emergency diesel generator was out of service for the extended allowed outage time. NRC
Inspection Report 05000482/2009004 will be amended to reflect the conversion of NCV 05000482/2009004-06, Performing Prohibited Elective Maintenance on Safety Bus NB02
Channel 4 during Emergency Diesel Generator Maintenance, to a noncited violation of 10 CFR
Wolf Creek Nuclear Operating Corporation - 5 -
50.65(a)(4).
NCV 05000482/2009004-07, Failure to Report Conditions that Could Have Prevented
Fulfillment of a Safety Function:
The referenced report stated, in part:
The inspectors identified a Severity Level IV noncited violation of 10 CFR 50.73, with three
examples in which the licensee failed to submit licensee event reports within 60 days following
discovery of events or conditions meeting the reportability criteria.
First, on April 10, 2008, the licensee submitted LER 2008-002 under 10 CFR 50.73(a)(2)(i)(B)
which is operation prohibited by technical specifications. For 11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> from February 13-14,
2008, Wolf Creek did not have an operable emergency core cooling system because no high
head charging pumps were operable. Wolf Creek was in Technical Specification 3.0.3 during
this time. Wolf Creek received enforcement discretion to remain at power. Charging Pump B
was required to be declared inoperable because emergency diesel generator B was inoperable,
and charging Pump A was inoperable because it did not have an operable room cooler. On
June 25, 2009, the inspectors identified that Wolf Creek failed to report this event as a safety
system functional failure under 10 CFR 50.73(a)(2)(v) for the emergency core cooling system
being inoperable. The inspectors discussed this with Wolf Creek and Condition
Report 00018156 was initiated. On July 30, 2009, the licensee completed the evaluation of this
condition report and concluded that the loss of high head charging was not reportable, however
no evaluation demonstrated operability of the charging pumps.
Third, on April 10, 2008, Wolf Creek filed Event Notification Report 44131 per 10 CFR 50.72(b)(3)(ii)(B) based on a possible trip of all four containment coolers. The containment
coolers have thermal overload protection such that if a cooler trips in fast speed during normal
power operation, that cooler will not restart in slow speed for an accident. Wolf Creek evaluated
this concern and issued Event Notification 44131. Wolf Creek later retracted the Event
Notification stating: "Further analysis of the main steam line break, if this concern had existed,
showed that the calculated post-accident pressure and temperature peak values would not
exceed the peak accident values in the USAR. Therefore, an unanalyzed condition did not exist
and Wolf Creek is retracting the 50.72(b)(3)(ii)(B) notification."
The inspectors found that Wolf Creek did not analyze the current draw for the motors prior to
receipt of a safety injection signal. Wolf Creek assumed that the coolers would not restart and
relied on containment, but this is still the loss of a safety function to remove heat from
containment. Wolf Creek found that without the coolers, containment pressure exceeds the
Analysis of Record but not the design pressure in the USAR. Inspectors found that this was not
an appropriate method to consider the coolers heat removal safety function met. At the end of
the report period, Wolf Creek did not have an analysis for the containment cooler motors to
determine if they would have tripped prior to receiving an accident signal. Wolf Creeks
condition report and reportability evaluation has been open since April 11, 2008. No licensee
event report has been submitted. The inspectors found insufficient evidence to show that the
containment coolers could accomplish their safety function and that this should have been
reported under 10 CFR 50.73(a)(2)(v).
In Attachment III of your reply, you stated that two examples of this violation did not prevent the
Wolf Creek Nuclear Operating Corporation - 6 -
fulfillment of the safety function of the structure, system or component and therefore were not
reportable in accordance with 10 CFR 50.73(a)(2)(v). Specifically, you stated the first and third
examples were not violations since:
- In the first example, if the leaking centrifugal charging pump A room cooler end plug
failed catastrophically, the resulting leak rate would not have threatened the capability of
either the ultimate heat sink or essential service water A to perform its safety function;
- Also in the first example, centrifugal charging pump A remained functional with its
respective room cooler out of service; and
- In the third example, you performed a calculation that demonstrated that the
containment fan coolers would have operated in fast speed under worst case
environmental conditions, and that the fans would start in slow speed on a safety
injection signal as required by the analysis of record.
The regional staff, in consultation with NRCs Office of Nuclear Reactor Regulation and Office of
Enforcement, has reviewed your request and the supporting information. We have concluded
that the first and third examples of the original noncited violation are both still applicable;
however, we have concluded the third example is more appropriately characterized as a minor
violation.
The staff reviewed the information provided in your response for the first example of the
noncited violation. The staff noted the calculations provided for the room cooler leak did not
address the mechanical stresses generated in the room cooler and potential consequential
failures following catastrophic failure of the end plug. The staff also noted that the calculations
for centrifugal charging pump A utilized the conditions that existed at the time instead of design
conditions. The staff concluded the computations provided in your response did not provide a
reasonable basis to demonstrate the operability of the structures, systems and components
described in the first example. Therefore, NRC staff determined that this example was
applicable.
For the third example of the original noncited violation, the staff reviewed calculation WCN003-
PR-01, Worst Case Brake Horsepower Requirements on Containment Air Cooler (CAC) Fan
Motors, Revision 0. The staff concluded the calculation provided a reasonable basis for
determination that the containment air coolers would not trip if a design basis accident were to
occur while the coolers were operating in fast speed. However, the staff determined that a
violation still occurred since the original event notification occurred on April 10, 2008, and the
station therefore did not file a licensee event report within 60 days following discovery of an
event meeting the reportability criteria as required by 10 CFR 50.73. Licensee event reports
can be revised or retracted after submittal based on new information or conclusions resulting
from the licensees review. In this case, since the new information provided by calculation
WCN003-PR-01 would have resulted in retraction of the licensee event report, this violation was
reviewed by NRC management and determined to be of minor significance. The inspection
report will be amended to remove the third example of NCV 05000482/2009004-07.
In Attachment III of your reply, you also identified a potential discrepancy in the information
documented on page 35 of the subject inspection report related to the initiation of Condition
Wolf Creek Nuclear Operating Corporation - 7 -
Report 00018156. Specifically, you stated that WCNOC believed the initiation of this condition
report was not based on issues raised by the resident inspection staff. Based on the
information you provided, Inspection Report 05000482/2009004 will be amended to reflect that
Condition Report 00018156 was initiated in response to concerns raised by the NRC at the
June Reactor Oversight Process meeting.
Based on our reviews, as described above, NRC Inspection Report 05000482/2009004 will be
amended to reflect the conversion of noncited violation NCV 05000482/2009004-06,
Performing Prohibited Elective Maintenance on Safety Bus NB02 Channel 4 during Emergency
Diesel Generator Maintenance, to a noncited violation of 10 CFR 50.65(a)(4), and
the third example of noncited violation NCV 05000482/2009004-07, Failure to Report
Conditions that Could Have Prevented Fulfillment of a Safety Function, to a minor violation.
The NRC concluded the remaining original noncited violations are still applicable.
In accordance with 10 CFR 2.390 of the NRCs Rules of Practice, a copy of this letter will be
made available electronically for public inspection in the NRC Public Document Room or from
the Publicly Available Records (PARS) component of NRCs document system (ADAMS),
accessible from the NRC website at http://www.nrc.gov/reading-rm/adams.html (the Public
Electronic Reading Room).
Sincerely,
/RA for AVegel/
Dwight D. Chamberlain, Director
Division of Reactor Projects
Docket: 50-482
License: NPF-42
cc:
Vice President Operations/Plant Manager
Wolf Creek Nuclear Operating Corporation
P.O. Box 411
Burlington, KS 66839
Jay Silberg, Esq.
Pillsbury Winthrop Shaw Pittman LLP
2300 N Street, NW
Washington, DC 20037
Supervisor Licensing
Wolf Creek Nuclear Operating Corporation
P.O. Box 411
Burlington, KS 66839
Wolf Creek Nuclear Operating Corporation - 8 -
Chief Engineer
Utilities Division
Kansas Corporation Commission
1500 SW Arrowhead Road
Topeka, KS 66604-4027
Office of the Governor
State of Kansas
Topeka, KS 66612-1590
Attorney General
120 S.W. 10th Avenue, 2nd Floor
Topeka, KS 66612-1597
County Clerk
Coffey County Courthouse
110 South 6th Street
Burlington, KS 66839
Chief, Radiation and Asbestos
Control Section
Bureau of Air and Radiation
Kansas Department of Health and
Environment
1000 SW Jackson, Suite 310
Topeka, KS 66612-1366
Chief, Technological Hazards
Branch
FEMA, Region VII
9221 Ward Parkway
Suite 300
Kansas City, MO 64114-3372
Wolf Creek Nuclear Operating Corporation - 9 -
Electronic distribution by RIV:
Regional Administrator (Elmo.Collins@nrc.gov)
Deputy Regional Administrator (Chuck.Casto@nrc.gov)
DRP Director (Dwight.Chamberlain@nrc.gov)
DRP Deputy Director (Anton.Vegel@nrc.gov)
DRS Director (Roy.Caniano@nrc.gov)
DRS Deputy Director (Troy.Pruett@nrc.gov)
Senior Resident Inspector (Chris.Long@nrc.gov)
Resident Inspector (Charles.Peabody@nrc.gov)
WC Administrative Assistant (Shirley.Allen@nrc.gov)
Branch Chief, DRP/B (Geoffrey.Miller@nrc.gov)
Senior Project Engineer, DRP/B (Rick.Deese@nrc.gov)
Public Affairs Officer (Victor.Dricks@nrc.gov)
Branch Chief, DRS/TSB (Michael.Hay@nrc.gov)
RITS Coordinator (Marisa.Herrera@nrc.gov)
Regional Counsel (Karla.Fuller@nrc.gov)
RIV Senior Enforcement Specialist (Ray.Kellar@nrc.gov)
Senior Enforcement Specialist (Gregory.Bowman@nrc.gov)
Congressional Affairs Officer (Jenny.Weil@nrc.gov)
OEMail Resource
Only inspection reports to the following:
OEDO RIV Coordinator (Leigh.Trocine@nrc.gov)
.
R:\_REACTORS\WC\Denial Reply.doc ML 100630900
ADAMS: No : Yes : SUNSI Review Complete Reviewer Initials: GM
- Publicly Available : Non-Sensitive GM
Non-publicly Available Sensitive
C: DRP/B DD:DRP ACES/OE D:DRP
GBMiller AVegel RKellar DDChamberlain
/RA/ /RA/ /RA/ /RA for AVegel/
3/3/10 3/4/10 3/4/10 3/4/10
OFFICIAL RECORD COPY T=Telephone E=E-mail F=Fax