ML18068A147
| ML18068A147 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  (DPR-029, DPR-030) |
| Issue date: | 03/09/2018 |
| From: | Karla Stoedter Division Reactor Projects III |
| To: | Lochbaum D Union of Concerned Scientists |
| References | |
| LER-2017-001-00 | |
| Download: ML18068A147 (4) | |
See also: IR 05000265/2017001
Text
UNITED STATES
NUCLEAR REGULATORY COMMISSION
REGION III
2443 WARRENVILLE RD. SUITE 210
LISLE, ILLINOIS 60532-4352
March 9, 2018
David A. Lochbaum
Director, Nuclear Safety Project
PO Box 15316
Chattanooga, TN 37415
SUBJECT: NRC RESPONSE TO UNION OF CONCERNED SCIENTISTS COMMENTS
REGARDING QUAD CITIES NUCLEAR POWER STATION, UNIT 2, HIGH
PRESSURE COOLANT INEJCTION LICENSEE EVENT REPORT
05000265/2017-001-00
Dear Mr. Lochbaum:
On July 26, 2017, the Region III office received a letter from you (ML17321A947) providing
comments based upon your review of Licensee Event Report (LER) 05000265/2017-001-00 for
Quad Cities Nuclear Power Station, Unit 2 (ML17194A817). This licensee event report is
related to an event that occurred on May 15, 2017. As stated in the report, the High Pressure
Coolant Injection (HPCI) system minimum flow valve did not open as expected during HPCI
system testing. Based upon our review of the LER and the specific HPCI system issue, the
inspectors concluded that the licensee immediately declared the HPCI system inoperable,
entered the appropriate Technical Specification Limiting Condition for Operation, replaced a
failed flow switch, and returned the HPCI system to service within the Technical Specification
allowed completion time.
As you are likely aware, letters to senior NRC officials are generally placed into ADAMS as
publically available documents unless there is a reason to exclude the letter from ADAMS.
Several weeks before your letter was received by our prior Regional Administrator, Cynthia
Pederson, the Quad Cities HPCI issue was under review by our resident inspectors. Shortly
after receiving your email, I and several members of the NRC staff conducted a phone call with
you to determine if our understanding of the issue was the same as yours. The result was that
we (you and the NRC) had a similar understanding of the issue and you provided no information
that would prompt us to modify our inspection of this issue; therefore, your letter was placed in
ADAMS as publically available. Ms. Pederson has since retired and Mr. K. Steven West has
been appointed as the Region III Regional Administrator. I have discussed your letter with him,
and he has authorized me to respond for him. This response will be placed into ADAMS as a
publically available document.
In your letter, you raised three concerns:
1. The licensee made two seemingly contradictory statements in the LER related to
whether the HPCI system minimum flow valve failure is an event or condition that could
have prevented the fulfillment of its safety function. Additionally, you questioned why the
licensee did not retract the LER if they determined that the event would not have
affected a safety function.
D. Lochbaum
-2-
2. The licensee stated that the failure of the minimum flow valve to open did not contribute
to an increase in risk since the operation of the minimum flow valve was not modeled in
the plants Probabilistic Risk Assessment (PRA). You referenced NUREG/CR-5934,
High Pressure Coolant Injection System Risk-Based Inspection Guide for Quad-Cities
Station, Units 1 and 2, and questioned whether this conclusion was appropriate.
3. The licensee stated that the HPCI system had a 10-minute mission time. You
questioned whether it is acceptable for the licensee to consider only one short-duration
design basis event and exclude all longer duration events when assessing safety
impacts.
The NRC staff has reviewed your concerns and provides our assessment below. We note that
the event described in the LER was under review by the NRC resident inspectors at the time we
received your letter.
Concern 1 - Contradictions Regarding Loss of Safety Function
The NRC reviewed the information provided in LER 2017-001, including the potential
contradictory information regarding the loss of safety function, and discussed this information
with the licensee. The NRC determined that the HPCI system was declared inoperable due to a
note in the surveillance procedure acceptance criteria. After declaring the HPCI system
inoperable, the licensee reported the HPCI system inoperability to the NRC in accordance with
the guidance provided in NUREG-1022, Event Report Guidelines, Revision 3, Section 3.2.7,
Event of Conditions that Could have Prevented the Fulfillment of a Safety Function. After
determining the cause of this event, the licensee performed an engineering evaluation as
discussed in NEI 99-02, Regulatory Assessment Performance Indicator Guideline, and
concluded that this event did not constitute a safety system functional failure because the HPCI
system remained available to perform its specified safety function. This conclusion was based
upon information provided by General Electric demonstrating that the HPCI system would
continue to function even though the HPCI system minimum flow valve was not operating as
expected.
The NRCs review of the LER is documented in Section 4OA3 of Integrated Inspection
Report 05000254/2017004 and 05000265/2017004 (ML18047A566). The inspectors reviewed
the licensees engineering analysis and agreed with their conclusion that HPCI remained able to
perform its safety function. In this instance, despite the conclusion of licensees engineering
assessment, the NRC does not require retraction of LERs if the system is later determined to
have always been operable. The inspectors review retracted event notifications to validate the
licensees conclusions and basis for the retraction. In addition, the inspectors review the safety
system functional failure performance indicator once per year, and this event would be in the
scope of that review.
Concern 2 - Risk Perspectives
As noted in the LER, the licensee stated the HPCI minimum flow valve was not credited in the
plants PRA and therefore did not contribute to an increase in risk. The NRC staff agrees that
this statement alone would not be an adequate justification for determining the risk significance
of the event. However, the licensee also stated in the LER that the overall safety significance
and risk impact of the event was minimal due to the fact that the HPCI system was available to
perform its safety function.
D. Lochbaum
-3-
The inspectors reviewed the licensees evaluation and found it to be in accordance with
NUREG/CR-5934. Specifically, Section 6.14 discusses that the medium risk aspect of a HPCI
minimum flow valve failure is due to a coincident normally open pump discharge valve failing
closed or becoming plugged. With respect to the issue discussed in the LER, the pump
discharge valve operated as expected. The NRC staff did not identify any additional concerns
with the licensees risk evaluation.
Concern 3 - Mission Time
As stated previously, the licensee ultimately determined that the HPCI system remained
operable and available to inject in the event of a loss of coolant accident. The NRC did not
identify any concerns with the licensees assessment. As part of the LER review, the NRC also
noted the statement regarding the HPCI mission time. This event and the condition of the
minimum flow valve had no impact on the HPCI systems function or the systems ability to
continue to run, and therefore the inspectors did not pursue the mission time statement further,
other than noting the 10 minute mission time was as described in the licensees UFSAR.
The 10 minute time is based on a limited set of event scenarios, as described in the licensees
fuel analysis, in which HPCI operates for 10 minutes and then other systems are used to
mitigate the postulated event. Finally, the NRC significance determination process generally
uses a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> mission time and if HPCI could not meet this mission time successfully due to a
performance deficiency, the NRC would assess the significance using this process and mission
time.
Thank you for communicating your comments to the Region III office. If you have any
questions, please contact me at 630-829-9731 or via e mail at karla.stoedter@nrc.gov.
Sincerely,
/RA/
Karla K. Stoedter
Chief, Branch 1
Division of Reactor Projects
D. Lochbaum
-4-
Letter to David A. Lochbaum from Karla K. Stoedter dated March 9, 2018
SUBJECT: NRC RESPONSE TO UNION OF CONCERNED SCIENTISTS COMMENTS
REGARDING QUAD CITIES NUCLEAR POWER STATION, UNIT 2, HIGH
PRESSURE COOLANT INEJCTION LICENSEE EVENT REPORT
05000265/2017-001-00
DISTRIBUTION:
RidsNrrDorlLpl3
RidsNrrPMQuadCities Resource
RidsNrrDirsIrib Resource
DRPIII
DRSIII
ROPassessment.Resource@nrc.gov
ADAMS Accession Number: ML18068A147
OFFICE
RIII
RIII
NAME
JHeller:lg
KStoedter
DATE
3/1/2018
3/2/2018
OFFICIAL RECORD COPY