05000247/LER-2012-009, Regarding Unanalyzed Condition and Safety System Functional Failure Due to Use of Rad Bypass Switch for Steam Generator Blowdown Isolation Valves Which Defeats Their Automatic Isolation for Analyzed Events
| ML13042A226 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 01/28/2013 |
| From: | Ventosa J Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-13-016 LER 12-009-00 | |
| Download: ML13042A226 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat |
| 2472012009R00 - NRC Website | |
text
Entergy Indian Point Energy Center 450 Broadway, GSB P.O. Box 249 Buchanan, N.Y. 10511-0249 Tel (914) 254-6700 John A. Ventosa Site Vice President NL-13-016 January 28, 2013 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop O-P1-17 Washington, D.C. 20555-0001
SUBJECT:
Licensee Event Report # 2012-009-00, "Unanalyzed Condition and Safety System Functional Failure due to Use of Rad Bypass Switch for Steam Generator Blowdown Isolation Valves which Defeats Their Automatic Isolation for Analyzed Events" Indian Point Unit No. 2 Docket No. 50-247 DPR-26
Dear Sir or Madam:
Pursuant to 10 CFR 50.73(a)(1), Entergy Nuclear Operations Inc. (ENO) hereby provides Licensee Event Report (LER) 2012-009-00. The attached LER identifies an event where there was an unanalyzed condition and a safety system functional failure due to use of the Rad Bypass switch for Steam Generator blowdown isolation valves during maintenance activities which defeats their automatic isolation for analyzed events. This condition is reportable under 10 CFR 50.73(a)(2)(ii)(B) and 10CFR50.73(a)(2)(v)(B). This condition was recorded in the Entergy Corrective Action Program as Condition Report CR-IP2-2012-02408, CR-IP2-2012-06920, CR-IP2-2012-06952, CR-IP2-2012-07356 and CR-IP2-2013-00191.
There are no new commitments identified in this letter. Should you have any questions regarding this submittal, please contact Mr. Robert Walpole, Manager, Licensing at (914) 254-6710.
Sincerely, JAV/cbr cc:
Mr. William Dean, Regional Administrator, NRC Region I NRC Resident Inspector's Office, Indian Point 2 Mrs. Bridget Frymire, New York State Public Service Commission LEREvents@ inpo.org
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Abstract
On November 26, 2012, Operator review of a tag-out for a Preventive Maintenance of the Steam Generator (SG) blowdown (SGBD) radiation monitor R-49 determined the tagout would have placed all the SGBD isolation valves (ISVs) in Rad Bypass.
Operators could not identify any procedure allowing this action and determined this action was previously reported in LER-2012-004 as an unanalyzed condition and safety system functional failure when an Auxiliary Feedwater pump is out of service.
The normal ISV position is open which allows the ISVs to Auto close for heat sink events (Loss of Normal Feedwater, Loss of All AC Power to the Station Auxiliaries) in addition to containment Phase A isolation.
Analyzed degraded heat sink events assume SGBD isolation occurs and continuous SGBD during these events has not been analyzed.
SG inventory would not be maintained if only one motor-driven AFW pump was operable as it may not provide adequate flow with the SGBD ISVs open.
A review identified previous tagouts that placed the SGBD ISVs in Rad Bypass with an Auxiliary Feedwater pump or its emergency power supply inoperable.
The apparent cause has not been determined.
Corrective action was revision of procedure 2-PC-2Y23-49 to delete steps to place in Rad Bypass while performing Radiation Monitor R-49 calibration and installation of a test jumper to disable the blowdown function (as reported in LER-2012-004).
Applicable archived tagouts were locked from further use.
UFSAR Section 14.1.9 was revised to state SGBD isolation is assumed starting from event initiation.
An apparent cause evaluation will be performed.
The event had no significant effect on public health and safety.
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During the time testing was being performed and during tagouts to support Maintenance work which required the SG blowdown isolation valve switches to be positioned in Rad Bypass, the turbine driven AFW Pump (AFWP) was available and capable of providing adequate feedwater flow to maintain SG inventory.
Operators have CR instrumentation available for monitoring SG level and alarms to alert them to low levels.
Alarm response procedures are provided for low SG level which would be entered and appropriate actions taken.
Operators would know the SGBD isolation valves were in Rad Bypass and would take mitigating action if a heat sink event occurred.
For the LONF or LOOP events, procedure 2-E-0 (Reactor Trip or Safety Injection) would be entered.
At step 4 (check Safety Injection (SI) Status),
for SI not required, the procedure requires 1) verification of AFWP(s) running as necessary to establish total feed flow greater than 760 gpm,
- 2) maintain total feed flow greater than 760 gpm,
- 3)
Go to 2-ES-0.1 step 1. The basis for 2-E-0 states for SI not required, AFWPs are started to satisfy SPU LONF/LOAC Analysis requiring 760 gpm AFW flow within 10 minutes for heat removal if only one motor driven pump auto starts.
Feedwater flow to the SGs will not be affected by the condition and heat sink cooling will be provided by use of the SG atmospheric dump valves (ADVs),
or condenser steam dump, and in this case blowdown.
SG inventory will be impacted but plant procedures will ensure SG narrow range level is reestablished in all SGs to maintain symmetric cooling of the RCS.
Additionally, SG blowdown is normally throttled by valve MS-71 to approximately 20 gpm even with the SG blowdown isolation valves open.
During the May 3, 2011 event per 2C20-1/RM-133-R-49 IYR PM, SG blowdown was approximately 25 gpm, and for the December 8, 2009 event, tagout SW-087-B-SWN-945 PM, SG blowdown was also approximately 25 gpm per SG.