05000247/LER-2006-003, Regarding Manual Reactor Trip Due to a Mismatch Between Reactor Power and Turbine Load Caused by Cycling of Steam Dump Valves After a Power Reduction for Loss of Heater Drain Tank Pumps
| ML062970240 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 10/23/2006 |
| From: | Dacimo F Entergy Nuclear Indian Point 2 |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-06-094 LER 06-003-00 | |
| Download: ML062970240 (9) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 2472006003R00 - NRC Website | |
text
Indian Point Energy Center 450 Broadway, GSB P.O. Box 249 fBuchanan, N.Y. 10511-0249 Entfffl(Tel (914) 734-6700 Fred Dacimo Site Vice President Administration October 23, 2006 Indian Point Unit No. 2 Docket No. 50-247 NL-06-094 Document Control Desk U.S. Nuclear Regulatory Commission Mail Stop O-P1-17 Washington, DC 20555-0001
Subject:
Licensee Event Report # 2006-003-00, "Manual Reactor Trip Due to a Mismatch Between Reactor Power and Turbine Load Caused by Cycling of Steam Dump Valves After a Power Reduction for Loss of Heater Drain Tank Pumps"
Dear Sir:
The attached Licensee Event Report (LER) 2006-003-00 is the follow-up written report submitted in accordance with 10 CFR 50.73. This event is of the type defined in 10 CFR 50.73(a)(2)(iv)(A) for an event recorded in the Entergy corrective action process as Condition Report CR-IP2-2006-05066.
There are no commitments contained in this letter. Should you or your staff have any questions regarding this matter, please contact Mr. Patric W. Conroy, Manager, Licensing, Indian Point Energy Center at (914) 734-6668.
Sincerely, Fred R. Dacimo Site Vice President Indian Point Energy Center
Docket No. 50-247 NL-06-094 Page 2 of 2 Attachment: LER-2006-003-00 cc:
Mr. Samuel J. Collins Regional Administrator - Region I U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission Resident Inspector's Office Resident Inspector Indian Point Unit 2 Mr. Paul Eddy State of New York Public Service Commission INPO Record Center
Abstract
On August 23, 2006, at 1035 hours0.012 days <br />0.288 hours <br />0.00171 weeks <br />3.938175e-4 months <br />, control room (CR) operators initiated a manual reactor trip (RT) due to a mismatch between reactor power and turbine load.
Power was initially reduced to 77% for loss of Heater Drain Tank (HDT) pumps then further reduced per Technical Specification 3.2.3 due to axial flux difference outside its required operating limit.
CR operators initiated a RT during the further power reduction due to a mismatch between reactor power and turbine load from cyclic operation of the high pressure steam dump (HPSD) valves.
All primary safety systems functioned properly.
The plant was stabilized in hot standby with decay heat being removed by the main condenser.
There was no radiation release.
The Emergency Diesel Generators did not start as offsite power remained in-service.
The Auxiliary Feedwater system (AFWS) started due to steam generator (SG) low level from shrink effect.
Feedwater (FW) isolation and actuation of the AFWS occurred due to a 22 SG high level as a result of overfeed from leakby through the 22 FW low flow bypass valve.
The cause of the RT was improper gain settings on the HPSD temperature modules which caused the HPSD's to respond increasingly disproportional to the input signal.
The improper settings were attributed to inadequate review during implementation of actions for the Power Uprate Project in 2004.
The cause of the loss of the HDT pumps was a failed HDT level controller power supply.
Contributing causes included incorrect information in the HPSD module calibration procedure and inadequate procedural guidance.
Corrective actions include properly setting the HPSD modules, replacement of the HDT power supply, preparation of a calibration procedure for the HPSD modules, calibration training and procedure revisions.
The event had no effect on public health and safety.
NRC FORM 366 (6-2004)
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A high level in any SG could result in excessive carryover to the main steam line and damage the main turbine if not isolated.
Damage to the main turbine could result in a main turbine protection system trip and a subsequent reactor trip.
Water carryover in the steam would not impact the motor driven AFWS which has adequate redundancy to provide the minimum required flow assuming a single failure.
FW is isolated to the SGs upon a RT, high SG level, and Safety Injection.
A high SG water level greater than 75% of the normal operating span in any SG narrow range level initiates a SG High-High level trip via the SG Water Level Control System which closes the main feed regulating valve and actuates closure of the MBFP discharge valves which trips the MBFPs.
A trip of any one of two MBFPs will actuate the start of the AFWS.
The limits on the AFD ensure that the reactor core Heat Flux Hot Channel Factor is not exceeded during either normal operation or in the event of xenon redistribution following power changes.
For postulated accidents, the AFD limits ensure that fuel cladding integrity is maintained for these transients.
Overheating of the fuel cladding is prevented by restricting fuel operation to within the nucleate boiling regime.
The Reactor Protection System (RPS) is designed to actuate a RT for any anticipated combination of plant conditions, when necessary, to ensure a minimum departure from nucleate boiling (DNB) ratio (DNBR) equal to or greater than the applicable safety analysis limit DNBR.
In addition, a manual RT can be initiated by control room operators.
The manual RT actuating devices are independent of the automatic trip circuitry.
The RPS design is of sufficient redundancy and independence to assure that no single failure or removal from service of any component or channel will result in loss of the protection function.
The protection system design is to fail into a safe state or state established as tolerable.
Therefore, there are no reasonable or credible alternative conditions that would have resulted in serious consequences.