05000423/LER-2010-002, Regarding Automatic Reactor Trip on Lo Lo Steam Generator Level

From kanterella
(Redirected from 05000423/LER-2010-002)
Jump to navigation Jump to search
Regarding Automatic Reactor Trip on Lo Lo Steam Generator Level
ML103340497
Person / Time
Site: Millstone 
Issue date: 07/15/2010
From: Jordan A
Dominion Nuclear Connecticut
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
10-425, FOIA/PA-2011-0115 LER 10-002-00
Download: ML103340497 (6)
v • d • e


LER-2010-002, Regarding Automatic Reactor Trip on Lo Lo Steam Generator Level
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)(i)
10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded
10 CFR 50.73(a)(2)(viii)(A)
10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
10 CFR 50.73(a)(2)(viii)(B)
10 CFR 50.73(a)(2)
4232010002R00 - NRC Website
v • d • e

text

Dominion Nuclear Connecticut, Inc.

Dom inion -

Millstone Power Station Rope Ferry Road Waterford, CT 06385

!JUL i 201a U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC>20555

- Serial No.

MPS IWi/L.ES Docket No.

.License 'No.10-425 50-423 NPF-49 DOMINION NUCLEAR CONNECTICUL INC.

MILLSTONE POWER STATION UNIT 3 LICENSEE EVENT REPORT 2010-002-00 MPS3 AUTOMATIC REACTOR TRIP ON.LO LO C STEAM GENERATOR WATER LEVEL This letter forwards Licensee -Event Report <LER),,2010-002-00 documenting an event that occurred at Millstone Power.Station Unit 3, on May 17, 2010. This LER provides the-follow-up report to an event was reported in accordance with 10 CFR 50.73 <aX2)(iv) via event notification 45931 pursuant to 10 CFR 50.72 (bX2Xiv)(B).

If you have any questions or require additional information, please contact Mr. William D. Bartron at (860) 444-4301.

Sincerely, Site ian President - Millstone Attachments: 1 Commitments made in this letter: None 1--r-L ý ý-

ýJPL

Serial No.10-425 Docket No. 50-423 Licensee Event Report 2010-002-00 Page 2 of 2 cc:

U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406-1415 C. J. Sanders Project Manager U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08B3 Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station

Serial No.10-425 Docket No. 50-423 Licensee Event Report.2010-002-00 ATTACHMENT LICENSEE EVENT REPORT 2010-002-00

,MILLSTONE POWER STATION DOMINION NUCLEAR CONNECTICUT, INC.

NRC FORM'n66

- U.S. NUCLEARREGULATORY-COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2010 (9-2007)

., the'NRC may not conduct or sponsor, diplits/characters for each block)'

and a person is not required to respond to, the information collection.

1. FACILITY NAME 2.'DOCKET NUMBER
3. PAGE Millstone,Power Station - Unit 3 05000423 1 oF3 4: TITLE Automatic Reactor Trip on Lo Lo'Steam Generator Level
5. EVENT DATE
6. LER NUMBER
7. REPORT DATE
8. OTHER FACILITIESINVOLVED

.. 1.1.'FACILITY NAME DOCKET NUMBER SEQUENTIAL REV MONTH

,A YA 50 MONTH DAY YEAR YEAR NUMBER NO.

M DAY YEAR 05000

  • FACIrlITY NAME jDOCKET NUMBER 05 17 2010 2010- 002 -00 07 15 2010 F05000
11. THIS REPORTVIS SUBMITTED PURSUANT TO THE:REQUIREMENTS OF 10 CFRj'.C heck all that apply)
9. OPERATING: MODE 20.2201(b)

.20.2203(a)(3)(i) 50.73(a)(2)(i)(C) 50.73(a)(2Xvii) 20.2201(d) 20.2203(i)(3)(fl) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 1 20.2203(a)(1) 20.2203(aX4) 50.73(a)(2)(ii)(B) [7 50.73(a)(2)(viii)(B)

__20.2203(a)(2)(i)

.50.36(c)(1)(i)(A) 50.73(aX2)(iii) 5.50.73(4j(2)(ix)(A) 20.2203(a)(2)(ii)

S

.50.36(c)(1)(ii)(A)

X 50.73(a)2)(iv)(A) 1.

50.73(a)(2Xx)

10. POWER LEVEL 20.2203(a)(2)(iii),

50'36(c)(2) 50.73(a)(2)(vX(A) 73.71 (a)(4) 20.2203(a)(2)(iv) 50.46(a)(3)(ii) 50.73(a)(2XvXB)

U 173.71 (aX5) 017 20.2203(a)(2)(v) 50673(aX)2Xi)(A) 50.73(a6(2)(v.XC) L OTIt-ER 20.2203(a)(2)(vi) 50.73(a.X2)(i)(B)

  • ,50.7 3(a)(

2)(v)(D)

Specify in Abstract below or in

1.

-.Event'Description On May 17, 2010 an automatic reactor trip occurred on Millstone.Power Station Unit 3 (MPS3);While the unit was in Mode 1, at 17 %,power, due to a low steam generator (S/G) [SB] [SG] water~level condition in 'C' S/G causedtby slow response of the feedwater (FW) regulating bypass valvei] in automatic and manual control.

The eventbegan with the FW regulating bypass valves in automatic control. Water level oscillations were observed, in the 'B' and 'C' S/Gs between 40% and 60% indicated level. Just prior to the event, the FW regulating bypass valves were taken from automatic to manual control to -permit scheduled adjustments to power range nuclearinstruments. Operators adjusted the 'C'.bypass valve controller to attempt to smooth outlevel.oscillations in the 'C' SIG. T he oscillations were not able to be dampened out, and shrink-caused by the introduction of cooler water caused the 'C' S/G waterlevel to decrease to the lo lo S/G waterlevel reactor trip setpoint (18.1%), and an automatic reactor trip occurred.

All control rods fully inserted into the reactor [AB] [RCT]. -The auxiliary feedwater (AFW) system [BA] started-as designed and maintained S/G level. All other post tripactions'were completed, as specified. Safety systems functioned as expected based upon the signalsreceived. -Therewere-no radiological challenges as a result~of the event.

This event'is being reported in accordance with 10:C-FR 50.73(a)(2Xiv)(A) as an event that resulted in 'manual or automatic actuation of the reactor protective system and the auxiliary feedwater system.

2.

Cause

Inadequate design of the system that controls MPS3 S/G levels at low power operations was determined to.be the cause of this event. The design allows for excessive oscillation in-S/G water levels while in automatic control-and equipment challenges while in manual control.

3.

Assessment of Safety Consequences

There were no safety consequences associated with this event. All control rods inserted following the reactor trip on S/G level. The operating crew responded to the reactor trip.by entering Emergency Operating Procedure (EOP) 35 E-0, "Reactor Trip or Safety Injection". The turbinegenerator [TA]'[TB] had 'not been synchronized to the grid prior to the trip. The turbine bypass valves were controlling steam -pressure.

Following the reactor trip, the turbine bypass valves continued to control main steam [SB] pressure and the main steam safety valves [RV] were not challenged. The AFW system started automatically on the trip as expected,

- and restored the S/G levels to their normal operating band, maintaining reactor coolant system (RCS) heat.

removal. With the reactor at 17% power following the completion of a refueling outage, RCS decay heat levels were low. As a result, a cooldown of the RCS to approximately'543 degrees F occurred. This is 14 degrees below the typical noload temperature of 557 degrees F. This slight cooldown was terminated by operator action to manually trip the turbine driven main FW pump in accordance with EOP ES-0.1, "Reactor Trip Response". There

  • was no safety injection system actuation.
- Operator-actions and plant mitigating equipment responses were as expected with no safety system failures.

There were no challenges to the fuel, RCS or containment fission prodictfbarriers.

4.,Corrective Action The control loop was dynamically tuned prior to restart. Additional short-term corrective actions,included adjusting the level controller to improve valve positioner performance and condUcting additional just-in-time training for the

,operatOrs.

Operations Procedure OP-3203 has been revised to perform,calorimetric calibration of nuclear instruments at a power leyel.during plant startup when the FW system is in a more-stable condition.

A design change is being evaluated to improve the performance of the ;S/G.level control system at low power.

5.

Previous Occurrences

There were no previous similar events found.

Energy Industry Identification System (EIIS) codes are identified in the textas'[XX].

I INRL FORM 366)lA (9d-2007)

Retrieved from "https://kanterella.com/w/index.php?title=05000423/LER-2010-002,_Regarding_Automatic_Reactor_Trip_on_Lo_Lo_Steam_Generator_Level&oldid=5288337"