05000260/LER-2003-001, For Browns Ferry, Unit 2, Automatic Scram Resulting from Low Reactor Water Level During Reactor Cooldown
| ML031150506 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 04/24/2003 |
| From: | Bhatnagar A Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 03-001-00 | |
| Download: ML031150506 (10) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 2602003001R00 - NRC Website | |
text
April 24, 2003 U.S. Nuclear Regulatory Commission 10 CFR 50.73 ATTN: Document Control Desk Mail Stop OWFN, P1-35 Washington, D. C. 20555-0001
Dear Sirs:
TENNESSEE VALLEY AUTHORITY - BROWNS FERRY NUCLEAR PLANT (BFN) -
UNIT 2 - DOCKET 50-260 - FACILITY OPERATING LICENSE DPR LICENSEE EVENT REPORT (LER) 50-260/2003-001-00 The enclosed report provides details of an unplanned, automatic scram which occurred on Unit 2 during cooldown of the reactor following the planned shutdown which began the Unit 2 Cycle 12 refueling outage. During the cooldown evolution, reactor water level briefly dropped below the low water level scram setpoint.
In accordance with 10 CFR 50.73(a)(2)(iv)(A), TVA is reporting this event as the valid actuation of the reactor protection system and of containment isolation valves in more than one system. There are no commitments contained in this letter.
Sincerely, original signed by:
Ashok S. Bhatnagar cc: See page 2
U.S. Nuclear Regulatory Commission Page 2 April 24, 2003 Enclosure cc (Enclosure):
(Via NRC Electronic Distribution)
Mr. Kahtan N. Jabbour, Project Manager U.S. Nuclear Regulatory Commission (MS 08G9)
One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852-2739 Mr. Stephen J. Cahill, Branch Chief U.S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth Street, SW, Suite 23T85 Atlanta, Georgia 30303-8931 NRC Resident Inspector Browns Ferry Nuclear Plant 10833 Shaw Road Athens, Alabama 35611-6970
U.S. Nuclear Regulatory Commission Page 3 April 24, 2003 TEA:DTL:PSH:BAB Enclosure cc (Enclosure):
A. S. Bhatnagar, PAB 1B-BFN M. J. Burzynski, BR 4X-C R. G. Jones, POB 2C-BFN J. Scott Martin, PMB 1A-BFN F. C. Mashburn, BR 4X-C D. C. Olcsvary, LP 6A-C C. L. Root, PAB 1G-BFN Jim Maddox, LP 6A-C K. W. Singer, LP 6A-C E. J. Vigluicci, ET 11A-K R. E. Wiggall, PEC 2A-BFN LEREvents@inpo.org NSRB Support, LP 5M-C EDMS-K s:lic/submit/lers/260-2003-01
Abstract
On February 24, 2003, during the Unit 2 reactor cooldown evolution following its shutdown to begin the cycle 12 refueling outage, at 1117 hours0.0129 days <br />0.31 hours <br />0.00185 weeks <br />4.250185e-4 months <br /> CST an automatic actuation of the reactor protection system (RPS) occurred as a result of a low reactor water level condition. Reactor water level control was being transferred from operation of a single turbine driven reactor feed pump (RFP) to the motor-driven condensate/condensate booster pumps via the reactor feedwater startup level control valve. Difficulties in closing the RFP discharge valve and subsequent slow operation of the startup level control valve allowed reactor water level to drop slightly below the scram setpoint of 2 inches. The lowest reactor water level observed was 1.6 inches. Reactor water level was immediately recovered to the normal operating range by increased make-up flow through the feedwater startup level control valve. No control rod motion occurred as a result of the RPS actuation, since all control rods had previously been fully inserted via the manual scram which had commenced the earlier, planned reactor shutdown. All expected system responses were received, including the actuation of primary containment isolation system groups 2, 3, 6, and 8 due to the same low reactor water level condition.
The cause of the event was off-normal RFP discharge valve operation combined with a slow response of the feedwater startup level control valve. Corrective actions include maintenance on the discharge valve, evaluation of the design of the control scheme, and additional operator training on the system response.
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Safety System Functional Failure Consideration:
This event does not involve a safety system functional failure which would be reported in accordance with NEI 99-02. The scram resulted from difficulties in closing a RFP discharge valve and the slow operation of a non-safety related level control valve. All safety-related equipment performed in accordance with the plant design in response to the event.
E.
Loss of Normal Heat Removal Consideration:
This unplanned RPS actuation event did not occur while the reactor was critical, therefore consideration of a loss of normal heat removal condition is not relevant. This event does not constitute a scram with a loss of normal heat removal which would be reported in accordance with NEI 99-02.
VIII. COMMITMENTS
None