ENS 40874
ENS Event | |
|---|---|
23:30 Jul 14, 2004 | |
| Title | All Three Units Exceeded the Maximum Power Level Specified in Their Operating License |
| Event Description | Palo Verde Nuclear Generating Station Units 1, 2, and 3 determined that the Maximum Power Level specified in Operating License Condition 2.C(1) was exceeded in the past due to a nonconservative feedwater flow input in the secondary calorimetric calculation since installation of ultrasonic feedwater flow measurement (UFM) instrumentation in Units 1 and 3 in 1999 and 2000 in Unit 2. On 06/09/2004, the vendor (Caldon) notified Palo Verde via a letter that there may be an error of up to one to one and one-half percent in the flow measurement. As a compensatory measure, all three units reduced power and removed the UFM from service. Feedwater flow venturis are used for measurement with the UFM out of service. Engineering evaluation concluded on 07/14/2004 the maximum Palo Verde specific calorimetric error was approximately 38.76 Mw in Units 1 and 3 and 39.90 MW in Unit 2 or approximately 1 %.
The error resulted in core power levels above the Operating License limit of 3876 MW thermal in Units 1 and 3 and the Operating License limit of 3990 MW thermal In Unit 2 while the UFM was in service. This report is being made because a review of historical operating data revealed that the Maximum Power Level was exceeded. The Palo Verde safety analyses bound a power level of 102%. Power level did not exceed the safety analysis. No ESF actuations occurred and none were required as a result of the miscalibration. There were no other structures, systems, or components that were inoperable at the time of discovery that contributed to this condition. There were no failures that rendered a train of a safety system inoperable and no failures of components with multiple functions were Involved. The event did not result in the release of radioactivity to the environment and did not adversely affect the safe operation of the plant or health and safety of the public. The NRC Resident Inspector was notified. |
| Where | |
|---|---|
Palo Verde  Arizona (NRC Region 4) | |
| Reporting | |
| Other Unspec Reqmnt | |
| Time - Person (Reporting Time:+17.78 h0.741 days <br />0.106 weeks <br />0.0244 months <br />) | |
| Opened: | Dan Hautala 17:17 Jul 15, 2004 |
| NRC Officer: | Chauncey Gould |
| Last Updated: | Jul 15, 2004 |
| 40874 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 2 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Hot Standby (0 %) |
| After | Hot Standby (0 %) |
Unit 3 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 500212013-11-06T20:07:0006 November 2013 20:07:00
[Table view]Other Unspec Reqmnt Discovery of After-The-Fact Emergency Condition - Unusual Event Due to Explosion ENS 483932012-08-26T19:31:00026 August 2012 19:31:00 Other Unspec Reqmnt Discovery of After-The-Fact Emergency Condition - Unusual Event ENS 408742004-07-14T23:30:00014 July 2004 23:30:00 Other Unspec Reqmnt All Three Units Exceeded the Maximum Power Level Specified in Their Operating License 2013-11-06T20:07:00 | |