ENS 40123
ENS Event | |
|---|---|
06:32 Aug 31, 2003 | |
| Title | 24-Hour Condition Of License Report Involving Potential Violation Of Maximum Power Level |
| Event Description | This 24-hour report is being made as required by Braidwood Unit 2 License Condition 2.G as a potential violation of the maximum power level (3586.6 Mwt) as stated in Unit 2 License Condition 2.C(1).
As a result of issues at Byron Unit 1 and Unit 2 concerning potential discrepancies in the ultrasonic flow measurements for the main feedwater system, Braidwood investigated both Unit 1 and Unit 2 to determine if similar issues existed. These flow measurements are used in the calorimetric calculation for reactor power. Ultrasonic flow measurements were taken on the four individual main feedwater lines on Braidwood Unit 2. These measurements identified the presence of flow signal noise in the data signals for two of the four ultrasonic flow measurement devices installed on the individual feedwater lines, which may adversely affect the integrity of these measurements. In response to identifying this flow signal noise, Braidwood removed corrections based on ultrasonic flow measurement from these two loops. Based on removing credit for these ultrasonic flow measurements, it was determined at 0132 on August 31, 2003, that Braidwood Unit 2 could have potentially exceeded its licensed thermal power limit by up to 0.8%. Ultrasonic flow measurements were taken on the main feedwater system piping header on Braidwood Unit 1 and were compared to the results from the ultrasonic flow measurement devices on the four individual feedwater lines. Based on the results of the data analysis, Unit 1 was determined to be acceptable. The power level on Unit 2 was reduced to less than 100% power consistent with the feedwater flow as measured directly by the venturis without using the correction factor on two of the four ultrasonic flow meters. Additional actions regarding the investigation of the condition, determination of the root cause and corrective actions, and the determination of the potential actual overpower will be included in the 30-day license event report. The licensee informed the NRC Resident Inspector. HOO NOTE: See Byron Event Notification#40117.
The following information was provided by the licensee: The venturis were installed during initial construction of both Units. They are the original design for the Units. AMAG is a method of calibrating our Feedwater Venturi flow instruments. These devices were installed by the Advanced Measurement and Analysis Group (AMAG). AMAG first applied: Unit 1 - 6/11/1999 and Unit 2 - 6/11/1999 Rated MWt [Mega Watt Thermal] 3411 to 3586.6: Unit 1 - 5/14/2001 [and] Unit 2 -5/24/2001 Of the above 5% uprate to 3586.6 MWt, we initially increased power only 1 % of the above. This 1 % increase was known as our mini-uprate. We did not increase the full 5% since our turbines had not yet been modified to withstand the higher flow rates. During the A_R09 outages, we modified the turbines and achieved full uprate as follows: Full Uprate to 3586.6 MWt: Unit 1 - 10/16/2001 [and] Unit 2 - 5/15/2002. Notified NRR (Reis) and R3DO (Gardner) |
| Where | |
|---|---|
Braidwood  Illinois (NRC Region 3) | |
| Reporting | |
| Other Unspec Reqmnt | |
| Time - Person (Reporting Time:+13.18 h0.549 days <br />0.0785 weeks <br />0.0181 months <br />) | |
| Opened: | Frank Ehrhardt 19:43 Aug 31, 2003 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Sep 2, 2003 |
| 40123 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 528022017-06-12T14:14:00012 June 2017 14:14:00
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