ENS Event | |
|---|---|
05:00 Feb 8, 2013 | |
| Title | Part 21 - Completed Evaluation for Potential Error in Main Steam Line High Flow Calculational Methodology |
| Event Description | GEH recently discovered that some calculations of the choked flow rate in the Main Steam Lines (MSLs) of GEH BWRs were non-conservative, with potential effects on margins between choked flow conditions and existing MSL high-flow Nominal Trip Setpoints (NTSPs), Allowable Values (AVs), and Analytical Limits (ALs).
GEH has now completed the evaluation of this condition and has determined this condition is not reportable under 10 CFR 21 for all U.S. BWR/2-6 plants. The effect of the discovered non-conservatisms in choked flow rate values was offset by unintended conservatisms in the GEH recommended formulation for calculating pressure drop across the MSL flow restrictor. As a result, GEH has determined that the flow-instrument pressure remain at conservative values (which would ensure that the associated NTSPs and AVs expressed in psid also remain at conservative values), and the MSL high-flow trip will function as designed. This update to the 60-day Interim Notification issued on December 12, 2012 (MFN 12-111 R1) will be sent to all US BWR/2-6 plants licensed using the GEH design basis and safety analysis. See previous NRC Event 48350. |
| Where | |
|---|---|
| Ge Hitachi Nuclear Energy Wilmington, North Carolina (NRC Region 1) | |
| Organization: | Ge Hitachi Nuclear Energy |
| Reporting | |
| 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | |
| Time - Person (Reporting Time:+11.53 h0.48 days <br />0.0686 weeks <br />0.0158 months <br />) | |
| Opened: | Dale Porter 16:32 Feb 8, 2013 |
| NRC Officer: | Pete Snyder |
| Last Updated: | Feb 8, 2013 |
| 48735 - NRC Website | |
Ge Hitachi Nuclear Energy with 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | |
WEEKMONTHYEARENS 553142021-02-18T04:00:00018 February 2021 04:00:00
[Table view]10 CFR 21.21(d)(3)(i), Failure to Comply or Defect Part 21 Report ENS 547562020-04-28T04:00:00028 April 2020 04:00:00 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect Part 21 Report - Non-Conservative Bwr/6 Side Entry Orifice Loss Coefficients ENS 496102013-10-09T05:00:0009 October 2013 05:00:00 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect Part 21 - Failure of Relay Logic Card Modules in 2 Out of 4 Voters for Power Range Monitors ENS 487352013-02-08T05:00:0008 February 2013 05:00:00 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect Part 21 - Completed Evaluation for Potential Error in Main Steam Line High Flow Calculational Methodology 2021-02-18T04:00:00 | |