ENS 49974
ENS Event | |
|---|---|
04:00 Mar 31, 2014 | |
| Title | Interim Part 21 Report - Containment Loads Potentially Exceed Limits with High Suppression Pool Water Level in the Abwr Design |
| Event Description | The following summary was excerpted from GE Hitachi Interim Part 21 Report received via email:
A potential analysis error has been identified that is associated with the ABWR (Advanced Boiling Water Reactor) hydrodynamic loads determined by using the Technical Specification Suppression Pool High Water Level (HWL) as an analysis input condition. Vessel coolant inventory is transferred into the containment Suppression Pool during a postulated LOCA blowdown, thereby increasing the Suppression Pool water level. The correction in the analysis may lead to a Suppression Pool water level greater than what is currently assumed in structural analyses which apply the containment hydrodynamic loads generated during a postulated LOCA event. Facility Identification: South Texas Project Units 3 and 4, Clinton ESP Site, Grand Gulf ESP Site, North Anna ESP Site, and includes the ESP application for the PSEG Site and Victoria County Station ESP application. If you have any questions, then contact: Dale E. Porter, GE-Hitachi Nuclear Energy Americas LLC, Ph. #(910) 819-4491.
June 26, 2014 MFN 14-013 R1 This letter provides supplemental information concerning an evaluation being performed by GE Hitachi Nuclear Energy (GEH) regarding the potential increase in hydrodynamic loads that may be experienced by containment structures during a postulated Loss of Coolant Accident (LOCA) associated with Reference 1, and requests additional time to complete the evaluation for the determination of reportability of this condition. A potential analysis error has been identified that is associated with the ABWR hydrodynamic loads determined by using the Technical Specification Suppression Pool High Water Level (HWL) as an analysis input condition. Vessel coolant inventory is transferred into the containment Suppression Pool during a postulated LOCA blowdown, thereby increasing the Suppression Pool water level. The correction in the analysis may lead to a Suppression Pool water level greater than what is currently assumed in structural analyses which apply the containment hydrodynamic loads generated during a postulated LOCA event. For example, a postulated Feedwater Line Break (FWLB) may transfer a large quantity of FW liquid into the Suppression Pool with a notable increase in pool water level, even assuming a portion of the discharged fluid spills over into the lower drywell region of the ABWR containment. A higher Suppression Pool water level may result in increased hydrodynamic loads acting on the submerged walls and structures in the containment. The higher Suppression Pool water level can extend the wetted regions of the Suppression Pool walls and the ABWR access tunnel, as well as result in wetted submerged structure segments that were not previously considered wetted. This potential analysis error affects the LOCA containment hydrodynamic loads including condensation oscillation (CO) and chugging, as well as Safety Relief Valve (SRV) actuation loads. Assessing the overall impact of increased hydrodynamic loads calculated with higher Suppression Pool water level requires an evaluation of the containment structural components' design bases. GEH is in the process of examining revised containment loads, and determining available margin in the ABWR containment component design specifications to accommodate potentially increased load source forcing functions. ABWR plants may then compare affected plant-specific containment structural design bases to these specifications for relative margin. An extended time period is needed in order to complete the revised containment load determination and evaluate the impact on containment structures. GEH is requesting additional time to complete the analysis previously noted in Reference 1. The information required for this GEH 60-Day Interim Report Notification per �21.21(a)(2) is provided in Attachment 1. The commitment for follow-on actions is provided in Attachment 1, item (vii). If you have any questions, please call me at (910) 819-4491. Sincerely, Dale E. Porter Safety Evaluation Program Manager GE-Hitachi Nuclear Energy Americas LLC Notified R2DO (Rich) and Part 21 Reactor Group via email.
August 29, 2014, MFN 14-013 R2, Specification 000N7289-R2 When considered with the realistic assumptions and the lowered scale factors, the condition reported in Reference 1 [of the final report] is determined as non-reportable, and there is no Substantial Safety Hazard nor will it lead to exceeding a Technical Specification Safety Limit for the affected plants and plant designs. The GEH evaluation within 10 CFR Part 21 is now closed. If you have any questions, please call; Dale E. Porter Safety Evaluation Program Manager GE-Hitachi Nuclear Energy Americas LLC Ph. (910) 819-4491. Notified R2DO (Rose) and Part 21 Reactor Group via email. |
| Where | |
|---|---|
| Ge-Hitachi Nuclear Energy Wilmington, North Carolina (NRC Region 1) | |
| Organization: | Ge-Hitachi Nuclear Energy |
| Reporting | |
| 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component | |
| Time - Person (Reporting Time:+5.12 h0.213 days <br />0.0305 weeks <br />0.00701 months <br />) | |
| Opened: | Dale Porter 09:07 Mar 31, 2014 |
| NRC Officer: | John Shoemaker |
| Last Updated: | Aug 29, 2014 |
| 49974 - NRC Website | |
Ge-Hitachi Nuclear Energy with 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component | |
WEEKMONTHYEARENS 513862015-04-16T04:00:00016 April 2015 04:00:00
[Table view]10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component Part 21 Report - Potential Failure of Electromatic Relief Valve Cutout Switches ENS 499742014-03-31T04:00:00031 March 2014 04:00:00 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component Interim Part 21 Report - Containment Loads Potentially Exceed Limits with High Suppression Pool Water Level in the Abwr Design 2015-04-16T04:00:00 | |