Semantic search
| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 53335 | 13 April 2018 17:08:00 | 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Two Cracks Identified at the Feed Water Line 'B' Containment Concrete Penetration | At 1208 CDT on April 13, 2018, GGNS (Grand Gulf Nuclear Station) identified cracks in the primary containment concrete penetration (outer wall) around feed water line 'B'. There are no available dimensions for crack width or depth until further inspections are performed. In accordance with NUREG 1022, Event Reporting Guidelines 10 CFR 50.72 and 10 CFR 50.73, Section 3.2.4, any event or condition that results in the condition of the nuclear power plant, including its principal safety barriers being seriously degraded, requires that when a principal safety barrier is declared inoperable the condition must be reported under 10 CFR 50.72 (b)(3)(ii). The licensee has notified the NRC Resident Inspector.
Grand Gulf Nuclear Station (GGNS) personnel performed an inspection of the wall around feed water line 'B'. This inspection included the protective coating in the identified area and a partial inspection of the underlying concrete. The inspection of the protective coating found a collection of non-linear anomalies, chipping, and flaking. The inspection found non-significant linear indications in the concrete. Grand Gulf Nuclear Station determined that the collection of non-significant coating imperfections and non-significant indications in the concrete do not constitute serious degradation of primary containment. The indications do not adversely impact the operability, mission time, or safety-function (as described per Technical Specification 3.6.1.1, Primary Containment) of the containment structure. The as-found conditions have been entered into the GGNS corrective action program for final disposition. The containment structure is operable, therefore, GGNS is retracting this event notification. The licensee has notified the NRC Resident Inspector. Notified R4DO (Kellar). | Primary containment | |
| ENS 47880 | 30 April 2012 23:01:00 | 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Weld Defect Indication Found in Residual Heat Removal System to Reactor Pressure Vessel Nozzle | Grand Gulf Nuclear Station is currently in Mode 4 (less than 200 degrees F) executing Refueling Outage 18 (RF-18) including in-service inspections. General Electric notified Entergy of a weld indication that was detected by automated ultrasonic testing. The indication is in the weld root area of N06B-KB Reactor Coolant System Pressure Boundary weld. The N06B nozzle connects Residual Heat Removal System 'C' to the Reactor Pressure Vessel. The dimension of the indication is approximately 0.9 inches in length, approximately 0.5 inches in depth and with no discernible width. Nominal wall thickness is 1.3 inches. The indication does not penetrate the entire thickness of the pipe wall and there is no leakage at the indication. There has been no release of radioactive material due to the indication. No systems were actuated due to this event. There are currently no other systems affected. The cause is under investigation and corrective action plans are being explored. The weld defect has been evaluated by Entergy Engineering and determined to meet the criteria for reporting identified in NUREG-1022: Welding or material defects in the primary coolant system that cannot be found acceptable under ASME Section XI, IWB-3600, 'Analytical Evaluation of Flaws,' or ASME Section XI, Table IWB-3410-1, 'Acceptable Standards'. The NRC Resident Inspector has been informed. | Reactor Coolant System Reactor Pressure Vessel Residual Heat Removal |