Semantic search
Jump to navigation
Jump to search
| Entered date | Event description | |
|---|---|---|
| ENS 54306 | 2 October 2019 11:37:00 | On October 1, 2019, the Arkansas Nuclear One (ANO) Site Vice President was notified of a defect on an ITE/Gould J20M Coil Block Relays which met the reporting criteria of 10 CFR 21.21. ANO is making this non-emergency notification in accordance with 10 CFR 21.21(d)(3)(I) concerning a defect on an ITE/Gould J20M Coil Block Relay which resulted in one of four safety related containment cooling fans failure to start at ANO Unit 2. On June 1, 2019, a failure occurred when the containment cooler fan hand switch was taken to 'start' during the recent Unit 2 forced outage. Troubleshooting identified the control power relay coil was found to have an open winding condition. The Unit 2 reactor was in shutdown (Mode 5) and no impacts to nuclear or radiological safety occurred because of this event. The failure of the containment cooling fan to start would have prevented the Containment Cooling System from performing its function of providing essential cooling/environmental controls for safety related equipment inside containment. On August 15, 2019, ANO approved a causal evaluation which determined the failure of the relay occurred due to a manufacturing defect associated with uneven varnish application on the coil windings. This defect lead to premature turn-to-turn shorting of the coils. This failure was determined to be limited to ITE/Gould relays that were part of a 1991 batch purchased by ANO. The 1991 relay batch had a manufacturing date code of 9132. As part of the ANO evaluation, an industry operating experience review identified INPO ICES OE 242045. This OE identified another utility had purchased three relays from ANO in 2007 and subsequently experienced coil failures on two of the three relays. The utility did not issue a 10 CFR Part 21 notification. During the ANO evaluation, NRC IN 92-27 Supplement 1 was reviewed. The IN noted the same component failure mode. However, the failure mechanism was different. The IN discussed failures associated with thermal degradation of the relay armature carriers in ganged mounting configurations. The failure mechanism at ANO is due to uneven varnish application to the coil windings. Entergy ANO performed a Part 21 Evaluation in accordance with 10 CFR 21.21(a)(1) which was completed on September 25, 2019. This evaluation determined this defect could create a substantial safety hazard as defined in 10 CFR 21.3. The licensee has two relays left that could be affected. One relay is installed and currently in use by the other containment cooling fan and the other relay is on parts hold in an ANO onsite warehouse. A Condition Report has been initiated to document the potential for failure of the installed control power relay. This ITE/Gould J20 is obsolete and other options are being evaluated to replace the ITE/Gould J20M Coil Block Relay. ANO has notified the utility to whom it sold the relays in 2007. ANO has also notified the vendor. The licensee notified the NRC Resident Inspector. |
| ENS 54152 | 8 July 2019 18:40:00 | A non-licensed contract supervisor had a confirmed positive for a controlled substance during a random fitness-for-duty test. The employee's access to the plant has been terminated. The NRC Resident Inspector has been notified. |
| ENS 54147 | 3 July 2019 18:32:00 | This 60-day telephone notification is being made in accordance with 10 CFR 50.73(a)(1) and 10 CFR 50.73(a)(2)(iv)(A) to provide information pertaining to an invalid Engineered Safety Feature actuation signal. On May 9, 2019, at Arkansas Nuclear One (ANO) Unit 1, while performing an Emergency Feedwater Initiation and Control (EFIC) Channel B monthly test, a test pushbutton was mispositioned, resulting in an inadvertent initiation of the Emergency Feedwater (EFW) System. In accordance with the Engineered Safeguards Actuation System (ESAS) Trip Test portion of the surveillance, the first technician placed EFIC Train B in the tripped condition. The second technician then went to the front of the control room to verify Remote Switch Matrix (RSM) indications. The first technician recalls thinking he was given the order to reset Train B EFW Bus 1 Trip. Therefore, the first technician performed the step using three-part communication, but there is uncertainty about what was said. Due to the amount of time the second technician spent in front of the control room, the first technician assumed Operations reset the RSM to complete the Train B reset. The second technician returned to the ESAS cabinet and directed the first technician to perform the reset of Train B EFW Bus 1 Trip. The first technician, expecting his next action to be the trip of Train B EFW Bus 2, placed Bus 2 in the tripped condition. This put both buses of Train B EFW in trip and caused the actuation of P-7A EFW Pump. This inadvertent actuation was caused by human error and was not a valid signal resulting from parameter inputs. The 1992 Statements of Consideration define an invalid signal to include human error. Therefore, this actuation is considered invalid. This event was entered into ANO's corrective action program for resolution. This event did not result in any adverse impact to the health and safety of the public. The plant responded as expected. In accordance with 10 CFR 50.73(a)(i) a telephone notification is being made in lieu of submitting a written Licensee Event Report. The licensee has notified the NRC Resident Inspector. |