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| Entered date | Event description | |
|---|---|---|
| ENS 50333 | 31 July 2014 19:02:00 | Voluntary notification per the NEI Groundwater Protection Initiative. On July 31, 2014, Callaway Plant received results of a sample from a new ground water monitoring well. The sample was taken on July 25, 2014. The sample results indicated a tritium concentration of approximately 1.6 E6 picocuries/liter and a Co-60 concentration of approximately 12 picocuries/liter. The new monitoring well is located within the plant's property and is adjacent to a manhole where the plant's discharge piping joins with the cooling tower blowdown piping. Both the plant discharge piping and the cooling tower discharge piping are buried. Releases from the plant discharge line have been suspended. A backup sample taken on July 25, 2014, will be sent to a lab for analysis. Another sample will be taken on August 1, 2014. There is no effect on drinking water, and therefore, no dose to the general public or plant staff. The licensee will notify the Missouri State Department of Natural Resources and Callaway County officials. The licensee will notify the NRC Resident Inspector. |
| ENS 49141 | 22 June 2013 13:04:00 | This 60-day telephone notification is being made per the reporting requirements specified in 10CFR50.73(a)(2)(iv)(A) and 10CFR50.73(a)(1) to report an event involving an invalid actuation signal affecting the Auxiliary Feedwater (AFW) and Essential Service Water (ESW) systems. Initial conditions on 04/24/2013: refueling outage was in progress, there was no fuel in the reactor vessel (No MODE), a B safety-related train outage was in progress, and the A ESW train was in operation to support cooling of the A train safety-related equipment. Some separation group 2 bistables were in a tripped condition because instrument power bus NN02 was de-energized. At approximately 0400 (CDT) on 04/24/2013, Separation Group 4 DC bus NK04 experienced a ground condition. Plant personnel were using a plant procedure to search for the ground. When breaker NK5409 was opened, some unexpected Engineered Safety Features Actuation System (ESFAS) signals occurred. Opening the breaker removed power to the B ESFAS cabinet. With power removed to the B ESFAS cabinet, the circuit cards that generate cross-train trips failed to a tripped condition (thus generating cross-train trip signals) which resulted in some A train ESFAS actuations, in particular, auxiliary feedwater actuations for the A motor-driven and the turbine-driven AFW pumps. Additionally, an AFW Low Suction Pressure (LSP) circuit card tripped, and when combined with the bi-stable that was in a tripped state because bus NN02 was de-energized, the 2-out-of-3 logic was made up, resulting in an auxiliary feedwater LSP actuation. The LSP actuation resulted in the A Train ESW pump receiving a start signal, and the A motor-driven and the turbine-driven AFW pump suction supply valves receiving an actuation signal to transfer the suction supply from the normal source to the ESW system. Neither the motor-driven nor the turbine-driven auxiliary feedwater pumps started because they had been properly removed from service earlier in the outage. The A ESW pump was already running. No water was transferred from the ESW system to the AFW system since system tagging had been previously placed to isolate the two systems. The actuations were considered invalid because they were caused by opening breaker NK5409 which resulted in loss of power to the B ESFAS cabinet. The Senior Resident Inspector was notified. |
| ENS 49103 | 10 June 2013 17:06:00 | This 60-day telephone notification is being made per the reporting requirements specified in 10CFR50.73(a)(2)(iv)(A) and 10CFR50.73(a)(1) to describe an invalid actuation signal affecting the emergency feedwater system. While the plant was in Mode 5 on 4/11/2013, during performance of a maintenance procedure for AMSAC system logic verification, an invalid MDAFAS occurred. (Note: AMSAC is ATWAS Mitigation System Actuation Circuitry and MDAFAS is Motor Driven Auxiliary Feedwater Actuation Signal). Both trains of the Motor Driven Auxiliary Feedwater Pumps (MDAFPs) started. While generation of the actuation signal is an expected result of the procedure, the actuation occurred several steps earlier in the procedure than expected. Additionally, the Control Room Operators were not expecting the MDAFPs to start. The pumps were manually stopped. The actuation was caused by procedural guidance not containing a sufficiently prescribed sequence of activities that should occur when simulating plant conditions leading to the intended actuation of the AMSAC system. The plant was not in a condition where feedwater was required. The Senior NRC Resident Inspector was notified. |