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| Entered date | Event description | |
|---|---|---|
| ENS 49729 | 15 January 2014 16:37:00 | Reactor Building (Secondary Containment) pressure increased to above the Technical Specification Surveillance requirement of 0.25 inches vacuum water gauge briefly (5 minutes or less). This is reportable as an event that could have prevented fulfillment of a safety function needed to control the release of radiation and mitigate the consequences of an accident. Reactor Building pressure has been restored to normal (greater than 0.25 inches vacuum water gauge), returning Secondary Containment to operable status. Highest actual value was 0.21 inches vacuum water gauge. There were no radiological releases associated with the event. The differential pressure change is believed to have been caused by a momentary shift in Heating and Ventilation Systems dampers. The licensee has notified the NRC Resident Inspector. |
| ENS 49425 | 10 October 2013 14:08:00 | At 0809 PDT on 10/10/2013, after starting Standby Service Water (SW) pumps, Columbia Generating Station (Columbia) received a flow low alarm for the Low Pressure Containment Spray (LPCS) pump motor cooling water. The flow indicator SW-FIS-19 was reported too low to support pump function. The LPCS system was declared inoperable, and the appropriate Technical Specification action statement was entered. The cause of the low flow alarm has not been determined. This event is reportable under criterion 10 CFR 50.72(b)(3)(v)(D) 'Any Event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to (D) Mitigate the consequences of an accident.' Columbia is continuing to troubleshoot and repair as appropriate to restore the SW flow to the LPCS pump. The licensee has notified the NRC Resident Inspector.
Subsequent to receipt of the low flow alarm, flushing of the flow indicating switch sensing lines was conducted. It has been determined that the instrument sensing lines are partially blocked providing a flow indication that is slow to respond to actual flow conditions. The flow is currently reading normally. The LPCS pump was declared operable on 10/10/13 at 1447 PDT. The initial notification incorrectly stated 'Low Pressure Containment Spray (LPCS)', the correct description is 'Low Pressure Core Spray (LPCS)'. The licensee has notified the NRC Resident Inspector. Notified R4DO (Hay).
Subsequent evaluation of this event found there was no actual low flow condition to the LPCS bearing cooler. A flow scan on the SW outlet line from the LPCS pump bearing cooler was conducted on 10/12/13 which confirmed the actual flow conditions were reading normally. The problem resides in the installed flow indication switch. Since there was no actual low flow condition to the LPCS bearing cooler, the LPCS pump could perform its safety function to mitigate an accident. Therefore, this event notification is being retracted. Notified R4DO (Azua). The licensee has notified the NRC Resident Inspector. |
| ENS 49327 | 6 September 2013 05:10:00 | At 2244 PDT on September 5, 2013, the Turbine Building Stack Radiation Monitor - Low Range detector, and the Turbine Building Stack Radiation Monitor - Intermediate Range detector were declared non-functional due to a failure of the sample rack supply fan. At 0156 hours PDT on September 6, 2013, a temporary sample cart was installed to return the Turbine Building Stack Radiation Monitor - Low Range detector, and the Turbine Building Stack Radiation Monitor - Intermediate Range detector to service. To compensate for the loss of assessment capability while the Turbine Building Stack Radiation Monitoring equipment was nonfunctional, a field team survey would have been used if required. This event is being reported as a loss of emergency assessment capability in accordance with 10 CFR 50.72(b)(3)(xiii). The licensee has notified the NRC Resident Inspector. |
| ENS 49306 | 25 August 2013 00:46:00 | At 1614 hours PDT on August, 24, 2013 the Reactor Building Stack Radiation Monitor - High Range and Reactor Building Stack Radiation Monitor - Intermediate Range detectors were declared non-functional due to a loss of supporting equipment. Corrective actions are being pursued to restore the affected monitors to functional status. To compensate for the loss of assessment capability due to the non-functioning Radiation Monitoring Equipment, an additional Health Physics (HP) Technician trained to acquire offsite dose assessment information on offsite releases is available. The additional personnel are pre-staged in support of the Radiation Monitoring System outage and will be mobilized in accordance with guidance in the compensatory measure instructions. This event is being reported as a loss of emergency assessment capability in accordance with 10 CFR 50.72(b)(3)(xiii). A follow up notification will be made when the Equipment has been returned to service. The licensee has notified the NRC Resident Inspector.
Repairs have been completed and both the Intermediate and High Range Reactor Building Stack Radiation Monitors have been returned to service. The licensee has notified the NRC Resident Inspector. Notified the R4DO (Hagar). |
| ENS 46604 | 8 February 2011 20:55:00 | On December 20, 2010, the low pressure core spray (LPCS) system was declared inoperable due to loss of power to the LPCS minimum flow valve. The minimum flow valve supports operability by providing a flow path to prevent pump damage during situations where the LPCS pump has been started in response to a transient, but reactor vessel pressure is not low enough to allow LPCS injection. The power loss was caused by the clearing of all 3 line power fuses for the motor starter for the minimum flow valve. An apparent cause evaluation concluded that the most likely cause of the fuses clearing was a random fuse failure of one of the fuses at less than design amperage attributable to a defect in the fuse solder joint. The Technical Specification (TS) Required Action for LCO 3.5.1 Condition A, one low pressure ECCS injection/spray subsystems inoperable, was complied with by restoring the LPCS system to operable within the allowed completion time. The safety functions for LPCS are to provide inventory makeup and spray cooling during large breaks in the reactor coolant system that uncover the core. All remaining ECCS subsystems were operable and at no time did this event result in the loss of a safety function. The low pressure injection function was not challenged due to all three loops of the Residual Heat Removal (RHR) system Low Pressure Coolant Injection (LPCI) mode being operable while the core spray function was satisfied by the operable High Pressure Core Spray (HPCS) system. This event is being reported under 10 CFR 50.72(b)(3)(v)(D) as an event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident tor a single train system. Historically, LPCS inoperabilities at Columbia (including initial review of this event) were not considered to be a single train system for reportability purposes. The basis for the historical consideration was assessment of LPCS inoperabilities consistent with the plant safety analysis and the associated system and safety function groupings which do not single out LPCS as a single train system. There are two pertinent groupings in the safety analyses which are aligned with the credited safety functions of LPCS. The two groupings are the low pressure injection system function (combined with LPCI), and a core spray system function (combined with HPCS). Industry precedent has been consistent with the historical position. However, recent NRC interpretations have considered safety function at the lowest system level which result in LPCS being considered as a single train performing a safety function in scope of the reportability rules in 10 CFR 50.72 and 50.73. A Licensee Event Report will be submitted for this event. As a result of the recent interpretation with regard to LPCS, a review of prior LPCS inoperabilities within the past three years is being performed to determine if the reporting criteria were met during prior events. If necessary, additional 10 CFR 50.72 and 10 CPR 50.73 notifications/reports will be made on prior LPCS inoperabilities . The licensee will notify the NRC Resident Inspector. |
| ENS 43344 | 4 May 2007 14:21:00 | This is a non-emergency Event Notification made in accordance with 10 CFR 20.2201(a)(1)(ii) to inform the NRC of a loss of accountability of a very small amount (e.g., particle size) of special nuclear material (SNM). As part of preparations for an NRC inspection of Columbia's SNM Control and Accounting Program (April 16-19, 2007), documentation concerning the recovery of two pieces of a broken fuel rod was obtained. The documentation revealed existence of potential fuel particles estimated to be less than 1 gram in aggregate located in the spent fuel pool. The location of these particles cannot be positively identified at this time and is therefore being reported as missing SNM under 10 CFR 20.2201(a)(1)(ii). The particles were created during a 1990 refueling outage while inspecting a leaking fuel bundle. To identify the leaking rod, the bundle was disassembled and rod-by-rod electronic sorting performed. Ultrasonic examination identified the leaking rod; however, during the inspection the rod bent and snapped while being guided through a fuel inspection funnel. A procedure was approved and successfully executed to recover the broken rod sections. Following the recovery, an inspection was performed with an underwater camera to determine if any fuel pellets had been released as part of the evolution. No fuel pellets were identified; however, a small dark particle of material surrounded by smaller black particles was observed in a stainless steel bucket which had been positioned under the broken fuel rod pieces. It is believed that the bucket containing the particles was suspended off the west wall of the spent fuel pool, north of the work table. The location of the particles within the bucket cannot be positively identified at this time. The contents of the bucket have been described by the individuals involved in the broken rod recovery as a small particle of material roughly the size of a fingernail clipping surrounded by a few black particles the size of ground pepper. An underwater survey indicated a radiation level of greater than 400 R on contact for the material. The total amount is believed to be considerably less than 10 percent of a single pellet's worth of material, or less than 1 gram. Energy Northwest is continuing to investigate this event. Based on the information gathered to date, the nature of the particles, and the existence of radiation monitoring, a high degree of confidence exist that the particles are located in the bottom of the spent fuel pool or in an otherwise radiologically controlled location such that the health and safety of the public would not be adversely affected. In addition, there is no evidence of theft or diversion. This notification satisfies the 30-day notification requirement of 10 CFR 20.2201(a)(1)(ii). A subsequent written report will be made in accordance with 10 CFR 20.2201(b). The NRC Resident and SNM Control and Accounting Inspectors have been informed of this issue. THIS MATERIAL EVENT CONTAINS A "LESS THAN CAT 3" LEVEL OF RADIOACTIVE MATERIAL Sources that are "Less than IAEA Category 3 sources," are either sources that are very unlikely to cause permanent injury to individuals or contain a very small amount of radioactive material that would not cause any permanent injury. Some of these sources, such as moisture density gauges or thickness gauges that are Category 4, the amount of unshielded radioactive material, if not safely managed or securely protected, could possibly - although it is unlikely - temporarily injure someone who handled it or were otherwise in contact with it, or who were close to it for a period of many weeks. This source is not amongst those sources or devices identified by the IAEA Code of Conduct for the Safety & Security of Radioactive Sources to be of concern from a radiological standpoint. Therefore is it being categorized as a less than Category 3 source |