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| Entered date | Event description | |
|---|---|---|
| ENS 50752 | 22 January 2015 18:51:00 | On 1/20/15, it was determined that a certain line up of component cooling heat exchangers and shutdown cooling heat exchangers could exceed the design basis temperatures for the component cooling water system following a design basis accident. Although not a safety concern at this time because of low ultimate heat sink temperatures (which cools component cooling water), in the past the ultimate heat sink temperatures have been high enough to create this condition. This particular heat exchanger line up was unanalyzed in that the ultimate heat sink temperature limits were not known until 1/22/15. This issue has been entered into the corrective action program. A review of Control Room logs for 2014 showed that in 1 instance for Unit 1 and 1 instance for Unit 2, the Units were in an unanalyzed lineup with ultimate heat sink temperature greater than the maximum now calculated. During these instances, both Units had an unanalyzed condition that had potential to significantly degrade plant safety and is reportable in accordance with 10 CFR 50.72(b)(3)(ii)(B). The NRC Resident Inspector has been notified.
Further engineering analysis has refined the ultimate heat sink temperature that provides an acceptable safety system response with the component cooling water and shutdown cooling heat exchanger lineups in question. The revised information demonstrates that the system lineups that occurred in the last 12 months did not result in an unanalyzed condition that significantly degrades plant safety. This event notification is retracted. The NRC Resident Inspector will be notified. The R1DO (Burritt) was notified.
The retraction statement provided on 3/3/15 incorrectly addressed system lineups limited to the last 12 months. The original withdrawal was prematurely submitted and therefore the original notification (Event report 50752) is not retracted and remains valid. The NRC Resident Inspector has been notified. The R1DO (Cook) was notified. |
| ENS 50078 | 1 May 2014 11:50:00 | At 1016 (EDT) CCNPP (Calvert Cliffs Nuclear Power Plant) Unit 1 automatically tripped due to an RPS actuation. Cause is under investigation. All safety functions are met with normal heat removal. Electric plant is in a normal lineup. No ESFAS (Engineered Safety Feature Actuation System) actuations have occurred. Steam Generator atmospheric dump valves momentarily opened and then closed. There is no known steam generator tube leakage. All control rods fully inserted on the trip. There was no impact on Unit 2 from this event. The licensee notified the NRC Resident Inspector and provided a courtesy notification to the Calvert County Control Center. |
| ENS 48116 | 17 July 2012 19:32:00 | At 1715 EDT on July 17th, 2012, Calvert Cliffs Nuclear Power Plant Unit 1 identified RCS Pressure Boundary Leakage from the instrument line to 1-PDT-123A, 11A reactor coolant pump differential pressure transmitter. Technical Specification 3.4.13, Action B was entered and requires that the Unit be placed in Mode 3 within 6 hours and Mode 5 within 36 hours. The licensee has initiated plant shutdown in accordance with this Technical Specification. Therefore, this is reportable under 10 CFR 50.72(b)(2)(i) Plant Shutdown Required by Technical Specifications. This is also reportable under 50.72(B)(3)(ii)(A) as a material defect in the primary coolant system that cannot be found acceptable under ASME Section XI, IWB-3600 or ASME Section XI, Table IWB-3410-1. The licensee initially discovered the leak during an RCS leak rate surveillance that indicated RCS leakage on the order of 0.08 gpm. A video camera was used to look for the leak and was found to be on the identified instrument line. The licensee has initiated a power reduction and is currently at approximately 50%. The recovery plan at this time is to reduce power to about 10% which will reduce radiation levels in the area of the leak and isolate the instrument line and isolate the leakage. The instrument line is for a reactor coolant pump differential pressure transmitter which is for monitoring purposes only and does not provide any safety related functions. If the leak can be secured, the licensee intends to return to power. If the leak cannot be secured, the plant will shutdown in compliance with the technical specification action statement. The licensee has notified the NRC Resident Inspector. |
| ENS 41051 | 17 September 2004 13:30:00 | Positive coliform in Eagles Den drinking water (unused, onsite building). Confirmed by backup sample. The licensee notified the Maryland Department of the Environment and the NRC Resident Inspector. |