05000249/LER-2013-001
| Dresden Nuclear Power Station, Unit 3 | |
| Event date: | 11-28-2013 |
|---|---|
| Report date: | 01-27-2014 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v)(C), Loss of Safety Function - Release of Radioactive Material |
| 2492013001R00 - NRC Website | |
PLANT AND SYSTEM IDENTIFICATION
Dresden Nuclear Power Station (DNPS) Unit 3 is a General Electric Company Boiling Water Reactor with a licensed maximum power level of 2957 megawatts thermal. The Energy Industry Identification System codes used in the text are identified as [XX].
A. Plant Conditions Prior to Event:
Unit: 03 Event Date: 11-28-2013 Event Time: 0258 hours0.00299 days <br />0.0717 hours <br />4.265873e-4 weeks <br />9.8169e-5 months <br /> CST Reactor Mode: 1 Mode Name: Power Operation Power Level: 100 percent
B. Description of Event:
On 11/28/13 a Radiation Protection Technician (RPT) and laborers went to the Unit 2 Secondary Containment [NG] X-Area (i.e., Main Steam Tunnel Area) to remove and demobilize the remaining lead blankets in the area. The RPT and laborers entered the Unit 2 X-Area by opening the outer door of the interlock that required an RP "R-Key" to open. The door was held open by the laborers while the RPT used his Dresden Station (DS) key to open the inner interlock door at the same time. The inner door seemed stuck closed to the RPT. He looked around and saw a manual button that defeats the interlock mechanism. The RPT pushed the button, and the inner door opened. The RPT and laborers entered the room and proceeded to remove and demobilize the lead.
Concurrent with the events taking place at the Unit 2 X-Area, the Unit 2 Control Room received alarm 902-4 F-19 on the X-Area interlock door. Operations sent an equipment operator into the field to investigate and found the RPT and laborers in the area removing lead blankets from the room. He notified the RPT that the control room had received an alarm for secondary containment. The RPT closed the doors and the alarm was reset.
This event is being reported in accordance with 10 CFR 50.73(a)(2)(v)(C), any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material. At the time of the event, the requirements of Technical Specification 3.6.4.1 were not applicable to Unit 2 because Unit 2 was in Mode 4.
Therefore, this event is only reportable for Dresden Unit 3.
C. Cause of Event:
The cause of this event was determined to be a failure to recognize a hazard while proceeding in the face of uncertainty. Specifically, an RPT did not recognize that there was a change in plant conditions (i.e., the X-Area was restored to part of the Secondary Containment boundary) and decided that it was permissible to override the X-Area interlock doors by using an emergency manual push-button without first stopping to question when conditions were not as expected.
A contributing cause of this event was a lack of procedural guidance that would communicate to RP the restoration of the X-Area to service. The procedure required communications (i.e., Signoffs) to Operations and to Engineering. However, the procedure did not require RP to be notified of the restoration.
D. Safety Analysis:
The Secondary Containment interlock doors were open for approximately fifteen minutes. Based upon the number of individuals present at the interlock that were capable of closing the interlock, and that the Secondary Containment differential pressure remained negative during the course of this event, this event is of low safety significance.
E. Corrective Actions:
As a result of this event, the station has completed or is planning to complete the following:
1. Performance management of the RPT involved in this event has been completed.
2. A Stand-Down with the RP Department, discussing this event, was completed.
3. An action was created for each RP employee to review human performance procedures.
4. Conducted a discussion with RPTs on how the U2 X-Area interlock doors work in order to verify understanding of the door operations.
5. Established requirement for additional briefs for X-Area entries.
6. Add additional communications to the station procedure for removal and restoration of the X- Area from service.
F. Previous Occurrences:
The station did not find previous occurrences over the past two years that specifically related to an event where an individual manually defeated interlocks.
G. Component Failure Data:
N/A