ENS 42981
ENS Event | |
|---|---|
23:30 Nov 9, 2006 | |
| Title | Hydrogen Accumulation Due to Loss of Water Seal |
| Event Description | On 11/9/06 at 0210 hours0.00243 days <br />0.0583 hours <br />3.472222e-4 weeks <br />7.9905e-5 months <br /> the Dry Conversion facility line 1 began starting up. At 0230 hours0.00266 days <br />0.0639 hours <br />3.80291e-4 weeks <br />8.7515e-5 months <br /> the fire alarm actuated in the Dry Conversion facility. Upon investigation, AREVA operations personnel discovered at approximately 0240 hours0.00278 days <br />0.0667 hours <br />3.968254e-4 weeks <br />9.132e-5 months <br /> that the Hydrogen detector in the HF [hydrogen fluoride] Recovery room had tripped. Operations personnel immediately shutdown the process system. Operations personnel discovered that there was no water plug in the drain P-trap from the exhaust. Therefore, H2 from the reactor and calciner offgas leaked through the drain into the room with H2 enough to the point of setting off the H2 detector which has a set point of 20% of the LEL [Low Explosive Limit]. Hand held readings were taken and determined to be approximately 7% of the LEL at the lower elevation in the room to 25% of the LEL near the ceiling of the room.
AREVA operations personnel contacted Environmental Health and Safety to determine the safety significance of the event. After reviewing the ISA for this system, EHS&L personnel deemed at approximately 1530 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.82165e-4 months <br /> that the analysis of this system configuration meets the 24 Hour Reporting Criteria, 'Any event or condition that results in the facility being in a state that was riot analyzed, was improperly analyzed, or is different from that analyzed in the ISA and which results in failure to meet the performance requirements of 10CFR 70.61.' Evaluations determined that it is possible that enough H2 gas could have filled the room to cause an explosion in the HF Recovery room potentially causing a rupture of the HF holding tanks and piping. If an operator were present (this room is occupied approximately 5 to 10 times a week for 10 to 15 minutes each time) at the time of the explosion, it would be possible for the operator to receive sufficient injuries from HFA exposure to potentially make this an intermediate or high consequence event. Although this system has an H2 detector which, actuates a fire alarm, it is not designated as an IROFS. The process equipment associated with this scenario is still shut down and will remain shut down pending establishment of sufficient IROFS to meet the performance criteria of 10CFR 70.61. All other systems with the potential for H2 gas leaks are being re-evaluated to ensure that the performance criteria of 10CFR 70.61 is met. The material in the identified system that is in the tanks that could spill onto an operator is HF solution with trace amounts of Uranium. Safety significance is low. The HF Recovery, room is not normally occupied during operation, and then for only short periods of time (this room is occupied approximately 5 to 10 times a week for 10 to 15 minutes each time). There is no potential of an accidental nuclear criticality in the as found condition. The process equipment associated with this scenario is shut down and will remain shut down pending establishment of sufficient IROFS to meet the performance criteria of 10CFR 70.61. Related process systems that might have a similar potential are under evaluation to ensure that the same potential does not exist in these areas. The licensee will notify NRC Region II. |
| Where | |
|---|---|
| Areva Np Inc Richland Richland, Washington (NRC Region 2) | |
| License number: | SNM-1227 |
| Reporting | |
| Part 70 App A (B)(1) | |
| Time - Person (Reporting Time:+-2.03 h-0.0846 days <br />-0.0121 weeks <br />-0.00278 months <br />) | |
| Opened: | Robert Link 21:28 Nov 9, 2006 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Nov 9, 2006 |
| 42981 - NRC Website | |
Areva Np Inc Richland with Part 70 App A (B)(1) | |
WEEKMONTHYEARENS 517572016-02-25T19:45:00025 February 2016 19:45:00
[Table view]Part 70 App A (B)(1) Potential Common Mode Failure of Item Relied on for Safety ENS 483662012-10-02T14:30:0002 October 2012 14:30:00 Part 70 App A (B)(1) Unanalyzed Conditions May Lead to Intermediate Consequence Events ENS 479082012-05-08T14:30:0008 May 2012 14:30:00 Part 70 App A (B)(1) Improperly Analyzed Condition ENS 449972009-04-16T23:00:00016 April 2009 23:00:00 Part 70 App A (B)(1) Unanalyzed Condition Due to Possible Unfavorable Geometry ENS 432342007-03-13T21:30:00013 March 2007 21:30:00 Part 70 App A (B)(1) Potential Hazard Affecting Criticality Controls Discovered ENS 429812006-11-09T23:30:0009 November 2006 23:30:00 Part 70 App A (B)(1) Hydrogen Accumulation Due to Loss of Water Seal ENS 429362006-10-23T17:50:00023 October 2006 17:50:00 Part 70 App A (B)(1), Part 70 App A (B)(3) Workers Exposed to Hydrogen Floride Release 2016-02-25T19:45:00 | |