ENS 51070
ENS Event | |
|---|---|
20:00 May 14, 2015 | |
| Title | Unanalyzed Condition Due to Excessive Toxic Chemicals Onsite |
| Event Description | On May 14, 2015, it was determined that the number of 55 gallon drums of 2-Butoxyethanol analyzed to be transported and stored within the owner-controlled area (OCA) at any one time had been exceeded. It was discovered that contrary to the toxic gas analysis performed, fourteen 55-gallon drums of 2-Butoxyethanol were transported and stored in the OCA to support the construction of a dome being built to provide storage for FLEX equipment. The number of drums exceeded the limitation specified in the toxic gas analysis performed as part of the design project for transportation and storage could potentially impact Control Room habitability, emergency diesel generator air intake and have an adverse impact on security personnel.
Upon determination that an unanalyzed condition existed, Operations placed the control room ventilation system in the 'isolation mode' until the number of drums on-site was reduced within the analyzed number. A substantial covering had been placed over the drums which also decreased the likelihood that any of the drums would fail and would also limit the potential dispersion of chemicals should a breach occur. The excess number of drums of 2-Butoxyethanol being transported and stored on-site is considered an unanalyzed condition that significantly degraded plant safety and is reportable in accordance with 10CFR50.72(b)(3)(ii)(B). The allowed number of 55 gallon drums of 2-butoxyethanol allowed per the current toxic gas analysis is 4 drums. The number of drums has been reduced to 2 as of 2024 EDT. The licensee has notified the NRC Resident Inspector.
Further investigation into the chemicals transported on-site (F183M, of which 2-Butoxyethanol is a component) revealed that an on-site spill of all fourteen 55-gallon drums will not adversely affect Main Control Room Habitability, Security Personnel, or the Emergency Diesel Generators (EDGs). The Control Room Habitability Determination flowchart in Attachment 3 of NMP-CH-002-002 establishes a 10 mmHg vapor pressure threshold for determining if chemicals need to be evaluated for impact on the Main Control Room. Chemicals with a vapor pressure less than 10 mmHg do not need to be evaluated for control room habitability. The basis for the threshold is found in Reg Guide 1.78 Revision 0 section C.5.a, 'For chemicals that are not gases at 100F and normal atmospheric pressure but are liquids with vapor pressures in excess of 10 torr (10 mmHg), consideration should be given to the rate of flashing and boil off to determine the rate of release to the atmosphere and the appropriate time duration of the release.' The individual chemical component (including 2-Butoxyethanol) vapor pressures are less than 10 mmHg. As their vaporization rate is too low to adversely affect Control Room Habitability, it is also too low to create a hazard for Security personnel or to adversely affect the Emergency Diesel Generators. Based on this information, the transportation and storage of these chemical barrels did NOT represent a condition that significantly degraded plant safety. As such, this condition has been determined to no longer meet reporting requirement 10CFR50.72(b)(3)(ii)(B) and is therefore NOT reportable. Based on this information the previous notification for Event 51070 is being retracted. The licensee notified the NRC Resident Inspector Notified the R2DO (McCoy). |
| Where | |
|---|---|
Hatch  Georgia (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+3.03 h0.126 days <br />0.018 weeks <br />0.00415 months <br />) | |
| Opened: | Guy Griffis 23:02 May 14, 2015 |
| NRC Officer: | Jeff Rotton |
| Last Updated: | Jul 8, 2015 |
| 51070 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 526502017-03-30T13:22:00030 March 2017 13:22:00
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