# Presentation: 895620

## Natural Gas Deflagration within an Electric Firewater Pump Controller

**Los Alamos National Laboratory,      **
**TA-55 Plutonium Facility **
**Presented by Dan Carter, Facility Representative at TA-55**

## Event Summary

**While performing a monthly Firewater Pump Surveillance a small natural gas deflagration event occurred within the firewater pump controller and adjacent conduit box. **
**No personnel were injured, however, pants had to be changed**
**The event was reported as a Significance Category 2 Management Concern  **

## Firewater Pump Controller

**Firewater Pump Controller**

## Immediate Actions

**The controller was immediately deenergized**
**Operation Center was notified**
**Initially the event was thought to have been an electrical breaker “Arc Flash” **
**Upon inspection a smell of natural gas was noted**
**The building was evacuated and ventilated**
**Natural gas was isolated to the fire water pump house**

## Slide 5

## Slide 6

## Description of Events

**The smell of natural gas was noted coming from the conduit box feeding power to the controller**
**No natural gas was detected in building PF-6, the electrical sub-station supplying power to the fire pump**
**Electrical and Maintenance personnel were consulted and recalled that an electrical pull box had been installed between PF-6 and the fire water pump house**
**Utilities personnel probed the soil around the electrical pull box and detected natural gas **
**The gas supply to the facility was isolated**

## Slide 8

## Slide 9

## Electrical Supply Line

**Electrical Supply Line**

**Gas Supply Line**

**Fire water pump house**

**Electrical Pull Box**

## Description of Events, continued

**The gas supply to an adjacent building was within 20 feet of the pull box**
**Utilities personnel excavated around the gas line and identified the gas leak**
**The leak was repaired**
**During the excavation, an additional broken  electrical communication conduit was identified **

## Slide 12

## Slide 13

## Background Information

**Pot holing activities and ground freeze-thaw cycles are believed to have initiated the gas leak**
**Gas leakage permeated horizontally underground due to the ground surface being frozen**
**Neither the electrical pull box nor the electrical communication conduit were indicated on plant drawings**
**Neither the electrical pull box nor the conduit entering the pump house were sealed as required by the National Electric Code**
**Natural gas was believed to have been leaking underground for at least a month**

## Corrective Actions/Lessons Learned

**Inspect and Seal all conduits to all buildings**
**Utilities will conduct a Gas Line Survey to identify any additional unknown code deficiencies or valve location concerns**
**Pot holing procedures will be modified to ensure that holes are backfilled within 24 hours and that pot holing activities are coordinated with the Operation Center**
**Facility drawings will be updated to reflect as-built piping/conduit configurations**
**Ensure electrical cabinets are properly secured and sealed to prevent personnel injury**

## Any Questions

**If you have any questions in the future please contact Dan Carter at:**
- 505-606-1883
- dcarter2@doeal.gov