# Presentation: 200135

## Line Breaks

- Steve Raftopoulos
**D&D Lessons Learned Workshop**
**June 25-26, 2002**
**PPPL**

## What is a Line Break?

- At PPPL, a **line break** is any operation that breaks into the nuclear boundary.
- The **nuclear boundary** is defined as the combined systems that provide primary containment of tritium.
- Since the nuclear boundary was being continually changed during the D&D project, documentation that had been relied upon for years, was no longer current.
- Extra diligence during the planning and engineering phases was critical to ensure that proper **(SAFE)** actions were taken.

## Types of Line Breaks

**Heavily contaminated pumpable spaces.**
**Heavily contaminated non-pumpable spaced**
**Lightly contaminated pumpable and non-pumpable spaces.**
**Line breaks involving oils.**
**Line breaks involving particulates.**

## Elephant Trunk System

- Extension of the building HVAC.
- Provides 3”, 6” or 12” diameter, flexible hose that draws air (and airborne contaminants) away from worker breathing zone.
- Effluents pass through HEPA filters before being released to stack.
- Stack monitors measure tritium being released, actions taken as necessary.

## Tritium Bubbler

**Relies on exchange of HTO with H****2****O for ~ a 10:1 reduction in airborne HTO tritium levels.**
**Refrigerant dryer at output end “wrings out” tritiated water vapor from exhaust stream, releasing ~40****o**** dew point air.**
**Output can be directed to stack or to the Gas Holding Tanks (GHT), depending on tritium concentration.**
***Has been used as the long-term cleanup system on the TFTR neutral beam boxes.***

## Oil Change Carts

- Used to remove and/or refill the oil from our vacuum pumps.
**Uses kegs to collect or feed oil from/to pump.**
- Pressure or vacuum is used as the motive force.  Mechanical equipment (and associated headaches) are eliminated.
**Pumps must be fitted with a means of connecting **
- PPPL has installed “quick disconnect” fitting on all the vacuum pump sumps.
***Separate carts are available for hydrocarbon and fluorinated oils.***

## Pump/Purge Carts

- Used to transfer tritium from various systems to the Torus Cleanup System (TCS).
**Incorporate a calibrated volume that’s used for assaying and calculating total tritium.**
- Incorporate vacuum pump(s) for moving the gasses.
**Two versions were available:**
- One design with a vane pump capable of evacuating to 10-3 torr.  This was used during TFTR operations to restore vacuum to operational levels.
- Second design with a bellows pump **(*****Oil**** ****Free*****)** that was used on highly contaminated systems and during D&D.
**Must have service ports on the systems to be able to connect the carts.**

## Heavily Contaminated Pumpable Spaces

- Pump/Purge method
**Typical system**
- Vacuum systems
- Tritium handing systems (Tritium Storage & Delivery System [TSDS], Tritium Purification System [TPS])
- Anything that can hold a good vacuum and has some type of access/service port.
**Methodology**
- Isolate the line break volume
- Using pump/purge cart, repeatedly evacuate and backfill the volume.  Evacuation does not have to be to “high vacuum” standards.  Effluents directed to the GHT or TCS (via tritiated vent).
- Backfill is with room air.  The moisture in the air does the work, therefore the humid New Jersey air is very effective.
- Elephant trunk ventilation set up for worker protection.
- Tritium concentration measured.  Concentration x Volume = total tritium, and is used in the decision making process.
- Line break(s) performed.  Caps & blank flanges are available to seal openings ASAP

## Heavily Contaminated Non-Pumpable Spaces

- Flow Purge method
**Typical system**
- Tritium levels too large to allow purging to stack via HVAC.
- Very large volume systems (vacuum vessel, TFTR vacuum roughing/backing lines, etc.)
- Tritium handing systems (TCS, waste gas systems)
- Anything that cannot hold a good vacuum.
- Systems without access/service port.
- Must have connectivity with the TCS
**Methodology**
- Isolate the line break volume.
- Establish valve lineup to TCS or the GHT.  Connecting piping may have to be installed.  Effluents directed to GHT.
- Open system and establish flow to the GHT.
- Purge until tritium concentrations are lowered enough to allow either:  Line breaks to commence or to allow switchover to stack purge.
- Elephant trunk ventilation set up at line break point(s) for worker protection.
- Line break(s) performed.  Caps & blank flanges are available to seal openings ASAP.

## Lightly Contaminated Pumpable and Non-Pumpable Spaces

- Flow Purge method
**Typical system**
- Tritium levels low enough to allow purging to stack via HVAC.
- Very large volume systems (TFTR, TFTR vacuum roughing/backing lines, etc.)
- Systems that were heavily contaminated, but have undergone tritium reduction and are now at low levels.
**Methodology**
- Isolate the line break volume.
- If necessary, establish valve lineup to allow flow purge through the entire system.  May have to remove flanges from “dead legs”.
- Open system and establish flow to the Elephant Trunk.
- Purge until tritium concentrations are lowered enough to allow line breaks to commence.
- Elephant trunk ventilation set up at line break point(s) for worker protection.
- Line break(s) performed.  Caps & blank flanges are available to seal openings ASAP.

## Line Breaks Involving Oils

- Typical systems:
- Vacuum pumps
- Vacuum piping
- Methodology:
- Remove oil from pumps using the oil change cart.
- Drill holes into large diameter piping and inspect with boroscope.
- Set up ventilated enclosure around line break point(s).
- Ensure that oil absorbing media (pads, petroset, rags) are available.
- Ensure that caps or blank flanges are available for immediate use after line break.
- Perform line break(s), solidify oils, foam fill piping, cap open ends.

## Line Breaks Involving Particulates

**Typical systems**:
- Molecular sieve beds.
- Graphite lined vacuum vessel (DWC process).
- In-vessel entry.
**Methodology:**
- Protect the workers!!!  The appropriate PPE is selected.  PPE has ranged from Tyvek suits/half face respirators, to double PCs/supplied air breathing systems.
- If possible, stabilize the  particulates.  This was done using foam for the pump ducts, and with concrete for the vacuum vessel.
- Use of filtration systems.  We used a closed-loop, industrial filtration system during TFTR DWC to capture the  particulates generated during the segmentation process.
- If proper precautions are taken, these become routine line breaks.

## Examples of Lines Breaks with Combined Hazards

- Roughing/backing lines up against the test cell basement ceiling.  Oil from the vacuum system pumps was a major concern.
- Holes were drilled in strategic locations.  Boroscope inspections were performed.
- Elephant trunk drew air through pipes from the opposite (far) end.
- Technicians were prepared to deal with oil, even though we did not find any during inspections.

- TFTR vacuum pumping duct.  Dust, from graphite tiles, was major concern.
- Technicians filled duct with expanding foam, stabilizing the airborne contaminants.

## “Snatch and Cap” Line Breaks

- Term given to line breaks involving component removal from the TFTR Vacuum Vessel.
**Vacuum Vessel was put into purge mode by connecting an elephant trunk to a 12” port.  Whenever a flange is removed, air flows into that opening.**
- Aluminum blank flanges were used (inexpensively fabricated via water jet cutter) to replace the conflat and custom TFTR port covers.
**Gore-Tex rope-gasket material was used to make seals.**
- Once the Vacuum Vessel was in purge mode, several ports could be replaced in one day’s effort.

## Conclusion/Lessons Learned

- Line breaks can be **successfully and safely** accomplished with the proper system in place.
- At PPPL this system includes:
- Engineered hardware;
- Trained, skilled personnel;
- Strict adherence to PPPL and DOE procedures and protocol.