Mobile Drum Venting and Hydrogen Gas Sampling Equipment

The mDVS is housed in a custom-built commercial cargo trailer that is separated into two areas:  (1) A Test Compartment, in the rear of the trailer, where waste drums are vented and; (2) An Operating Area, toward the front of the trailer, where the Control Station and Analytical Equipment are located and operated.  The Test Compartment and Operating Areas are separated by a partition wall equipped with gloveports that isolates the Operator from the Test Compartment. In addition, an Equipment Compartment located at the front of the trailer houses the air compressor and the analytical system and Continuous Air Monitoring (CAM) system vacuum pumps.

Mobile Drum Venting System

The Test Compartment, located in the rear of the trailer, is where waste drums are vented. Drums are queued onto an incoming conveyor and taken inside of the trailer where the venting and sampling process occurs. “Cold Drilling” uses software to start and stop the drill motor regularly during the drilling cycle to decrease the heat generated during drilling.  The Powerhead performs the “cold drilling” and sampling process in an enclosed Seal Housing, preventing the escape of headspace gas.  Testing for an adequate vacuum seal is performed prior to drilling.  During the “cold drilling” and sampling process, a NucFil-007 series filter is installed. The specific filter length is chosen to penetrate the drum lid and any liner present in the drum.  The patented drum vent filters provide maximum hydrogen permeability and ensure exclusive headspace gas sampling and analysis from within the liner (a WIPP requirement).  For drums without liners, a NucFil-007S is installed.  The NucFil-007S is identical to the standard NucFil-007 except it has a shorter drill stem.  For 85-gallon overpacked drums, the NucFil-007LS (long stem) is used, which penetrates both drum lids as well as any inner liner.

Seal Housing and Installed Filter		NucFil-007LS, 007, and 007S

		The Operating Area consists of the Control Station and Analytical Equipment. The Control Station includes an Operator Interface Terminal (OIT) and a digital scale display. There is also a Programmable Logic Controller (PLC), used to sequence the drum handling, automatic “cold drilling”, and sampling process.  The PLC and associated hardware are powered by a dedicated 24 VDC power supply in the main control panel.   The device used for analyzing hydrogen concentration in each drum is a Shimadzu GC-14-BPDT Gas Chromatograph.
Operating Area

After sampling and filter installation, metal filings are vacuumed from around the filter and radiological surveys of the drum, drum lid and filter are performed. Silicone sealant is applied to the filter o-ring and the drum exits the Test Compartment on a second conveyor, completing the drum venting process.

Contracting Approach

A fast-track project has inherent risks and is not the preferred method for these type of procurements. When this is the only option, there are things that can be done to minimize the risk and exposure of both companies. The following is a list of actions taken to minimize risks:

• Make sure that both parties understand the scope and deliverables.
• Enhance regular communication, including site visits and documented telephone conferences.
• Require quick turnaround on decisions/submittals.
• Expect challenges on design/build turnkey projects.
• Consider the experience/expertise of the contractor.
• Perform extensive testing in the shop as well as in the field prior to startup.
• Learn from others (LANL, NFT-SR, INEEL).
• Lock the Safety Basis in as soon as possible.  A delay in the mDVS was caused because the Safety Basis had not been finalized prior to the contracting process.  (The finalized Safety Basis required a barrier that had not been mandated in the contract, which resulted in having to use a remote unit to vent the drums).
• Instill the attitude of doing work right the first time.  Schedule was critical on a project like this. A specific lessons learned involved making certain that design submittals were accurate and compliant with project requirements to reduce the number of review cycles. Significant time and cost were expended trying to speed through incomplete design submittals.