West Valley’s MPPB: 3D model proves instrumental for disposition

A fork truck removes a vent washer from the Main Plant Process Building at the West Valley Demonstration Project. (Photos: DOE)

The MPPB is a five-story, 1960s-era concrete structure that was used for the dissolution and preparation of irradiated nuclear fuel to recover usable nuclear materials. Historical activities in the MPPB left the facility radiologically contaminated. Some hazardous items, such as asbestos-containing materials and lead, are also present in some locations. A small number of the original components and vessels remained for removal during demolition.

Accurate depiction of the structure, sensitive components, and high-dose areas were identified early in the demolition planning process. This was crucial in helping to ensure a safe and compliant demolition.

The team accomplished this through a detailed engineering effort that culminated with the generation of a 3D model that precisely located all areas and components within the structure. The model became a valuable tool for the company as it planned daily demolition activities with crews.

Demolition history

On October 1, 1980, President Carter signed the West Valley Demonstration Project Act (WVDP Act), which provided a roadmap for cleaning up the site. The WVDP Act authorized the U.S. Department of Energy to demonstrate the solidification of approximately 600,000 gallons of high-level radioactive waste left behind at the site from reprocessing operations. The WNYNSC is owned by the New York State Energy Research and Development Authority (NYSERDA), with the DOE given temporary possession of approximately 200 acres referred to as the “Project Premises” to complete their responsibilities under the 1980 legislation.

The demolition of the MPPB was a contractual obligation with the DOE’s Office of Environmental Management and reflected the culmination of years of discussion, planning, and preparation. CH2M HILL BWXT West Valley (CHBWV), the prime contractor at the site, is overseeing the removal and disposal of the MPPB to the grade-level floor slab. Structures that extend below the grade level are scheduled for removal in a follow-on contract.

Since the 1990s, more than 7 miles of contaminated piping and more than 50 tons of contaminated equipment and debris had been removed from the MPPB. Workers also reduced the building’s total inventory of radiologically contaminated material by 98 percent and removed seven facilities surrounding the MPPB.

Development

WVDP workers use the site’s 3D model at pre-job briefings each workday to prepare for demolition activities.

In the planning phase of the demolition, the engineering team assigned to demolition realized that the number of drawings needed to be analyzed to successfully plan the engineered demolition would be immense. Engineers needed to evaluate the MPPB’s walls, components, structural members, and obstructions. The engineering team analyzed the structural integrity of the building to maintain stability when performing demolition, and so the safest demolition sequence needed to be considered. To assist in not only the planning phase of demolition but also the day-to-day execution of the work, on-site engineers from CHBWV worked with a contracted company to develop a 3D model of the facility.

Thousands of original construction drawings were referenced to create 3D models of over 80 individual cells that make up the MPPB using Bentley Navigator V8i software. The drawings referenced were original construction drawings created by Nuclear Fuel Services (NFS) from the 1960s. The photocopies of the drawings made them difficult to read in some instances, so gaining access to the original drawings was sometimes necessary. Despite using original drawings, deciphering the dimensions, details, call-outs, or line numbers was at times problematic because of the age of the materials. Due to the number of drawings and amount of information requiring interpretation and transfer, the process of creating the 3D model of the MPPB took approximately two years to complete. Each drawing was recorded on a reference drawing spreadsheet that could be linked to the model via nodes for future reference to show more details if needed. Engineers reviewed each cell model that was developed to ensure accuracy in the model.

Implementation

“The implementation of the 3D model proved successful due to various elements the model provided that aided in the demolition of the MPPB,” said Tom Dogal, CHBWV facility disposition manager.

Each one of the following subsections explain different aspects of the 3D model that contributed to the success and ease of the 3D model at WVDP during the MPPB demolition:

Layers

Fig. 1. A schedule of the various layers for one cell area.

“The model was generated to give each cell model individual layers that segregated concrete, steel, piping, hatches, doors, specialty equipment, and asbestos-containing material (ACM), which is a hazardous material,” said Dogal.

The individual layers within each cell model (Fig. 1) gave engineers and planners the ability to simulate the demolition sequence and create renderings outlining the potential hazards or specialty equipment that needed specific handling or packaging requirements. That information was then used to develop the demolition sequence and special instructions in the work instruction package.

“To enhance safety and controls, the individual layers could also be used to isolate a particular area of interest focusing on a specific cell or problematic pipe or piece of equipment requiring special handling,” said Scott Chase, CHBWV deputy facility disposition manager.

Volumes

Fig. 2. The 3D model allows for the estimation of the volume of areas of the building. Here, the volume of a concrete slab is found, ensuring that that adequate waste disposal resources are available once demolition begins.

Using the model, the volumes of each cell’s concrete, piping, ACM, and steel can be obtained.

“This proved to be a more accurate way of estimating waste volumes compared to using general calculations,” said Neil Armknecht, CHBWV lead planner and engineer. “It also led to the development of a series of ‘protected assumptions,’ or limiting conditions, that were integrated into the work instruction package, such as demolition time durations for specific areas. This ensured the demolition project progressed safely and in compliance with regulatory parameters.”

Using the model, engineers used the volumes of the waste as well as the contamination levels/characterization and assigned a minimum time duration on every cell of the MPPB as one way to manage airborne contamination levels during the demolition of the cells. The volumes could also be used to approximate the number of waste containers needed to complete the project (Fig. 2).

Measurements

Fig. 3. In addition to volumes, estimated linear measurements, such as those here for a waste catch tank, can be made to make the demolition process faster and more accurate.

The measuring tool within the 3D model was useful for planning MPPB demolition. Measuring reach requirements for heavy demolition equipment can be determined using the 3D model. Distance between areas of concern can also be easily determined. Thickness of walls, lengths of pipe or steel members, and elevations and distances between penetrations can be determined within a few moments on the computer, increasing workflow and decreasing downtime referencing cumbersome amounts of cross-referenced drawings (Fig. 3).

Transparency

Fig. 4. This transparent rendering of the 1C sample station allows for better planning of demolition as crews can see what’s behind otherwise opaque materials.

Because each individual cell model had been created by segregating various components with layers, each individual layer within each individual cell can be made transparent.

“The walls can be made transparent to show how they interact structurally with an adjacent wall, or to show embedded piping or vessels that require special handling or contain ACM,” said Dogal. “This helped our crews ‘see’ inside the building during pre-job briefings before starting demolition.”

There were more than 120 items requiring special handling and packaging, such as the vent washer, weighing approximately 6,803 kilograms (15,000 pounds), uranium load-out vessels 5D15A and 5D15B, weighing approximately 8,164 kg (18,000 lbs.) and 6,350 kg (14,000 lbs.), respectively, and the 1C sample station, weighing approximately 39,462 kg (87,000 lbs.) (Fig. 4).

“The model was used to show in detail where the items are located and give the crews a visual aid to better understand how they would be handled. The transparency function can also show heavy equipment operators what they will encounter during that step in demolition that day, including starting and stopping points and obstructions or hazards,” said Chase.

Nodes

Fig. 5. A rendering showing a node linked to a drawing set.

Fig. 6. A rendering used in a work instruction package showing where cuts are to be made and in what order.

A node is a feature in which you can link references to locations within the model. The nodes can reference any piece of information you would like to be referenced in PDF form, such as a radiological survey or a picture, as an additional reference. Nodes embedded within the model can link to original construction drawings and details as well as engineering change notices of work performed in the area (Fig. 5).

Renderings

The renderings produced were very beneficial in terms of communication among work groups and to the public. For anyone who doesn’t regularly transcribe engineering drawings, renderings are a nice visual aid that represents a large amount of engineering drawings all in one easy-to-interpret illustration. Renderings produced by the 3D model were used in the development of the MPPB work instruction package and inserted as figures as well as other work instruction packages approved to work on site (Fig. 6).

Renderings were used to enhance CHBWV’s communication efforts before and during the demolition. With the help of an off-site contractor, the renderings were used to create a five-minute animation of how the plant would be taken down safely and compliantly. CHBWV found that the animation proved to be an excellent communication tool as it combined audio, visuals, graphics, and text to help improve understanding and comprehension. Renderings were also used in public meeting presentations to show demolition progress.

Conclusion

“The 3D model became an indispensable tool for demolition safety,” said Jason Casper, CHBWV president and general manager. “Hazards could be highlighted and discussed with a visual representation showing what real-life conditions could be. The model provided a better way to communicate to the workforce about the scope of the work.”

The 3D model provided a more accurate way to plan demolition and more accurately estimate waste volumes. From the start of MPPB demolition, the model had been used every day to show the first and second shift their scope of work for the day, highlighting penetrations, landmarks, and areas of concern during daily pre-job briefings. It also aided in communicating to the public when showing demolition progress during public meetings.

David J. Smith is a planner and Joseph T. Pillittere is a communication manager with CH2M HILL BWXT West Valley.