Note: All papers from 2017 as well as the 2018 WM Conference papers pertain to robots that were predecessors to our current RadPiper robot. Currently, we have news articles pertaining to RadPiper, and will have more papers to come shortly.
WM Conference 2018 Papers
This research exploits in-pipe access to develop robotically deployed, high-cadence, accurate, certain, paperless assay of U-235 in holdup deposits within process piping. Prior radiometric assay from outside the pipes suffered from manual deployment challenges, attenuation of detection through pipe walls, long counting times, approximate modeling, and shortfalls associated with transcription and human interpretation. These downsides limited the speed, quality, and economy of assay resulting in vast cost and budget consequences to D&D. D&D of outdated facilities cuts into these pipes as part of the demolition process, creating the unique, previously unexploited possibility of robotic in-pipe assay.
The assay collimates radiation emanating from all but a short segment of pipe wall from reaching a gamma detector. Hence, the detector only views and measures source from a short segment of pipe at a given time. This is achieved by an innovative pair of collimating discs that are coaxial with the pipe and positioned fore and aft of the detector.
The detector assembly is translated through pipes by an autonomous mobile robot. Beyond radiometric assay of U-235, the robot images and geometrically models the pipe interior and deposit appearance. The robot is recovered from the same pipe opening from which it is launched, hence it drives the same distance out and back, measuring the same deposits twice. This achieves redundant radiometric and odometric measurements which adds further to statistical significance of the method.
During D&D of old gaseous diffusion uranium enrichment facilities, radiometric assay of U-235 holdup in pipes is a costly, time consuming, and labor-intensive process. Subject to human interpretation using approximate modeling, radiometric assay introduces significant challenges. Taking advantage of routine demolition activities in which D&D cuts pipes open, robotic in-pipe assay is explored. The novel method introduced here generates models of the internal pipe and deposit surface geometries that are used to derive volumetric quantities. The pipe surface is sensed using a non-contact inductive proximity sensor and the deposit surface is sensed using an optical laser triangulation sensor. These sensors are mounted on a spinning disk and driven down the pipe to construct a helical point cloud of discrete measurements. Surfaces are fit to each of the two point clouds to create a watertight volume that represents the holdup. This provides the location and volume per foot of pipe that is used to compare against criticality incredible (CI) thresholds during evaluation. The robotic system collects data autonomously, deploying and returning to the same pipe opening from which it is launched. This provides redundant measurements of the pipe and deposit surfaces as well as odometry used in localization.
Measurement of U-235 in pipes within old uranium enrichment facilities is time-consuming and very costly. Radiometric assay from outside the pipes suffers from manual deployment challenges, attenuation of detection through pipe walls, long counting times, approximate modeling, and shortfalls associated with transcription and human interpretation. The D&D process of cutting into these pipes creates a unique possibility of robotic in-pipe assay to address these problems. This paper presents the results of testing a first-of-kind radiometric non-destructive assay (NDA) robot for high-cadence, accurate, certain, paperless assay of U-235 in holdup deposits within process piping. The robot’s enabling capability is an innovative radiometric collimation method that views only a one-foot moving annulus of pipe wall. This exploits the internal axisymmetry of pipes to provide a direct measurement of industry-standard grams per foot U-235.
The initial proof-of-application robot was successfully hot tested by operators at the Gaseous Diffusion Enrichment Facility in Piketon, Ohio, in late 2017. This testing achieved all goals of traversing pipe, measuring U-235, deployment by facility personnel, and displaying analyzed radiation, visual, and geometric information. The success was a Kitty Hawk moment. The system demonstrated robotic in-pipe measurement of holdup deposit to a resolution, accuracy, and speed unachievable by alternate methods.
Hot Test 2017 Results
A team from Carnegie Mellon University and University of Nevada, Reno developed two robots for evaluation of holdup deposits in deactivated gaseous diffusion piping. The effort was supported by DOE EM. Facility expertise throughout development, as well as robot operation at the DOE Portsmouth site, was provided by Fluor-BWXT. The RadPiper robot conducts radiation-based assay. The PipeDream robot conducts volumetric deposit characterization. Both robots were demonstrated in tests conducted at the DOE Portsmouth site on 19 and 20 September 2017. An additional test of the RadPiper robot was conducted on 17 October 2017. Results from these tests are presented below, with RadPiper discussed first, followed by PipeDream.
WM Conference 2017 Paper
Automation capabilities that enable communication-denied nuclear robotic operations have come of age. These layer over tethered operation or enable untethered systems for some operations. Teleoperated, tethered devices are traditionally preferred for nuclear remote systems. The tethers provide comm, power, and a means for mechanical extraction - especially for nuclear operations. Tethers, however, are the bane of some mobile operations, since long tethers restrict mobility, tethers are failure points, and some circumstances preclude mechanical recovery by tether. Tethering has superb advantages where it is viable, but a subset of nuclear EM challenges compel mobile remote systems that forgo tethering. Tethering was essential at a time when autonomy or wireless comm could not accomplish viable operations. The possibility now is an emerging class of untethered exploration and service robots that are compelling for situations where tethers compound waste and exposure, or are not viable. Technical advances in localization, modeling, planning, autonomy, integration and reliability have made it possible to augment tethered operations or operate altogether without tether in selective operations. Tether preclusion technologies include localization, perception, navigation, safeguarding and task prescription. These effectively accomplish tasks like waypoint following, wall-following, coverage patterning, navigate-to-goal, next-best view and many others. Although these are not yet general for the broad agenda of the nuclear complex, these are already useful for many operations. These are a foundational base that can be built upon over time for more complex operations yet to come. As a context and analog study, the technologies are exhibited by robotically (without tether) modeling a coal mine with tracks and train car. This is analogous to technology and operation that might apply for inspection of waste storage at WIPP or the PUREX tunnels. Autonomous exploration of this nature is within state-of-art and possible with or without tether. Even simple autonomy like wall-following and waypoint following prescriptions succeed in operations of this type.