Confined Entry Nuclear Canister Inspection Rover(CENCIR)

Researcher: Qingtian Chen & Jonathan Liu Mentor: Professor Jizhong XiaoRobotics Lab, City College of New York

Application Scenarios- Over 1500 welded stainless steel dry storage canisters loaded with spent fuel in the U.S. and approximately 200 additional canisters being loaded each year

- Canisters provide the primary confinement barrier to prevent release of radionuclides into the environment

- Chloride Induced Stress Corrosion Cracking of stainless steels is possible

Specific FeaturesThe climbing robot employs vacuum pads with a non-perfect vacuum seal. This design allows for:

1) a higher degree of flexibility for curve and uneven surfaces2) handling both convex and concave surfaces3) operation in all orientations4) tolerating small leaks5) passing over small obstacles, such as welds, protruding bolts, and the edges of internal cask cladding

This gives the rover greater maneuverability compared to both magnet-ic and suction cup style climbing systems.

Technical ChallengesThe surface of the canisters needs to be inspected for defects such as stress corrosion cracking, corrosion pitting, and leakage of internal helium. Major challenges of the robotic delivery system include:

1) traversing the narrow and tortuous vents2) scaling vertical surfaces and traversing gaps3) moving around obstacles (e.g. support beams, corners, bolts, & welds)4) moving from inner to outer surfaces5) inspecting the container surface inside narrows gaps (2.5˝ - 4˝)6) radiation shielding, high temperature (50-80 °C), dusty surfaces

Conceptual DesignCENCIR provides a remotely operated system that is capable of de-livering a NDE package which can effectively inspect the canister sur-face. Our design consists of two vacuum chassis connected by a motor controlled hinge. This allows it to move around corners, span gaps, or transition between inner and outer surfaces. The robot folds in order to get through tight sections of the vent or tortuous pathways. A flexible power/communications cable allows for the rover to be safely deployed and operated from a distance which eliminates the exposure of opera-tors to radiation.

Project GoalThis project aims to design and test a robotic delivery system for on-site in-situ non-destructive evaluation (NDE) of dry storage casks used to store spent nuclear fuel. These dry storage casks consist of in-ternal stainless steel canister covered by the concrete over-pack, and require periodic inspection of the canister integrity in order to ensure safe and long term storage. The Confined Entry Nuclear Canister In-spection Rover (CENCIR) is designed to traverse through tight spaces inside storage casks in order to inspect the canister surface in hazard-ous and radioactive environment.

System Overview

Figure 1. Horizontal (top) and Vertical (bottom) Storage Canister

Figure 2. Vertical Storage Canister CAD models

Figure 3. Cutaway view of horizontal canister showing potential entry and exit pathways

Figure 4. Inspection and Robotic Delivery System

Figure 5. Conceptual Design using multiple on-board vacuum

Figure 7. Single Module Prototype Figure 8. Double Module Prototype

Figure 6. Current CAD Model