Phase 2 PFDR System for Fukushima Reactor

The Challenge

To design, construct and test a remotely controlled, boom-type robotic arm system (PFDR) for validating the techniques and technology for removing small volumes of fuel debris from the highly contaminated environment of the disabled Fukushima Unit 2 Reactor.

The preceding project (PFDR Phase 1, aka "Distal Boom") was developed from the PCVI investigation system, and introduced a revised Distal Boom arrangement that verified through testing in a mockup of the reactor chamber that the Distal section of the Boom could deploy the End Tool onto the debris floor and apply controlled force.

The key goal of PFDR Phase 2 was to verify that the complete Boom (comprising Distal Boom and Links Assembly) can pass through the Reactor X6 Port passage, which connects the air-tight cell, which will house the Boom system, with the Reactor Primary Containment Vessel (PCV). All of this was to be verified in a mock-up of the x6 port in the Abingdon facility.

PROJECT: Unit 2 Reactor Investigation

DURATION: 2022 to date

CLIENT: Mitsubishi Heavy Industries (MHI)

EXPERTISE: Robotics, Remote Handling and VR simulation

Veolia's Solution

The Links Assembly portion of the PCVI Boom was re-designed, removing one element and adding the smaller "Lateral Offset Link" between the Telescope and the Wrist elements. Significant mechanical re-design and stress analysis was performed to account for the increased loads with the revised Boom geometry and load cases.

A VR (Virtual Reality) study was performed to plan the Boom movements to allow passage through the X6 port assembly and assess the potential clashes. Several mechanical design revisions resulted from this study.

The Boom carriage, links and Distal Boom was assembled and integrated with the in-house developed control system at the VNS UK Abingdon facility. Mastering of the Boom joint positions employed a laser tracker coordinate measuring machine to maximise accuracy.

The Boom was successfully deployed and retracted through the mock-up of the X6 Port verifying the capability of the Boom and control systems. There is a separate case study for the design of the End Tools for fuel debris retrieval.