Pile Fuel Cladding Silo – Potential use of Remotely Operated Vehicles (ROVs) for waste retrieval

NES’ facilities at Beckermet, Cumbria have hosted a demonstration showing the use of remotely
operated vehicles (ROVs) and how they could be potentially used as part of the decommissioning
process. Commissioned by Sellafield Ltd via Cavendish Nuclear who are part of Progressive DSA, NES
have been working alongside Sellafield Ltd to demonstrate the concept of utilising tried and tested
remote operated vehicles (ROVs) to extract Intermediate Level Waste (ILW) from the Pile Fuel
Cladding Silo (PFCS) for containerisation and storage in purpose built stores on the Sellafield site.

The PFCS, built more than 60 years ago, was Sellafield Ltd’s first storage facility for ILW. The original
purpose was to store the cladding (outer metallic parts) removed from the irradiated fuel elements
from the Windscale Piles.

In the intervening years, fuel cladding from the Magnox fleet, including Calder Hall and Chapelcross,
was also transferred to the facility until it reached capacity in the early 1960s. The composition of this
mixed radioactive material poses one of the more onerous challenges for the project team.

The series of demonstrations at NES Beckermet showcased a means of removing the waste from the
silo that is currently being used on the equivalent Berkeley and Trawsfynydd Magnox stations, both are
currently undergoing decommissioning. The demonstration involved the use of ROVs operating within
a facility that mimics aspects of a silo compartment on a small scale. The two ROVs used were
approximately half the size of the proposed active system and the facility was scaled accordingly.

Two Brokk ROVs demonstrated a range of operations for the potential handing of the PFCS waste
material in at the Sellafield Ltd site. One ROV was configured as a standard off the shelf unit. The
second incorporated a sophisticated control system with a "teach and repeat" capability which
potentially reduces operator fatigue, at the expense of increased complexity. These alternative options
gave the Sellafield Ltd operators an early indication of what is available and enabled their initial
thoughts and comments to be taken on by the team.

There are thousands of these ROVs in use in other industry sectors around the world and as a
consequence a wide variety of end effectors has been developed. The end effectors can be rapidly
exchanged to handle the waste material inside the silo, which may have become compacted over time.
If required, the ROV can size reduce the waste prior to its removal from the compartment.

The demonstrations at NES’ facilities were attended by visitors from the Nuclear Decommissioning
Authority (NDA) and Sellafield Ltd including Jack DeVine Chief Decommissioning Officer and Steve
Bostock Head of the Spend Fuel Management Directorate. These were accompanied by a number of
the PFCS operators who were able to take the opportunity of gaining hands on experience under the
safety supervision of Callum Nelson, QHSE Coordinator for NES. Also in attendance were NES
Chairman Tony Eckford and George Andrews NES Programme & Deputy Managing Director.

Jack DeVine, Sellafield Ltd’s Chief Decommissioning Officer, commented:

"A bridge has been crossed in terms of time, safety, and commercially available equipment allowing us
to confront real material sooner to prevent future delays."

The Sellafield Ltd host John Eldridge, Principal Engineer Spent Fuel Management, commented:

"We were delighted by the interest shown in our demonstrations and in particular the enthusiasm
shown by the PFCS operators for this potential approach. All without exception were asking to
continue to be directly involved with any future development of the concept in NES. We really
appreciate the rapid response to our request to NES, Cavendish Nuclear and others enabling a quick,
efficient and safe mobilisation. "

Caption: John Eldridge (left) with Jack DeVine and Tony Eckford


Caption: Chemical Engineer Kristy Donovan, who has been investigating the options for the safe
management of the inerting silo gas, takes to the controls of an ROV


Caption: George Andrews (right) with Sellafield Ltd team (left to right) Kirsty Donovan, Byron Smith
and John Eldridge take a closer look at one of the ROVs.


Caption: Training with the "teach and repeat" controller