POWER April 2014 - 40

NUCLEAR POWER
condition, including waste stores and sealedup
reactors that will remain in situ for several
decades. The contents are expected to be
transferred to the GDF when it becomes operational.
Bradwell and Trawsfynydd will be
the first to enter this C&M phase in 2015 and
2016 respectively, with the remaining sites
entering by 2027-2028.
Another significant benefit expected from
the Lead and Learn approach Burnett said,
is optimum safety results. By focusing on
control and management aimed at major
hazards-elevated work, electrical safety,
fire safety, chemical safety, confined spaces,
and radiological safety-the SLCs' average
rate for 2012/2013 was 128 per 100,000 employees.
This is a significant drop from 244
for the previous financial year. As a comparison,
the latest statistics from the Health and
Safety Executive (similar to the U.S. Occupational
Safety and Health Administration)
showed an average UK rate of 446 incidents
per 100,000 employees.
The Bradwell Project
The SLC and site licensee for the Bradwell
site (Figure 2) is Magnox Ltd., the PBO is
EnergySolutions Inc., and the site stakeholder
group is Bradwell Local Community Liaison
Council. Descriptions of recent decommissioning
accomplishments at Bradwell follow.
FED Treatment Program. A total of 290
drums have been filled with FED and gravel
from vault 1A at Bradwell, the first vault to
be completely emptied, marking a major step
forward in managing the site's radioactive
waste streams.
The work was not without significant challenges
due to the unknown physical condition
of the waste, which had been stored for several
years. Final retrieval of gravel from the bottom
of the vault was achieved by worker access to
the area. By pre-planning the entry, the team
registered a lower dose rate than forecasted.
More than 250 drums of FED have also been
removed from a second vault, 1B.
Magnox has, to date, transferred three
shipments of FED waste from Bradwell to
Dungeness A for dissolution.
As part of its accelerated C&M program, a
new dissolution facility at Bradwell is taking
shape thanks to the arrival of two reaction vessels
in early 2013. The vessels will be where
the actual dissolution of the waste, currently
being removed from vaults, will be undertaken.
Shield walls have also been poured, stainless
steel cladding installed, and an overhead
crane lifted into place to support operations.
Fuel Storage Ponds. Following fuel element,
debris, and sludge removal, ultra-high-pressure
water jetting was used to clean Bradwell's empty
fuel storage ponds, reducing operator doses and
removing contamination (Figure 3).
40
After cleaning, a polyurea coating supplied
by Protective Coating Solutions Ltd.
is sprayed on in a single application using
several passes to build up a 4-mm thickness
(Figure 4). The polyurea material, typically
used as a protective lining for large surface
area projects such as tunnels and tanks, forms
a durable membrane, improving the stability
of the decontaminated surfaces and enabling
easier monitoring of potential defects during
the C&M phase.
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Innovations such as the use of coatings and
pontoons resulted from adapting techniques
and off-the-shelf equipment from outside the
nuclear industry rather than developing expensive,
bespoke solutions.
Intermediate Level Waste Management.
To maximize cost efficiencies, a generic
interim storage facility (ISF) design for ILW
material has been adopted at sites awaiting the
construction of medium-term stores, and the
first was officially opened at Bradwell.
POWER | April 2014
3. Pontoon in the pond. A floating pontoon system, as used in marinas, formed a working
platform on the fuel storage pond surface, dropping lower as the liquid drained. The pontoons
were first introduced at Hunterston, which has the largest Magnox pond-about the size
of an Olympic swimming pool-when workers were using ultra-high-pressure jets to remove
contamination from the pond walls. Courtesy: Magnox Ltd.
4. Sealed. A spray-on coating of Dekguard was applied to seal Bradwell's fuel storage pond
walls and floors. Courtesy: Magnox Ltd.

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POWER April 2014

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