POWER April 2014 - 34

NUCLEAR POWER
UK Uses " Lead and Learn "
Strategy for Magnox Reactor Fleet
Decommissioning
Energy policy responses to the nuclear disaster at Japan's Fukushima site,
changing economics, and aging first-generation nuclear infrastructure are
all contributing to what promises to be a sizeable wave of nuclear plant
decommissioning projects worldwide. The United Kingdom has something
of a head start, and even though its first-generation reactor technology
was unique, its approach to the complicated task of decommissioning
may offer lessons for other nations.
James M. Hylko
M
any American readers may not realize
that, although the first major nuclear
fission successes were achieved in
the U.S., after World War II, when nations expanded
their nuclear research to include power
generation, the United Kingdom (UK) started
up the world's first commercial-scale nuclear
power reactor in 1956. The first 26 UK reactors
were Magnox design models, and those are
reaching the end of their operating lives.
In November 2001, the UK government
decided to have taxpayers fund the nation's
nuclear legacy cleanup up front in order to
reduce the burden to future generations. Initial
developments toward that goal included
the creation of a liabilities management authority
to ensure that all long-term nuclear liabilities
would be managed in a unified way.
In this context, the term " liability " describes
the financial liability of managing a site when
there is little operating income or selling of
assets. The term " legacy " distinguishes the
first generation of facilities, either shut down
or operating, from the proposed " new build "
nuclear power stations and newer gas reactor
and pressurized water reactor fleet.
This authority, later renamed the Nuclear
Decommissioning Authority (NDA, nda.
gov.uk) began operating in 2005 and took
responsibility for providing a clear and unified
approach to decommissioning the UK's
first-generation nuclear sites (1940s to 1960s).
The Three Stages of Decommissioning
The timing and actions taken during these three stages can vary
significantly, depending on a country's particular waste management
policies and strategies.
For example, the waste management policy and strategy for
England and Wales is to have a geological disposal facility (GDF)
ready by 2040. Therefore, it is not sensible to dismantle the reactors
now, as the packaged waste would have to be stored on site.
When the GDF becomes operational, and with adequate funding,
the Nuclear Decommissioning Authority will be in a position to
properly dismantle the reactors. Scotland's emerging strategy is
not to have a GDF but to have intermediate level waste stored
at or adjacent to a site with the long-term goal of having nearsurface
disposal and retrievability of that waste.
Stage 1: Post-operational removal of bulk radioactive
material. This includes removing fuel from the facility
for reprocessing, which removes about 99.9% of the radioactivity
from the site. The remaining hazards are primarily associated with
the reactor vessels and their internals and operational wastes (such
34
as debris, redundant chutes and control rods, and spent resins).
This stage also utilizes traditional chemical and mechanical decontamination
methods, such as strippable coatings, scabbling-
where several electrically or pneumatically driven piston heads
strike simultaneously on a concrete surface to remove radioactive
contamination-and cutting apart structures and equipment into
smaller pieces using diamond wire or plasma cutting machines.
Site safety also focuses on mitigating conventional hazards,
typically electrical, chemical, asbestos, noise, working at elevated
heights, and confined spaces hazards.
Stage 2: Initial dismantling and removal of contaminated
parts or care and maintenance. The reactor
is left, allowing the radioactive materials to decay. Most of the
structures are removed, and the reactor building is left in a safe
state that requires minimal supervision until final site clearance.
Stage 3: Dismantling and demolition of the structure.
Demolition is followed by remediation of land and water to
meet an agreed-upon end state for future use.
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POWER | April 2014
In addition to the reactors, nuclear liabilities
include fuel reprocessing, fabrication, and
enrichment plants plus nuclear laboratory
complexes (Figure 1). As in the U.S., many of
these legacy facilities were built and operated
during the Cold War, thus they require significant
liability characterization efforts.
The NDA recently introduced a " Lead
and Learn " strategy that accelerates decommissioning
at Bradwell and Trawsfynydd,
the first two Magnox stations scheduled to
enter into the Care & Maintenance (C&M)
phase in 2015 and 2016, respectively. The remaining
former power station sites will enter
C&M in subsequent years, until 2028.
Innovations and off-the-shelf equipment
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POWER April 2014

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