POWER March 2020 - 27

NUCLEAR
it, and Framatome recently bagged contracts
to deliver ATRIUM 11 to Talen Energy's
Susquehanna plant in Pennsylvania
by 2021, and to the Tennessee Valley Authority's
Browns Ferry plant in 2023.
According to Framatome, positive mar1.
Framatome is testing chromium-coated
cladding and chromia-doped fuel pellets to improve
the performance of current light-water
reactor fuels at Southern Nuclear's Vogtle 2
reactor. The special coating is designed to protect
the fuel cladding from damage and oxidation
at higher temperatures. The new fuel
pellet mixture of chromium oxide and uranium
oxide powders is expected to help the pellet
last longer and perform better at high temperatures.
Courtesy: Southern Nuclear
ther, the innovative coating offers increased
resistance to debris fretting during normal
operations. " The company told POWER in
early February that it is now in " early manufacturing
stages " for delivering complete
fuel assemblies-full-length chromia-coated
rods and chromium-enhanced pellets-to
Exelon's Calvert Cliffs reactor in Maryland in
2021.
Around the world, meanwhile, TVEL,
Russian state-owned corporation Rosatom's
nuclear fuel fabrication and
supply arm, last October loaded two
experimental ATF fuel assemblies with
VVER (a Russian-designed water-cooled,
water-moderated reactor) and pressurized
water reactor (PWR) fuel rods at its
MIR research reactor at the State Research
Institute of Atomic Reactors in
the Ulyanovsk Region.
Market Forces Driving Innovation
Framatome, a French nuclear technology
giant, notably credited its rapid development
for GAIA, a PWR solution, to DOE
support and favorable conditions in the
U.S. market-including its competitive
electricity markets, which demand large
cost reductions. " This demand drives for
more efficient designs, " it said. The U.S.
fleet, which is committed to lifetime extensions,
is also receptive to new innovative
technologies, it noted. Among other
fuel offerings Framatome is advancing in
the U.S. market is ATRIUM 11, an 11 x 11
fuel rod array for boiling water reactors
(BWRs), whose " unique geometry " inherently
boosts safety, fuel cycle savings,
as well as plant flexibility capabilities.
Since it launched the ATRIUM 11 fuel in
the U.S. in April 2015, two unnamed reactors
have begun producing power using
March 2020 | POWER
ket signals are especially imperative to the
development of advanced fuel designs
because it is an intensely complex process.
Contrary to perceptions that fuel assemblies
are produced in a specific plant,
" the entire supply chain is global, " it noted.
Meanwhile, far from being a commodity,
" nuclear fuel assemblies are a highly
engineered and complex product built to
extremely demanding quality standards, "
and they are often " designed to operate
flawlessly in an aggressive environment
for many years, " the company noted. And
though " great advancements " in digital
and additive manufacturing have helped
improve fuel systems, the industry often
bears critical risks, such as those associated
with funding, regulations, and with
its supply chain.
A World of VVER Fuel Innovations-
and Beyond
TVEL, the world's largest supplier of fuel for
VVERs (most of which are in Europe and
require distinct hexagonal fuel assemblies),
meanwhile, told POWER its drive to advance
fuel offerings is boosted by Rosatom's
introduction of new reactor models and improvements
to fuel for existing VVER-440
and VVER-1000 reactors-but also by cost
considerations. " Our engineering projects
for the development/licensing/introduction
of new fuel cost very little in comparison
with modernization of the main power
equipment, reconstruction, [or] construction
of new facilities. And the new modified fuel
itself will be purchased just within regular operation
costs of a power plant, " it said.
In recent years, TVEL has introduced
new models of VVER-1000 fuel at the
Temelin nuclear power plant (NPP) in
the Czech Republic (TVSA-T.mod.2) and
the Kozloduy NPP in Bulgaria (TVSA-12).
" Soon after that, Unit 6 of the Kozloduy
NPP started operations at increased
thermal capacity, 104% of the nominal, "
the company said. Fuel modifications are
also ongoing at the Paks NPP in Hungary
and Loviisa NPP in Finland. Last July, the
company also signed a key agreement
to supply a " third-generation " fuel for a
VVER-440 Dukovany NPP in the Czech
Republic. Deriving from a prototype fuel
installed at Kola 4 in Russia's Murmansk
region in 2010, the new fuel design uses
a longer fuel rod pitch that streamlines
the water-uranium ratio in the reactor
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core to increase the fuel efficiency.
As significantly, TVEL in 2016 also began
exploring developing fuel for " Western
design " reactors with its TVS-K
program in a bid to break into the PWR
market-which for years had only two
suppliers: Westinghouse and Framatome.
(Westinghouse in 2018 made a
foray in the VVER market backed by a
European Union-funded project to help
European countries diversify their fuel
supply.) TVEL's first project was a 17 x 17
lattice for Westinghouse reactors slated
for Vattenfall's Ringhals plant in Sweden.
In July 2018, Exelon asked the NRC if it
could install TVS-K at the financially flailing
Braidwood plant in Illinois, but it withdrew
its application about six months
before the 2019 refuel outage began.
Perhaps TVEL's most-notable fuel design
achievements are closely connected
to Russia's Proryv (or " Breakthrough " )
project, which is aimed at closing the
nuclear fuel cycle, and, as the company
explained, creating " a dual-component
nuclear power system, which would involve
both thermal and fast neutron reactors. "
TVEL in January loaded 18 MOX
fuel assemblies at Beloyarsk 4 (a POWER
magazine 2016 Top Plant), one of the
world's only commercial fast neutron reactors.
It now plans to replace all remaining
uranium-based fuel assemblies with
MOX fuel by the end of 2021. If completed
as planned, it will be the first time
a Russian fast neutron reactor operates
with a full load of MOX fuel. MOX fuel
pellets are based on the mix of nuclear
fuel cycle derivatives, such as plutonium
oxide bred in commercial reactors and
uranium oxide derived by defluorination
of depleted uranium hexafluoride-the
so-called secondary tailings of uranium
enrichment facilities.
As notable is TVEL's development
of REMIX (regenerated mixture) for
VVERs, a fuel of up to 17% U-235 that
is produced from a non-separated mix of
recycled uranium and plutonium from reprocessed
fuel. It can sustain burnup of
50 gigawatt-days per metric ton of uranium
over four years and be recycled with
100% core load in current VVER-1000
reactors up to five times. The World Nuclear
Association notes, " with three fuel
loads in circulation, a reactor could run
for 60 years using the same fuel, with
[low-enriched uranium] recharge. " TVEL
told POWER development for VVER REMIX
is " at the stage of calculation and
experimental validation now. " ■
-Sonal Patel is a POWER senior
associate editor.
27
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POWER March 2020

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