following the coast and joining the Sellafield releases
in the NCC. A small amount of the Sellafield releases
and some of the Cap de la Hague releases, which
flow closer to the coast, flow east through the
Skaggerak and Kattegat to enter the Baltic Sea.
The NCC is formed of a mixture of coastal waters
(containing the reprocessing tracers) and warm, saline North Atlantic surface waters. Dilution of the
reprocessing signal with Atlantic water continues
along the northward flow path of the NCC. There is
evidence from reprocessing tracers that turbulent
eddies between the NCC and Atlantic water result in
episodic transport westward into the surface waters
of the Norwegian Sea, in addition to a fairly welldefined westward advective transport towards Jan
Mayen Island. The NCC branches north of Norway,
with one branch, the North Cape (or Nordkap)
Current, flowing eastward through the Barents Sea
and thence into the Kara Sea and Arctic Ocean, and
the remainder flowing north and west as part of the
West Spitsbergen Current (WSC). This latter flow
branches in the Fram Strait west of Spitsbergen, with
some recirculation to the west and south joining the
southward flowing East Greenland Current (EGC),
and the remainder entering the Arctic Ocean. The
majority of surface outflow from the Arctic is
through the Fram Strait into the EGC, thus the bulk
of the reprocessing nuclides entering the Arctic
Ocean will eventually exit to the Nordic (Greenland,
Iceland, and Norwegian) Seas and the North Atlantic. The presence of high concentrations of radionuclides derived from reprocessing in the surface
waters of the Barents and Nordic Seas is also an indication of their utility as tracers of deep-water
ventilation and formation in these regions, as discussed below.
The Use of Reprocessing Releases in
Oceanography
Historical Background
The first papers reporting measurements of Sellafield-derived
137 Cs in coastal waters appeared in the
early 1970s. Much of this early work arose from
monitoring efforts by the Division of Fisheries Research of the UK’s Ministry of Agriculture, Fisheries,
and Food, which holds a joint oversight role on the
Sellafield discharges and which continues to this day,
now as the Centre for Environment, Fisheries and
Aquaculture Science, to be a leader in studies of the
distribution and oceanographic application of reprocessing radionuclides. In the late 1970s scientists
at the Woods Hole Oceanographic Institution published the first of a number of papers detailing the
unique utility of the reprocessing tracers and demonstrating their application. Leading studies of reprocessing tracers in the oceans have been
undertaken by researchers in numerous other countries affected by the radiological implications of the
releases, including France, Germany, Denmark,
Canada, Norway, and the former Soviet Union.
Coastal and Surface Circulation
A great deal of work has been published using the
documented releases of radioisotopes from Sellafield
and Cap de la Hague to study the local circulations of
the Irish Sea, North Sea, and English Channel. Early
studies of the Sellafield releases examined a variety of
isotopes, including
134
Cs,
137
Cs,
90
Sr, and Pu isotopes. Most attention focused on
137
Cs and
90
Sr, and
their activity ratio, because: (1) the releases of these
two isotopes were well documented, (2) they had
been studied extensively since the 1950s and 1960s in
weapons test fallout; and (3) the
137
Cs/
90
Sr ratio in
reprocessing releases (particularly those from Sellafield) was significantly higher than in global fallout
and thus could be used to distinguish the sources of
these isotopes in a given water sample. The use of the
134
Cs/
137
Cs ratio enabled estimates of transit times,
assuming the initial ratio in the releases was constant
and making use of the short half-life of
134
Cs. The
short-lived isotope
125
Sb has been used as a specific
tracer of the circulation of Cap de la Hague discharges through the English Channel and North Sea,
into the Baltic and the Norwegian Coastal Current.
Summaries of transit times and dilution factors for
the transport of Sellafield and Cap de la Hague discharges to points throughout the North Sea, Norwegian Coastal Current, Barents and Kara Seas,
Greenland Sea, and East and West Greenland Currents
have been published in recent reviews. Numbers are
not included in this article because they are currently
under revision. In terms of transport to the NCC,
where the two waste streams are generally considered
to merge, the consensus has been that the transit time
from Sellafield to about 601N is three to four years,
and that from Cap de la Hague to the same area is one
to two years. Compilations of ‘transfer factors,’ which
relate observed concentrations to the discharge
amounts, and factor in the transit times, suggest that
the two reprocessing waste streams meet in approximately equal proportions in the NCC. In other words,
if Sellafield and Cap de la Hague released equal
amounts of a radionuclide, with the Cap de la Hague
release two years later, they would make equal contributions to the NCC.
Recently, detailed studies have been undertaken of
the dispersal of the EARP
99 Tc pulse from Sellafield,
NUCLEAR FUEL REPROCESSING AND RELATED DISCHARGES 295
in the NCC. A small amount of the Sellafield releases
and some of the Cap de la Hague releases, which
flow closer to the coast, flow east through the
Skaggerak and Kattegat to enter the Baltic Sea.
The NCC is formed of a mixture of coastal waters
(containing the reprocessing tracers) and warm, saline North Atlantic surface waters. Dilution of the
reprocessing signal with Atlantic water continues
along the northward flow path of the NCC. There is
evidence from reprocessing tracers that turbulent
eddies between the NCC and Atlantic water result in
episodic transport westward into the surface waters
of the Norwegian Sea, in addition to a fairly welldefined westward advective transport towards Jan
Mayen Island. The NCC branches north of Norway,
with one branch, the North Cape (or Nordkap)
Current, flowing eastward through the Barents Sea
and thence into the Kara Sea and Arctic Ocean, and
the remainder flowing north and west as part of the
West Spitsbergen Current (WSC). This latter flow
branches in the Fram Strait west of Spitsbergen, with
some recirculation to the west and south joining the
southward flowing East Greenland Current (EGC),
and the remainder entering the Arctic Ocean. The
majority of surface outflow from the Arctic is
through the Fram Strait into the EGC, thus the bulk
of the reprocessing nuclides entering the Arctic
Ocean will eventually exit to the Nordic (Greenland,
Iceland, and Norwegian) Seas and the North Atlantic. The presence of high concentrations of radionuclides derived from reprocessing in the surface
waters of the Barents and Nordic Seas is also an indication of their utility as tracers of deep-water
ventilation and formation in these regions, as discussed below.
The Use of Reprocessing Releases in
Oceanography
Historical Background
The first papers reporting measurements of Sellafield-derived
137 Cs in coastal waters appeared in the
early 1970s. Much of this early work arose from
monitoring efforts by the Division of Fisheries Research of the UK’s Ministry of Agriculture, Fisheries,
and Food, which holds a joint oversight role on the
Sellafield discharges and which continues to this day,
now as the Centre for Environment, Fisheries and
Aquaculture Science, to be a leader in studies of the
distribution and oceanographic application of reprocessing radionuclides. In the late 1970s scientists
at the Woods Hole Oceanographic Institution published the first of a number of papers detailing the
unique utility of the reprocessing tracers and demonstrating their application. Leading studies of reprocessing tracers in the oceans have been
undertaken by researchers in numerous other countries affected by the radiological implications of the
releases, including France, Germany, Denmark,
Canada, Norway, and the former Soviet Union.
Coastal and Surface Circulation
A great deal of work has been published using the
documented releases of radioisotopes from Sellafield
and Cap de la Hague to study the local circulations of
the Irish Sea, North Sea, and English Channel. Early
studies of the Sellafield releases examined a variety of
isotopes, including
134
Cs,
137
Cs,
90
Sr, and Pu isotopes. Most attention focused on
137
Cs and
90
Sr, and
their activity ratio, because: (1) the releases of these
two isotopes were well documented, (2) they had
been studied extensively since the 1950s and 1960s in
weapons test fallout; and (3) the
137
Cs/
90
Sr ratio in
reprocessing releases (particularly those from Sellafield) was significantly higher than in global fallout
and thus could be used to distinguish the sources of
these isotopes in a given water sample. The use of the
134
Cs/
137
Cs ratio enabled estimates of transit times,
assuming the initial ratio in the releases was constant
and making use of the short half-life of
134
Cs. The
short-lived isotope
125
Sb has been used as a specific
tracer of the circulation of Cap de la Hague discharges through the English Channel and North Sea,
into the Baltic and the Norwegian Coastal Current.
Summaries of transit times and dilution factors for
the transport of Sellafield and Cap de la Hague discharges to points throughout the North Sea, Norwegian Coastal Current, Barents and Kara Seas,
Greenland Sea, and East and West Greenland Currents
have been published in recent reviews. Numbers are
not included in this article because they are currently
under revision. In terms of transport to the NCC,
where the two waste streams are generally considered
to merge, the consensus has been that the transit time
from Sellafield to about 601N is three to four years,
and that from Cap de la Hague to the same area is one
to two years. Compilations of ‘transfer factors,’ which
relate observed concentrations to the discharge
amounts, and factor in the transit times, suggest that
the two reprocessing waste streams meet in approximately equal proportions in the NCC. In other words,
if Sellafield and Cap de la Hague released equal
amounts of a radionuclide, with the Cap de la Hague
release two years later, they would make equal contributions to the NCC.
Recently, detailed studies have been undertaken of
the dispersal of the EARP
99 Tc pulse from Sellafield,
NUCLEAR FUEL REPROCESSING AND RELATED DISCHARGES 295