NUCLEONICS WEEK -May 15, 2003
NORTH SEA STUDY: OIL, GAS EMIT
MORE RADIOACTIVITY THAN NUCLEAR
North Sea oil and gas operations now contribute more
man-made radioactivity to North European marine waters
than the nuclear industry, according to the Marina II study, a
European Commission (EC)-funded project undertaken by
international experts to update data on the impact of radioac-
tivity in the region's seas.
The study found that nuclear industry discharges to sea
are back at the same level as the early 1950s, and that natural-
ly occurring radioactive materials (NORM) now dominate
doses to the European Union (EU) population from industrial
discharges, both in terms of alpha activity and overall impact
(collective dose).
Norway is the largest oil producer in the North Sea and is
estimated to provide the greatest impact from current dis-
charges. Norway is closely followed by the U.K., with Den-
mark and the Netherlands contributing relatively little.
In 2000, according to the study, radioactive discharges
from the non-nuclear industries were estimated to contribute
more than 90%of the European population's total exposure
from discharges into the marine region covered by the Ospar
(Oslo &Paris) Convention. Oil and gas operations contribut-
ed 35.3% and phosphates, 55.4%.
This compared with the contribution to the collective
dose rate from discharges of 3.8% from British Nuclear Fuels
plc's (BNFL) Sellafield reprocessing complex, 1.7% from
Cogema's La Hague facilities, 3.3% from weapons fallout,
0.2% from Chernobyl fallout, and 0.1% from nuclear power stations.
However, the overall impact of the discharges to the EU
population can be gauged from the fact that, even at the dis-
charges' peak, the collective dose rate was around a factor of
20 less than the annual collective dose from natural radioac-
tivity in the marine environment.
The Marina II results have been circulating within the
expert community for some time and have been placed on the
Internet and issued as a "Radiation Protection 132 Pre-Publi-
cation Copy," but the official report is not expected to be
published for another month or so.
NORM is discharged as a result of phosphate fertilizer
production, although such discharges have been reduced
since the 1990s, and from the extraction of oil and gas from
the continental shelf in the North Sea, mainly in the Norwe-
gian and U.K.sectors.
NORM accumulates as scale inside pipework and valves
at offshore oil and gas production platforms. It also gathers as
sludge in separator tanks and other vessels. It is discharged in
"produced water " and its radionuclides of radium--226 and
Ra-228 and Pb-210 (lead) become available in concentrated
form for consumption by marine biota.
The study was managed by U.K.-based NNC Ltd.under a
contract with the EC's Directorate General for Environment
(NW, 22 March '01,11). NNC worked with experts belonging
to scientific institutions such as the U.K.'s National Radio-
logical Protection Board,the Netherlands' Institute for Fishery
Investigation and NRG nuclear consultancy, Denmark 's
Riso National Laboratory, France's CEPN, Russia's SPA
Typhoon, and Ireland's University College in Dublin. The
team collaborated with Greenpeace, IAEA, the International
Union of Radioecologists, Friends of the Earth, and the World
Nuclear Association.
The study's results have been considered by the Ospar
parties and resulted in a decision to recommend the reporting
of discharges from the non-nuclear industries.
The Ospar Convention for the Protection of the Marine
Environment of the North East Atlantic was established in
1992. Its target is to ensure that radioactive discharges to the
marine environment in the region are reduced to levels "close
to zero" by 2020.. The Marina II data is expected to help
establish a baseline against which progress in implementing
the strategy can be evaluated.
Marina II concluded that the overall civilian nuclear and
other anthropogenic inputs of radioactivity into the North
East Atlantic decreased by several orders of magnitude for
alpha-and beta-emitters and for tritium since the maximum
levels were reached in the 1960s and early 1970s. Over the
same period, this resulted in reductions in radionuclide con-
centrations in the marine environment and in the individual
doses to members of critical groups and in collective doses to
the public.
Since the mid-1980s, the main contribution to discharges
of beta activity into the Ospar region is from nuclear repro-
cessing while the discharges of alpha-activity have been
dominated by the phosphate industry and, later, by oil pro-
duction in the North Sea.
Remobilization of radionuclides from the marine sedi-
ments is the other major factor in radioactive exposure. "The
importance of this phenomenon in the Irish Sea results from
the fact that the discharges from Sellafield have been reduced
around 100-fold since the 1970s," said one of the study's
authors, NNC 's Mark Gerchikov.
"Now these remobilized radionuclides are more important
than those resulting from any new discharges. In practice, this
means that reducing current discharges to zero -Ospar poli-
cy -will not affect concentrations of some important radionu-
clides such as the plutonium isotopes."
Nuclear industry discharges are still dominated by repro-
cessing activity. Excluding the Chernobyl fallout in 1986,
the input of beta activity (excluding tritium,which has a very
low radiotoxicity) into the Ospar region decreased by more
than a factor of four from 1986 to 1991. By this date, the
annual discharge had reached the same level as in the early
1950s. The reason was the major reductions in discharges by
reprocessors BNFL and Cogema.
Over the same period, the discharges of alpha activity into
the Ospar region from Sellafield and La Hague decreased by a
factor of three. Inputs of tritium, which decreased after the
mid-1960s, have increased since the mid-1980s due to the
increase in reprocessing at La Hague.
The Marina II study can be accessed at:
(www.europa.eu.int/comm/environment/radprot/execsummary.pdf ).
-Pearl Marshall, London