DOSE IMPLICATIONS OF VERY
LOW-LEVEL RADIOACTIVE WASTE DISPOSAL
The Scottish Environment Protection Agency (SEPA), the
Environment and Heritage Service of Northern Ireland (EHS), and the
Environment Agency for England and Wales (EA) are responsible for the
regulation of radioactive waste disposal in the UK.
In conjunction with the Environment Agencies, and with the support of
the Scottish Government and the Department for Environment Food and
Rural Affairs (Defra), the Scotland and Northern Ireland Forum for
Environmental Research (SNIFFER) commissioned this research project to
review the practice of disposing small amounts of very low-level
radioactive waste (VLLW) with other wastes.
The objective of the project was to establish whether current practices
of VLLW management and disposal remain acceptable, and to provide
guidance on any necessary revisions to the conditions of authorisations
governing VLLW disposal.
The project has identified the types and amounts of VLLW being
produced, examined trends in waste management, and has assessed the
potential impacts of exposure to VLLW during waste management and
A survey has been made focusing on non-nuclear industry organisations
in the UK that hold VLLW disposal authorisations. This survey
found that in 2006, ~680 organisations, including hospitals,
universities and pharmaceutical and biotechnology companies, were
authorised to dispose of VLLW in the UK. Of these, 562 were
located in England and Wales, 100 in Scotland, and 24 in
The project identified two main types of VLLW: primary VLLW, which
is produced directly by, for example, universities and hospitals, and secondary VLLW,
which is produced as a result of incinerating radioactive wastes.
The survey identified that approximately 3,600 tonnes of primary VLLW
was produced by non nuclear industry organisations in 2005.
To put this into context, the mass of primary VLLW from non nuclear
organisations was ~0.01% of the total annual mass of municipal waste
produced in 2005. The total activity of the primary VLLW
produced by the non-nuclear industry in 2005 is estimated to have been
<17.5 GBq. The vast majority (~15 GBq) of this
activity was short lived. 14C was by
far the most abundant long-lived radionuclide and accounted for ~98% of
the ~2.5 GBq of radionuclides with half-lives greater than 30 years.
Information from the primary VLLW producers suggests that in 2005, ~52%
(by mass) was incinerated and ~48% sent for disposal in
landfill. In reality, these percentages will have been lower
than this because an uncertain proportion of the wastes will have been
recycled or composted. Even so, the relative amount of
primary VLLW incinerated is likely to have been greater than for
municipal waste because much of the primary VLLW was treated as
The actual percentage of primary VLLW recycled or composted has not
been quantified, but is thought to be significantly less than the
percentage of municipal waste that is currently recycled or composted
Secondary VLLW arises in residues of waste incineration arising from
air pollution controls (lime, bicarbonate and sludge) and
ash. The radionuclide content arises from small amounts of
LLW and VLLW in the general wastes incinerated. Approximately
20,000 tonnes of secondary VLLW was produced in 2005.
Relatively little detailed information is available on the radionuclide
content of secondary VLLW. Secondary VLLW contains
radionuclides that are not volatile and therefore has low levels of
volatile radionuclides such as 14C, tritium, 35S
and iodine, because these radionuclides are mainly discharged to the
atmosphere in the incinerator flue gases despite lime
scrubbers. The radionuclide content of secondary VLLW also
differs from that of primary VLLW because secondary VLLW inherits
radionuclides from solid radioactive wastes with activities initially
above the upper limit for VLLW. For example, some secondary
VLLW contains a relatively higher proportion of 90Sr than primary VLLW
of average composition.
The sludge and the majority of the ash from the incineration process
are sent to landfill. Ash wastes may be considered to be
hazardous. A proportion of the ash from municipal waste
incinerators may be used in road and building construction.
Some of the lime and bicarbonate may be used in the chemicals industry,
and some sent to landfill.
Since the last review of VLLW disposal was conducted about 10 years
ago, there have been several main changes in conventional waste
management practice, including:
Over the next 10 years, these changes and trends are expected to
continue and intensify, and the amounts of controlled waste and VLLW
from non-nuclear industries following the various disposal/recovery
routes may change quite significantly. In addition, there is
expected to be a shift away from conventional incinerators, in favour
of incineration at energy-from-waste facilities, including those that
use refuse-derived fuel pellets. Results from the survey of
non-nuclear industry VLLW production suggest that there may be a slight
net increase in the quantities of primary VLLW over the coming
years. Increased waste incineration would lead to increased
production of secondary VLLW. It is expected that there will
be fewer landfills that can take hazardous wastes. Secondary
VLLW in the form of ash may therefore be disposed of to relatively few
- The introduction of source segregation of waste streams.
- An increase in the proportion of waste being recycled.
- Development of new waste recovery technologies.
- An increase in the proportion of waste composted.
- A decrease in the proportion of waste landfilled.
Doses from the disposal of primary and secondary VLLW were
estimated. Doses from the disposal of primary VLLW from the
non-nuclear industry are low and fall below 20 μSv/yr.
The annual arisings of primary VLLW (~3,600 tonnes, with an overall
specific activity of 400 kBq per 0.1 m3) could
be consigned to a single
landfill site for 15 - 20 years without exceeding the 20 μSv/yr
radiological dose criterion.
The estimated annual arisings of primary VLLW could be incinerated at
one incinerator and give annual doses of less than 20
ÁSv. The most significant radionuclide in terms of
radiological impact and quantity is 14C because
of its long half-life.
Doses to waste workers from sorting of primary wastes that may contain
VLLW are also low and below 20 ÁSv/yr.
A single landfill could take ~3,000 tonnes of secondary VLLW at the 400
kBq per 0.1m3 level without calculated doses
On a case by case basis, some VLLW authorisations in England and Wales
allow disposal of alpha emitting radionuclides - at lower levels than
the standard conditions. The study identified that more than
1 MBq of 241Am, 226Ra,
and 228Ra were disposed of in primary VLLW in
2005. Doses from the alpha emitters were generally low;
however, doses from items containing 226Ra
handled by waste sorters
were close to 20 ÁSv/yr.
A dose of 20 μSv/yr can be broadly equated to an annual risk of
death of about one in a million. Government Policy is that
where exposures are calculated to be less that 20 μSv/yr, the
Environment Agencies should not seek to secure further reductions in
the exposure of members of the public, provided they are satisfied that
the operator is using the Best Practicable Means to limit discharges.
We conclude that current practices of management and disposal for VLLW
from the non nuclear industry remain acceptable, and that the
increasing occurrence of waste segregation and recycling does not
appear to be significant in terms of radiological safety, taking into
account current waste disposal practises including waste segregation
and sorting. However doses from some alpha emitters in
individual waste items handled during sorting come close to 20
The study however recommends as follows:
The study also notes that the Environment Agencies substitute fuel
protocol currently precludes the inclusion of radioactive
waste. The low administration burden associated with VLLW
disposal does not require the tracking of VLLW. Therefore, it
will not be possible to be confident that VLLW is not being
inadvertently included in wastes used as substitute fuel.
However, the radiological consequences of VLLW being combusted in
substitute fuels will be very small.
- The Environment Agencies use clearer,
simpler language in Certificates of Authorisation, and give clear
guidance on how authorisations allowing VLLW disposal should be
interpreted (e.g., in relation to current waste management practices).
- Because of the low radiological
impact, the current arrangements allow VLLW to be disposed of with a
minimum of regulatory and administration burden. There is
currently no requirement to report to the Environment Agencies the
quantities disposed of or to track the fate of the wastes.
This study confirms that the radiological impact of the disposal of
VLLW remains low and that, therefore, there is no need on radiological
protection grounds to significantly alter these low burden arrangements.
- 14C is the most significant
radionuclide in primary VLLW in terms of dose. However, the
low overall doses from VLLW means that there are no radiological
protection grounds to require a change to the current relaxation in the
limit for 14C adopted by the Environment Agency and now in Government
Policy for LLW.
- Doses are low from incineration of
primary VLLW. Therefore, there are no radiological protection
grounds for suggesting incineration is not appropriate for wastes
- There are large quantities of
secondary VLLW, in particular ash, that may have to be consigned to a
limited number of hazardous landfill sites. These volumes may
increase in future whilst the number of hazardous landfill sites that
can accept ash wastes may not increase. It may therefore be
appropriate to keep generation and disposal of secondary VLLW under
- In ten years time a review similar to
this current review would be advisable to check the validity of the
current findings in the light of the expected changes in waste
management practices that will have occurred.
There may be advantages in requiring the returning of records of VLLW
disposal to the Environment Agencies in future, in particular to
prevent inclusion in substitute fuel and to allow future radiological
assessments. However, these benefits would have to be weighed
against the costs of increasing the administration burden associated
with a low impact disposal route.
Limitations to the study
The study focused on the production of primary VLLW from the
non-nuclear industry. Cognisance was given to the production
of VLLW by the nuclear industry, both operational and
decommissioning. However, it was identified at an early stage
that the volumes and fingerprints of these wastes were significantly
different and could not be covered by this project. Likewise,
VLLW production by the oil and gas industry was not considered by the
The disposal of VLLW from the non-nuclear industry has low regulatory
and administration burdens for users. This impacted on the
information that could be obtained from users who have not been
required to keep records on their disposal of VLLW.
Additionally, the response rate to the questionnaires was such that
only limited interpretation of the waste produced in terms of activity
and mass by sector and geographic region was possible.
Key words: Dose, Exposure, Incineration, Landfill, Very Low-Level
Radioactive Waste (VLLW), Controlled Waste, Waste Management, Waste
Copies of this report are available from the Foundation, in electronic
format on CDRom at ú20.00 + VAT or hard copy at
ú35.00, less 20% to FWR members.
N.B. The report is available for download from the SNIFFER Website