Growing awareness of the NORM risks from non-nuclear industries

Radiation protection and the management of radioactive material have hitherto been concerned mainly with artificial nuclides arising within the nuclear fuel cycle. In the last few years, there has been an increasing awareness of naturally occurring radioactive materials (NORM) and the enhancement of its concentration in various non-nuclear industrial processes.

  This technologically enhanced NORM (also termed TENORM in the United States) can be of the same activity levels as “regular” low level waste in the nuclear industry, but occurs in quantities that are huge in comparison. Table 1 illustrates some of the technologically enhanced NORM arising annually in the United States. Ra 226 with a half-life of 1600 years is by far the most important radionuclide. These data are shown only to give an idea of quantities and activity levels. Other industries with significant radioactive waste streams are coal ash, petroleum processing, geothermal plants and paper mills. More or less comparable quantities of NORM arise in Europe, with similar concentrations of radioactivity.

RADIOLOGICAL IMPACT OF NORM A characteristic of NORM is that, because of their wide distribution from many sources, they give rise to relatively large collective radiological doses to the public in comparison to those caused by the nuclear industry. This is vividly illustrated in a study, made in 19902 by the radiation protection authorities from the five Nordic countries, on the annual collective dose to their populations from natural radioactive sources, including some NORM-related ones. A pie diagram was prepared in connection with the report, showing the respective contributions of the various sources and comparing them with the collective dose taken by the Nordic populations during the first year after the Chernobyl accident as well as with the annual collective dose from the operation of the 16 nuclear reactors in Sweden and Finland.

On closer examination, the comparative impact of some of the NORM-related industries are, in fact, even more significant than shown.

The 20 person-Sv/year from the operation of the nuclear reactors is mostly occupational doses to the operating personnel. The total collective dose to the general public from plant emissions is less than 1 person-Sv/year.

The annual 50 person-Sv dose shown in the pie chart coming from artificial fertiliser covers only the internal doses taken by the Nordic public, through ingestion of food produced on the fertilised soil. The external doses have not been included. The chart does not either cover the use of the by-product, gypsum, as a building material. Even a modest use of gypsum in homes could lead to an annual collective dose of about 100 person-Sv.

The figure of 80 personSv/year due to energy production from coal (mainly in Denmark) and from peat (mainly in Finland) refers only to radioactive emissions from the power plants. Not shown are the effects of the use of some of the fly ash in concrete, which increases the external gamma radiation in buildings and is likely to dominate the total dose from the use of coal and peat. The report mentions that most of the bottom ash ends up on municipal tips but does not attempt to estimate the radiological impact.

The Nordic study thus shows that the collective dose from the operation of the 16 nuclear plants is 1 person-Sv, while the use of artificial fertiliser and the operation of coal and peat for energy production causes two to three orders of magnitude higher collective population doses.

Another interesting study illustrating the comparative impact of nuclear facilities and NORM was published recently in Sweden.3 The dose to individuals in a critical group from radioactive emissions from three sources were compared:

• The Barsebäck nuclear power plant with 2 x 500 MWe BWRs (each 1800 MWt).

• The 50 MWt Materials Testing Reactor, R2, at Studsvik.

• The 8 MWt wood chip briquette burning plant, used for heating office buildings at the Studsvik site. (Even such a source as wood chips has NORM, which is released during combustion.) The results are shown in Table 2.

At the same site as the R2 reactor and the wood chip plant, Studsvik RadWaste has an incinerator for burning dry active waste from both nuclear plants and hospitals, as well as a melting facility for recycling contaminated metal scrap from nuclear power plants (see photo).

During 1996, the incinerator gave rise to a dose of 11 nSv to members of critical groups (mostly due to tritium in waste from hospitals and pharmaceutical manufacturers) while the melting facility, which treated 500 t of metal during the year, caused a dose of 0.9 nSv.

In summary, per GWh heat generated, the wood chip burning plant at Studsvik releases seven times as much radioactivity to the atmosphere and dose to the public as the two BWRs at the Barsebäck nuclear power plant. The radioactive emissions from the wood chip plant are also almost three times that from the neighbouring facility, which melts contaminated scrap from nuclear power plants.

REGULATION OF NORM To a large extent, the radiation protection regulators have been focusing on the nuclear fuel cycle with little attention given to the technological concentration of radioactivity in the NORM industries. Consequently, the current regulatory management of NORM is very inconsistent with that of similar material arising in the nuclear industry.

The following are examples of the different criteria used (see panel for definition of key terms):

• Current level for clearance of material from the nuclear industry in Sweden is 0.5 Bq/g, while the current exemption level for non-nuclear industries (by European Commission Directive 84/467/Euratom of 1984) is 100 Bq/g (or 500 Bq/g for “solid natural material”).

• Exemption level for oil and gas industry NORM wastes:5 - In the Netherlands, 100 Bq/g.

- In Germany, 500 Bq/g.

• For subsurface road stabilisation in Germany: - Clearance level for concrete from a nuclear plant was 0.5 Bq/g, - Exemption level for slag from melting of scrap from the oil and gas industry was 65 Bq/g (to be diluted by a factor of 4).

The EC came out with a new Directive in May 1996, with revised basic safety standards (BSS) for the radiation protection of both workers and the general public.6 The Directive covers radioactivity in both nuclear and non-nuclear industries and will have to be ratified by member states within four years, ie by May 2000. In the BSS, industries are divided into “practices” (where radionuclides are, or have been processed in view of their fissile or fertile properties) and “work activities” (where the presence of radioactivity is incidental). Broadly speaking, “practices” refer to the nuclear industries, while “work activities” to the non-nuclear ones, ie the oil and gas or phosphate industries. The table of exemption values in the new EC-BSS covers only practices. The exemption values for work activities are not explicitly given. However, it seems clear from presentations made at the NORM II meeting in November 1998 in Krefeld, Germany, that the exemption values for material from non-nuclear industries can be based on a criterion of 1 mSv/year individual dose to the public, which is a factor of 100 times greater than that for similar material from the nuclear industry.

In the United States, a draft set of regulations for technologically enhanced NORM (TENORM) was given out in February 1997 by the Conference of Radiation Control Program Directors (CRCPD). The CRCPD is an organisation primarily consisting of directors and technical staff from state and local radiation control programmes and functions as the common forum for state, local and federal regulatory agencies to address NORM-related health and safety issues. Several states have already regulations in place to meet their specific individual needs. There is, however, no uniformity in these regulations. One of the main aims of CRCPD is working towards uniformity in regulations governing radiation.7 One of the main problems regarding NORM in non-nuclear industries is that plants handling such materials are typically not aware that radioactivity is being concentrated in various technological processes. Very often, the first indication is received when waste is taken to a melting plant or a landfill with portal monitors for radioactivity, which are usually set to alarm at a level only slightly above background.4 Steel melters recycling scrap have become increasingly aware of the risks of radioactivity contaminating their products. Even though the most serious incidents have involved Co-60 and Cs-137 sources, the largest single contribution to radioactivity in scrap in the United States has been NORM.5 In any event, monitoring devices at melting plants, just like human beings, cannot discriminate between natural and artificial radionuclides. For this and many other reasons, all radioactivity, whether from the nuclear or the non-nuclear NORM-related industries, needs to be regulated in a consistent manner.

SIGNIFICANCE OF NORM TO THE NUCLEAR INDUSTRY The current international recommendations for the exemption of radioactive material from being regulated and the clearance (release) of such material already regulated are both based on criteria laid down by the IAEA Safety Series* 89 regarding individual doses (10 µSv/year) and collective doses (1 person-Sv/year). Typically, exemption levels are a factor 10 higher than clearance values, the explanation being that exemption is intended to be applied to moderate quantities of material (say 1-10 t), while clearance concerns large quantities (10 000 t/year used in European studies).

If radioactivity is to be regulated in a consistent manner, it will not be practically feasible to relate release levels to quantities, when the very large inventories of NORM (100 000 to 1 000 000 t) is brought under regulation. So the resolution of the NORM issue is of the highest interest to nuclear decommissioners, whose projects are characterised by the potentially large volumes of very low level materials arising, with very similar activity concentrations as in NORM.

One of the main problems for the nuclear industry has been its artificial separation from other industries also resulting in risk to the public. As a part of the NORM regulatory discussions, direct, exposure-to-radioactivity comparisons can be made between nuclear and other industries and the relative impacts can be brought into perspective.

Considering the large number of industries involved, the relevant activity levels, the collective radiological dose actually being received by the population, as well as the vast quantities of technologically enhanced NORM, the main message from the NORM issue is that radioactivity is not only part of the human habitat but needs to be viewed globally. This message could hopefully be useful to promote a constructive dialogue – and bridge the gap – between “environmental” and “nuclear” agencies and interest groups. This would be useful not only in regulatory decision-making but also in various on-going discussions, eg with the steel industry on recycling of materials from decommissioning of nuclear plants, or with the public regarding, say, the location of deep geological repositories. The latter are built to isolate the waste over many thousands of years and to never cause any harmful radiological dose to the public.

In a broader sense, the nuclear industry has been, for decades, regarded by the general public, some environmentalists and other industries as being uniquely hazardous, due to its radioactive roots. With the emergence of the NORM issue, it can be seen that, in the area of waste management and disposal, the nuclear industry represents just one of the global radioactive waste generators. A full open-minded discussion of the NORM issue may not only help resolve current national waste management problems but may help preserve nuclear power generation as an additional option for the sustainable development of society at large. Indeed, by adding some economic analysis, comparative risk assessment can be transformed into comparative cost-benefit analysis to suggest national policies of prioritisation of societal resources.

* This document is presently under revision.