The management of radioactively contaminated soils
This survey was carried out from September to November 2006 via the EAN Forum. The aim was to establish the state of the regulations concerning the management of radioactively contaminated soils due to activities related to facilities from the nuclear fuel cycle (i.e. nuclear power plant, research reactors, fuel cycle facilities, excluding uranium mines and mining sites). The questionnaire contained the following questions:
- What is the regulatory framework within your country regarding the management of radioactively contaminated soils?
- Are there any release criteria (in terms of individual or collective dose, Bq/g...) for unrestricted and/or restricted use of such a site?
- What are these criteria and how are they used?
- Do you have any example of such a contaminated site which was finally released from regulatory control after remediation?
Answers from 15 different countries have been received.
The Government of Armenia has approved the Radiation Protection General Standards and Rules. The general exemption and clearance criteria for public are stipulated in these regulations: effective dose shall be no more than 10 µSv per year for any member of the public or collective dose committed to public no more than 1 Sv.Man as well as the activities and specific activities for radionuclides (well known table in IBSS).
The Armenian regulation also stipulates conditional and unconditional release criteria for slightly contaminated materials which could be used for soil as well:
- If the activity of radionuclides in solid materials is less than 0.3 kBq/kg, the materials can be released from regulatory control without any conditions
- Some conditions could be putted for use of materials (Regulatory Body decision) if:
- Summary activity of beta radionuclides is between 0.3 and 100 kBq/kg
- Summary activity of alpha radionuclides is between 0.3 and 10 kBq/kg
- Summary activity of transuranic radio nuclides is between 0.3 and 1.0 kBq/kg
In the same regulation, the activity concentrations above 100 kBq/kg, 10 kBq/kg and 1.0 kBq/kg for beta, alpha and transuranic radionuclides respectively are defined as low bounds of low level radioactive wastes.
Denmark is a small country with - in practice - only one site that might have contaminated soil areas (site of the first nuclear reactor in Denmark). The radiation protection authorities is by law authorized to deal with such cases. For the one site the authorities have in their license for operation (which is now decommissioning of the nuclear facilities at the site) stated that the clearance of soil areas will have to be dealt with on an ad hoc basis. I.e activity concentration measurements and dose calculations must be presented to the authorities case by case.
This is opposed to the clearance of materials, objects and buildings where clearance principles and values taken from the IAEA (RS-G-1.7) and the European Commission (RP113) applies.
The regulatory framework for removal of control of decommissioned nuclear sites is included in the Finish Nuclear Energy Act. The procedure is called the expiry of nuclear waste management obligation, similar to that of approval of a closure of a repository (in the Finish legislation decommissioning is regulated as waste management). The relevant paragraphs of the legislation are below.
Expiry of waste management obligation
The Ministry of Trade and Industry or the Radiation and Nuclear Safety Authority (STUK), having granted a licence for operations that generate nuclear waste, shall order that the waste management obligation has expired when:
- it has been transferred to another party in accordance with section 30; or
- the nuclear waste has been transferred outside Finlands jurisdiction in the approved permanent manner referred to in section 6 a(2); or (1420/1994)
- the final disposal of nuclear waste, including clean-up of the site of a decommissioned nuclear facility, has been carried out in accordance with section 33, and the licensee under a waste management obligation has paid a lump sum to the State for the monitoring and control of the nuclear waste.
Should the Government issue an order referred to in section 31, the State shall be responsible thereafter for the nuclear waste management measures not yet carried out for the waste referred to in the order, and for the costs to be incurred in carrying out these measures by the licensee under a waste management obligation.
Final disposal is considered implemented when the Radiation and Nuclear Safety Authority (STUK) has confirmed the nuclear waste to be permanently disposed of in a manner it approves. Clean-up of a decommissioned nuclear facility is considered implemented when STUK has confirmed that the residual quantities of radioactive materials in soil and buildings are within acceptable ranges.
Responsibility for nuclear waste after their final disposal
When the licensees waste management obligation has ceased by virtue of paragraph 3 of section 32(1), the ownership right to the nuclear waste is transferred to the State, which shall be responsible thereafter for the nuclear waste.
Should it become necessary after the final disposal, the State has the right, at the disposal site, to take all measures required for the monitoring and control of the nuclear waste and for ensuring the safety of the repository.
The acceptance criteria for removal of control of contaminated sites is under preparation and will be issued as a STUK-guide (probably at the end of 2007). The envisaged criteria allow both unrestricted and restricted release of sites. For unrestricted release buildings, there will be surface contamination constraints (in Bq/m2), derived on the basis of the trivial dose of 0.01 mSv/a. Higher surface contamination levels can be allowed on the basis of case-by-case optimization assessment and the dose target can then be up to 0.1 msv/a. For contaminated soil at the sites, no Bq-based constraints will be established but the acceptance will be based on a dose target from 0.01 to 0.1 mSv/a based on optimization assessment.
Georgia has not great experience with site release createria. However IAEA RS-G-1.7, IAEA drafts Ds172 Ds332 and IAEA TecDoc-855 could be useful.
The release of radioactively contaminated soil is regulated in the German Radiation Protection Ordinance (RPO - 2001). General release criteria for clearance are defined in § 29 of the RPO: radioactively contaminated or activated material may be cleared, if the dose for a single person of the population resulting from clearance is in the order of 10 µSv in a year. The criterium for the collective dose is 1 person.Sv per year and is defined in the Euratom Basic Safety Standards (1996).
The RPO distinguishes between unrestricted clearance of soil material more than 1000 Mg per year (Column 6 Table 1 Appendix III RPO), clearance for disposal in a repository site of soil with less than 1000 Mg per year (Column 9 Table 1 Appendix III RPO), and areas, where soil material remains after clearance (Column 7 Table 1 Appendix III RPO). The clearance values are given in Bq/g. If the above dose criteria are met, case to case decisions may be applied.
Sites that have been contaminated by activities of facilities from the nuclear fuel cycles are e.g.:
- NPP Ohu (1998) remediation finished
- Fuel Production Plant Hanau (NUKEM): the remediation of the site was finished in may 2006. With exception of an area for restoration of ground water the total area is released from regulatory control.
- NPP Rheinsberg remediation to be expected by 2011.
The general clearance levels for release of artificial radioactive materials resulting from practices according to Title III of the Basic Safety Standards are referred to the Greek Radiation Protection regulations (Joint Ministerial Order 1014 (FOR) 94, Official Gazette No 216/B/6-03-2001, "Radiation Protection Regulations"). Since Greece has neither nuclear power plants nor uranium mines, the main issue related to the contaminated soil is due to enhanced levels of natural radioactivity due to NORM activities. There are no particular release criteria for contaminated soil, but conditional clearance levels are used on a case by case basis adapting the 10 μSv/y dose criterion from any pathway for the general public.
For NORM materials, Greece has adapted in the form of GAECs circular the values and the procedures provided by the European Commission publications: Radiation Protection No 122 Part II (Practical use of the concepts of clearance and exemption Part II, Application of the concepts of exemption and clearance to natural radiation sources), and Radiation Protection No 112 (Radiological protection principles concerning the natural radioactivity of building materials - EU 1999).
1. Decommissioning of a fertilizer industry
The applied clearance levels for the decommissioning project of the fertilizer industry were more strict than the proposed ones by the European Commission, first, due to the owners demand to set the area at the natural background (returned to normality), therefore, the produced waste was greater than the amount which would have been produced if the clearance levels of Radiation Protection No 122 had been applied. Also due to political and public demands the As Low As Reasonably Achievable (ALARA) principle in the sense of cost-benefit was not taken into account.
2. Use of phosphogypsum for agricultural purposes
In order to assess the doses to a population target group, a dosimetric calculation was performed. The dose criterion of 10 μSv/y was applied for the specific exposure pathway corresponding to the ingestion of rice produced from a phosphogypsum enriched soil. Based on the above mentioned assumptions and phosphogypsum measurements, GAEC issued specific regulations on how phosphogypsum can be removed from a stack and commercially distributed for agricultural use. The average Ra-226 concentration in the stack from which the phosphogypsum is removed must not exceed 400 Bq/kg.
According to the Hungarian legislation, the release of low (or very low) level contaminated bulk material from regulatory control needs case-by-case evaluation. The licensee is expected to perform a safety assessment including different exposure pathways demonstrating that the radiation exposure will not exceed the dose limit of 30 µSv/y given in the Decree of the Minister of Health 16/2000. (VI. 8.). The authority (Office of the Chief Medical Officer of State) makes a case-by-case decision on the unrestricted or restricted use.
The Ministerial Decree 16/2000. (VI. 8.) does not stipulate any predefined limits for clearance (beside the dose limit of 30 µSv/y). (Note that the Hungarian legislation applies the exemption levels set by the BSS of IAEA and BSS of European Commission, but only for material of moderated quantity)
At the moment, preliminary studies are being carried out for the clearance (including unconditional/conditional) processes and for the other technical aspects of decommissioning of a nuclear site in Hungary. So the criteria regarding the end of decommissioning and the authorized dose constraints for decommissioning of nuclear reactors (and for release of site) will be determined within a few years. It is worth remarking that the criteria system will be in line with the establishment of new repository of L/ILW and the radioactive waste policy concerning nuclear reactors, too.
Apart from the fact that Ireland does not have any nuclear fuel facilities, they do not have any criteria or guidance for the release of land from any sort of regulatory control.
There was one nuclear research reactor in Latvia. It has been shut down since 1998. It is planned to dismantle it (approximately 2010 or later). For use this site in future, decontamination will be performed.
In Latvia's legislation release criteria are inserted in Cabinet Regulation "Requirements for Operations with Radioactive Waste and Materials Related Thereto" (adopted 19 March 2002). This is fragment of this regulation:
7. Materials related to radioactive waste shall be classified in the following groups:
7.1.1. is less than 100 µSv per year for an individual user (for the whole body);
7.1.2. is less than 5 mSv per year for an individual user (for the skin surface); and
7.1.3. is less than 1 mSv per year for a collective dose (for the critical group of population); and
Download the full text of the regulation (Pdf)
There are no specific criteria for use of radioactively contaminated soils. If a decision is to be made the general criteria of clearance would be used. These criteria are doses to members of critical groups (10 µSv per year) and collective doses (1 man.Sv per year). Investigations of soil contamination and dose assessment shall be done. Results of dose assessment will be the basis for decision making.
Lithuania does not have any contaminated sites which were earlier under regulatory control. One radium contaminated site was detected in the former soviet military area. The site has been investigated, possible doses assessed and measures to be taken recommended.
Radioactively contaminated soils exist in Serbia. The problem is not explicitly treated in the legislation. The new law (expected at the end of 2006) and regulations may address this problem adequately.
Serbia had a nuclear research reactor stopped in 1984 (now in pre decommissioning phase), uranium mine (closed more than thirty years ago, but not closeout - in meaning of the IAEA Safety Glossary), closed (but not decommissioning) uranium processing facility, artificial fertilizer factories sites, sites bombarding with depleted uranium (DU) munitions.
Regulatory Commission for Nuclear Safety, established a year ago, gives general requirement to use IAEAs recommendations in each issue where Serebia does not have its owns. Being understaffed, temporary, this Regulatory Commission is involved only in regulation activities concerning research reactor in Institute of Nuclear Science Vinca.
As far as the criteria in cleaning sites bombarded with DU munitions is concerned, the strategy was to collect all bullets with contaminated surrounding soil and put them in a radioactive waste storage. The criterion for soil contamination is the natural level from annually radioactive contamination monitoring reports.
Besides dose limits for occupational and exposure of population (fully according BSS No. 115), there is the Article 24 from the Regulation on limits of radioactive contamination of the environment and the method of decontamination, Official Gazette of the FRY, 9/99. However this article contains a mistake in treatment of artificial radionuclides. So, Regulatory Commission for Nuclear Safety recommends applying Article 24 only for natural radionuclides. For artificial radionuclides it is recommended to use Safety Guide No. RS-G-1.7.
Slovak legislation does not enact the details on clearance of contaminated areas. Nevertheless there are levels for clearance of contaminated material (for example 0.3 Bq/g for Cs-137) which could be used for these purposes. Moreover there is the general criterion - anual dose for member of the critical group of 10 µSv and and collective dose of 1 man.Sv. On the other hand the optimization plays a role in this case too. Slovak opinion shows (there are contaminated river banks after accidents on NPP A1 in Jaslovske Bohunice in 1976 and 1977), that especially in case of intervention it is very important to optimize the whole procedure and to set the priorities for treatment of radioactive residues from past accidents or practices during remediation action. Sometimes it could happen that it would be not very practical to have fixed values in legislation because of variety of possible situations. Slovak authorities suppose that they will enforce the levels for clearance of building and areas in the next amendment of our regulations (probably the values recommended by the European Union).
The Spanish regulatory framework regarding the management of radioactive contaminated soils comprises two decrees: Decree 1836/1999, Regulation on Nuclear and Radioactive Facilities, and Decree 783/200, Regulation on Sanitary Protection Against Ionising Radiation. These decrees do not include specific release criteria for unrestricted or restricted use of such a site. Because of that, and taking into account that in the near future such criteria will be necessary, the Nuclear Safety Council (CSN) has prepared a technical instruction about radiological criteria for release of nuclear installations sites, that will be issued soon.
The CSN technical instructions are general or regulatory provisions that are binding and are addressed to groups or indeterminate numbers of individuals in relation to technical matters relating to the exercising of the Councils own realms of competence regarding nuclear safety and radiation protection. Non-compliance with these instructions would be legally typified as an administrative infringement. The general release criteria established in the draft instruction are the following:
- Effective dose to the representative member of the critical group, due to residual activity in the site soil, shall not be higher than 0.1 mSv per year. This criterion is applicable for unrestricted or restricted use of the site.
- Buildings and structures that is foreseen will remain on site shall meet the criterion recommended by the European Union in the document Radiation Protection 113, Recommended radiological protection criteria for the clearance of buildings and building rubble from the dismantling of nuclear installations (0.01 mSv per year).
In addition to the former criteria, site release under restricted conditions is considered acceptable provided that:
- The licensee demonstrates that further reductions in residual radioactivity necessary to release the site without restrictions would result in net public or environmental harm or that the residual levels associated with restricted conditions are ALARA
- The licensee has made provisions for legally enforceable institutional controls that provide reasonable assurance that the radiological criteria are met
- The licensee guarantees that residual radioactivity at the site has been reduced to a level that the effective dose to the representative member of the critical group does not exceed the established value, but if the institutional controls are no longer in effect and the restrictions are not effective, this dose will not exceed 1 mSv per year.
The Swedish authority (SSI) has recently (in 2006) put a draft regulation out for comments (in Swedish) on clearance from regulation of radioactive material. Conditional clearance has already been used on a case-by-case basis.
In Switzerland there is no particular release criteria for contaminated soil. They had no problems up to now with radioactive soil since the enactment of radiation protection law 1992.
Nevertheless in such a case, the limits for immission from Article 102 in the Radiation Protection Ordonance would be used. Additional the soil would be eliminated as radioactive material (there are severals ways possible) if the specific concentration of radioactivity exceeds the clearance values in annex 3 column 9 in the Radiation Protection Ordonance unless the annual dose for the critical group of persons is smaller the 10 µSv/a (all pathways considered).