Nuclear waste
 
What is radioactive waste?

Radioactive waste is a hotly debated and emotional issue in today's society. Few other topics can polarise a community faster than the discussion of what to do with radioactive waste or whether we should be generating any at all.
For legal and regulatory purposes, radioactive waste is defined as material that contains or is contaminated with radionuclides at concentrations or activities greater than clearance levels as established by the NNR (National Nuclear Regulator), and that has no use.
Radioactive waste can be classified according to radiological properties (quantity and type of radioactivity), physical properties (form in which the material occurs, i.e. gas liquid or solid) and also whether it is heat producing or not. The hazard involved as well as the final disposal methods to be used for the waste also plays a part in the classification.

Waste classification

Very low-level waste (VLLW) contains very low concentrations of radioactivity, originating from the operation and decommissioning of nuclear facilities.
Low-and intermediate level waste (LILW) contains concentrations or quantities of radionuclides above the clearance levels established by the regulator, but with a radionuclide content and thermal power below those of high level waste. Low and intermediate level waste is often separated into short-lived and long-lived wastes. Short-lived waste may be disposed of in near surface disposal facilities. Plans call for the disposal of long-lived waste in geological repositories.
High-level waste (HLW) contains heat-generating radionuclides with long- and short-lived radionuclide concentrations. One of the characteristics that distinguish HLW from less active waste is its thermal power. HLW results from the reprocessing of spent nuclear fuel.
NORM contains low concentrations of naturally occurring radioactive materials.
 
Origin

In South Africa radioactive waste is produced by the nuclear fuel cycle.
Necsa's nuclear fuel production facilities, namely the conversion, enrichment and fuel fabrication plants produced radioactive waste until 1997. After that the last of these facilities were shut down. Presently waste is produced as a result of the decommissioning of these facilities. Eskom’s Koeberg nuclear power plant produces spent fuel and operational radioactive waste.
Research and development facilities
Necsa’s Safari research reactor at Pelindaba produces spent fuel and operational waste. Radioactive waste is produced from radioisotopes production activities at Necsa. The iThemba LABS also produces radioactive waste. Historically waste has been produced by various research activities.
Mining and minerals processing industry
Naturally occurring radioactive waste materials (NORM) are produced by various facilities in the mining and minerals processing industry.
Commercial and Industrial users
Radioactive wastes are produced from various applications of radioactive materials in industry and the medical sector.

WHAT HAPPENS TO IT?
Necsa Waste

  • Radioactive waste is stored at Pelindaba in various locations on the site. The waste occurs in the form of low and intermediate level waste (LILW). Some of the waste is short-lived waste and some are long-lived waste. All surface stored radioactive waste at Pelindaba will be moved to a centralised storage facility on site called the Pelstore, situated in the disused enrichment plant building.
  • Spent fuel from the Safari reactor is presently stored in a pipestore facility at Pelindaba. Radioactive waste produced in the Hot Cell Complex and Isotope production centre will also be stored in the pipestore.
  • Historical waste, consisting of combinations of low and intermediate level waste as well as spent radiation sources are presently stored in covered trenches at Thabana on the Pelindaba site.

Eskom Waste

  • Koeberg spent fuel is stored in reactor pools. These pools have been recently further re-racked in order to facilitate lifetime storage of spent fuel. Koeberg spent fuel should not be regarded as waste until it’s specifically declared as waste.
  • Koeberg operational waste (low and intermediate level waste) is temporally stored at Koeberg before being transferred to Vaalputs for final disposal.

Mining and Process Industry Waste

Various quantities of NORM waste are stored in different locations in the mining and minerals industry.
 
Waste from iThemba LABS

Relatively small quantities of research waste are presently stored at Faure in the Western Cape.
 
Other Generators' Waste

Various quantities of spent radiation sources are generated e.g. by hospitals and industrial users. This waste is managed by Necsa.

Is it dangerous?

Radioactive waste emits energy in the form of radiation. This energy appears as alpha, beta and gamma radiation. The radioactivity produced by radioactive waste is only potentially dangerous and are categorised into different waste types according to the radioactivity they produce.
Radioactive waste is categorised according to the hazards associated with the different waste types. Low-level waste does not pose a significant radiation hazard, whereas high-level waste is potentially dangerous and needs to be properly contained and shielded.
Damage to living tissue can be caused if sufficient quantities of alpha, beta or gamma radiation interact with genetic material within the cells of our bodies. Whether the radiation causes us any harm depends on the quantity of the radiation, how energetic it is and what part of the body is affected.The radiation dose describes the health hazard caused by radiation. The dose unit is Sievert (Sv).
The dose is often given in thousandths of Sieverts, i.e. millisieverts (mSv) or in millionths, i.e. microsieverts (µSv).
The global background radiation is measured at 2.4 mSv and South Africa's average is close to this.

Some examples of radiation dose:

0.01 mSv The radiation dose received by a patient having his/her teeth X-rayed
0.01 mSv The radiation dose received by a patient having his/her lungs X-rayed
2 mSv The annual dose of cosmic radiation received by a person working in an aeroplane
4 mSv The average annual radiation dose for South Africans caused by indoor radon, X-ray examinations, etc
100 mSv The highest permitted dose for a radiation worker over a period of five years
1000 mSv The dose which may cause symptoms of a radiation sickness (e.g. tiredness and nausea) if received within 24 hours
6000 mSv The dose which may lead to death when received all at once

At Pelindaba and Vaalputs the probability of a serious radiation exposure is small. Nonetheless, the risk of accidents still exists and precautions are taken to prevent such occurrences. The radiation exposure of Necsa workers is monitored regularly and measures taken when deviations from the norm occur, such as withdrawing workers from their place of work for a specified period of time. This information is available from Necsa's Risk Management Division.

Laws and agreements

The management of radioactive waste at Necsa is governed under the provisions of the following acts:

  • The constitution of the Republic of South Africa, (Act no. 108 of 1996)
  • Nuclear Energy Act, (Act no. 46 of 1999)
  • Dumping at Sea Control Act (Act no. 73 of 1980)
  • National Nuclear Regulator Act (Act no. 47 of 1999)
  • Hazardous substances Act (Act no. 15 of 1973)
  • National Water Act (Act no. 36 of 1998)
  • National Environmental Management Act (Act no. 107 of 1998)

National Policy and Strategy on Radioactive Waste Management
 
The Department of Minerals and Energy (DME) are presently developing a national radioactive waste management policy and strategy in conjunction with the various role players in South Africa. Draft policy and strategy documents will soon be made available to the public for discussion.

Regulation

NLM is regulated by:

  • Minister of Minerals and Energy in concurrence with the Minister of Environmental Affairs and Tourism and the Minister of Water Affairs and Forestry (Nuclear Energy Act 1999)
  • National Nuclear Regulator (National Nuclear Regulator Act, 1999)
  • Directorate radiation control (Hazardous Substances Act, 1973)
  • Department of Water Affairs and Forestry (National Water Act)

Licensing

The following licenses have been granted by the NNR:

  • NL-25: Nuclear license granted to the mines, under which license NLM carries out waste management/decommissioning projects.
  • NL-27: Nuclear license granted to Necsa for the Pelindaba site.
  • NL-28: Nuclear license granted to Necsa for the Vaalputs site.

Standards

  • Conformance of quality systems to the requirements of the regulator, as documented in the standard LD1002, and to the requirements as documented in SABS ISO 9002 (latest revision)
  • ISO 14001: ISO Environmental Management Systems – specification with guidance for use
  • ISO 10006: ISO for quality management – guidelines to quality in project management

Benchmarking

The DACST/DME Review Committee benchmarked NLM liability assessment methodology in April 2000 and made certain recommendations. These recommendations were aimed at ensuring conformance to international norms.



Copyright Necsa 2012