RADIATION TECHNOLOGY EQUIPMENT WITH USE OF RADIOACTIVE SOURCES

The Russian Federation and countries of the former Soviet Union possess more than 250 girradiators of various types (Table I). Gamma irradiators mostly use sources based on ⁶⁰Co and ¹³⁷Cs. There is a large variety of g irradiators, from small laboratory types to large industrial complexes. For example, laboratory systems for microbiological and biochemical investigations have a mass of 800 kg and contain 24 ¹³⁷Cs sources with a total activity of 2900 Ci.

The PXM-g-30 and Investigator g irradiators use ⁶⁰Co sources with a total activity of up to 30 000 Ci each.

Industrial plants contain some hundreds of ⁶⁰Co sources, each with an activity of up to 1200 Ci.

At present, more than 40 g irradiators are to be taken out of operation, and the sources are to be unloaded and stored. Meanwhile, the total number of sources which should as a matter of urgency be removed and stored is more TABLE I. TYPES AND QUANTITIES OF ⁹⁰Sr RTGs IN THE RUSSIAN FEDERATION AND IN THE FORMER REPUBLICS OF THE USSR

Activity Russian Federation

Type of RTG at time

At temporary

Former of production In operation

storage locations

Soviet

(kCi) republics

IEU-1 330 27 5 1

IEU-2 89 82 2 —

IEU-2M 100 23 — —

IEU-1M 471 1 — —

Beta 35 542 150 25

Gong 45 37 — —

Gorn 168 67 9 —

Efir 105 38 2 —

Grab 270 — 1 —

REU-2 276 8 — —

Pingvin 10 4 — —

Sum, items 829 169 26

Total, items 998 26

Total activity at time

of production (kCi) 57 108 9 070 1 205

than 5000 for the various spent ⁶⁰Co ionizing sources and about 1000 for ¹³⁷Cs.

The problem of ¹³⁷Cs source removal is a complicated one owing to the g irradiator design, as further decommissioning was not foreseen.

DISCUSSION

A. HUSEYNOV (Azerbaijan): We have found two RTGs in Azerbaijan.

One was sent back to the Russian Federation, to the manufacturer, and the other one, with an activity of 53 000 Ci, is in temporary storage. How many Beta type RTGs were shipped to Azerbaijan?

N.R. KUZELEV (Russian Federation): According to the information available to VNIITFA, which we have passed on to the IAEA, there is one such RTG in Azerbaijan.

A. HUSEYNOV (Azerbaijan): Would the Russian Federation take back, free of charge, the ⁹⁰Sr sources of RTGs discovered in Azerbaijan?

N.R. KUZELEV (Russian Federation): That is a legal matter for intergovernmental discussion. On the technical side, Minatom is conducting a source disposal programme, beginning with investigations of the condition of RTGs and the sources extracted from them.

K. GRYSHCHENKO (Ukraine): Could you say more about the Kandalaksha incident mentioned by you in your presentation?

N.R. KUZELEV (Russian Federation): The personnel who detected and located the RTGs in question were not overexposed, but during the dismantling of the RTGs four persons received rather high doses as a result of taking unauthorized actions.

K. GRYSHCHENKO (Ukraine): Is the Mayak enterprise prepared to make the technology developed by it for the disposal of RTGs available to other countries which have RTGs?

N.R. KUZELEV (Russian Federation): That is the first time I have been asked that question, which would have to be discussed with Minatom and with VNIITFA and the Mayak enterprise.

Seon Bin KIM (Republic of Korea): What is being done to preserve information about RTGs?

N.R. KUZELEV (Russian Federation): Unfortunately, many documents of the manufacturing enterprise — Baltiyets, in Estonia — have been lost. During the past five years, we have established a databank covering the Russian Federation and other countries of the Commonwealth of Independent States, and that databank has been provided to the IAEA. We are now carrying out investigations to determine the condition of as many RTGs as possible and then to refine the data in the databank.

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P. ZIMMERMAN (United States of America): The Government of Norway has reported that the Russian Federation has 136 RTGs powering lighthouses between the Norwegian–Russian frontier and Murmansk, and the IAEA has indicated that there are some 600 RTG powered lighthouses along the Arctic coast of the Russian Federation. Apparently Norway has replaced five of the 136 RTGs by power sources based on solar technology. When and how will the Russian Federation replace the remaining RTGs, and how will it in the meantime prevent them from being stolen, breached, misappropriated or orphaned?

N.R. KUZELEV (Russian Federation): Along the Arctic coast of the Russian Federation and on various offshore islands there are about 500 RTGs, and they constitute a major cause for concern. For example, their operating temperature is 70°C, so they may well melt the underlying ice and disappear.

A.J. GONZÁLEZ (IAEA): There is a lot of uncertainty about the numbers of RTGs in different countries. The IAEA has indeed received information about RTGs, but I believe it relates only to RTGs which were supplied through Minatom and that there were other organizations in the former Soviet Union also supplying RTGs.

E. GIL LÓPEZ (Spain): It would seem that RTGs do not present unacceptable risks if they are under appropriate control. Are there any which are operating but not under appropriate control involving periodic inspections?

N.R. KUZELEV (Russian Federation): The organizations in the Russian Federation now responsible for regulatory activities have assumed control over all the RTGs referred to in my presentation. Some of these, however, are located in remote areas and are not protected. Unfortunately, that was not taken into account when they were designed, 30 years ago.

V. KOSENKO (Ukraine): We in Ukraine have had very good experience working with VNIITFA.What kinds of failure do you expect to occur when an RTG has been in service for 40 years?

N.R. KUZELEV (Russian Federation): The design service lifetime was ten years, but in the light of our experience with about 300 RTGs we now consider a service lifetime of 25–30 years to be quite realistic. We have not had a single case of source damage leading to an escape of radioactive material during such periods of operation, and the prognosis for a 40 year service lifetime is positive given normal operating conditions.

RTG cavities, including cavities with depleted uranium, may cease to be airtight if the devices are dismantled, struck or subjected to other unauthorized actions.