Studies on the Waste Depository of the Sillamaee Plant

-ii*. f I SSI-rapport 93-06

!".••••' •'• Shit t 'us Box 6020- OS -~'.'*9 ssi 10-; 01 STOCKHOLM Soha

Hans Ehdwall et al

Studies on the Waste Depository of the Sillamäe Plant -Sur..

fctftBStatens strålskyddsinstitut Nummer / Number: 1993-06 Swedish Radiation Protection Institute

ISSN: 0282-4434

Titelblad / Title page Datum / Date of issue: 1993-03-15

Författare / Author: Hans Ehdwall, Björn Sundblad, Vladimir Nosov, Henno Putnik, Raimo Mustonen, Laina Salonen, Erkki Illus, Henning Qvale Avdelning / Division:

Dokumentets titel / Title of the document:

Studies on the Waste Depository of the Sillamäe Plant State of the art report from the project group

Sammanfattning / Abstract:

Nyckelord (valda av författaren) / Key words (chosen by the author):

Sillamäe, uranium waste, waste deposit, thorium, loparite, environmental radiation

Antal sidor / Number of pages: 10 THE SILLAMÄE PROJECT 93-03-15

STUDIES ON THE WASTE DEPOSITORY OF THE SILLAMÄE PLANT

State of the art report from the project group

SUMMARY

The studies on the waste material in the Sillamäe depository indicate that the wall material of the depository is typical mill tailing from chemical enrichment of uranium ore. The results from the sea sampling show that the impact from the depository on the marine environment is obvious close to the shore-line. However, the concentrations of radioactive elements decrease very rapidly as the distance from the shore increases. The farthest distance where elevated radionuclide concentrations were observed was 300 meters from the shore-line. The results on the ground water used as a tap water in Sillamäe indicate that the waste depository ooes not contaminate the local ground waters.

BACKGROUN', Until 1970, only uranium ore and alum- shale were processed at the plant. Sillamäe is a .'I town, some 185 km Elemental uranium was enriched with east of Tallin . ,:i onia. It has about 20 a chemical treatment of the crushed COO inhabita rt. ; nd has been develo- ore by: ped around £ Sillamäe Metallurgy -leaching Uranium from groun- Plant, today 1 State join-stock com- ded ore using sulphuric acid pany callec rS Silmet. Unti! recently, -solid liquid separation and the plant t: nged to and was mana- washing ged by the 3SR Ministry of Medium- -solvent extraction of Uranium Scale Engei -;ering and it's production was uraniun, ,or military and civil use. After the recovering of Uranium the leached liquid was neutriized by the The Sillamst Plant was built in 1948 addition of ammonia and oil-shale ash as a top se ;'et facility, originally for from a local thermal power plant and processing aljm-shale (about 300 ppm discharged together with the the solid of U) from Estonia. Later uranium ore residues of the Uranium ore into tai- from eastern Europe (up to 10 000 lings. Between 1948 and 1959, waste ppm) was processed. As a total, 4 013 from the Uranium processing was 000 tons of uranium ore were pro- transported to the first marine terrace cessed at the plant. Most of the ore of Päite cape and stored at the sur- was brought from Czechoslovakia (2.2 face. In 1959 , a waste depository was million tons) and from Hungarv (1.2 established. The site was surrounded million tons). Minor amounts of ura- by a dike made from local ground and nium ore were brought from Poland, production residues whir i permit drai- Romania, Bulgaria and DDR. nage. The depot has been reconstructed a couple of times in the last decades and in 1969-70 it was ex- ' f

panded to it's present size. Waste 'K- material from whithin the depot was 4 million tons of uranium mining resi- then used for the construction 01 the duals, walls of the impoundment. 1.5 million tons of oil-shale ash, and 0.2 million tons of calcium fluoride Today, the depot is an oval retention (CaF2), including impoundment with an overall area of about 330 000 m2, the top of the dam 1.2 thousand tons of uranium, being about 25 meters above sea le- 0.8 thousand tons of thorium, and vel. About 50% of it's area is covered 4.4 x 1015 Bq (1.2 x 105Ci) of radioac- by a sedimentary pond containing tive elements (decay products of ura- about 150-200 000 m3 of waste water nium and thorium) of which about 3 x with a depth of 0-3 meters. The bottom 104 Bq (7000 Ci) is radium. of the depository concists of a perme- able sandy-gravel-shingle ground THE PROJECT (thickness varying from 1 to 8 meters) lying on a 2 -10 meter thick layer of in June 1992, an international project watertight Cambrium clay. was established. The tasks of the group were defined as: In the beginning of the 1970s the plant switched to processing of loparite - a 1. to estimate the amounts of ra- mineral from the Kola Peninsula rich of dioactive and chemical pollutants in Niobium, Tantalium and other rare the depository, earth metals. In addition loparite also 2. to estimate the amounts of ra- contains Uranium (about 0.03%) and dioactive and chemical pollutants lea- in paticular Thorium (0.6%). Since king from the depository to the Gulf of 1977, no Uranium ore has been pro- Finland, cessed, the depot has been used for 3. to estimate the environmental the disposal of oil-shale ash and was- impact of the Sillamäe waste pond to tes from loparite processing (1977-89). the Gulf of Finland, to the Sillamäe The annual volume of disposal of lo- town, and to the ground water in parite waste has been about 20 000 Sillamäe area, and tons per year, and oil-shale ash has 4. to make proposals for getting been disposed over different areas the waste depository to an acceptable during the last years. Today the plant condition. is operating only about 15-20% of it's production capacity due to shortage of Two alternatives for environmental im- raw material and chemicals for the pact to the Gulf of Finland and the Bal- process. tic Sea are to be studied. The first is if the depository remains as it is and the It can be concluded that the Sillamäe second if, of some reason, ali the waste depot has been formed of waste contents in the depository, in short ti- with various chemical and physical me period, will enter the Gulf of Fin- properties accumulated over the years land. due to various technological processes used for production. The first meeting of the group was held in Sillamäe in June 15-17. The mee- An estimation of the substances dis- ting resulted in a plan for sampling that posed in the aam, given by the plant, should be performed during autum indicates the following: 1992. The second meeting was held in ' f

Helsinki in November 23-25, after most In order to estimate the impact of air- of the collected samples were ana- borne radon originating from the pond, lyzed. The members of the project passive radon monitors were set out at group and other participants in the 10 different locations. The exposure project are listed in the appendix. time is expected to be around 5-7 months. SAMPLING RESULTS OF THE MEASUREMENTS In September 14-17, sampling was done at Sillamäe. Soil samples from Solid samples from the depository the pond wall were taken at 25 different places. Preparation for the sam- Twentyfive samples of the solid waste pling was done by the Silmet Plant in were collected from small pits dug in advance so that the pits were dug to a the wall of the depository. During depth of about half a meter into the sampling, dose rates were measured wall. At each place soil samples were inside the pits. Two samples were taken for measurement of radioactive collected outside the wall of the de- and chemical substances. The exter- pository and these samples represent nal gamma radiation was also measu- the older waste deposited in the be- red at each pit. ginning of the industrial operation at Sillamäe. Two samples were taken Water samples were taken from nine from the top of the depository to repre- different drilled well holes around the sent the waste of the present produc- depository. The samples are ground tion of the plant. Places for different water samples and they are assumed samples are shown in Figure 1. to be representative for liquid effluents leaving the disposal area to the Gulf of Concentrations of 238U and 226Ra in the Finland. Water samples from a little wall samples showed that the wall pool between the depository and the material of the depository is typical Gulf of Finland, from the top of the waste of chemical enrichment of ura- pond and from a spring outside the nium ore. The uranium concentrations disposal site were also taken as well varied between 2000 and 9000 Bq/kg as samples of domestic tap water. The dry weight, and radium concentrations K K spring was choosen after considering between 1000 and 73 000 Bq/kg. the direction of ground water flow and These uranium and radium concentra- is used as a reference. Tap water used tions are roughly 100 to 1000 times in Sillamäe originates from deep drilled higher than typical concentrations in wells (depths varying between 125 and soil. Concentrations of 232Th in the wall 230 meters). were around its typical soil concentrations, except at four places in the Samples of sea water, bottom sadi- southeastern part of the wall, where ment and seaweed were taken from the thorium concentrations were the sea area outside the Sillamäe de- between 250 and 800 Bq/kg, about ten pository. The most distant sampling times higher than typical soil concent- point was located about 11 km north of rations . the depository and the nearest was in the shoreline straight below the pond. The measured dose rates in the sam- Weather conditions were optimal for ple pits varied between 3.1 and 17 [i sampling. Sv/h, values being typical for uranium f

mill tailings The dose rate above nor- depository is not homogenious. To be mal soil is typically 0.08 - 0.15 |iSv/h. able to estimate the inventory with some reasonable accuracy, it is neces- There is one place outside the wall of sary to drill samples also from the in- the depository where external dose ner parts of the depository. rate is varying between 26 and 38 u. Sv/h. Two samples collected from this Water samples place contained very high amounts of radium, 85 000 and 139 000 Bq/kg. Nine water samples were collected The uranium concentrations were 5 from holes drilled in the wall of the de- 500 and 3 500 Bq/kg, respectively. pository or just after the wall between This waste is assumed to have been the depository and the Gulf of Finland. produced in the beginning of the ura- One water sample was also taken from nium enrichment at the plant or it is the a little pool between the depository waste brought thereto from elsewhere and the sea, and one sample from the between 1948 and 1959. pondwater and from a spring outside the disposal area. The sampling pla- The waste from the present production ces are shown in Figure 1. Two tap of the plant contains high amounts of water samples were taken from the thorium and also elevated amounts of factory area (laboratory and the main uranium and radium. 232Th concentra- factory), one tap water sample in the tions of the two samples of the present hospital outside the factory area and waste from the top of the depository one tap water sample in the hotel, a were 26 000 and 15 000 Bq/kg dry few kilometers from the factory. All ra- weight. Uranium concentrations were 2 diochemical analyses on the Wdter 200 Bq/kg and 1 500 Bq/kg, and ra- samples from drilled holes are rut yet dium concentrations were 1 800 Bq/kg ready. and 1 400 Bq/kg, respectively. Concentrations of 238U in tap water Comparison with the uranium mill tai- samples are varying from below 0.01 226 ling at the Ranstad site in Sweden has to 0.15 Bq/I, and Ra concentrations been performed. The former waste in between 0.02 and 0.15 Bq/I. These Sillamäe that nowadays is partly found concentrations are quite low and they in wall of the pond has a quite similar can be expected to be natural levels in composition, as an average, as the ground waters of this area. These re- Ranstad tailings. However, the waste sults also indicate that the waste de- that recently has been produced has a pository does not contaminate the higher content of especially Th, Nb local ground waters. and La. The total amounts of uranium and radium in the uranium mill tailings The spring water running outside the in Ranstad are about 100 tons and 5 x waste pond (about 40 meters) contains 1012 Bq, respectively. These figures quite high amounts of uranium, about are about one order of magnitude 90 ng/l (this corresponds about 1.1 lower than at the Sillamäe depository. Bq/I of 238U). The concentration of 226Ra in the spring water, however, is It is not possible to estimate the total low, about 0.01 Bq/I. The spring is inventory of radioactive or chemical running through old alum-shäle mines substances in the depository on the and high uranium concentration may basis of these results, because it is be explained by that and by the fact obvious that the composition of the r t:**

that uranium is more soluble than ra- rest samples were taken from the dium or thorium. shore-line, straight below the pond, and the most distant place was about Uranium exists in high concentrations 11 kilometers from the shore. The re- also in the pond water, more than 800 sults in sea water show that the impac- fj.g/1 (about 10 Bq/I of 238U). 226Ra con- ts of the depository OP the marine en- centration in the pond water is only 0.1 vironment are clear in the waters close Bq/I. The little pool between the de- to the shore-line, but the concentra- pository and the sea is clearly conta- tions of radioactive substances decre- minated by the radionuclides leaking ase very rapidly when going farther from the pond. Uranium concentration away from the site. On the shore-line, in the pool water is around 100 u.g/1 straight below the pond, the highest (about 1 Bq/I of 238U). Also the isotope uranium concentration was 190 \ig/\ 238 226 ratio between the two uranium iso- (2.3 Bq/! of U). Ra concentration topes,23^/238^ indicates that the ra- in that place was only 0.03 Bq/I. The dionuclides in the pool water are from farthest detections of elevated radio- the depository (ratio = 1.02). nuclide concentrations were made at a distance of 300 m from the shore-line. Uranium concentration was there 3 \i Water samples were also analysed for 238 226 macro constituents as well as for he- g/l (about 0.04 Bq/I of U). Ra concentration at that distance was 0.01 avy metals, altogether there were 27 238 elements analysed including the total Bq/I. The normal level of U concent- amount of uranium. ration in the water of the Gulf of Fin- land is 0.01-0.02 Bq/I. Large variations of the elemental com- posision of the water samples collec- The isotope ratio between the two ted in the wells within the wall were uranium isotopes, 234^1/238^1, jn the sea observed. For example Cu and Zn va- water near the shoreline is near one. ries with more than two orders of This also indicates, in addition to high magnitude, <25 to 13 000 ng/l, respec- uranium concentrations, that the ra- tively <20 to 4 410 u.g/1. dionuclides originate from the waste depository. Due to rapid mixing and Comparison between background va- dilution of the leaking waters with the lues of ground water and pondwater sea water, elevated radionuclide con- shows that the concentration of many centrations can be seen only in a very elements are more than 100 times narrow coastal area. higher in the pondwater. These elements are Zn, Cu, Al, Cr, Fe, La, Sr, In bottom sediments, elevated radio- Co, P, Ni and V in decreasing order. nuclide concentrations were detected in a shallow cove alongside the pond, The concentration of different ele- where the sediment was typical orga- ments in the tap water from four diffe- nic "gyttja-clay". The concentrations of 238 226 rent places is lower compared to the U and Ra were 450 and 470 background values. Bq/kg dry weight. At all the other sampling places the concentrations Samples from the Gulf of Finland were at the same level characteristic for the Gulf of Finland. The concentra- l37 Nine sea water samples were collec- tions of artificial cesium isotopes, Cs l34 ted from the Gulf of Finland. The nea- and Cs, were in all samples at the rr same level as in the Gulf of Finland in general. Investigation of the stability of the walls of the depository must be made in or- It is most likely that the actual con- der to assess the possibility for the sequences of the Sillamäe depository contained material entering the Gulf of to the marine environment can be Finland- found only in a very narrow coastal From the received results, an estima- area. This can be explained by a rela- tion of the environmental impact to the tively small releases through the em- bankment and by the exposed charac- sea will be made for the case that all ter of the sea area. The coast is open the deposited mateiial would, of some without any archipelago. Thus the cur- reason, enter the Gulf of Finland in a rents and the effective water exchange short time period. with the open Gulf of Finland are pro- moting dispersion of radioactive and A proposal for remedial actions for the chemical substances in large water Sillamäe waste pond will be outlined. masses. Furthermore, the bottoms in the Narva Bay are mostly hard sand Recommendations bottoms (erosion bottoms), where se- dimentation does not occur, and the In order to perform remedial actions, particulate matter is transported farther the present deposition of waste must to the open sea. be changed and localised to some other area in order not to stop the pro- Future activities duction at the Silmet plant. The group therefore proposes that a special pro- In order to estimate the contents in the ject for the waste management for the pond, a drilling project is planned. A facility is established. number of drill cores will be taken and analyzed in respect to radioactive elements and other compounds. The Appendix: Merbers of the project group stability of the contents might also be and other participants. estimated. The drilling should be prefe- Fig 1: Map of the disposal area. rebly be performed in summer time Sampling points are marked. (April-Sebtember) and the task will be Fig 2: Photograph of the Sillamäe area made by a Norwegian company. Costs 1962. for preparation and drilling could be Fig 3: Photograph of the Sillamäe area estimated to about 500 000 NOK and 1986. analyzing, depending on ambitions, 250 000- 500 000 NOK. APPENDIX

Merbers of the project group and other participants.

Mr Hans Ehdwall National Institute of Radiation Protection SWEDEN

Mr. Björn Sundblad SWEDEN

Mr. Vladimir Nosov Sillamae Plant of Metal and Chemical Production ESTONIA

Mr. Henno Putnik Institute of Meteorology and Hydrology ESTONIA

Mr. Raimo Mustonen Finnish Centre for Radiation and Nuclear Safety FINLAND

Mrs. Laina Salor.en Finnish Centre for Radiation and Nuclear Safety FINLAND

Mr Erkki Mus Finnish Centre for Radiation and Nuclear Safety FINLAND

Mr. Henning Qvale Institut för energiteknik NORWAY sr*

S0L10 AND LIQU1U iAM^LtS mun mt JIU»MI - dose rates measured Inside the sample pits),

Solid samples nos.2G arid 27 Well r,o^j_X3;7.5 uSv/h

L 1 ttle pool

Solid samples of the present waste

j-Water samples outs i tfc the *4;io »t ' 14. Tap water/f»ctory/I aborator/ 15. Tap water/main factory 2 ; 16. Tap water/hospi ta 1 17. Tap wa ter/hote 1

B a c k g round water

9 Utgivna SSI-rapporter 1993 SSI-reports published in 1993

Nummer Titel Författare Number Title Author

01 Publikationer Informationsenheten

02 Survey and Evaluation of the External Research Lars Persson and Development Programme 1977-1983 of the Swedish Radiation Protection Institute

03 SSIs granskning av SKBs forskningsprogram 1992 Mikael Jensen

04 Ett arbetsnormalinstument för kontinuerlig radon- Hans Möre mätning

05 LENA_ P A probabilistic version of the LENA code Ulf Bäverstam version 1.0 January 1993 Olof Karlberg

06 Studies on the Waste Depository of the Hans Ehdwall et al Sillamäe Plant State of the art report from the project group