The production of cement involves the heating, calcining and sintering of blended and ground raw materials, typically limestone and clay or shale and other materials to form clinker. This clinker burning takes place at 1450oC in kilns. The formed clinker is then ground and mixed with small amounts of gypsum to give Portland cement, although, in addition, blended cements are produced from cement clinker with fly-ash. Large cements plants can produce of the order of 4000t of cement per day.

Because of the very high temperature of the raw materials in the kilns, volatilization of 210Po and 210Pb is the main potential source of aerial discharges. Data included in UNSCEAR 2000 indicates that the estimated Annual aerial discharges for a ‘typical’ cement plant with a 2000 kt/y output of different types of cement are the following: 0.2 GBq/y for 210Pb and 78 GBq/y for 210Po. These estimations are based on the assumption that 50% of the polonium escapes from the thermal process.

http://digital.csic.es/bitstream/10261/75835/1/EstoniaProceedings.pdf

See also:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4471646/

https://ec.europa.eu/energy/sites/ener/files/documents/135.pdf

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3881159/

https://www.researchgate.net/publication/299344753_The_national_survey_of_natural_radioactivity_in_concrete_produced_in_Israel

https://www.academia.edu/2538032/Radioactivity_level_measurement_of_some_cement_samples

www.iaea.org/inis/collection/NCLCollectionStore/_Public/32/016/32016603.pdf

https://www.researchgate.net/publication/26884400_Assessment_of_natural_radioactivity_levels_and_radiation_hazards_due_to_cement_industry

https://ec.europa.eu/energy/sites/ener/files/documents/112.pdf

http://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0140667

https://www.researchgate.net/publication/270876651_Determination_of_Natural_Radioactivity_Levels_of_Some_Concretes_and_Mineral_Admixtures_in_Turkey

http://irpa11.irpa.net/pdfs/6a21.pdf

Article The national survey of natural radioactivity in concrete pro...

Article Assessment of natural radioactivity levels and radiation haz...

Article Determination of Natural Radioactivity Levels of Some Concre...

The production of cement involves the heating, calcining and sintering of blended and ground raw materials, typically limestone and clay or shale and other materials to form clinker. This clinker burning takes place at 1450oC in kilns. The formed clinker is then ground and mixed with small amounts of gypsum to give Portland cement, although, in addition, blended cements are produced from cement clinker with fly-ash. Large cements plants can produce of the order of 4000t of cement per day.

Because of the very high temperature of the raw materials in the kilns, volatilization of 210Po and 210Pb is the main potential source of aerial discharges. Data included in UNSCEAR 2000 indicates that the estimated Annual aerial discharges for a ‘typical’ cement plant with a 2000 kt/y output of different types of cement are the following: 0.2 GBq/y for 210Pb and 78 GBq/y for 210Po. These estimations are based on the assumption that 50% of the polonium escapes from the thermal process.

http://digital.csic.es/bitstream/10261/75835/1/EstoniaProceedings.pdf

See also:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4471646/

https://ec.europa.eu/energy/sites/ener/files/documents/135.pdf

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3881159/

https://www.researchgate.net/publication/299344753_The_national_survey_of_natural_radioactivity_in_concrete_produced_in_Israel

https://www.academia.edu/2538032/Radioactivity_level_measurement_of_some_cement_samples

www.iaea.org/inis/collection/NCLCollectionStore/_Public/32/016/32016603.pdf

https://www.researchgate.net/publication/26884400_Assessment_of_natural_radioactivity_levels_and_radiation_hazards_due_to_cement_industry

https://ec.europa.eu/energy/sites/ener/files/documents/112.pdf

http://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0140667

https://www.researchgate.net/publication/270876651_Determination_of_Natural_Radioactivity_Levels_of_Some_Concretes_and_Mineral_Admixtures_in_Turkey

http://irpa11.irpa.net/pdfs/6a21.pdf

Article The national survey of natural radioactivity in concrete pro...

Article Assessment of natural radioactivity levels and radiation haz...

Article Determination of Natural Radioactivity Levels of Some Concre...

Po-210 and Pb-210 are produced.

A study on surface exhalation rate and mass exhalation rate from cement used as building material in palestine estimates a value of 5mSv/y.

In addition to the detailed responses of Florian and Ghassan, it is worth mentionning that cement production is often (always in modern factories !) controlled in line by activated neutron analysis. In essence, cement is made as a combination of different compounds with precise percentages of them. It is quite easy to activate by neutrons the mixture being fabricated as it circulates on a conveyor belt and to get "instantaneously" the radiations resulting from the nuclear reactions, which spectra reflect precisely the chemical composition. In case of abnormal results the production can be stopped. This neutron activation method is used because the alternative, i.e., the chemical analysis of samples, is not as efficient !

Thus neutron activation analysis introduces artifical radioactivity in the fabrication of concrete. As far as I know the deacy is quite fast and in a few hours the level of artificial radioactivity returns to "Baseline", i.e., very low levels in the range of natural activity athough detectable with clever instruments.

I do not have a reference of a report in English. I can find one in French if you wish !