Complex sentence: As the radioactive decay of strontium-90 generates significant amount of heat, and is cheaper than the alternative 238 Pu, it is used as a heat source in many Russian/Soviet radioisotope thermoelectric generators, usually in the form of strontium fluoride.
Split into simpler sentences: As the radioactive decay of strontium-90 generates significant amount of heat and is cheaper than the alternative 238 Pu. It is used as a heat source in many Russian/Soviet radioisotope thermoelectric generators, usually in the form of strontium fluoride.