Question

5. Strontium-90 is to be used as a heat source for generating electrical energy in a satellite. (a) How much of 90Sr activity is required to generate 50 W of electric power if the conversion efficiency from heat to electricity is 30%? (b) Weight of the isotopic heat source is an important factor in design of the power source. If weight is to be kept at a minimum and if the source is to generate 50 W after 1 year of operation, would there be an advantage to using 210Po ?

Answer 1

Po-210 gives high ammount of energy because of it high decay rate. And its life time is also shorter , 138 days only. Where as the life time od Sr90 is 28.8 years. So afrer one year of operation rest no of Po 210 will be one-third times. So weight will be lower a bit. And also Po210 is a alpha emmiter, it does not emmit gamma ray or x ray. So shielding effect will be reduced. So i think after one year there will not such advangates left. Bye the way Po210 is a better choice than sr90. Because of very low energy released from Sr 90.