Patent Number: 062263404
Section: claims

1. A control material for a nuclear system that uses lumped absorbers for parasitic absorption of neutrons, the control material comprising a thermal absorber disposed surrounding a resonance absorber such that the resonance absorber is screened by the thermal absorber, wherein said resonance absorber comprises a mixture of hafnium, dysprosium and europium. 2. A control material as claimed in claim 1, wherein said thermal absorber comprises a 1/v absorber. 3. A control material as claimed in claim 2, wherein said thermal absorber comprises boron carbide. 4. A control material as claimed in claim 1, wherein said thermal absorber comprises boron carbide. 5. A control rod for a nuclear reactor comprising a plurality of absorber tubes loaded with a thermal absorber disposed surrounding a resonance absorber such that the resonance absorber is screened by the thermal absorber, wherein said resonance absorber comprises a mixture of hafnium, dysprosium and europium. 6. A control rod as claimed in claim 5, wherein said thermal absorber comprises a 1/v absorber. 7. A control rod as claimed in claim 6, wherein said thermal absorber comprises boron carbide. 8. A control rod as claimed in claim 5, wherein said thermal absorber comprises boron carbide.