Patent Number: 059463678
Section: claims

1. A neutron absorbing pin, comprising: at least, a neutron absorber, a pipe surrounding the neutron absorber, and a cladding disposed at a distance from the pipe; wherein the difference between the coefficient of thermal expansion (.alpha.1) of the neutron absorber and the coefficient of thermal expansion (.alpha.2) of the pipe has an absolute value of .vertline..alpha.2-.alpha.1.vertline..ltoreq.10.times.10.sup.-6 /K. 2. A neutron absorbing pin according to claim 1, wherein the pipe comprises a fiber-reinforced ceramic. 3. A neutron absorbing pin according to claim 2, wherein the fiber-reinforced ceramic is fiber-reinforced silicon carbide (SiC) or fiber-reinforced alumina (Al.sub.2 O.sub.3). 4. A neutron absorbing pin according to claim 1, wherein the neutron absorber comprises boron carbide (B.sub.4 C).