US 4,304,632 A · Nuclear reactor shutdown system

Abstract

An inherent shutdown system for a nuclear reactor having neutron absorbing rods affixed to an armature which is held in an upper position by a magnetic flux flowing through a Curie temperature material. The Curie temperature material is fixedly positioned about the exterior of an inner duct in an annular region through which reactor coolant flows. Elongated fuel rods extending from within the core upwardly toward the Curie temperature material are preferably disposed within the annular region. Upon abnormal conditions which result in high neutron flux and coolant temperature, the Curie material loses its magnetic permeability, breaking the magnetic flux path and allowing the armature and absorber rods to drop into the core, thus shutting down the fissioning reaction. The armature and absorber rods are retrieved by lowering the housing for the electromagnet forming coils which create a magnetic flux path which includes the inner duct wall. The coil housing then is raised, resetting the armature.

Claims10

Dependent claims

A nuclear reactor inherent shutdown system comprising an annular region formed between an inner duct and an outer duct, means, disposed at least partially within an envelope formed by said inner duct and lineal extensions thereof, for creating a magnetic field, a neutron absorber assembly having a movable absorber disposed within said inner duct and said movable absorber being releasably coupled by a magnetic circuit to structure so as to position said movable absorber above a core region and being decoupled so as to drop said absorber downwardly into said core region through lowering of the magnetic permeability of a Curie point material assembly, said inner duct having a ferromagnetic portion and a non-magnetic portion, said Curie point material assembly being annular and fixedly disposed within said annular region and positioned about said non-magnetic portion of said inner duct.

An inherent shutdown system for a core of a nuclear reactor circulating a liquid coolant comprising

a. an outer duct;
b. an inner duct fixed relative to said outer duct, said inner duct being spaced from said outer duct so as to form annulus therebetween;
c. a neutron absorber movably disposed within said inner duct;
d. an armature affixed to said absorber rods;
e. an enclosure disposed at least partially within said outer duct, said enclosure being selectively movable within said inner duct;
f. a preselected Curie temperature material disposed within said annulus;
g. means for creating a magnetic circuit through said armature and enclosure, and selectively through said Curie temperature material;
and
h. fissionable material extending upwardly from within said core, said fissionable material being disposed within said annulus;
i. whereby coolant flowing within said annulus, about said fissionable material, and about said Curie temperature material is segregated from coolant flowing within said inner duct throughout the length of said annulus.

7 more elements

Dependencies are inferred from the claim text.

Nuclear reactor shutdown system

Life of this patent

Nuclear reactor shutdown system

Life of this patent

Abstract

Claims10