Method for planting and harvesting radioisotopes on a mass production basis
A method and apparatus for modifying an existing nuclear reactor moveable in-core detector system to insert and withdraw target specimens from a reactor core during reactor operation without practically impeding the moveable in-core detector system's ability to obtain flux maps of the core throughout the reactor's operation. The apparatus provides a separate drive unit and delivery cable that is independent of the detector drive system, but uses most of the same core delivery conduits to access the core. A specimen holder is remotely detachable from the delivery cable when appropriately positioned and can be remotely reattached for withdrawal after a scheduled period of radiation.
1. A method of irradiating multiple specimens within a core ( 14 ) of a nuclear reactor ( 16 ) that has a moveable in-core, radiation detector flux mapping system, wherein the core comprises a plurality of fuel assemblies respectively having instrument thimbles into which a radiation detector ( 12 ) of the flux mapping system can be inserted and travel through, comprising the steps of:
inserting a first specimen holder ( 48 ) containing a first specimen ( 72 ) at a lead end of a first drive cable ( 36 ) driven by a first drive unit ( 34 ), into a first instrument thimble in the core ( 14 );
remotely detaching the first drive cable ( 36 ) from the first specimen holder ( 48 ) and fixing an axial position of the first specimen holder within the first instrument thimble;
withdrawing the first drive cable ( 36 ) from the reactor ( 16 );
attaching a second specimen holder ( 48 ) containing a second specimen ( 72 ) to the lead end of the first drive cable ( 36 ) driven by the first drive unit ( 34 );
inserting the second specimen holder ( 48 ) containing the second specimen ( 72 ) into a second instrument thimble in the core ( 14 );
remotely detaching the first drive cable ( 36 ) from the second specimen holder ( 48 ) and fixing an axial position of the second specimen holder within the second instrument thimble;
withdrawing the first drive cable ( 36 ) from the reactor ( 16 );
in between the withdrawing step and the second inserting step inserting a moveable in-core radiation detector ( 12 ) from the moveable in-core detector radiation flux mapping system, attached to a second drive cable ( 50 ) driven by a second drive unit ( 24 ), into and through a third instrument thimble; and
withdrawing the moveable in-core radiation detector ( 12 ) from the reactor ( 16 ) after performing a flux mapping exercise.
2. The method of claim 1 wherein the inserting steps insert specimen holders ( 48 ) into as many as half the instrument thimbles accessible by the flux mapping system for simultaneous irradiation at a time when a flux map is to be conducted.
3. The method of claim 1 wherein the steps of fixing the axial position of the specimen holders ( 48 ) within the respective instrument thimbles includes the steps of determining when the respective specimen holders are at a preselected axial position within the corresponding instrument thimbles.
4. The method of claim 1 wherein the step of withdrawing the first drive cable ( 36 ) from the reactor comprises withdrawing the first drive cable out of the moveable in-core, radiation detector flux mapping system prior to the running of a flux map.