Patent Number: 050842293
Section: summary

FIELD OF THE INVENTION This invention relates to an apparatus for testing a specimen under a high temperature heat transient, and more particularly, relates to such an apparatus which is capable of rapid heating and cooling rates under vacuum conditions to prevent oxidation of the specimen and/or release of entrained gases. DESCRIPTION OF THE PRIOR ART It has been important to perform rapidly repeatable heat transient tests on fuel elements for nuclear power plants. These test are used to determine the state of the fuel cells (elements), i.e., the change in the composition of a fuel element as it is used during the fission process. Typically, a sample number of fuel elements are tested from a "bank" of fuel elements loaded at the same time. In the past, a sampling of fuel elements to be tested have been removed by robot from reactor and placed into a sealed "Hot Cell" testing area. The sampling of fuel elements are then subjected to high temperatures and the gaseous materials released by the fuel elements are analyzed. Each fuel element tested is raised to a critical heat temperature, i.e., the temperature before the sample begins to change state. Once it reaches this temperature it must be rapidly cooled before it can be further handled. This has been a rather cumbersome and time consuming process which required a substantial area (floor space) of the reactor. Furthermore, the movement of the fuel elements out of the hot cell area creates a handling problem, which in and of itself adds to the time and expense of testing. What is desired is testing apparatus for testing in situ in the hot cell. An object of this invention is to provide an in situ critical heat test apparatus for fuel elements. A second object of this invention is to provide this test apparatus with a remotely controlled and powered induction flux heating furnace. A further object of this invention is to provide this test apparatus with structure to draw off the gaseous materials released when the fuel element is heated and to permit the examining of these gaseous materials at a separate location. Another object of this invention is to provide this test apparatus with a rapid temperature reduction of hot fuel elements. A still further object of this invention is to provide this apparatus with structure to permit rapid heating and cooling rates under vacuum conditions to prevent oxidation of the specimen and/or release of entrained gases. SUMMARY OF THE INVENTION The objects of this invention are realized in an in situ test apparatus for testing irradiated fuel elements and corrosion coupons within a hot cell to simulate conditions in a nuclear reactor. A specimen, which has been welded to thermocouple wires and attached to a riser clamp at its lower end and a furnace cap at its upper end, is placed by robot apparatus in a quartz heating tube located within the hot cell. A specimen riser clamp rests upon a movable metal pin which is sealed inside the quartz heating tube. The furnace cap rests on the upper portion of the tube and closes the apparatus. The quartz heating tube is coupled to an evacuation pipe having a valve which, when opened, allows access through the evacuation pipe to a vacuum pump system. All gas present in the apparatus is evacuated before the apparatus is put into use. Gaseous materials released during the test are collected by a remote apparatus which measures the fission gas collected. An induction coil around the quartz furnace tube generates heat in the specimen by electrically induced EMF energy. A remote radio frequency generator is used to provide the power to the induction wires. After the specimen has been heated for a desired time, the metal pin supporting the specimen riser clamp is magnetically removed. The specimen drops into a cooling chamber or quench chamber which is filled with water. This chamber cools the specimen. The quench chamber is supplied with water from a reservoir. The flow of water is controlled with a valve in a circulation tube connecting the reservoir and the quench chamber. Cooling water is circulated from the quench chamber by a remotely controlled circulation pump which pumps the water from the quench chamber to the reservoir. Because the specimens may be highly irradiated, all operations are capable of being performed in a hot cell by slave manipulators. A welding station and an inspection station are located with the hot cell for making up specimens. A welder power supply, temperature recorder, radio frequency generator, pump control and fission gas collection apparatus are all located outside the hot cell, being connected through the cell wall at one of four cell plugs.