Experimental Breeder Reactor I, Mark III

1958 film, with transcript

Catalog description: This film presents some major aspects of the fabrication, installation and operation of a new core (Mark III) for the Experimental Breeder Reactor I.

This is film 88388 in our catalog.

Show transcript
00:30 Argonne National Laboratory's Idaho Division,
00:41 located at the National Reactor Testing Station,
00:44 operates the experimental breeder Reactor 1.
00:49 Experience gained since 1951 in the operation of this reactor
00:54 forms the foundation for fast power reactor development.
00:58 This is the first reactor to employ sodium-potassium alloy as a coolant
01:02 and to utilize the direct current electromagnetic pump.
01:06 During this time, the reactor performed satisfactorily as a steady power source,
01:11 demonstrated the breeding concept, generated the world's first electricity from nuclear power,
01:15 and served its primary function in providing fundamental fast reactor information.
01:21 When EBR-1 was operated at power-to-flow ratios one and one-half times,
01:27 the design ratio, some undesirable dynamic characteristics were observed. These were
01:33 a prompt positive temperature coefficient and a tendency toward spontaneous oscillation
01:38 of power. It was believed these characteristics were related and that the cause of the prompt
01:43 positive temperature coefficient was either the Doppler effect, which increases the effective
01:48 fissioning cross-section due to heating enriched uranium, or to mechanical motion of the fuel
01:53 elements. Enriched uranium in the form of the helix was prepared for measurement of the Doppler
01:59 effect in fast reactors. This experiment was performed in the laboratory's critical assembly
02:07 facility, ZPR-3. The helical form was adopted to minimize motion due to heating, which could
02:15 produce undesirable side reactivity effects. Positioned within an assembled EBR-1 core
02:22 mock-up the helix was periodically heated then cooled on a 20 second cycle time
02:30 careful measurement of the power oscillations resulting from the cycling
02:34 made it fairly certain the doppler effect was much too small
02:37 to have been the primary cause of the prompt temperature coefficient observed in the reactor
02:44 concluding that the primary problem was mechanical motion it was decided to investigate ebr1
02:49 performance as part of an overall program to study reactor dynamics.
02:56 A rigid core assembly to restrict mechanical motion was designed for EBR-1.
03:03 Designated Mark III, the core structure consisting of laminated steel disks was machined and
03:09 assembled by the laboratory's central shops.
03:14 The inside hexagonal surface fits the outer perimeter of the blanket sub-assemblies.
03:20 These discs are held and aligned with tie rods.
03:26 Paralleling the assembly of the core structure, fabrication of Mark III fuel was underway by the metallurgy division.
03:33 The fuel for the Mark III core is uranium enriched to 93%.
03:38 The blanket is normal uranium.
03:41 Both blanket and core uranium are alloyed with 2 weight percent zirconium.
03:46 Clad with zircaloy 2, they are co-extruded into the form of a rod.
03:52 The rough cores for the blanket extrusion billets are produced by casting in a multi-cavity
03:56 graphite mold.
04:00 The enriched uranium is melted in a 5-kilogram batch and cast in a single-cavity mold.
04:08 A graphite crucible, coated with ceramic wash, is charged with the uranium biscuit and zirconium
04:13 sponge for the blanket alloy.
04:16 Melting and alloying is done by induction heating in a vacuum of ten
04:20 microns or less. After alloying the metal is bottom poured into the mold by
04:29 lifting a stopper rod. These castings after machining are tested for
04:39 homogeneity by a non-destructive method. A sound transmission principle is
04:44 utilized. Five mega cycle ultrasonic waves are generated by means of a quartz
04:49 transducer and sent through the metal. The quality of the casting is
04:55 graphically recorded on a strip of electrosensitive paper. The casting, after
05:04 further machining, yields two extrusion billet cores. These cores, assembled with
05:09 copper nickel end plugs are encased in a sleeve of Zercaloy II. A copper jacket is added to
05:18 prevent contamination of the billet components during heating and to provide lubrication
05:23 during extrusion. Closed by Heliarc welding, the assembled billet is then evacuated, outgassed
05:38 and sealed.
05:43 The billets are co-extruded by nuclear metals incorporated to rods of one-half inch diameter.
05:49 Upon return, they are inspected, pickled to remove the copper, and swaged to a specified
05:55 diameter.
05:59 Heat treated for stabilization, the rods are cut to appropriate fuel and blanket lengths,
06:04 and the cladding thickness measured.
06:07 To join the sections of either type rod, a commercial glass lathe was specifically adapted
06:12 at Argonne for tungsten arc butt welding.
06:16 This welding operation is extremely precise because of the difficulty of fusing the high
06:20 melting zircaloy without excessive melting of the uranium.
06:29 A 10-mil zirconium spacer disc separates the enriched and blanket sections on each fuel rod.
06:43 Chill and gas retainers surround the electrode and weld area.
06:48 Welding is purposely limited to the 20-mil zircaloy cladding and is made in a double pass,
06:54 each pass requiring a different welding current.
06:59 A section bond is made at each weld by fusing the metal in a small zone to add mechanical
07:08 strength.
07:18 The cladding is protected against oxidation by passing a stream of helium through the
07:22 Vicor II.
07:29 After heat treatment, cladding thickness is measured by an eddy-current method.
07:34 Eddy currents are induced in the Zircaloy cladding by means of a point probe.
07:38 The apparent impedance of the probe is influenced by the cladding thickness.
07:46 The bond on the rods is then scanned by the ultrasonic transmission technique.
07:53 testing methods help to ensure the quality of the completed fuel and blanket rods.
08:03 Zirconium ribs are spot welded to rods ground to their finished diameter.
08:08 These will provide accurate spacing of the tightly clustered rods in their final geometry.
08:17 The welding operation is performed automatically on a specially designed
08:20 condenser discharge type spot welder. Welds are placed at one quarter inch intervals along each
08:26 of the three ribs, a total of 240 welds per rod. Machining operations complete the fuel and blanket
08:35 rod fabrication. The completed core structure ready for installation in the reactor tank
08:45 has a total height of nine feet and five inches.
08:50 The reduced diameter at the bottom will receive the core and inner blanket rods.
08:56 The structure rests on this shoulder with the inlet plenum chamber located just above the upper blanket.
09:02 This plenum chamber contains four two-way inlet valves for switching from series to parallel flow.
09:09 The up position of the valves permits series flow through the inner blanket and core,
09:14 while the down position allows parallel flow.
09:16 The plate above the inlet plenum chamber has seal rings to prevent bypass leakage between the inlet and outlet plenum chambers.
09:26 This seal plate also contains two flow control valves for throttling the exit flow from the inner blanket under parallel flow conditions.
09:35 Under series flow conditions, these valves are closed.
09:38 Additional rigidity is obtained by an arrangement of clamps around fuel and blanket sub-assemblies
09:48 at the core center line and at the seal plate.
10:04 The upper part of the structure is primarily shielding with an overflow plenum chamber
10:07 near the top.
10:10 The top plate holds the actuators and position indicators for the various valves and clamps
10:15 in the structure.
10:23 The core structure is installed in the same reactor tank that housed the EBR-1, Mark I
10:28 Mk. II cores. Fuel and blanket rods, with their attached extensions for handling, are
10:41 positioned within a hexagonal can. Complete sub-assemblies within the hex can contain
10:55 36 rods, and depending upon location within the structure,
10:59 will consist of fuel and or blanket material.
11:05 A tightening rod is located at the center of each sub-assembly
11:09 and, when expanded, provides additional rigidity.
11:16 The thorough temperature instrumentation of Mark III
11:19 includes thermocouples in the plenum chamber structure,
11:23 fuel rods, blanket rods, and coolant passages.
11:29 The complete Mark III loading contains 19 sub-assemblies.
11:33 Seven enriched sub-assemblies comprise the core.
11:37 These are surrounded by a ring of 12 inner blanket sub-assemblies.
11:45 Criticality was achieved on November 11, 1957.
11:49 It was determined to be 47 and 4 tenths kilograms of uranium-235,
11:56 within 2% of the critical mass determined from the mock-up of the core
12:00 on the zero-power reactor 3.
12:05 Operating test data indicates that Mark 3 would be stable
12:08 at several times design power, and the instability apparent in Mark 2 was due to mechanical design
12:15 and is not inherent in fast reactors.
12:20 This investigation of reactor dynamics is continuing
12:23 and will establish parameters affecting the stability of fast reactors.