OMRE Fuel Element Removal and Second Core Loading

1959 film, with transcript

Catalog description: This film reports on operations of the Organic Moderated Reactor Experiment, an experimental nuclear power project conducted by Atomics International for the USAEC at the National Reactor Testing Station, Idaho. A summary of operating experience and test programs from reactor start-up in September 1957 to July 1959 is presented. The simplicity of operating the reactor is highlighted. Removal of the first reactor core and loading of the second core are detailed.

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Show transcript
00:30 This is a report on operations, first core removal and second core loading,
00:35 of the Organic Moderated Reactor Experiment, called the OMRE.
00:41 This reactor experiment, located at the National Reactor Testing Station in Idaho,
00:46 is an Atomic Energy Commission project conducted by Atomics International.
00:51 The OMRE is designed for a maximum fuel element temperature of 800 degrees Fahrenheit
00:56 and organic coolant temperatures of from 500 to 700 degrees Fahrenheit with a
01:01 coolant velocity of 12 feet per second. The reactor produces 12,000 kilowatts of
01:06 heat. 31 fuel elements with a total uranium-235 content of 25.5 kilograms
01:14 are used to provide operating reactivity. An important function of the OMRE is to
01:23 test organic coolant behavior under conditions similar to those of large central station
01:28 power plants.
01:34 Another major function of this reactor is the testing of prototype fuel elements for
01:38 full-scale organic moderated and cooled reactors.
01:45 The OMRE began operating during September 1957.
01:49 By March 1958, thermal stability predictions on organic fluid were confirmed by a successful
01:55 three-week test conducted at reduced power with the bulk coolant temperature at 700 degrees
02:00 Fahrenheit.
02:06 A subsequent series of tests demonstrated the degree of radiation stability of the organic
02:11 coolant.
02:12 No significant decrease occurred in the overall heat transfer properties of the coolant.
02:22 Operation of the OMRE during this period proved to be simple.
02:28 Low activation of the coolant allowed access to the primary coolant system.
02:33 The use of standard components and piping eliminated long delays for parts in need of
02:37 repair or replacement.
02:40 Most of the OMRE shutdown time was scheduled for test program modifications.
02:45 For example, during one of the shutdowns, the OMRE fuel elements were relocated within
02:50 the core to allow higher power operation of the reactor.
02:55 Based on the records of the dimensions of each OMRE fuel element built, hot channel
03:00 factors have been determined for critical points in all fuel elements.
03:05 When suitable radio flux plots are obtained, the fuel elements in the core are redistributed.
03:12 All work of this type is done over the open reactor with the coolant level approximately
03:17 15 feet above the core.
03:20 There are no permanent fuel handling or reloading facilities for the OMRE.
03:25 A tractor-mounted crane is used to handle reactor components.
03:31 To remove irradiated fuel elements from the reactor, three casks were constructed.
03:37 Each cask will transport one OMRE fuel element or one OMR test element.
03:43 The casks are also used to transport in-pile corrosion specimen holders.
03:50 All radiation shielding is designed in conformance with government regulations and the casks
03:54 have been approved for interstate shipment of radioactive materials.
04:01 The casks have supplemental shields.
04:04 A fuel element with 1,200,000 curies of activity can be transported in a cask if all three
04:10 supplemental shields are attached.
04:16 This shows the casks being tested at an Atomics International facility in California.
04:22 Each cask is removed from its cradle trunnion and placed onto an auxiliary shield which
04:26 is mounted on a pipe stand.
04:30 When permissible fuel heat generation rates and heat transfer characteristics have been
04:34 determined, fuel element removal operations are checked.
04:38 An OMRE fuel element head casting is used in this test.
04:43 The tool assembly is lowered and contact made with the fuel element head.
04:49 When the assembly latch is secured to the lifting plug of the fuel element, the tool
04:53 assembly is withdrawn into the cask.
04:56 The cask bottom closure plug is then rotated and raised.
05:02 After satisfactory completion of tests, the fuel casks and auxiliary shielding are shipped
05:07 to the OMRE facility to remove a fuel element and an in-pile corrosion specimen during a
05:13 scheduled reactor shutdown in July 1958.
05:19 A work platform is used on the open reactor to permit placement of the fuel element in
05:23 proper position for removal. After removal of the work platform, a tractor mounted crane
05:30 lowers the frame and auxiliary shield onto four pipe columns around the reactor. Shock
05:38 absorbing pieces are attached to the pipe columns. The auxiliary shield is centered
05:43 by guide pins through holes in the frame and corresponding holes in the reactor flange.
05:50 The cask is lifted from the cradle assembly and lowered into the auxiliary shielding.
05:59 The bottom closure plug of the cask is lowered and rotated to open the cask.
06:04 Using safety lock pins to prevent accidental drop, the tool assembly is lowered into the
06:09 reactor vessel. When contact is made with the fuel element head, the tool assembly latch is
06:16 is secured to the lifting plug of the fuel element and the element lifted into the cask.
06:23 After the bottom closure plug is rotated and closed, the cask is lifted from the auxiliary
06:28 shielding and lowered into the cradle trunnion. Clamps secure the cask in the cradle.
06:40 The afterglow heat output from the hottest OMRE fuel element is reduced to about 3.6
06:45 kilowatts one day after reactor shutdown. If the heat generation rate of an element
06:51 exceeds 0.8 kilowatts, the cask is filled with organic liquid. Thermometers are installed
06:58 in the cooling water inlet and outlet to check proper cooling of the element. An expansion
07:04 tank for the organic is connected to the cask which is in a horizontal position on the trailer.
07:10 The two cooling water systems for the cask, one of them an auxiliary, maintain fuel element
07:15 temperatures as low as possible for experimental reasons. The cooling systems need not be used
07:22 with the less active fuel elements. The two casks shown here, one containing an OMRE fuel
07:31 element, the other containing an in-pile corrosion specimen, are transported to a hot cell on
07:36 a 25 ton low bed trailer. Hot cell examination of the OMRE fuel element confirmed the satisfactory
07:44 performance of this element in the reactor. By January 1959, the OMRE had completed 23,000
07:56 megawatt hours of successful operation, and the reactivity of the fuel elements in the original
08:01 core had diminished. A second core loading was initiated to provide higher reactor operating
08:08 reactivity for continuation of OMRE test programs.
08:13 The reactor was shut down and removal of irradiated elements in the original core was started.
08:21 For this operation, all used fuel elements from the first core loading are transferred
08:26 in casks to a fuel element washing facility adjacent to the reactor.
08:32 The washing facility consists of two independent wash cells embedded into the ground.
08:39 Lead filled adapter rings center the fuel casks in a vertical position and allow the
08:44 safe insertion and removal of the elements from the wash cells.
08:49 The washing cycle for each fuel element is a solvent wash, a detergent wash, and a water
08:55 rinse.
08:56 This washing cycle removes undrained organic material from the used fuel elements.
09:04 After the elements are washed, they are transported in casks to a water canal at the engineering
09:09 test reactor for storage.
09:13 When a cask is partially submerged to a safe shielding depth, the cask bottom closure plug
09:18 is opened and rotated.
09:24 The element is lowered by the tool assembly and nested in the canal.
09:37 The fuel cask is raised and given a water rinse before being returned to the OMRE for
09:42 continued fuel removal and washing operations.
09:48 After all used fuel elements are removed, the criticality control rod support structure
09:53 is placed over the core vessel and the control rods and other associated
09:57 components are checked for proper operation prior to proceeding with the
10:00 second core loading. In April 1959 new fuel elements of the same type used in
10:11 the initial loading were inserted into the core. Nuclear control is furnished by
10:19 modified reactor control rod system and neutron counters. The temperature of the
10:27 organic moderator coolant is maintained at 250 degrees Fahrenheit during the
10:31 core assembly. Nine fuel elements are inserted into the core for the first
10:39 fuel addition. Fuel elements are carried into the reactor housing one at a time.
10:48 The core position of each element is decided in advance.
10:55 No more fuel than one half the difference between the estimated critical mass
10:59 and the fuel already in the core is inserted during any fuel addition.
11:07 The second fuel addition consists of six elements.
11:13 The third fuel addition is comprised of three elements.
11:17 Each remaining fuel addition consists of one element.
11:25 Subcritical multiplication counts are obtained after each individual fuel
11:28 addition.
11:33 As in the initial core loading, critical conditions are achieved with the insertion of the twentieth element.
11:41 Additional elements are inserted for the loading of excess reactivity
11:45 to about eight percent Delta K over K.
11:52 To furnish data for the continuing research and development of the organic reactor concept,
11:57 thermocoupled fuel elements are installed in the OMRE.
12:02 Six of these elements are located in one quadrant of the core.
12:06 Assuming the core flux to be symmetrical,
12:09 the temperature profile of the core can thus be inferred.
12:14 Another advantage of locating the thermocoupled elements in proximity is the clearance of thermocoupled conduits from a large area of the core.
12:22 This arrangement lessens the possibility of conduits interfering with the handling of OMR test elements.
12:29 Three test elements of the type to be used in organic cooled reactor power plants are installed in the OMRE.
12:38 They are instrumented to measure temperatures and coolant flows during reactor operation.
12:44 and will provide results on the performance of fuel elements being considered for full-scale OMR power plants.
12:54 After completion of control rod calibrations, low power operating tests are performed
13:00 and the reactor is brought to power in June 1959
13:03 with an inlet coolant temperature of 600 degrees Fahrenheit,
13:08 a maximum fuel plate surface temperature of 800 degrees Fahrenheit,
13:12 at a nominal power level of 11 megawatts.
13:16 This proven and reliable organic moderated reactor experiment
13:21 is the basis for a continuing extensive effort
13:24 to develop the organic reactor concept for small and large power plants,
13:30 nuclear-powered ships, and processed heat plants.