Research Reactors U.S.A.

1958 film, with transcript

Catalog description: This semitechnical film presents, via live action and animation, a summary of the major types of research reactors — swimming pool, tank, water boiler, and graphite moderated — with descriptions of their uses in research, industry, chemistry, physics, metallurgy, biology, and medicine. Used as illustrations are the following reactors: CP-5 (Argonne), University of Michigan reactor (Ford reactor), Omega West (Los Alamos), (Armour), Brookhaven, Argonaut (Argonne), 10- watt solution type (Atomics International), and the solid- homogeneous (Aerojet General Nucleonics).

This is film 88247 in our catalog.

Show transcript
00:00 Beneath the surface of the water
00:28 lies the heart of an operating nuclear reactor.
00:31 The blue glow is made by gamma rays emitted from the source of radiation and is known as the Cherenkov effect.
00:38 This glow identifies the active core of a pool-type reactor.
00:44 One of four basic types of research reactors, versatile tools of nuclear exploration.
00:53 Another is the tank-type research reactor, with the core buried deep inside a thick concrete shielding.
00:59 A third type, the aqueous homogeneous reactor, has a small steel vessel containing liquid
01:07 fuel deep inside a reflector of graphite blocks and a shield of concrete.
01:15 The fourth is the graphite-moderated type, a research reactor in which the core itself
01:20 is a huge cube of graphite and fuel surrounded by concrete.
01:26 Storage reactors of all types have in common the means of providing access to the core
01:31 for irradiating samples and conducting various experiments.
01:37 Beam holes extending into areas of different neutron flux intensity, vertical irradiation
01:43 tubes, through tubes extending directly through the core itself, rabbit tubes operated pneumatically
01:51 or hydraulically, allowing rapid insertion and withdrawal of samples. Irradiation tunnels
01:57 for the exposure of large objects, including animals, to lower neutron fluxes beneath the
02:04 core. And thermal columns of graphite, where large volumes of thermal neutrons are easily
02:10 accessible. Throughout the world, research reactors of the types described, and modifications
02:19 and applications of these types are being used at various locations.
02:24 The operation of the first pool type reactor began at Oak Ridge National Laboratory in 1950.
02:31 Since then this type has gained popularity because of its simplicity, flexibility, and moderate cost.
02:39 On the campus of the University of Michigan is an example of the pool reactor.
02:46 The water in the pool is demineralized to remove impurities that would become
02:50 hazardously radioactive.
02:52 A depth of 22 feet above the core provides shielding.
02:56 Down at the core level, the beam holds and through tubes
03:00 converge on the core to make use of the high neutron intensity,
03:04 about 10 to the 13th neutrons per square centimeter
03:07 per second when the reactor is operating at a thousand kilowatts.
03:12 The core of a pool reactor consists of a number of fuel elements
03:15 mounted vertically on a grid plate.
03:19 Usually surrounded by reflector elements of beryllium or graphite
03:23 encased in aluminum.
03:26 Ion chambers and a fission chamber
03:29 are added to detect neutron activity within the core.
03:34 Each fuel element consists of a number of thin aluminum-clad fuel plates,
03:38 spaced to permit free circulation of cooling water between them,
03:42 to carry off the heat.
03:45 Plates are like a sandwich, having enriched uranium as the meat
03:49 and aluminum as the bread.
03:51 The aluminum cladding protects the uranium from corrosion
03:55 and prevents the radioactive fission products from contaminating the water.
04:00 A few fuel elements have several plates removed
04:03 to provide a channel for inserting control rods.
04:07 and movable control rods can be introduced among the fuel elements.
04:12 A fuel loading consists of only 3 or 4 kilograms of enriched uranium
04:17 in a small volume compared with the many tons of natural uranium
04:21 in a graphite reactor.
04:23 The water serves as moderator, coolant,
04:26 and the major part of the shield.
04:28 The core is mounted on a frame and suspended in the water
04:31 from a motor-driven bridge across the pool.
04:34 The bridge carries much of the operating equipment,
04:37 including the safety and control rod drive assemblies.
04:41 The design of research facilities varies for different pool type reactors.
04:45 At the University of Michigan, when access to the core through other beam holes or the thermal column itself
04:52 is desired, the core is moved
04:55 out across the pool and into another position.
05:02 The far end of the pool is utilized for core storage and reloading.
05:06 Here also gamma ray irradiation work may be done with highly radioactive used fuel elements.
05:14 The instrumentation and operational controls are located in the control room overlooking the reactor.
05:20 A wall diagram enables the operator to keep track of the fuel elements,
05:24 which are moved to suit various experiments and to compensate for burn up of uranium.
05:30 Access to the thermal column is afforded from outside the pool at its base.
05:36 Directly behind the sliding door is the graphite with several stringers that can
05:41 be readily removed for the insertion of samples to be irradiated by highly
05:46 thermalized neutrons. Pool-type reactors provide a substantial number of beam
05:53 holes, tubes, and other irradiation facilities for research purposes. This
06:00 reactor has 12 beam holes converging on the core and two large tubes that go
06:06 entirely through the reactor, through the high neutron flux close to the core.
06:12 There are also a number of pneumatic tubes
06:17 to provide convenient short-time exposure of samples.
06:22 During continuous operation at power levels above a few hundred kilowatts,
06:29 dissipation of the heat by natural convection becomes impractical.
06:33 The water in the pool has to be pumped from the plenum to A heat exchanger and the heat from the exchanger water dissipated from a cooling tower.
06:43 A portion of the returning pool water is continually circulated through a demineralizer to remove
06:49 dissolved minerals, which could become radioactive.
06:54 An open pool reactor can be designed to operate at a few megawatts.
06:58 However, the design is complicated by increased pool depth, thicker shielding, and by thermal
07:05 convections which bring enough radioactive nitrogen 16 to the surface to create a radiation hazard.
07:15 It becomes necessary to go to the tank-type reactor,
07:18 a compressed pool in effect, to facilitate handling the cooling water.
07:25 An example of this type is the Omega West reactor at Los Alamos scientific laboratory.
07:30 The pool is only a few feet in diameter. Ordinary water circulated by pumps acts as both coolant
07:40 and moderator. The top of the tank is sealed to allow slight pressurization to obtain sufficient
07:46 water flow through the core of the reactor. The operating mechanism for the control rods is on
07:53 the top, also the access hole through which the fuel elements are replaced. The elements contain
08:00 enriched uranium in sandwich type plates. Several ports are available for access
08:08 to the core and the thermal column. In operation since early 1954 at the Argonne
08:16 National Laboratory, near Chicago, is a tank type research reactor using heavy
08:22 water. It is called the CP5. The reactor portion of the building is sealed off
08:30 from the rest of the structure by a double door airlock and maintained at slightly less
08:35 than atmospheric pressure.
08:39 This safety measure is to guard against the escape of radioactive gases to the environment
08:45 in the unlikely event of an accident.
08:48 The reactor uses enriched uranium as fuel and heavy water for the reflector, coolant
08:54 and moderator.
08:57 heavy water permits a design that provides more space for irradiation of samples with less fuel.
09:05 Because of the long neutron diffusion length in heavy water, high neutron fluxes of over 10 to
09:11 the 13th at 2000 kilowatts are available in a relatively large volume for experimental use.
09:19 Graphite is used for a secondary reflector. The shielding consists of a thin boral liner
09:25 to absorb thermal neutrons and a lead liner to reduce gamma ray radiation.
09:32 It is backed by a high density concrete wall nearly five feet thick.
09:39 The tubular fuel elements contain enriched uranium clad with aluminum.
09:46 The cylindrical form provides access for fast neutron bombardment.
09:50 Under normal operation, only two kilograms of uranium-235 are required for a fuel charge,
09:59 which, because of fuel consumption, has to be replaced in about six months. Four cadmium safety
10:07 rods of the signal arm type move between the fuel elements to provide course control of the
10:13 chain reaction. Fine control is provided by one cadmium regulating rod operating
10:21 vertically near the core. A flow of heavy water circulates through a heat
10:27 exchanger and demineralizer and is returned. The radioactive nitrogen is
10:34 confined to this system. A gas handling system provides for recombining deuterium
10:41 and oxygen dissociated by radiation.
10:47 At the top of the reactor 45 vertical exposure holes are available for inserting and removing
10:55 samples and fuel elements.
10:58 The highly radioactive spent fuel elements are withdrawn into a lead coffin weighing
11:03 approximately eight tons and transferred to storage.
11:07 The CP5 reactor has two large thermal columns, providing variable space for irradiation and
11:14 other experimental work with slow neutrons.
11:20 For beam experiments, eight large beam holes are provided.
11:25 The neutron flux is high at the face of the reactor because high density concrete reduces
11:30 the shield thickness.
11:33 Two special isotope channels extend under the core.
11:37 Two large through tubes pass close to the core as do pneumatic tubes for quick exposure
11:42 of samples.
11:44 The argon CP5 reactor is designed primarily for neutron physics experiments.
11:50 But it has been found useful for producing isotopes and for some engineering test experiments.
11:58 A simple and relatively low-cost research reactor of low power but moderately high neutron flux
12:04 is the aqueous homogeneous or solution type.
12:09 The first reactor of this type was put into operation in 1943 at the Los Alamos Scientific Laboratory.
12:17 Enlarged twice, the present version has been in use since 1950.
12:21 In the city of Chicago, Illinois, another research reactor of the homogeneous type is
12:29 operated by the Armour Research Foundation and financed jointly by 24 industrial firms.
12:37 It is a simple and relatively low cost research reactor of low power, but fairly high neutron
12:43 flux, more than ten to the twelfth neutrons at 50 kilowatts.
12:48 The active core consists of enriched urinal sulfate dissolved in distilled water.
12:53 The water also serves as the moderator.
12:57 The solution is held in a stainless steel sphere.
13:01 Thus the enriched fuel and the water moderator are homogeneous, as contrasted with the lattice
13:07 arrangement of solid fuel in heterogeneous reactors.
13:11 A reflector of graphite completely surrounds the core.
13:17 rods enter thimbles built into the vessel. Water circulating in a coil of
13:24 stainless steel tubing removes the heat generated by fission and the fuel
13:29 solution. Leading from the core are other stainless steel pipes for handling the
13:36 fuel and the gases resulting from the fissioning process and from radiolysis
13:41 of the water. Above the core is an overflow assembly providing a space into
13:46 to which the liquid fuel is ejected, in case of a rapid power excursion resulting in a
13:52 reactor shutdown.
13:59 Neutron-absorbing control rods penetrate the sphere through the top.
14:05 They are actuated by electric motor drives and a housing on top of the shield.
14:11 To ensure against the accidental release of radioactivity to the surrounding area, this
14:16 reactor utilizes a steel core vessel, an aluminum envelope, and an airtight room as a triple
14:26 containment system.
14:30 A gas tight room containing the highly radioactive fission gas handling system provides an essentially
14:37 neutron-free gamma irradiation facility. A large graphite thermal column includes
14:46 several features which provide a variety of convenient exposure openings.
14:57 There are four vertical beam tubes penetrating the graphite reflector, two
15:04 two pneumatic tubes for rapid exposure of samples,
15:16 eight horizontal beam tubes that reach to the core,
15:20 as well as an exposure tube through the center of the core.
15:25 Instrumentation and controls are provided in a room above the reactor.
15:29 in all reactors, shutdown is easily accomplished by the use of the scram button. Because of its
15:36 low fuel inventory of only 1,300 grams, its high flux-to-power ratio, its neutron-free gamma
15:44 irradiation facility, and its compactness and relatively low cost, the solution-type reactor
15:50 is finding wide acceptance and utility. At the Brookhaven National Laboratory near New York City
15:58 is the United States' largest graphite research reactor.
16:02 The reactor built in 1942 by Enrico Fermi was of this type.
16:08 This multimillion-dollar reactor, at its full load power level of 30,000 kilowatts of heat,
16:15 produces a high neutron flux over 10 to the 12th
16:19 in a very large volume.
16:21 Behind the 5-foot wall of what we see simply as a concrete box
16:25 is the natural uranium fuel
16:30 in horizontal channels through a large mass of graphite moderator.
16:35 The core is a cube measuring about 25 feet on the side.
16:40 A neutron reflector of graphite surrounds the core.
16:44 Control rods operate in the fuel zone.
16:49 The heat produced in the core is removed by air
16:53 And finally, the reactor is enclosed in a thick concrete shield.
16:58 There are 700 tons of graphite in the 25-foot cube.
17:03 Through this run nearly 1,400 fuel channels.
17:06 In the original fuel element, 33 natural uranium slugs fit into an aluminum cartridge,
17:14 which was sealed to prevent corrosion and the escape of radioactive fission products.
17:19 The uranium slugs were encased in an aluminum cartridge with fins
17:23 to aid transfer of heat efficient to the cooling air.
17:27 Using these elements, the natural uranium loading was approximately 55 tons.
17:33 However, the natural uranium has been replaced with a new type fuel element
17:37 with enriched uranium and curved sandwich type plates of aluminum
17:41 requiring only about 60 kilograms of fuel for a loading.
17:45 The result, a four to five times increase in flux density without going to higher power.
17:54 At full power, the temperature of this air leaving the reactor is 350 degrees Fahrenheit.
18:01 Five 1500 horsepower exhaust fans pull 750 tons of filtered air through the fuel channels
18:08 every hour at velocities approaching the speed of sound.
18:15 discharge it harmlessly to the atmosphere. The reactor is operated from a control room
18:23 which is manned around the clock. Safety is a primary consideration. Many independent
18:30 checkpoints automatically shut down the reactor if the power level goes too high, if fuel
18:35 temperature becomes excessive, or other abnormal operating conditions occur. A chief advantage
18:42 of the natural uranium-graphite reactor is the numerous openings and very large spaces
18:48 it provides for experimental purposes, with thermal neutron fluxes as high as 10 to the
18:54 13th, quite adequate for most purposes.
18:58 Coming out from the core are 30 experimental holes, which provide neutrons for experiments
19:04 either outside or inside the reactor.
19:07 11 pneumatic rabbit tubes penetrate the reactor to the center of the core
19:12 to provide very short-lived radioisotopes for immediate laboratory use
19:17 before much of the activity is lost.
19:22 On top of the reactor also are many large openings.
19:26 Although the capital investment is high,
19:29 the large irradiation space and natural uranium fuel offer many unique features.
19:37 Most research reactors clearly belong to one of these four basic types.
19:41 However, numerous adaptations are being tried, and new types may be developed.
19:48 At the Argonne National Laboratory is an adaptation of the tank type.
19:54 It is called the Argonaut, and is useful for some research,
19:59 but designed primarily for nuclear technology training.
20:02 At full power of a few kilowatts, it produces up to 10 to the 11th thermal neutrons per square centimeter per second.
20:11 Built into this low-cost, low-power reactor are many features of convenience, safety, and flexibility.
20:18 At one end is a thermal column, and at the other a movable tank for conducting shielding experiments.
20:24 The reactor design is so simple that laboratory people are urged to build it themselves.
20:29 The annular shape of the reactor vessel makes possible arrangements of aluminum clad fuel plates
20:36 in a ring around an internal graphite reflector. Approximately four kilograms of U-235 in 20%
20:45 material are used and plates can be put in different positions to meet the needs of the
20:50 experiment. Within the graphite center are five access holes. The outside of the tank
20:56 is also surrounded by graphite, in which the control elements are located. Ordinary water
21:02 is pumped through the tank as both coolant and moderator. The instrumentation and controls
21:09 consist of easily procured standard devices. The uses of the argonaut in training include
21:15 start-up, criticality experiments and reactor operation, demonstrations in engineering and
21:21 nuclear physics and a variety of research experiments. Other very low
21:28 power reactors have been developed by industry. For example, solid homogeneous
21:33 reactors are being built to operate at a few watts to serve training and limited
21:38 research needs. They offer the unique feature of complete portability as well
21:43 as safety in operation. Its fuel consists of less than 700 grams of uranium-235
21:49 at 20 percent enrichment. Uranium oxide is mixed with solid polyethylene
21:55 moderator and molded into disks which are housed in a graphite reflector and
22:00 shielded by lead and water. The small size, portability, and low cost make the
22:07 solid homogeneous reactor a practical classroom trainer. A low power solution
22:18 type homogeneous reactor with a flux of ten to the eighth has also been developed.
22:28 The reactor is fueled with about 1500 grams of uranium-235 in 20 percent material. It is dissolved
22:36 in 20 liters of uranyl sulfate in a small stainless steel sphere. This core surrounded
22:43 by a lead reflector shield is housed in an eight foot diameter tank of water.
22:48 This reactor is suitable for low flux research and training.
22:53 It can be shipped as a unit and its small size makes it practical for use in schools.
23:00 Research reactors are contributing to a continual program of experimentation and research,
23:06 probing and serving the fields of chemistry, physics, metallurgy, biology, and medicine.
23:13 The most familiar use is the production of radioisotopes.
23:16 Several hundred radioactive isotopes, one or more for nearly every element in the periodic table, are being employed in research, medicine, and industry.
23:27 For example, they are used as tags in tracer study of every description.
23:33 The measurement of fertilizer uptake in plants.
23:36 The diagnosis of thyroid carcinoma and other diseases by obtaining with the center scanner a plot of the localization of radioisotope deposit in the glands.
23:46 In the field of chemistry, radioisotopes trace the behavior of elements and compounds in chemical reactions.
23:55 Special machines, using large gamma sources of cobalt-60 produced in high flux reactors,
24:02 are employed in the treatment of cancer and leukemia,
24:06 and in industry for making radioautographs of dense structure.
24:10 Radioisotopes are used in density gauges for various industrial purposes, such as continuously
24:19 measuring and controlling the thickness of a plastic sheet.
24:24 In addition to the production of radioisotopes, another major use of the research reactor
24:29 is in the study of basic physics.
24:32 Several experiments may be conducted simultaneously, such as the continuous cloud chamber experiment.
24:40 The neutron diffraction spectrometer experiment to study crystalline structure of elements and compound.
24:49 The time of flight spectrometer, it employs a mechanical rotor or neutron chopper, a long flight tube, and a thousand channel analyzer.
25:00 This experiment measures nuclear cross-sections of isotopes.
25:05 For capture gamma-ray studies, the bent crystal spectrometer is used to cover
25:12 the gamma range from a few thousand to several million electron volts.
25:16 Irradiation of materials by fast neutrons produces changes in such mechanical properties as
25:24 tensile strength, creep and shear, and significant changes in electrical and thermal conductivity.
25:30 For effective engineering studies of changes in metals, samples must be irradiated to a total
25:37 exposure of about 10 to the 18th neutrons per square centimeter. Only with very high flux test
25:44 reactors can such irradiations be made in a reasonable time. In biology, mice and rats are
25:51 utilized for radiation experiments. A study of the effect of radiation on bone marrow in immunity and
26:00 genealogy.
26:11 Reactors of low fluxes are used for activation analyses.
26:15 A quantitative analysis can be made faster, and in some cases more accurately than by
26:20 conventional chemical means.
26:27 fuel elements provide an intense source of pure gamma rays for food irradiation studies.
26:35 Pasteurization of foods and drugs allow for longer storage life. These are but a few of
26:40 the rapidly multiplying applications of research reactors. A practical program that utilizes
26:46 a research reactor involves a considerable financial investment. Detailed planning and
26:52 care must be exercised in the selection of the type of research reactor for a particular
26:57 only a realistic objective review
27:00 and appraisal of the broad aims of an organization, its research
27:04 needs or training requirements can determine this selection
27:08 where research requires a reactor capable of producing
27:12 neutron fluxes in the range of 10 to the 12th to 10 to the
27:16 13th, the pool type will do the job
27:19 another is the homogeneous reactor
27:22 which also produces fluxes in this range, but in a smaller volume
27:26 and at a lower operating cost.
27:30 The tank type using heavy water
27:33 provides a larger volume of irradiation space at these fluxes.
27:39 The greater volume makes possible a large research program,
27:43 but the cost of heavy water must be justified by the research needs.
27:49 The graphite-moderated type, with the same flux in a very large volume,
27:54 can support an extensive research program.
27:59 Where the neutron fluxes required are substantially above the 10 to the 12th to 10 to the 13th range,
28:08 a reactor for materials or engineering testing is essential.
28:13 In limited research programs and for teaching purposes,
28:18 a simple low-flux reactor may satisfy the need.
28:20 The procurement of the reactor itself is not the only financial obligation imposed on a
28:28 research program.
28:30 There is also the need for associated equipment and facilities, manpower and supplies.
28:36 An entire scientific community, including chemical, physical, biological, metallurgical
28:45 in other laboratories, are all essential facilities.
28:50 Intensely radioactive specimens must be handled in hot cells equipped with
28:55 intricate remote controlled devices. Heavy shields of dense concrete with
29:00 special shielding windows protect the operator while specimens are processed
29:05 and examined. A counting room is necessary, shielded to protect counting
29:13 devices from outside radiation.
29:24 An electronic shop for the maintenance of sensitive controlling, measuring and
29:28 recording devices.
29:31 Personnel must be trained for the operation and maintenance of the reactor.
29:37 All of these are important considerations
29:40 for the organization that undertakes a research program with a reactor.
29:45 Wisely the functional requirements of the reactor will be kept close to the
29:49 needs of the planned program.
29:52 The nuclear reactor is a powerful research tool
29:56 offering to every branch of science new horizons in the service and needs of mankind.