Swimming-pool reactors

A number of pool, also called swimming pool, reactors have been built at educational institutions and research laboratories. The core in these reactors is located at the bottom of a large pool of water, 6 m deep, suspended from a bridge. The water serves as moderator, coolant, and shield. An example is the Lord nuclear reactor at the University of Michigan, started in 1957. The core is composed of fuel elements, each having 18 aluminum-clad plates of 20% enriched uranium. It operates at 2 MW, giving a thermal flux of 3 x 10 (cm -s). The reactor operates almost continuously, using a variety of beam tubes, for research purposes. 

An xmusual exception to the swimming pool reactor design is the IBR-2 reactor (Dubna, Russia) [7], shown in Fig. 3.3. The core of this... 

A swimming-pool reactor produces a flux of 3 x lo thermal neutrons m s at 1 m from the reactor center. Assuming a parallel beam of neutrons diffusing up to the surface of the pool where the neutron flux is measured to be 10 n m s, calculate the thickness (x m) of the water layer required. For thermal neutrons the flux is reduced exponentially with the exponent x L, where L is the diffusion length (2.75 cm in HjO). 

Low-temperature irradiation devices are used with increasing frequency, especially to study radiation-induced defects in solids. A liquid-nitrogen irradiation device, which has operated for over 15,000 hours, has been described previously P]. However, certain defects anneal out or are transformed well below 77 °K and their study requires irradiation at lower temperatures. Two liquid-helium [ " ] and one liquid-hydrogen [ ] reactor irradiation devices have been reported in the literature. This paper describes an irradiation device at the temperature of boiling neon, which was installed in the Melusine swimming-pool reactor of the Nuclear Research Center of Grenoble. 

On the area of ENET, there exist already two reactors. One twin-core swimming pool reactor, with a total power of 3.8 MVVt, was erected in 1964 and is still in service. The purpose of this reactor is to perform shielding and irradiation tests In 1989, a 5 MWt water cooled reactor was erected in INET, mainly for the demonstration of district heating with nuclear energy. This reactor now is also used for performing tests on nuclear... 

Swimming Pool reactor, along with the principal dimensions of the system, are given below ... 

Table 8.7 Two-groi p Constants for ORNL Swimming Pool Reactor...

Nuclear fuel recovery and waste - 729 Nuclear steam generator tubing - 729 Nuclear swimming pool reactor liner - 203 Nuclear waste - 203, 729 Nujol (see Mineral oil) - 234 Nutmeg oil (see Essential oils)... 

A research reactor s power is usually in the range 0-100 MW thermal. The fission product inventory and the stored energy in research reactors are smaller than in power reactors. However, some of the research reactors have large power density (>5000 kW thermal per kg of fuel). The typical research reactor is of the swimming pool type, as shown in Fig. 7.6. 

Lutetium-177 was produced by irradiation of lutetium samples in the core of PARR-1, a swimming pool type reactor, at a thermal neutron flux of 1 X 10 n-cm -s for specified periods of time ranging from 1 to 96 h. Naturally abundant LU2O3 and enriched UiiO were dissolved in IM HNO3, evaporated to dryness and reconstituted in O.IM HNO3, and again evaporated to dryness. The Lu(NO3)3 (2.59% Lu) powder and enriched Lu(NO3)3 (68.9% Lu) powder thus obtained were sealed in quartz ampoules and cold welded in aluminium containers for irradiation. In another experiment, quartz ampoules were filled with 0.2 mL of liquid Lu(NO3)3, sealed and cold welded in aluminium containers. These targets were then irradiated in PARR-1. The... 

Research reactors are based on the swimming pool concept the reactor core sits in the middle of a large tank of water that acts as both coolant and moderator and allows sufficient space for specialised moderators and guide tubes. FRM-II is designed to provide the maximum possible thermal neutron flux from a small core cooled with... 

Safety is clearly a major consideration and research reactors are designed to fail-safe to prevent fission product release. Reactors operate under a triple containment philosophy. The first container is the cladding of the fuel itself, the second is the swimming pool which is made from heavy, 1.5 m thick, concrete lined with stainless steel. Finally the whole reactor is housed inside a reinforced building that is kept at a slightly sub-ambient pressure and is accessed by an air-lock. 

The Br and Cl contents were measured by the INAA method. The irradiations were performed in the Institute of Nuclear Techniques, University of Technology and Economics, Budapest. The swimming-pool type thermal reactor ((ij max 2 X lO ncm s max = lOOkW) is operated with an... 

Figure 7 Nuclear reactor Thetis dedicated to neutron activation analysis. View in the swimming pool with nuclear fuel element, Cerenkov radiation, safety and control plates and pneumatic transport tubes. (Reproduced with permission from Institute of Nuclear Sciences, Gent, Belgium.)...

Five racks of test coupons were immersed in the spent fuel basin of the swimming pool research reactor at the CIAE. The rack numbers, the coupon materials and the immersion dates are listed in Table 7.1. The coupons were assembled in the rack to evaluate general corrosion, crevice attack and galvanic... 

Reactor type Swimming pool research reactor... 

The experiment assembly was loaded into the Low-Temperature Irradiation Facility (LTIF), a combination of a continuously operating liquid-helium refrigerator and a cryostat next to the core of the swimming-pool-type Oak Ridge Bulk Shielding Reactor. The sample chamber was then purged with dry helium gas and evacuated to about 13 Pa (0.1 torr) several times before initial cooldown. 

PRINCIPLE OF A LIQUID NITROGEN IRRADIATION DEVICE AND ITS REALIZATION FOR USE IN A SWIMMING-POOL TYPE REACTOR... 

Because there are no drain connections at the bottom of the fuel storage pool, the spent fuel assemblies can never be exposed by an accidental valve opening or pipe break. Fuel is not stored in the upper containment pool during normal operation. A portable underwater vacuum system, similar to that used in swimming pools, can be used to clean pool walls, floors, and internals removed from the reactor vessel. Deposition at the water line of the pool walls is minimized by several surface skimmers. These devices remove a portion of the surface water and recycle it to the pool. 

Reactor type Thermal heterogeneous swimming pool... 

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