Reactor, breeder intermediate

LDH LEU LIBD LAW LET LILW LIP LLNL LLW LMA LMFBR LOI LREE L/S LTA LWR Layered double hydroxide Low enriched uranium Laser-induced breakdown detection Low-activity waste Linear energy transfer Low- and intermediate-level nuclear waste Lead-iron phosphate Lawrence Livermore National Laboratory Low-level nuclear waste Law of mass action Liquid-metal-cooled fast-breeder reactor Loss on ignition Light rare earth elements (La-Sm) Liquid-to-solid ratio (leachates) Low-temperature ashing Light water reactor... 

When plutonium-239 is produced from urani-um-238 in a breeder reactor, the process occurs in three steps. In the first step, uranium-238 absorbs a neutron. In the second step, a shortlived intermediate element is made through beta decay. In the third step, the plutonium-239 is produced through beta decay. Write a balanced nuclear equation for each of the three steps. 

The principal uses of ThF4 are as intermediate in the production of thorium metal or, potentially, as a compound in the fuel mixture of the molten-salt breeder reactor. For both applications anhydrous, oxide-free ThF4 is required. 

The rate of dissolution of PUO2 in nitric acid is slower than UO2 and depends on the plutonium/uranium ratio, the methods used to fabricate fuel, and the conditions of irradiation. At one extreme, plutonium produced at low concentration in UO2 by transmutation dissolves almost as rapidly as the associated UO2. At the other extreme, plutonium present as PUO2 mixed mechanically with UO2 without proper sintering dissolves much more slowly and less completely than UO2. Plutonium present as a solid solution (U,Pu)02 at the concentration of 20 to 25 percent used in breeder-reactor fuel dissolves at an intermediate rate. ... 

Fuel cost and performance is an important part of the economy of power reactors. Approximately 20% of the expense of the electrical production in a power reactor can be attributed to the cost of the fuel. This is due about equally to the expense of the consumption of fissile material and to the production and, when applicable, reprocessing costs or intermediate storage costs. In the fast breeder reactors, it is anticipated that fuel costs would be substantially lower because of a higher bum-up. 

The primary system includes four primary pumps and eight intermediate heat exchangers connected with four secondary loops. The total amount of sodium in these four secondary loops is 1500 tons. The core of SPX is made of fuel elements (mixed UO2-PUO2), breeder elements, rods plus complementary control rods (pins containing pellets of boron carbide B4C). The power of SPX reactor was 3000 thermal MW converted to 1242 electric MW. At the date of the decision of the final shutdown of the reactor, SPX was in operation only 320 Equivalent Full Power Days. During this time there was no cladding failure. Therefore it can be assumed that SUPERPHENIX has a very low residual activity and minor contamination in the primary sodium. Thus the residual activity of the primary sodium was measured. The values in 2000 were ... 

It is also possible to supplement the RVACS heat removal capacity using a direct reactor auxiliary cooling system (DRAGS) based on natural circulation of an intermediate coolant from bayonet heat exchangers in the reactor vessel to air-cooled heat exchangers. This type of DRAGS system was used in the Experimental Breeder Reactor II (EBR-II) with sodium-potasium as the intermediate coolant. There are a variety of potential intermediate coolants, several of which have been used extensively in industry for similar heat transfer applications. 

A molten salt reactor (MSR) is a reactor in which fluorides of fissile and fertile elements such as UF4, PuFg, and/or Thp4 are combined with carrier salts to form a fluid fuel. MSRs can operate as simple burner reactors with high fuel economy or with the addition of online fission product removal and can achieve breeder status. Typical operation sees molten salt flowing between a critical core and an intermediate heat exchanger. A secondary coolant salt then transfers heat to a steam or closed gas cycle. The majority of work has involved fluoride salts, as corrosion-resistant alloys have been shown to be compatible with these salts. 

Intensive studies have been made not only on pure fusion reactors but also on breeder type fusion reactors as the intermediate stage for the use of fusion systems. In the uranium blanket in the breeder case, the main part of the energy is released by nuclear neutron-induced fission of... 

The 500 MW(e) prototype fast breeder reactor (PFBR) is under construction in India. PFBR is a 500 MWe capacity, pool type sodium cooled fast reactor with 2 primary pumps, 4 intermediate heat exchangers and 2 secondary loops. There are 8 integrated steam generator (SG) units 4 per secondary loop where steam at 763 K and 17.2 MPa is produced. Four separate safety grade decay heat exchangers are provided to remove the decay heat directly from the hot pool. The hot and cold pool sodium temperatures are 820 and 670 K, respectively. 

Capital cost of the MSR could be almost the same as that of the LWR. There are many pros and contras for choosing between these two reactors. The MSR has 3 circuits with an intermediate heat transport system similar to fast breeder reactors. On the other hand, the thermal efficiency is -30% higher than that in a pressurized water reactor, the core pressure is very low, and the safety system is simplified. 

Budov, V.M., et al.. Intermediate Heat Exchangers Design and Experimental Testing, Int. Symp. on Design, Constmction and Operating Experience of Demonstration Liquid Metal Fast Breeder Reactors, Bologna, Italy, April 10-14,1978. 

All these projects were designed for a power output of 250-300 MWe. They were supposed to form an important intermediate step on the way to fast breeder reactor power plants with a power output of 1000-1500 MWe. Such a power plant has been built in France already, SUPERPHENIX (SPX 1). 

Roy, P., and Licina, G.J., Carbon Activity Determinations in a Bimetallic Sodium Loop Mock-up of the Intermediate Heat Transport System of a Liquid Metal Fast Breeder Reactor. Proceedings of the Third International Conference on Liquid Metal Engineering and Technology in Energy Production, Oxford, USA, April 1984,3,207. 

The modular double pool fast breeder reactor (MDP), a sodium cooled fast reactor of 325 MW(e) per module output, has been designed to reduce the construction costs and improve the reliability by factory production of most the components, see Annex XXII, Specifically, the MDP is proposed for use within a 4-module plant of 1300 MW(e).The development of the MDP concept has been performed and funded by the CRIEPI. The double pool design is intended to reduce the distances in the intermediate heat transport system by installing steam generators and secondary pumps in the sodium filled annular space formed between the primary and secondary vessel. The preliminary conceptual design has been completed but, at the moment, there is no financial support for further R D. 

For practical deployment of fast breeder reactors (FBRs) it is necessary to reduce construction costs. The construction cost of an FBR is high in comparison with an LWR due to the use of sodium as the coolant and the adoption of intermediate heat transport system. Therefore, the reduction and limitation of the sodium handling area and the simplification of intermediate heat transport system are effective measures for cost reduction. The objective of the MDP study is to establish a modular reactor concept that can compete with an LWR on construction costs. 

Figure 15.15 Prototype fast breeder reactor (PFBR) heat transport systems. SGDHR, Secondary sodium decay heat removal IHX, intermediate heat exchanger.

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