Sodium-water reaction

An important consideration in the initial water addition is the use of water at the boiling point. This is a safety consideration, since the chemical reaction heat of any unremoved sodium will locally boil the water, thus quickly steam blanketing the region and probably minimizing the local sodium-water reaction vigor. 

One run was also carried out to determine the effectiveness of air as a means of removing residual sodium. Heated air was introduced to the reaction vessel at a rate thermochemically equivalent to nitrogen containing 50% water vapor — i.e., the total heat evolved by the sodium-oxygen reaction in the formation of sodium oxide was equivalent to that realized by the sodium-water reaction in the production of sodium hydroxide. 

Evaluation of the Sodium-Water Reaction in Heat Transfer Systems... 

ADAMS, BARENBORG AND KENDALL—SODIUM WATER REACTION IN HEAT TRANSFER... 

The pressure, temperature, and plugging effects which result from a sodium-water reaction are based on the following chemical equations ... 

The thermal effects of a sodium-water reaction are largely influenced by Reaction 1 alone. The heat produced by Reaction 2 is negligible in comparison, and the heat evolved by a moderate rate of sodium hydride formation would largely be blanketed by the heat exchanger load and by heat losses from the system. Plugging effects result from the fact that all of the solid reaction products formed are practically insoluble in sodium. 

In the first test run the two pressure traces represent measurements at inlet and outlet of the boiler. Both traces show the characteristic pressure pulses obtained in the work of King. The first, second, and fourth pulses detected at the sodium inlet appear the strongest, thereby indicating the reaction producing these pulses was nearest to this pressure detector. The third pulse is due to a reaction taking place nearer the sodium outlet. These pressure pulses were produced by nonuniform reaction effects similar to those previously discussed. The pressures obtained at the inlet and outlet are different, indicating that appreciable plugging of the tube took place. When the unit was disassembled, a mixture of sodium, mercury, and sodium-water reaction products was found in the tube. 

Criteria presented in Equations 4 and 8 can be used to design the system to withstand the pressure and temperature effects of the sodium-water reaction. The use of these criteria requires a reasonable estimate of the maximum leak rate expected. 

The experience gained with the sodium-water reaction has also indicated the desirability of some design considerations in order to minimize the effects of leakage in a sodium heat-transfer system. The considerations are ... 

An under-sodium leak occurred in PFR superheater 2, one of the original units made from austenitic steel, in February 1987. It provided valuable information on the behaviour of sodium-water reactions in an operating steam generator and led to a complete re-assessment of the design-basis steam generator accident for subsequent fast reactors. 

Other tubes already weakened by fretting failed quickly, within a second or so, causing an increase in the heat generated by the sodium-water reaction. 

The loss of internal cooling when the steam flow stopped and external heating by the sodium-water reaction made tube wall temperatures rise. 

Examination of the failed modules has shown that the most likely reason of a sodium-water reaction is a manufacturing fault failed to be found during anufacturer s tests using applicable inspection methods.Over a total period of operation a series of the following activities on the steam generators has been fulfilled aiming at improvement of their reliability ... 

Successful operation of steam generator (SG) holds the key to achievement of high capacity factors. SG requires the high quality during manufacture and a sensitive leak detection system for sodium-water reaction detection and mitigation. PFR incident of failure of 40 tubes of superheater has led to redefinition of design basis leak for SG from the earlier considered incident of double ended rupture of one tube [6]. 

Tnp of all pnmary pumps with coastdown and the loss of IHX heat removal capability due to sodium water reaction in the steam generator is assumed for the ULOF combmed with LOHS event Reduction of the core flow is due to the coastdown of pnmary electromagnetic pumps, and the reactor power decreases to about 6% of the rated power due to negative reactivities When there were no... 

In addition to the safety evaluation analyses of the IHTS for large leaks, R D work on sodium water reaction carried out to date includes small water leak experiments for the determination of a design base leak rate, development of reliable and real time detection system of water leaks using the acoustic signal as well as hydrogen detection, among others. Sodium fire characteristics and... 

E-6 Design basis steam generator sodium/water reaction E-7 One loop natural circulation heat rejection from initial two loop operation E-8 Rupture disk failure in SGS sodium/water protection system... 

Physical phenomena of sodium-water reaction. Sodium-water chemical interaction proceeds in two stages at the first stage the reaction proceeds at a high rate with release of gaseous hydrogen and heat ... 

This method has got better control of sodium water reaction. Also corrosion of the component is not taking place due to absence of alkali. After the bubbling stage, the component is rinsed with water and DM water. The gas effluent is sent to the stack and the liquid effluent is sent to waste treatment. With this the sodium cleaning of the component is over and ready for decontamination. 

This process is designed to treat small quantities of sodium with an excess of water and to support the rapid raise of pressure due to the reaction. Sodium is placed in a vessel in the upper part of the autoclave. Inside air is swept out and the reactor is filled with a neutral gas. The bottom of the reactor is then filled up with water. Sodium is dropped into this water volume, and a violent sodium/water reaction is obtained. When the pressure is stabilized, reactor is decompressed and gas effluents are diluted after filtration and dehumidification. 

Sodium wastes are processed by a discontinue water jet, thrown by a hose, under air atmosphere. Operators are outside the process area and they drive the hose. Sodium/water reactions are sudden. The main advantage of this process is its processing speed, and its adaptability. Though, gas effluents control is tricky. 

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