Prodyot Roy

Electrochemical oxygen sensor for measurement of oxygen in liquid sodium

The results obtained from approximately 4000 h of operation of an electrochemical oxygen meter developed at General Electric Company for measuring oxygen activities in liquid sodium are described. In the present design, a small ceramic cup (ThO/sub 2/ with 7 to 8 wt % Y/sub 2/O/sub 3/) has been brazed to a metal tube that is inserted into the liquid sodium via a standard sodium flange. The reference electrode used in the present design consists of In/In/sub 2/O/sub 3/. Several meters were tested in a flowing sodium system, where the oxygen concentrations were controlled by a cold trap. At 500/sup 0/C, the oxygen electromotive force (emf) output can be expressed as emf/sub (V)/ = 0.269 + (160/T) (+-0.003 V), where T is the cold-trap temperature in K. The temperature coefficient of the meters can be expressed as (dE/dT) = 0.51 +- (0.02) mV//sup 0/C.

Hydrogen burden from the steam side corrosion in sodium-heated steam generators

It has been observed that in sodium-heated steam generators most of the hydrogen produced from water- or steam-side corrosion permeates into the secondary sodium. The amount of hydrogen that diffuses into the secondary side is extremely important from the standpoint of the design of the cold trap, hydrogen background levels, and tritium concentrations in the secondary system. We have compiled all the available data on H/sub 2/ permeation from all operating sodium-heated steam generators. In addition, based on the available steam-side corrosion data, we have made tentative recommendations: Steady-state H/sub 2/ flux, (1) Evaporator (2/sup 1///sub 4/ Cr--1 Mo)--1.8 to 2.2 x 10/sup -11/ g H/cm/sup 2/.s. (2) Superheater (2/sup 1///sub 4/ Cr--1 Mo)--1.2 to 1.7 x 10/sup -11/ g H/cm/sup 2/.s. Initial H/sub 2/ flux (up to 2000 h): Evaporator and superheater (2/sup 1///sub 4/ Cr--1 Mo)--approximately 7 to 8 x 10/sup -11/ g H/cm/sup 2/.s.

HUTEC a high efficiency thermally regenerative fuel cell for space applications

The Hydrogen Thermo‐Electrochemical Converter (HYTEC) is an improved means of thermal‐to‐electrical energy conversion for space or other remote locations. The system is based on a fuel cell where the fuel element, hydrogen gas, is regenerated from the fuel cell product, metal hydrides. The HYTEC work at General Electric has resulted in a system concept design and supporting experimental data. Unique features in the system include the use of a niobium‐titanium alloy for the electrodes and a lithium‐sodium mixture to transport the hydride reaction product. Experimental data to date has shown the feasibility of the concept.

Progress in SP-100 tribological coatings

The SP-100 Tribology Development program to investigate candidate coating materials for the SP-100 reactor is discussed. The SP-100 will operate at temperatures up to 1500 K in high vacuum. Background information, specific bearing requirements, the basis for coating material selection, testing methods, and initial results of the program are addressed.

Steam Generator Leak Detection in Liquid-Metal Fast Breeder Reactors by Chemical Methods

Chemical methods are the primary means for detecting steam generator leaks in liquid-metal fast breeder reactor (LMFBR) systems. Both hydrogen and oxygen detectors may be used for this purpose. Diffusion of hydrogen through a thin nickel membrane provides the basis for the primary LMFBR leak detection tool. Spurious sources of hydrogen (e.g., from waterside corrosion) and partition of hydrogen between sodium and cover gas are major disadvantages with the use of leak detection systems that incorporate only hydrogen monitors. Electrochemical oxygen meters, which are not subject to these problems, provide a complementary method for leak detection. Hydrogen meters (both diffusion tube and electrochemical designs) and electrochemical oxygen meters have demonstrated the capability to detect water intrusions in sodium test systems.

Inpurity Monitoring in Liquid Sodium Systems by Electrochemical Oxygen and Hydrogen Monitors

Liquid sodium is used as the coolant in both primary and secondary circuits of the liquid metal fast breeder reactor. The oxygen content of the sodium has a profound effect upon the corrosion of structural materials and upon the tribology of materials pairs. A change in the hydrogen concentration in the sodium can signal excessive water-side corrosion in the steam generators or an oil leak from a pump. Changes in oxygen or hydrogen content in the secondary circuit may also indicate a leak of water into sodium. Thus, oxygen and hydrogen detectors can be used to detect steam generator leaks and are utilized as a part of the steam generator protection system. The performance of electrochemical cells for hydrogen and oxygen under both steady- state and simulated steam generator leak conditions is described.

The Evaluation of Particulates Deposited in Flowing Non-Isothermal Sodium Systems

Recent experimental evidence suggests that the corrosion and deposition processes in a flowing non-isothermal sodium system are interdependent, and each exerts considerable influence over the extent and characteristics of the other. Therefore, a performance analysis of non-isothermal sodium systems must consider these processes as complementary and equal in significance to the overall system behavior. This report will focus on the factors which influence the composition and structure of particulates (deposits) and the location and rate at which they are deposited.