Density of Gadolinium Nitrate Solutions for the High Flux Isotope Reactor

Taylor, Paul Allen¹  Lee, Denise L¹ 

[1] ORNL

关键词: AVAILABILITY;    CADMIUM NITRATES;    CONTROL;    COOLANTS;    COOLING;    CORRELATIONS;    CURRENTS;    DENSITY;    EQUATIONS;    FREEZING;    GADOLINIUM;    GADOLINIUM NITRATES;    HEAT;    HFIR REACTOR;    INJECTION;    NEUTRONS;    ORDERS;    PERSONNEL;    PLANNING;    RANGE;    REACTORS;    SAFETY;    SOLUTIONS;    TANKS;    TEMPERATURE RANGE;    UNITS;    VOLUME;    WATER gadolinium nitrate;    density;   

DOI  :  10.2172/953188
RP-ID  :  ORNL/TM-2009/091
PID  :  OSTI ID: 953188
Others  :  Other: KC0402020
Others  :  ERKCR01
Others  :  TRN: US1000855

美国|英语

来源: SciTech Connect

【 摘 要 】

In late 1992, the High Flux Isotope Reactor (HFIR) was planning to switch the solution contained in the poison injection tank from cadmium nitrate to gadolinium nitrate. The poison injection system is an emergency system used to shut down the reactor by adding a neutron poison to the cooling water. This system must be able to supply a minimum of 69 pounds of gadolinium to the reactor coolant system in order to guarantee that the reactor would become subcritical. A graph of the density of gadolinium nitrate solutions over a concentration range of 5 to 30 wt% and a temperature range of 15 to 40{sup o}C was prepared. Routine density measurements of the solution in the poison injection tank are made by HFIR personnel, and an adaptation of the original graph is used to determine the gadolinium nitrate concentration. In late 2008, HFIR personnel decided that the heat tracing that was present on the piping for the poison injection system could be removed without any danger of freezing the solution; however, the gadolinium nitrate solution might get as cold as 5{sup o}C. This was outside the range of the current density-concentration correlation, so the range needed to be expanded. This report supplies a new density-concentration correlation that covers the extended temperature range. The correlation is given in new units, which greatly simplifies the calculation that is required to determine the pounds of gadolinium in the tank solution. The procedure for calculating the amount of gadolinium in the HFIR poison injection system is as follows: (1) Calculate the usable volume in the system; (2) Measure the density of the solution; (3) Calculate the gadolinium concentration using the following equation: Gd(lb/ft{sup 3}) = measured density (g/mL) x 34.681 - 34.785; (4) Calculate the amount of gadolinium in the system using the following equation: Amount of Gd(lb) = Gd concentration (lb/ft{sup 3}) x usable volume (ft{sup 3}). The equation in step 3 is exact for a temperature of 5{sup o}C, and overestimates the gadolinium concentration at all higher temperatures. This guarantees that the calculation is conservative, in that the actual concentration will be at least as high as that calculated. If an additional safety factor is desired, it is recommended that an administrative control limit be set that is higher than the required minimum amount of gadolinium.