Simulated fuel assembly-type flow measurement apparatus for coolant flow in reactor cor

Lanzo, C. D.

Savino, J. M.

English

NASA Technical Reports Server

5 
9 
c 
d (NASA CR OR TMX OR AD NUMBER) (CATEGORY) 
https://ntrs.nasa.gov/search.jsp?R=19700025353 2020-03-17T02:02:29+00:00Z
Sept. 7, 1965 
Filed May 31, 1963 
J. M. S A V i N O  ETAL 3,205,14 1 
SIMULATED FUEL ASSEMBLY 
4 Sheets-Sheet 2 
il NVENTORS 
JOSEPH M. S A V l  NO 
CHESTER D. LANZO 
ATTORNEYS 
S p t .  7, 1965 J. M. SAVINO ETAL 3,205,141 
SIMULATED FUEL ASSEMBLY 
Filed May 31, 1963 4 Sheets-Sheet 3 
F IG .  3 
INVENTORS 
JOSEPH M. SAVINO 
BY GYESTER O. L A N Z B  
ATTORNEYS 
SIMULATED FUEL ASSEMBLY 
Filed May 31, 1963 4 Sheets-Sheet 4 
INVENTORS 
JOSEPH M. SAVINQ 
3,285,141 United Statgs Patent Ofice ,, ?, 1965 
P 
I Q &
side of each fuel assembly positioned in a reactor core 
'3,205,141 under steady and transient flow conditions. 
SIMULATED FUEL ASEMDLU Another object of the invention is to provide an in- 
Joseph M. Savino, Berea, and Chester D. Eanzo, Rocky strument for measuring coolant flow in a nuclear re- 
River, Ohio, assignors to the United States o f  America actor core which is compact in size and exhibits sub- 
as represented by the the lVational stantially the same overall pressure loss versus flow rate Aeronautics and Space Administration 
Filed May 31,1963, Ser. No. 284,757 characteristics as a typical reactor fuel assembly. 
5 Claims. (C1. 176--19) A further object of the invention is to provide a fluid 
(Granted under Title 35, U.S. Code (1952), sec. 266) flow measuring device which is extremely accurate and has a short response time to changes in flow. 
The invention described herein may be manufactured Other objects of the invention will be apparent from 
and used by or for the Government of the United States the specification which follows and from the drawings 
of America for governmental purposes without the pay- wherein like numerals are used throughout t o  identify 
ment of any royalties thereon or therefor. like parts. 
The present invention relates to measuring the flow of 15 In the drawings: 
fluid through a flow passage having known overall pres- FIG. 1 is a cutaway perspective view of a contain- 
sure drop versus flow rate characteristics and is concerned ment tank that encloses a typical nuclear reactor which 
with the flow of cooling water in the area occupied by utilizes fluid flow measuring instr~ments constructed in 
the fuel assemblies in a nuclear reactor. This invention is accordance with the present invention to measure coolant 
particularly directed to a simulated fuel assembly con- 20 flow rates; 
taining flow measuring apparatus that is adapted to be FIG. 2 is an enlarged horizontal sectional view of the 
mounted in a reactor core. reactor taken along the lines 2--2 in FIG. 1. 
Before a nuclear reactor can operate satisfactorily at FIG. 3 is a sectional view taken along the line 3-3 
maximum power, the coolant flow in its core must be in FIG. 2. 
adequate. The cores of nuclear reactors generally in- 25 FIG. 4 is an enlarged sectional view of a simulated 
elude fuel assemblies arranged in a predetermined fa&- fuel assembly constructed in accordance with the inven-, 
ion. Two flow characteristics of any nuclear reactor that tion; and 
are important to proper cooling are the flow distribution FIG. 5 is a sectional view taken along the line 5-5 
among the fuel assemblies in the core and the transient in FIG. 4. 
flows inside the assemblies during the coast-down period 30 The present invention is particularly useful in a nu- 
after an accidental pump failure. clear reactor assembly of the type shown in FIG. 1 
During ,,ormaI steady-state operations knowledge of which is identical with the reactor disclosed in copending 
the flow distribution is necessary for calculating the heat- application Serial No. 277,402 by John W. Macomber 
transfer characteristics and temperatures throughout the which was filed on May 1, 1963. The reactor 22 is 10- 
core. m e n  a pump failure occurs, the reactor is shut 35 cated within a vertically extending pressure tank 24 that 
down simultaneously to prevent it from overheating dur- is mounted in high density concrete 26 and surrounded 
ing the flow coast-down period because of the lack of by water for biological shielding. Thermal shield 28 in 
proper cooling. Although the reactor is shut down, it the form of concentric annuli of curved steel plates en- 
continues to generate a sizable afterheat by fission prod- circle the reactor 22. Suitable supporting structure in 
uct decay which decreases rapidly with time to a low 40 the form of a core pedestal 30 in the lower portion of 
value. If the flow coast-down rate is too rapid, the re- the Pressure tank 24 mounts the reactor 22 in the proper 
actor can overheat and be damaged. For this reason, p ~ ~ i t i o n  relative to the tank and shields. The core 
it is very important to know accurately how rapidly the pedestal 30 also functions to separate cooling water flow- 
primary flow rate decreases after the pumps stop run- ing upward from an inlet pipe 32 and downward to an 
ning. outlet pipe 34 in a core exit chamber 36 formed by the 
It has been proposed that the rate of coolant flow be Space between the core wdestal 30 and a hemispherical 
measured by a flow meter mounted in series with a typical plate 38 in the tank 24. 
fuel assembly. Such a combined unit is installed in the For full-power operation, the cooling water is supplied 
reactor core and is used to measore the flow rare through by the three primary pumps When 
the unit. This arrangement has a disadvantage in that 50 the reactor 22 is shut down, the afterheat is removed 
it fails to measure the true flow at the location where it by cooling water supplied by a shut down flow circuit 
is installed because the flow meter increases the overall connected to the pipes 32 and 34. In both situations, 
flow resistance of the assembly. Thus, the overall pres.. the water entering the tank 24 is fed into a large plenum 
sure loss versus flow rate characteristics of the combined 40 which is on the opposite side of the pedestal 30 from 
unit are not the same as those of a typical fuel assembly. 55 the chamber 36 and beneath a divider plate 42 
This problem has been solved by utilizing a flow meas- shown in FIG. 3. This water then flows upward through 
uring instrument in the form of a simulated fuel assembly a 4 X 8 beryllium reflector lattice 44, between the ther- 
which comprises a housing that encloses both a turbine mal shields 28, or through suitable holes in the plate 42. 
type flow meter and a flow resistor in the form of a The flow rate of water through the lattice 44 is dependent 
of elongated tubes. The housing has a configuration that 60 'pan the number in the plate 42. The water 
is identical with that of a typical fuel as., entering the reactor 22 is divided at a lower grid 46 
sembly so that the instrument may be readily substituted into streams which feed various cooling Passages in the 
for any fuel assembly in the reactor core. The flow re- lattice 449 and as the water 'pward through an 
sistor includes a flow adjustment so that the overall pres- upper grid 48 it is dispersed in the large water volume in the tank 24. 
sure loss versus flow rate characteristics of the instru- G5 A pair of parallel tubes and 52 extend horizontally 
merit can be made with those of the through the pressure tank 24 to form horizontal through 
sembly. holes while three horizontally positioned pipes 54, 55 and 
It is, therefore, an object of the Present invention to 56 extend outward from the reactor 22 through the tank 
provide a flow measuring instrument in the form of a 24 to form horizontal beam holes as shown in FIGS. 1 
simulated fuel assembly which measures accurately, 'O and 2. A thermal column 58 extends through the op- 
quickly, and easily the coolant flow rate through the in- posite side of the pressure tank 24 while a pair of carrier 
3,205,141 
3 4 
tubes 59 and 60 also may be providcd. Vcttical tubes 61 A turbinc typc flow mctcr 88 having a flow resistance 
and 62 having closed lower ends project downward from that is less than that of a typical fuel assembly 64 is 
the top of the tank 24. mounted within the upper portion of the simulated fuel 
The reactor 22 comprises a boxlike assembly which assembly 86 by inserting it into the upper end of the hous- 
houses not only a core 63 comprising an active lattice of 5 ing 76A prior to attaching the inlet end box 78A. While 
stationary fuel assemblies 64 arranged in a grid array, the outside of the housing 76A is generally rectangular, 
but also the reflector lattice 44 which comprises a grid the inside is in the form of a cylinder having a diameter 
of beryllium blocks 66. The reactor 22 shown in FIG. slightly greater than that of a cylindrical housing 90 for 
2 has twenty-two stationary fuel assemblies 64 and thirty- the flow meter 88 which is properly positioned and sup- 
two beryllium blocks 66 which are all supported by the 10 ported by a shoulder 92 in the housing 76A. A tubular 
lower grid 46. Twelve beryllium reflector pieces 67 oc- sheath 94 of stainless steel or the like extends upward 
cupy the outer grid positions shown in FIG. 2 while a from the housing 90 through a spider 96 in the top of the 
row of five control rod assemblies 68 is located in certain inlet end box 78A. The spider 96 centers and supports 
of the central grid positions adjacent fuel assemblies 64. the sheath 94 which, in turn, encloses leads from the up- 
An adjacent row of five control rod assemblies is likewise 1 j stream bearing support for a turbine wheel in the flow 
provided, and these control rod assemblies are mounted meter 88 where a signal pickup is located. The sheath 94 
in certain of the outer grid positions adjacent some of the and the enclosed leads extend upward through the upper 
fuel assemblies 64 and between some of the reflector grid 48 to a rubber tube sheath 98 in the tank 24. 
pieces 67. The control rod assemblies in this adjacent Braided wire cables 100 and 102 are secured to opposite 
row each contain beryllium, and the row includes three 20 sides of the upper portion of the inlet end box 78A and 
reflector shim rods 70 located between two regulating support the leads in the rubber tube sheath 98 under ten- 
rods 71. sion to prevent whipping. The output of the flow meter 
The aforementioned p a t s  of the reactor 22 are con- 88 is measured by a pulse rate counter 104 as well as a 
tained within a core box 72 that is divided into two parts strip-chart recorder 106 which is used primarily for tran- 
by a vertical partition 73. As shown in FIG. 2 a smaller 23 sient flow tests. 
compartment encloses the core 63 of uranium bearing A flow restrictor 108 in the form of a bundle or cluster 
fuel assemblies 64, and the control rod assemblies 68, of elongated tubes 110 of stainless steel or the like is 
70 and 7 1  pass through this compartment. The larger mounted within the housing 78A in series with the flow 
compartment contains the beryllium reflector elements 66 meter 88. These tubes 110 are connected together with 
which form the reflector lattice 44. The various assem- 30 the silver solder and their ends are retained in sleeves 
lies in the core 63 are so arranged and spaced by the up- 112 and 114. The flow restrictor 108 is inserted in the 
per grid 48 that the cooling water from the large quies- lower end of the housing 78A, and the upper edge of the 
cent reservoir in the tank 24 can pass through them to outlet end box 80A engages the sleeve 114. 
carry away the generated heat. This flow, which experi- A vernier flow adjustment 116 is provided in the re- 
ences a sharp contraction as it leaves the reservoir above 33 strictor 108 so that the coolant flow can be altered. The 
the core 63, feeds into the control rods 68, 70 and 71, the vernier flow adjustment 116 includes a larger tube 118 
fuel assemblies 64 and the reflector pieces 67. The water which extends along the axis of the cluster of smaller 
flowing through the inside of the fuel assemblies 64 is tubes 110 and protrudes downward from the sleeve 114 
supplied through holes in the upper grid 48. into the outlet end box 80A. To illustrate that the tube 
Each fuel assembly 64 comprises a brazed assembly 10 118 is substantially larger than the tubes 110, a typical 
of uranium bearing aluminum-clad curved plates 74 as simulated fuel assembly 86 having a cluster of ninety 
shown in FIG. 2 that are mounted in a housing 76 hav- tubes, each having a length of twelve inches and an inside 
ing a generally rectangular configuration. The housing diameter of 0.22 inch, utilized a central tube 118 with a 
76 is hollow to accornnlodate the passage of cooling water 0.75 inch inside diameter. The protruding end of the 
and has a pair of end boxes 78 and 80 mounted at the top 45 tube 118 has slots 120 formed therein, and a slot area 
and bottom respectively as shown in FIG. 3. The outlet adjusting nut 122 is mounted thereon. Any minor mis- 
end box 80 converges through a transition from a rectan- matching of the overall pressure loss of the simulated fuel 
gular portion adjacent the housing 76 to a cylindrical assembly 86 with that of a typical fuel assembly 64 is 
portion 82 that engages a mating hole in the lower grid 46 corrected by an appropriate change in the total area of the 
while suitable recesses 84 are provided in the inlet end 50 slots 120 resulting from rotating the nut 122. 
box 78 to receive handling tools. In operation, when it is desired to measure the flow 
According to the present invention, there is provided a rate of the cooling water supplied by the inlet pipe 32 to 
flow measuring instrument 86 shown in FIG. 4 which is the outlet 34 at the position of any of the fuel assemblies 
in the for111 of a simulated fuel assembly and is substi- 64 in the reactor 22, a simulated fuel assembly 86 is sub- 
tuted for one of the fuel assemblies 64 in the core 63 to 5.5 stituted for the fuel assembly 64 in question. This is 
measure the coolant flow through that area. The simu- readily accomplished because of the similarity of con- 
lated fuel assembly 86 includes an elongated housing 76A figurations between the housings 76 and 76A. Before 
having a configuration sho~bn in FIG. 5 identical with the such a fuel assembly 64 is removed from a reactor core, 
housing 76 of the fuel assembly 61 shown in FIG. 2. its pressure loss versus flow rate characteristics are de- 
The housing 76A is likewise hollow and has a top open- 00 termined experimentally, and the total flow resistance 
ing that mates with an inlet end box 78A that is identical of the simulated fuel assembly 86 is adjusted by the 
with the box 78 on the upper end of the housing 76. A vernier flow adjustment 116 so that the flow restrictor 
bottom opening in the opposite end of the housing 76A 108 and the turbine meter 88 together produce the same 
mates with an outlet end box 80A that is identical with characteristics as the fuel assembly 64. Thereupon the 
the box 80. ~ h ~ ~ .  the simulated fuel assemblv $6 65 simulated fuel assembly 86 is placed in the core 63 of the 
may be readily stlbstituied for any of the twenty-two-fuel. leactor 22. 
assemblies 64 in the reactor core 63. In fact, more than As the cooling water passes from the inlet opening at  
the end box 78 to the outlet opening at the end box 80 
one simulated fuel assembly 86 may be mounted in the through the housing 76A of the simulated fuel assembly 
core 63 at one time, and very good results have been ob- 7 0  86, the turbine wheel in the turbine flow meter 88 is ro- 
tained when two such instruments are mounted simul- tated t~ a signal which is monitored by the pulse 
taneously in the rcactor 22. In this case, one instrument rate countef 104. when the circulating pumps are shut 
remains in a fixed position while the other instrument is off, the flow characteristics during the coast-down period 
moved to the positions occupied by each of the fuel as- are likewise accurately determined by the recorder 106 
semblies 64. -- 1.) because of the fast reaction time of the metering device. 
3,205,141 
5 6 
Whilc the preferred embodiment of the invention has 4. Apparatus as in claim 1 wherein said flow resistor 
hccn shown and described. it will be appreciated that comprises 
various modific:ltions may be made in !his disclosed a cluster of clongntcd tubult~r rncu~bcrs, 2nd 
structure without departing from the spirit of the inven- means for sclectively altering the flow of f uid through 
tion of the scope of the subjoined claims. For example, 5 said tubular members. 
the resistor m;1y be placed ahead of the turbine flow 5. A simulated reactor fuel assembly comprising, 
meter if desired. an elongated housing adapted to be mounted in a nu- 
What is claimed is: clear reactor, said housing having opposed openings 
1. In a nuclear reactor of the type having at least one therein for the admission and discharge of coolant, 
fuel assembly located at a predetermined position therein 10 a turbine flow meter mounted in said housing for meas- 
with means for circulating coolant through said fuel as- uring the flow of said coolant between said opposed 
sembly in said position; the improvement comprising openings, and 
means for duplicating the pressure loss versus flow rate a flow resistor within said housing in the flow path of 
characteristics of said fuel assembly and measuring said coolant. 
the flow rate of said coolant at said position in said 15 
reactor when said fuel assembly is removed from References Cited by the Examiner 
said reactor, said means comprising UNITED STATES PATENTS 
a housing having an inlet for admitting said coolant and 3,036,965 5/62 Braun ------- 
- 17176-56 an outlet for discharging said coolant, 
a flow meter within said housing for measuring the 20 FOREIGN PATENTS 
flow of said coolant from said inlet to said outlet, and 792,171 3/58 Great Britain. 
a flow resistor within said housing in the flow path of 840,332 7/60 Great Britain. 
said coolant from said inlet to said outlet. 
2. Apparatus as claimed in claim 1 wherein said hous- OTHER REFERENCES 
ing has a configuration substantially identical with that of 25 Truxal: "Control Engineer's Handbook," 1958, publ. 
said fuel assembly whereby said means is readily substi- by McGraw-Hill, pages 15-67 to 15-70. 
tuted for said fuel assembly in said nuclear reactor. 
3. Apparatus as claimed in claim 1 including REUBEN EPSTEIN, Pritnary E,rarniner. 
a turbine flow meter, and CARL D. QUARFORTH, Exanliner. 
means for operably connecting said turbine flow meter 30 
to an output detecting means. 


Simulated fuel assembly Patent

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server