Calculation results for enhancing ability of I-131 radioisotope production using tellurium dioxide target on the Dalat nuclear research reactor

Nuclear Science and Technology, Vol.9, No. 3 (2019), pp. 09-20  
Calculation Results for Enhancing Ability of I-131  
Radioisotope Production Using Tellurium Dioxide Target  
on the Dalat Nuclear Research Reactor  
Nguyen Kien Cuong, Huynh Ton Nghiem, Le Vinh Vinh, Luong Ba Vien,  
Pham Quang Huy, Tran Quoc Duong, Bui Van Cuong  
Dalat Nuclear Research Institute, Vietnam Atomic Energy Institute (VINATOM)  
(Received 05 November 2019, accepted 25 November 2019)  
Abstract: The paper presents the calculation results in re-design of neutron trap of the Dalat Nuclear  
Research Reactor (DNRR) for I-131 radioisotope production using TeO2 target. The new design  
permits for loading more TeO2 capsules from 9 to 12, 15 and 18 in the neutron trap. The enhancement  
of radioisotope production was implemented by re-arrangement of the neutron trap without changing  
the dimension or geometry of irradiation capsules. By using neutronics computer code as MCNP6, the  
obtained calculation results of I-131 activity in 6 investigated cases showed that the new design by the  
re-arrangement of the neutron trap can be used effectively for radioisotope production with thermal  
neutron flux in average range from 5.3×1012 to 1×1013 n/cm2.s and the total activity of I-131 isotope  
was increased from about 19.2% to 38.8% comparing with the original design using 9 capsules. The  
negative reactivity insertion was from 0.60 βeff to 0.96 βeff when loading capsules that also met the  
safety requirements of operational conditions of the DNRR.  
Keyword: The DNRR, Radioisotope Production, TeO2, I-131, MCNP6 code.  
production needs to be considered to satisfy the  
domestic market [3]. Therefore, the design  
calculation for enhancement of I-131  
radioisotope production was carried out.  
I. INTRODUCTION  
Research reactor is a very useful facility  
for radioisotope production by using neutron to  
irradiate the target under normal operation. The  
most convenience of this method is simple in  
preparation of target capsules and in their  
irradiation at fixed positions inside or outside  
reactor core. I-131 isotope is an important  
radioisotope that can be used for cancer  
diagnostics and treatment and it is also  
produced easily by using research reactor with  
neutron irradiation on TeO2 target [1]. Even the  
DNRR has low power of 500 kWt and average  
thermal neutron flux is smaller than 5.0×1012  
n/cm2.s, radioisotope production is still applied  
as a main purpose to exploit the reactor during  
more than 35 years from 1984 until now [2].  
The demand of I-131 isotope utilization in  
nuclear medicine is increasing so the effective  
utilization of the DNRR for radioisotope  
By modifying the neutron trap  
structure, the activity of I-131 radioisotope  
was increased by loading up to18 target  
capsules but keeping their geometry and  
dimension. In original design, 9 TeO2 capsules  
have been irradiated at neutron trap of the  
reactor core with 150 hours continuously, and  
the average activity of I-131 isotope can be  
reached to 35 Ci in each reactor operation  
cycle. Basically, the method to produce I-131  
isotope with half-life of about 8.05 days can  
be expressed as follows [1]:  
    
   
    
   
 
 
         
       
 
    
   
    
   
 
 
         
  and the half-life of Te-  
131 is only 25 minutes.  
©2019 Vietnam Atomic Energy Society and Vietnam Atomic Energy Institute  
CALCULATION RESULTS FOR ENHANCING ABILITY OF I-131 RADIOISOTOPE PRODUCTION…  
Fig. 1. The micro cross section of Te-130 isotope [4]  
The neutron capture cross section of Te-  
130 isotope (see in Fig. 1) in the range from  
0.01 eV to 1000 eV is quite high compared  
with cross section at higher energy region. The  
linear of Te-130 capture cross section is in  
thermal energy range under 0.625 eV. So the  
main calculation results for the I-131 isotope  
production are in the thermal neutron energy  
group. The average cross section of neutron  
capture reaction of Te-130 is about 67 mili-  
barns in this region.  
The DNRR is a pool type reactor with  
nominal power of 500 kWt and its main  
purposes are radioisotope production,  
neutron activation analysis and training.  
Recently the demand of radioisotope market,  
especially I-131 isotope is increasing so the  
enhancement of I-131 production on the  
DNRR has been considered in calculation by  
using neutronics computer codes as MCNP6  
[5] and ORIGEN2.1 [6]. The detailed  
calculation about the neutron fluxes inside  
TeO2 target and reaction rate as well as  
neutron fluxes on the irradiation capsules  
were done by MCNP6 code.  
I-131 isotope can be chemically  
separated from the TeO2 target after  
irradiation by thermal neutron on research  
reactor. By this method, high specific  
activity of target can be obtained by  
irradiation with high thermal neutron flux.  
Of course, another method can be used on  
the research reactor to produce I-131 as  
fission product by irradiation of the U-235  
HEU or LEU but the facility chain is very  
complicated with solid waste treatment and  
separation of I-131 through fission products  
as well.  
The number of loaded TeO2 capsules in  
the neutron trap after modifying is about 12,  
15 and 18 capsules. The rearrangement of  
neutron trap with beryllium rods around can  
be created more new irradiation channels.  
The disadvantage of this rearrangement is  
mainly in reducing the neutron flux and  
adding more negative reactivity, however  
the loaded mass of TeO2 increases and I-131  
isotope activity increases from about 19.2%  
to 38.8%.  
10  
NGUYEN KIEN CUONG et al.  
II. CALCULATION MODEL AND METHOD  
A. Calculation model  
the total activity of I-131 after 150-hour reactor  
operating continuously approximated 35 Ci.  
Fig. 2 shows the loading positions of 9 TeO2  
capsules at neutron trap.  
Since 2014, the neutron trap of the DNRR  
was modified for loading up to 9 capsules and  
Fig. 2. The irradiation positions of 9 TeO2 capsules at neutron trap of the DNRR.  
The TeO2 target material used for I-  
131 isotope production is in powder with  
99.9% purity and the mass of Te-130  
isotope is about 27% in weight. The TeO2  
target of 16 cm height is covered by  
aluminum container with the dimension of  
2.6 cm in diameter, 1.5 mm in thickness and  
20 cm in height. The total volume of target  
is about 65 cm3 that is equivalent with 200  
to 230 gram of TeO2.  
power days with the configuration of 92 LEU  
fuel assemblies so the power peaking factor is  
smaller than those at the beginning of  
operation cycle, and the fuel cladding  
temperature is lower than those of the fresh  
core [7]. This means that the operational  
conditions of the reactor meet safety  
requirements.  
After modifying the neutron trap, 6  
available positions can be loaded by maximum  
3 TeO2 capsules in each hole. At the present  
work, the loading of 12 capsules with and  
without graphite reflector on the top and  
bottom, and the loading with 18 capsules was  
considered in calculation models. The MCNP6  
calculation models are shown in Fig. 3.  
By removing the whole neutron trap  
with beryllium blocks (about 6 half beryllium  
blocks), the center of the neutron trap was  
replaced by a beryllium rod to avoid the core  
has too high power density. Until now, the  
DNRR was operated about more than 300 full  
Fig. 3. The arrangement of 12 and 18 TeO2 capsules at neutron trap of the DNRR  
11  
CALCULATION RESULTS FOR ENHANCING ABILITY OF I-131 RADIOISOTOPE PRODUCTION…  
By rearrangement of the beryllium rods  
around neutron trap, 2 new positions for  
loading 3 capsules each hole can be created.  
The total 15 capsules can be loaded in the new  
neutron trap including 9 capsules are still in the  
old positions. The calculation model by using  
MCNP6 code is depicted in Fig. 4. The  
rearrangement of the neutron trap satisfies the  
safety condition as well as the thermal neutron  
flux for radioisotope production.  
5-2  
5-1  
5-3  
5-4  
5-5  
Fig. 4. Loaded positions of 15 TeO2 target capsules in the neutron trap after its rearrangement  
with 5 different options.  
In the new design, it is very simple and  
easy for carrying out experiments to test and to  
confirm the calculation results. Under this  
arrangement, the violation in thermal  
hydraulics limitation is avoided as calculation  
results were confirmed in the design of new  
LEU core as the second candidate core for  
reactor conversion from HEU to LEU fuel [7].  
The calculations were carried out for 6  
cases with different loading capsule numbers  
from 9 to 18. The explanation of loading  
scheme for detail calculations is described in  
the Table I. It is convenient that all cases  
studied were used old capsules and only adding  
more capsules at neutron trap after its  
rearrangement.  
Table I. Calculation cases for enhancement of isotope production on the DNRR  
Number of loaded  
capsules  
Detailed explanation  
9
Original neutron trap using 9 capsules currently (Fig. 2) with 3 layers and in  
each layer 3 capsules can be loaded  
12  
NGUYEN KIEN CUONG et al.  
12 – Normal  
12 – Graphite  
All capsules located at the second ring with beryllium rod at center (Fig. 3).  
Optimizing axial direction of thermal neutron flux.  
Top and bottom of all capsules covered by light water reflector.  
As the first new case above but top and bottom of all capsules covered by  
graphite reflector.  
15 – Long  
(5-1, 5-3, 5-4)  
Creating two more irradiation channels next to neutron trap following axial  
direction in the reactor core (Fig. 4). It is an easy way for rearrangement of  
neutron trap with 3 options to select.  
15 – Wide  
(5-2)  
Creating two more irradiation channels next to neutron trap following radial  
direction in the reactor core (Fig. 4). It is also very easy way for rearrangement  
of neutron trap.  
15 – Normal  
(5-5)  
Creating two more irradiation channels next to neutron trap at cell 5-6 and 9-6  
(Fig. 4).  
18  
As the first new case above but each irradiation channel can be loaded with 3  
capsules in axial direction.  
Neutron fluxes have to be normalized to  
get absolute value of neutron flux under  
thermal power of reactor. The absolute neutron  
flux can be obtained as follows [5]:  
B. MCNP code for neutron fluxes and  
reaction rate calculation  
The MCNP6 code was used for neutron  
flux and reaction rate calculation for TeO2  
target in capsules. The calculation models of  
the DNRR together with target capsules were  
described as detail as possible in Fig. 2, Fig. 3  
and Fig. 4. The ENDF/B7.1, JEFF3.3.1  
libraries [8] were used for calculation. The  
kcode option of MCNP6 code was chosen for  
the calculation with positions of control rods  
were set nearly critical status. The standard  
deviation of keff in the calculation was lower  
than 8.0×10-5 with 160 active cycles and 1  
million particles in each calculation cycle. The  
errors of obtained neutron flux as well as  
reaction rates were smaller than 0.3%. The  
burn-up calculations of the DNRR were mainly  
at two points: after 300 full power days and  
120 full power days.  
Pv  
1
(2)  
m   
m  
1.60221013wf keff  
v
where P is power of reactor (MW), is  
the average number of neutrons released per  
fission, wf is effective energy released per fission  
(~ 193.7 MeV/fission to VVR-M2 LEU fuel  
type) and keff is the effective multiplication factor.  
Actually, getting data including neutron  
flux, reaction rates and effective multiplication  
factor from MCTAL file is easier than reading  
from output file of MCNP6 code. Reaction  
rates R are received in tally as:  
Rmnx xn (E)m (E)dE  
(3)  
where Rmnx is reaction rate type x of nuclide  
n in cell m, micro cross section has unit barns.  
Neutron fluxes and reaction rates of Te-  
130 reactions and multiplication factor were  
calculated by using the MCNP6 code and three  
group neutron fluxes in active cell are  
provided by tally F4:  
C. I-131 activity calculation after its  
irradiation and cooling  
The number density of I-131 can be  
calculated by equation [9]:  
(E)dE  
(1)  
m
m
13  
CALCULATION RESULTS FOR ENHANCING ABILITY OF I-131 RADIOISOTOPE PRODUCTION…  
    
    
        
    
    
        
      
   
   
                
+
 
 
   
   
   
    
    
    
  (  
    
    
    
    
  (  
  )  
   
  (  
  )  
   
 )  
         
        (   )                
     
      
   
   
   
   
(    
)(  
   
)
    
    
(4)  
 (  )  (   )  
   
   
    
(9)  
       
   
 
   
The number density of Te-130 can be  
    
    
    
    
                          
   
   
   
   
calculated by  
(5)  
    
          
 
    
   
    
 (   )   
(10)  
We can interfere that  
   
       
   
    
       
   
   
   
With                   Avogadro  
number;  
 
 
   
    
    
    
  (   )  
   
        (   )(      
)
   
   
    
 (   )is mass of Tellurium in grams;  
   
    
    
            
(6)  
   
   
    
 (   ) is Atomic mass of Tellurium  
   
With is micro cross section (barn); is  
neutron flux (n/cm2.s); is decay constant (s-1)  
and N is the number density of isotopes  
(atoms/cm3).  
in grams.  
The activity A by Curie unit of I-131 can  
be determined by formula:  
The equation can be solved by using  
numerical method or direct calculation after  
integrating the equation (6). Then, the number  
density of I-131 can be obtained as follows:  
    
    
    
                   
(11)  
   
   
   
So the activity in each TeO2 target  
capsule can be determined through the  
calculation by applying equations from (4) to  
(11).  
I-131 activity can also be determined by  
using ORIGEN2.1 code with input data  
including irradiation time under specified  
neutron flux, cooling time and substituted  
capture cross section of Tellurium isotopes in  
activation material library. The thermal neutron  
flux and micro cross section of Tellurium  
isotope were estimated by MCNP6 code.  
    
    
    
    
    
    
     
   
    
    
     
   
      
         
     
(    
)(  
   
)
 
    
 (  )        
   
   
(7)  
And tirr and tdecay are irradiation and  
decay time (hour), respectively.  
III. CALCULATION RESULTS AND  
DISCUSSIONS  
In the equation (7), we can separate as  
two parts with build-up process and decay time  
as follows:  
A. Thermal neutron flux  
In the axial direction, the thermal  
neutron flux distribution of 1 cm/node at the  
original neutron trap without loading target  
compares with modified for loading 9 capsules  
(OLD) and the case having 6 irradiation  
(8)  
14  
NGUYEN KIEN CUONG et al.  
channels (NEW). The profiles of thermal  
trap. However in case adding only 2 new  
irradiation channels as in Fig. 4, the reducing  
of thermal neutron flux at neutron trap is not  
much and only under 5%. Fig. 5 depicts the  
profile of thermal neutron trap without loading  
capsules for radioisotope production.  
neutron flux in three cases have different in  
maximum point of 10% and in the average  
between OLD and NEW type. It is a  
disadvantage of thermal neutron flux when  
creating new irradiation channels around neutron  
Fig. 5. Thermal neutron flux distribution at original neutron trap and modified for loading 9 capsules (OLD)  
and new irradiation positions (NEW)  
Basing on the obtained calculation  
results, the best distance in axial direction that  
has the highest thermal neutron flux is from 8  
to 48 cm at bottom to the top direction. The  
height is equivalent to the length of 2 capsules  
with light water or graphite reflector at the top  
and the bottom.  
just of 8.8×1012, 8.3×1012 and 8.0×1012 with  
15, 18 and 12 capsules loaded, respectively.  
The micro cross section in barn unit of Te-  
130 isotope in thermal energy is about  
1.53E-01 barns.  
The thermal neutron flux inside all  
capsules is high enough from 5.3×1012  
n/cm2.s to 1.0×1013 n/cm2.s at top and  
middle position at irradiation channel. The  
detail axial distribution of each node of  
0.78 cm/node inside 3 TeO2 target capsules  
from bottom to the top is depicted in the  
Fig. 7.  
When loading TeO2 capsules at different  
irradiation positions inside the reactor core  
as in Table I, the average thermal neutron  
flux inside TeO2 target capsules is described  
in the Fig. 6. The maximum of average  
thermal neutron flux in the 9 capsules loaded  
is about 1.0×1013 n/cm2.s while in other cases  
15  
CALCULATION RESULTS FOR ENHANCING ABILITY OF I-131 RADIOISOTOPE PRODUCTION…  
1.1E+13  
1.0E+13  
1.0E+13  
9.8E+12  
9.5E+12  
15-Long  
15-Wide  
9-old  
9.3E+12  
9.0E+12  
8.8E+12  
8.5E+12  
8.3E+12  
8.0E+12  
7.8E+12  
7.5E+12  
7.3E+12  
7.0E+12  
6.8E+12  
6.5E+12  
6.3E+12  
6.0E+12  
5.8E+12  
5.5E+12  
5.3E+12  
5.0E+12  
12-Nor  
12-Graph  
18-Nor  
10-Cont  
15-Nor  
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18  
Number of container  
Fig. 6. The average thermal neutron flux in each capsule of 6 calculated cases  
Fig. 7. Relative thermal neutron flux of 3 capsules at each node in an irradiation channel  
from bottom to the top  
number of capsules is depicted on the Table  
II with the difference of TeO2 mass in the  
capsules. The maximum of the negative  
reactivity insertion depends on the mass of  
loaded targets and it will be increased when  
increasing mass of Te-130.  
B. Negative reactivity and safety  
The negative reactivity insertion when  
loading capsules was also estimated by  
comparing with the core configuration  
without  
capsules.  
Detailed  
negative  
reactivity insertion for different loading  
16  
NGUYEN KIEN CUONG et al.  
Table III. Negative reactivity insertion with different mass of Te-130 from 54 to 62 gram in each  
TeO2 target capsule  
Number of capsule  
Negative reactivity (cents)  
(60.2 – 70.2)  
9
12 normal  
12 with graphite  
15 long  
(69.2 – 79.2)  
(63.4 – 73.4)  
(83.8 – 93.8)  
15 wide  
(81.4 – 91.4)  
18  
(86.5 – 96.5)  
The range of negative reactivity is met  
requirements for the reactor safety in normal  
operation. In thermal hydraulics, fuel cladding  
temperature is a parameter needed to be  
evaluated to assure the nuclear safety. As  
calculation results in the design of new LEU  
cores of the DNRR, the maximum temperature  
of the hottest channels in 2 core configurations  
is lower than permission temperature 1030C.  
So the rearrangement of neutron trap in 5  
investigated cases will be also satisfied the  
limit of fuel cladding temperature after  
operating of 8 years.  
irradiation time from 24 to 150 hours and the  
same target mass of 62 gram Te-130,  
calculation results are shown in Table II and  
Fig. 8. The increasing of neutron flux is  
proportional with I-131 activity in the scale 1  
by 1. So the improvement of thermal neutron  
flux is  
a
way to enhancement for  
radioisotope production. In case of the  
DNRR, the method to increase neutron flux  
is difficult because of its low power and  
design especially using fuel with low power  
density. If upgrading power of the DNRR  
from 0.5 MW to 0.6 or 0.8 MW the expected  
thermal neutron flux can be increased 16 to  
35% respectively. Because the irradiation  
positions in axial direction of 3 capsules in  
each channel have different thermal neutron  
flux, the archived activity of I-131 after 150-  
hour irradiation of current 9 capsules has the  
ratio as 1.00:1.20:1.54 as top, bottom and  
middle positions of target.  
C. Activity of I-131 isotope in 6 investigated  
cases  
The main effects of irradiation for  
radioisotope production include thermal  
neutron flux, mass of target and irradiation  
time or decay time. With different neutron  
flux range from 5.3E+12 to 1.0E+13 n/cm2.s,  
Table II. Calculation results of I-131 activity (Ci) at different thermal neutron flux and the mass of Te-130 is  
about 62 gram in a capsule  
Activity of I-131 (Ci) with different thermal neutron flux (n/cm2.s)  
Irradiation  
F=5.3E+12 F=5.5E+12  
F=6.8E+12  
0.65  
F=8.5E+12  
0.81  
time (hr.)  
F=6.5E+12  
0.62  
F=7.8E+12  
0.75  
F=1.0E+13  
0.96  
24  
48  
0.51  
0.99  
1.42  
1.83  
2.20  
2.54  
0.53  
1.02  
1.48  
1.90  
2.28  
2.63  
1.21  
1.26  
1.45  
1.58  
1.86  
72  
1.75  
1.83  
2.10  
2.28  
2.69  
96  
2.24  
2.34  
2.69  
2.93  
3.45  
120  
144  
2.69  
2.82  
3.23  
3.52  
4.14  
3.11  
3.25  
3.73  
4.07  
4.78  
17  
CALCULATION RESULTS FOR ENHANCING ABILITY OF I-131 RADIOISOTOPE PRODUCTION…  
150  
160  
170  
180  
2.62  
2.75  
2.87  
2.99  
2.71  
2.85  
2.98  
3.10  
3.21  
3.37  
3.52  
3.67  
3.36  
3.52  
3.68  
3.84  
3.85  
4.04  
4.23  
4.40  
4.19  
4.40  
4.60  
4.80  
4.93  
5.18  
5.42  
5.65  
Fig. 8. Activity of I-131 using about 62 gram TeO2 target capsule with different thermal neutron flux  
The calculation results of I-131  
activity with different target mass in 6  
investigated cases are described in Table III  
and Fig. 9. The irradiation condition includes  
150-hour irradiation time, mass of target  
from 54 to 62 gram of Te-130. The obtained  
results showed that the total activity of I-131  
in new design comparing with old design  
using 9 capsules is increased from 19.24 to  
38.77%. It is satisfied the requirements for  
enhancement of radioisotope production on  
the DNRR.  
Table III. Calculation results of I-131 activity of 6 cases with different mass of TeO2 target  
9
12-normal  
12-graphite  
Mass of  
TeO2 target  
(gram)  
After 150  
hrs  
Decay 18  
hrs  
After 150  
Decay 18  
hrs  
After 150  
Decay 18  
hrs.  
hrs  
hrs  
200  
210  
220  
230  
31.23  
32.79  
34.35  
35.91  
29.27  
30.74  
32.20  
33.66  
38.67  
40.60  
42.53  
44.47  
36.25  
38.06  
39.87  
41.69  
39.47  
41.45  
43.42  
45.39  
37.00  
38.85  
40.70  
42.56  
Increasing %  
(comparing  
with 9  
19.24  
20.89  
capsules)  
15-Long (5-1, 5-3, 5-4)  
After 150 Decay 18  
15-Wide (5-2)  
After 150 Decay 18  
18  
Mass of  
TeO2 target  
After 150  
Decay 18  
18  
NGUYEN KIEN CUONG et al.  
(gram)  
200  
hrs.  
hrs.  
hrs.  
hrs.  
hrs.  
hrs.  
44.95  
47.20  
49.44  
51.69  
42.14  
44.24  
46.35  
48.46  
43.86  
46.05  
48.25  
50.44  
41.12  
43.17  
45.23  
47.29  
51.00  
53.55  
56.10  
58.65  
47.81  
50.20  
52.59  
54.98  
210  
220  
230  
Increasing %  
(comparing  
with 9  
30.53  
28.81  
38.77  
capsules)  
10 (5-5)  
13 (5-5)  
15 (5-5)  
Mass of  
TeO2 target  
(gram)  
After 150  
hrs.  
Decay 18  
hrs.  
After 150  
hrs.  
Decay 18  
hrs.  
After 150  
hrs.  
Decay 18  
hrs.  
200  
210  
220  
230  
37,18  
34,85  
41,26  
38,68  
45,32  
42,48  
39,03  
40,89  
42,75  
36,59  
38,33  
40,08  
43,32  
45,39  
47,45  
40,61  
42,55  
44,48  
47,58  
49,85  
52,11  
44,61  
46,73  
48,85  
Increasing%  
(comparing  
with 9  
16.00  
24.32  
31.10  
capsules)  
Fig. 9. Total activity of I-131 with different TeO2 mass and under 150-hour irradiation  
In 6 new cases considered, the simplest  
way is rearrangement of neutron trap with an  
option to create 2 irradiation channels by  
replacing the beryllium rods at cell 5-6 and 9-  
6 to load 6 capsules more. The new core  
configuration still keeps the neutron trap, 92  
LEU fuel assemblies and 10 beryllium rods.  
And this core configuration was confirmed the  
safety by evaluating the maximum fuel  
cladding temperature by PLTEMP4.2 code  
[10] at hottest fuel assembly located at cell 4-  
5. Following the calculation results, under  
27oC of water at core inlet, the maximum  
temperature is still lower than 88oC and meets  
requirements for operating limit condition of  
the VVR-M2 LEU fuel type of the DNRR.  
19  
CALCULATION RESULTS FOR ENHANCING ABILITY OF I-131 RADIOISOTOPE PRODUCTION…  
production on the Dalat Nuclear Research  
Reactor” with grant number ĐTCB.10/191  
VNCHN.  
IV. CONCLUSIONS AND REMARKS  
The calculation about the enhancement  
radioisotope production for I-131 by  
rearrangement of neutron trap to loading more  
target capsules using MCNP6 code were  
conducted. In general, 6 cases for enhancement  
of I-131 radioisotope production on the DNRR  
can be carried out easily and meet the safety  
requirements in reactor operation. Comparing  
with old design using 9 containers, the total  
activity of I-131 isotope was increased from  
about 19.2% to 38.8% with loading TeO2 target  
mass increasing from 25% to 50%. The  
rearrangement of beryllium rods around  
neutron trap at cell 5-6 and 9-6 to create 2 new  
irradiation channels is highly considered  
because of safety, easy implementation and  
effectiveness in production of I-131.  
REFERENCES  
[1]. International Atomic Energy Agency, Manual  
for reactor produced radioisotopes, IAEA  
TECDOC-1340. IAEA, Vienna, Austria; 2003.  
p. 121-4.  
[2]. Nuclear Reesearch Institute, Safety Analysis  
Report for the DNRR, version 2012.  
[3]. Nguyen Kien Cuong et al., “Some  
enhancement plans for radioisotope production  
at neutron trap of the reactor core using LEU  
fuel”, the 10th National Conference on Nuclear  
Science and Technology, Vung-tau City, 2013.  
[5]. X-5 Monte Carlo Team, MCNP – A General  
Monte Carlo N-Particle Transport Code,  
Version 5, LAUR-03-1987, Los Alamos  
National Laboratory, Los Alamos, New  
Mexico (2003).  
The design calculation is a very  
important step before carrying out testing a  
reactor operating cycle with new design for  
changing neutron trap to satisfy safety of the  
normal operation condition of the DNRR. The  
increasing I-131 product and operation time as  
well as using economical fuel are the main  
purposes in effective utilizations and  
applications of the DNRR. The calculation  
results can also be used as reference for the  
new research reactor in design of radioisotope  
production especially of I-131 isotope.  
[6]. A.G. Croff, A User Manual for the ORIGEN2  
Computer Code, Oak Ridge NL, 1980.  
[7]. LUONG Ba Vien, LE VinhVinh, HUYNH  
Ton Nghiem, NGUYEN Kien Cuong, “Design  
Analyses for full core conversion of the Dalat  
Nuclear Research Reactor”, Nuclear Science  
and Technology,Vol. 4. No. 1 (2014), pp. 10-  
25, Vietnam Atomic Energy Association,  
August, 2014.  
ACKNOWLEDGEMENT  
The authors would like to express  
special thanks for the helpful discussions and  
willing carrying out experiments on the DNRR  
of the staff in Reactor Physics and Engineering  
Department, Reactor Center. We also  
appreciate the financial support, valuable  
helping of Ministry of Science and Technology  
and VINATOM for implementation of the  
research project: “Study on effective, economic  
in using fuel and enhancement of radioisotope  
[9]. Abdessamad Didi, Ahmed Dadouch, Hassane  
El Bekkouki, “Feasibility study for Production  
of Iodine-131 using dioxide of Tellurium-  
130”, International Journal of Pharmaceutical  
Sciences 2016, Vol. 8, Issue 11, 327-331.  
[10]. P. Olson and M. Kalimullah, “A User’s Guide  
to the PLTEMP/ANL Code, Version 4.2”,  
Nuclear Engineering Division, Argonne  
National Laboratory, USA, July 7, 2015.  
20  
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