We present the testing as neutron shielding material of a new high-density concrete (commercially available under the name Hormirad™, developed by the Spanish company CT-RAD). The purpose of this work was to characterize the material behavior against neutrons, as well as to test different mixings including boron compounds in an effort to improve neutron shielding efficiency. Hormirad™ slabs of different thicknesses were exposed to a 241Am-Be neutron source under controlled conditions in the neutron measurements laboratory of the Nuclear Engineering Department at UPM. The original mix, which includes a high fraction of magnetite, was then modified by adding different proportions of anhydrous borax (Na2B4O7). The same experiment was repeated with HA-25 concrete slabs, looking for a reference against ordinary concrete used to shield medical accelerator facilities. In parallel to the experiments, Monte Carlo calculations of the experiments were performed with MCNP5, with some differences found, attributable to uncertainties in the elemental composition of the samples tested. The first and equilibrium tenth-value layers have been determined for the different types of concrete tested. The results show an advantageous behavior of the Hormirad™ one, when comparing neutron attenuation against real thickness of the shielding. Although borated-concretes show a little better neutron attenuation with respect to mass-thickness, the resulting reduction in density and structural properties makes them less practical

Gallego Díaz, Eduardo F.

Lorente Fillol, Alfredo

Vega-Carrillo, Héctor René

Servicio de Coordinación de Bibliotecas de la Universidad Politécnica de Madrid

1 
 
TESTING OF A NEW HIGH-DENSITY CONCRETE AS NEUTRON 
SHIELDING MATERIAL 
 
 
Eduardo Gallego, Alfredo Lorente,  
Nuclear Engineering Department, Technical University of Madrid (UPM), Spain 
 
Héctor René Vega-Carrillo 
Unidad Académica de Estudios Nucleares, Universidad Autónoma de Zacatecas, 
Mexico 
 
Corresponding Author:  
Eduardo Gallego 
Nuclear Engineering Department, Escuela Superior de Ingenieros Industriales 
Universidad Politécnica de Madrid, José Gutiérrez Abascal, 2, E-28006 Madrid, 
Spain 
Tel.: +34 91 336 3112; Fax: +34 91 336 3002  
E-mail: eduardo.gallego@upm.es 
 
Total number of pages: 18 
Total number of tables: 2 
Total number of figures: 5 
Total number of footnotes: 1 
2 
 
 
Abstract 
We present the testing as neutron shielding material of a new high-density 
concrete (commercially available under the name Hormirad™, developed by the 
Spanish company CT-RAD). The purpose of this work was to characterize the 
material behavior against neutrons, as well as to test different mixings including 
boron compounds in an effort to improve neutron shielding efficiency. 
Hormirad™ slabs of different thicknesses were exposed to a 241Am-Be neutron 
source under controlled conditions in the neutron measurements laboratory of the 
Nuclear Engineering Department at UPM. The original mix, which includes a 
high fraction of magnetite, was then modified by adding different proportions of 
anhydrous borax (Na2B4O7). The same experiment was repeated with HA-25 
concrete slabs, looking for a reference against ordinary concrete used to shield 
medical accelerator facilities. In parallel to the experiments, Monte Carlo 
calculations of the experiments were performed with MCNP5, with some 
differences found, attributable to uncertainties in the elemental composition of the 
samples tested.  
The first and equilibrium tenth-value layers have been determined for the 
different types of concrete tested. The results show an advantageous behavior of 
the Hormirad™ one, when comparing neutron attenuation against real thickness 
of the shielding. Although borated-concretes show a little better neutron 
attenuation with respect to mass-thickness, the resulting reduction in density and 
structural properties makes them less practical.  
3 
 
 
I. INTRODUCTION 
 A new high-density concrete based on magnetite has been developed by a 
commercial Spanish company (CT-RAD) and is available under the name 
Hormirad™a. The shielding properties of the new concrete against photons were 
previously studied
1
 and the material is being used to build bunkers, mazes and 
doors in medical accelerator facilities with good overall results. The purpose of 
this work was to test and characterize the material behavior as neutron shielding 
material. The basic Hormirad™ material was compared with conventional 
concrete as well as with new mixings including boron compounds in an effort to 
improve their neutron shielding efficiency.  
 
II. MATERIALS AND METHODS 
HORMIRAD™ concrete is very rich in magnetite, which represents 
almost 90% of its weight. Based on information provided by the manufacturer and 
by the magnetite stone supplier, the elemental composition is indicated in Table I. 
Its main characteristic is the elevated content of iron, about 60%, compared to 
48% cited in the literature for magnetite concretes
2, 3
. The manufacturing 
procedure is made carefully so that homogeneity of the resulting blocks is rather 
high. The resulting density is on the order of 4 g·cm
-3
. For the tests, Hormirad™ 
slabs of 25 cm x 25 cm and different nominal thicknesses (1, 2, 5, 10 cm) have 
been used in different combinations. The actual dimensions and weight were 
measured with calibrated instruments and the resulting density determined to be 
between 3.44 and 4.10 g·cm
-3
, 3.99 g·cm
-3
 on average. Thicker slabs got higher 
                                                          
a
 US and European patent applications have been presented by the producer for the Hormirad™ 
“heavy mass for manufacturing products with a high radioprotection capacity”. 
4 
 
density, because the thinner need some steel mesh inside to reinforce them against 
breaking.  
The slabs were exposed to a 
241
Am-Be neutron source under controlled 
conditions in the neutron measurements laboratory of the Nuclear Engineering 
Department at UPM
4
. The experimental configuration is shown in Fig. 1. A 
calibrated Berthold LB6411 monitor was used to measure and register the ambient 
dose equivalent rate, *(10). Measuring time was typically 400 s, with data 
recorded every 20 s, so the used values were the average between at least 20 
recorded values. For all the measurements, the distance between the source axis 
and the center of the detector was fixed in 65 cm. The source and the detector are 
situated 3 m above the ground in a large room of 9 m x 15 m x 8 m in order to 
reduce the neutron room return as much as possible. This was determined with a 
shadow cone and by calculations
4
 to be on the order of 4 μSv·h-1.  
MCNP5
5
 calculations were performed to corroborate the validity of the 
experimental results. Models of the source, the room and the experimental setup 
were prepared as realistic as possible, both with respect to geometry and the 
atomic composition of the tested materials.  
Conventional concrete slabs (ref. HA-25), with measured density 2.2 
g·cm
3
 were also tested by the same procedure in order to have a reference to 
concretes usually employed in building clinical accelerator rooms.  
Additionally, in an attempt to find better shielding materials against 
neutrons, other slabs were prepared by adding anhydrous borax (Na2B4O7) to the 
magnetite concrete, with the following fractions in weight: 1.19% , 5% and 
25.13% (equivalent to 5% in B). 
5 
 
Finally, we combined a fixed thickness layer of Hormirad™ (15.6 cm) 
with layers of different thicknesses of borated Hormirad™ and polyethylene with 
5% boron.  
 
III. RESULTS 
 
III.A. Hormirad™ alone 
A problem was found when comparing the calculated and experimental 
values, since they fit reasonably well for small thicknesses (higher dose rate), but 
deviate for thicker layers (lower dose rate). The comparison is illustrated in Fig. 2 
in terms of *(10). For layers beyond 5 cm systematically all the calculated 
values with MCNP5 are smaller than those measured, with differences tending to 
grow as the thickness increases. This probably indicates uncertainties about the 
exact elemental composition of the Hormirad™ material, which in the calculation 
attenuates neutrons more than in the experiments. 
Fig. 3 displays the relative attenuation of *(10) with regard to mass-
thickness. As can be observed, there is a double tendency, and an exponential 
fitness of the first points indicates an experimental first Tenth-Value Layer (TVL) 
of 1091.2 kg·m
-2
, in units of mass-thickness, equivalent to a real thickness of 27.4 
cm. The exponential fitness of the last points suggests an extrapolated value for 
the second and equilibrium TVL of 897 kg·m
-2
, equivalent to a real thickness of 
22.5 cm. 
 
III.B. Ordinary concrete 
6 
 
The corresponding experimental attenuation for ordinary concrete (HA-25) 
and the exponential fitness of the measured points is displayed in Fig. 4. The 
resulting first TVL is 875.5 kg·m
-2
, equivalent to a real thickness of 39.8 cm. It is 
comparable to values indicated in Ref. 4, and clearly higher than the one for 
Hormirad™.   
 
III.C. Borated mixings  
The results of adding anhydrous borax to the Hormirad™ magnetite 
mixture in different percentages in weight is summarized in Table II. The 
reductions obtained in the first TVL with regard to the value for the Hormirad™ 
alone are indeed not significant. Moreover, these compound materials have 
several disadvantages that make them not good options, like the increase in cost 
and the poorer structural properties, especially if the fraction of borax is elevated.  
 
III.D. Combined shielding with Hormirad™ and borated materials  
The last test series consisted in combining an inner layer of 15.6 cm of 
Hormirad™ with outer slabs of mixed materials with boron in their composition: 
the borax-added Hormirad™ and also borated polyethylene (5% in B). The 
relative transmission is displayed in Fig. 5. It appears that the combination of an 
internal layer of Hormirad™ with an external layer of borated polyethylene can 
lead to optimized solutions for door shielding in accelerator rooms. 
 
IV. CONCLUSIONS 
For 
241
Am-Be neutrons, the magnetite-based Hormirad™ concrete has shown 
a clearly advantageous behavior, when comparing neutron attenuation against real 
7 
 
thickness of the shielding with regard to ordinary concrete. Although borated 
compounds show better neutron attenuation with respect to mass-thickness, the 
resulting reduction in density and structural properties makes them less practical.  
However, more research seems necessary to better characterize the elemental 
composition of the materials, and also to determine its neutron attenuation 
properties for typical spectra of clinical accelerators. 
 
ACKNOWLEDGEMENTS 
We wish to thank Juan Manuel Caruncho and Isabel Delicado, from CT-RAD, for 
their collaboration in supplying the shielding materials tested and data about their 
composition. 
 
 
REFERENCES 
1. M. A. DUCH, V. PANETTIERI, Technical Reports SPR005/06 and 
SPR008/06. Instituto de Técnicas Energéticas. Universidad Politécnica de 
Catalunya (In Spanish) (2006). 
2. R.G. JAEGER, E.P. BLIZARD, A.B. CHILTON, M. GROTENHUIS, A. 
HÖNIG, TH. A. JAEGER, H.H. EISENLOHR, Engineering Compendium on 
Radiation ShieldingVolume II: Shielding Materials, Springer, 
Berlin/Heidelberg (1975). 
3. NATIONAL COUNCIL ON RADIATION PROTECTION AND 
MEASUREMENTS, Radiation Protection for Particle Accelerator Facilities, 
NCRP Report No. 144, Bethesda, Maryland (2005). 
8 
 
4. E. GALLEGO, A. LORENTE and H.R. VEGA-CARRILLO, “Characteristics 
of the neutron field of the facility at DIN-UPM”, Radiation Protection 
Dosimetry, Vol. 110, Nos. 1-4, pp. 73-79 (2004). 
5. X-5 MONTE CARLO TEAM, “MCNP – A General Monte Carlo N-Particle 
Transport Code, Version 5”. Report LA-UR-03-1987, Los Alamos National 
Laboratory, California (2005). 
 
 
 
9 
 
 
TABLE I. Elemental composition of Hormirad™ based on information provided 
by the manufacturer. 
 
Fe  60.07%  
O  31.95%  
Ca  4.307%  
Si  1.847%  
H  0.568%  
Mg  0.389%  
P  0.287%  
Ti  0.192%  
Al  0.165%  
K  0.063%  
Mn  0.062%  
V  0.050%  
C  0.036%  
S  0.007%  
N  0.003%  
 
 
10 
 
 
TABLE II. TVL obtained for 
241
Am-Be neutrons with borated mixings of 
different characteristics. 
 
 
Shielding Material  Average density  
First TVL for 
241
Am-Be neutrons  
Mass thickness  Real thickness  
Mixed Hormirad™ 
with 1,19% borax  
3,94 g/cm
3
  1046.6 kg/cm
2
  26.56 cm  
Mixed Hormirad™ 
with 5% borax  
3,62 g/cm
3
  959.4 kg/cm
2
  26.50 cm  
Mixed Hormirad™ 
with 25.1% borax  
2.68 g/cm
3
  794.0 kg/cm
2
  29.64 cm  
 
 
11 
 
NEUTRON 
DOSEMETER 
LB6411
SLABS OF 
SHIELDING 
TESTED
241Am-Be 
NEUTRON 
SOURCE
 
 
 
Fig. 1. View of the experimental setup. 
12 
 
   
Fig. 2. Experimental versus 
calculated ambient dose 
equivalent rate for different 
combinations of Hormirad™ 
slabs.  
13 
 
y = e-0.00211x
R² = 0.984
y = 1.545e-0.00257x
R² = 0.996
0.01
0.10
1.00
0 200 400 600 800 1000 1200 1400
T
ra
n
s
m
is
s
io
n
Mass thickness (kg / m2)
   
Fig. 3. Transmission of 
241
Am-Be neutrons in Hormirad™ shielding slabs. Two linear adjustments are shown: one for the full set of data, from 
which the first TVL is determined; the second, for those points with mass thickness beyond 600 kg/m
2
, from which the second TVL is 
extrapolated. 
14 
 
 
y = e-0.00263x
R² = 0.984
0.1
1.0
0 50 100 150 200 250 300 350 400 450 500
T
ra
n
s
m
is
s
io
n
Mass thickness (kg/m2)
 
Fig. 4. Transmission of 
241
Am-Be neutrons in ordinary concrete HA-25 (density 2.2 g·cm
-3
) shielding slabs. 
15 
 
 
 
Fig. 5. Attenuation of 
241
Am-Be neutrons in combined shielding configurations (15.6 cm of Hormirad™ plus other borated compounds). 
16 
 
List of Table captions 
 
TABLE I. Elemental composition of Hormirad™ based on information provided 
by the manufacturer. 
 
TABLE II. TVL obtained for 
241
Am-Be neutrons with borated mixings of 
different characteristics. 
 
 
17 
 
 
List of Figure captions 
 
Fig. 1. View of the experimental setup. 
 
Fig. 2. Experimental versus calculated ambient dose equivalent rate for different 
combinations of Hormirad™ slabs.  
 
Fig. 3. Transmission of 
241
Am-Be neutrons in Hormirad™ shielding slabs. Two 
linear adjustments are shown: one for the full set of data, from which the first 
TVL is determined; the second, for those points with mass thickness beyond 600 
kg/m
2
, from which the second TVL is extrapolated. 
 
Fig. 4. Transmission of 
241
Am-Be neutrons in ordinary concrete HA-25 (density 
2.2 g·cm
-3
) shielding slabs. 
 
Fig. 5. Attenuation of 
241
Am-Be neutrons in combined shielding configurations 
(15.6 cm of Hormirad™ plus other borated compounds). 
18 
 
 
List of Footnotes 
 
a
 US and European patent applications have been presented by the producer for 
the Hormirad™ “heavy mass for manufacturing products with a high 
radioprotection capacity”. 
 


Testing of a New High-Density Concrete as Neutron Shielding Material

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Testing of a New High-Density Concrete as Neutron Shielding Material

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