Castable Reactor Shielding

JC277 & JC277Z-5

JC277 and 277Z-5 are excellent high flux neutron shields due to the inclusion of temperature resistant additives that provide hydrogen for moderation and boron for thermal neutron absorption.  It provides more than twice the hydrogen of ordinary concrete (equal to approximately ½ that of pure water) along with a boron content of 1.6% and 5% respectively.

Power reactor and other industrial neutron shielding applications often require a material that exhibits a high-temperature resistance.  Kretekast is a refractory material that retains its shielding properties at temperatures up to 450°F (230 °C) and its physical integrity up to 1900°F (1038 °C). It is entirely non-combustible and is designed to be cast in the field.    

JC277 is provided as a dry mix for casting in the field.  It can be shaped using standard concrete cutting/drilling tools.  Kretekast is typically provided in 300lb fibre barrels.

Approximately 96lbs. of dry mix are required to obtain one-cubic ft. of cast material. (1.54 kg of dry mix will give one litre). Detailed mixing instructions are provided with each order.  Recommended shelf-life under dry storage conditions is twelve months.

  • Contains more than two times as much hydrogen as ordinary concrete along with 1.6% to 5% boron additives
  • Rugged “concrete-like” shielding is easily cast in the field
  • Low cost material is completely non-combustible
Composition Data JC277 JC277Z-5
Hydrogen atom density / cm³: 4.93 x 10²² 4.76 x 10²²
Hydrogen Weight Percent: 4.90% 4.73%
Boron atom density / cm³: 1.53 x 10²¹ 4.67 x 10²¹
Boron Natural isotope distribution: 19.6% ¹⁰B and 80.4 % ¹¹B 19.6% ¹⁰B and 80.4 % ¹¹B
Boron weight percent: 1.63% 4.99%
Total Density: 1.68 g/cm³ (105 lbs./ft³) 1.68 g/cm³ (105 lbs./ft³)
Radiation Properties
Macroscopic thermal neutron cross section: 1.17 cm⁻¹ 3.54 cm⁻¹
Gamma resistance: 1 x 10¹¹ rad 1 x 10¹¹ rad
Neutron resistance: 5 x 10¹⁹ n/cm² 5 x 10¹⁹ n/cm²
Physical Properties
State: Solid composite Solid composite
Colour: Light grey Light gray
Odour: No odour No odour
Machinability: Fair: saw cut or drilled Fair: saw cut or drilled
Tensile Strength (ASTM D368): 100 psi 100 psi
Compressive Strength: 1000 psi 1000 psi
Thermal Properties
Recommended Temperature Limit: 176°C (350°F) 176°C (350°F)
Coefficient of thermal conductivity: 1.24 x 10⁻³ cal-cm/sec-cm²-°C 1.24 x 10⁻³ cal-cm/sec-cm²-°C
(0.3 BTU-ft/hr-ft²-°F) (0.3 BTU-ft/hr-ft²-°F)
Heat Capacity: 0.22 cal/g-°C 0.22 cal/g-°C
Cubical Coefficient of Expansion: 8 x 10⁻⁶ cm³/cm³-°C 8 x 10⁻⁶ cm³/cm³-°C
(1.4 x 10⁻⁵ in³ /in³ -°F) (1.4 x 10⁻⁵ in³ /in³ -°F)
Chemical Properties
Chemical Name & Synonyms: Borated hydrogenated mix Borated hydrogenated mix
Trade Name & Synonyms: JC277 Kretekast JC277Z-5 Kretekast Plus
Chemical Family: Calcium salts, boron, hydrogen compounds Calcium salts, boron, hydrogen compounds
Solubility in Water: Negligible Negligible
Get in touch with The JCS team