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Collaborating Centre – A recognition from IAEA

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Safety and Security

Working with radioactive material requires a high safety and security culture. BATAN has implemented the nuclear safety and security culture accordance with national and international regulations.

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Reaktor Triga


The Kartini reactor was developed starting at the end of 1974 and operated in January 1979, one of the facilities possessed by the Center for Research of Pure Material and Instrumentation – BATAN Yogyakarta, a pool type reactor with a power of 100 kilowatts, designed for research, training and education purposes.

FOREWARD

The Kartini reactor is located in the Center for Research of Pure Material and Instrumentation – BATAN Yogyakarta. The location of this center is situated at Km 7 east of Yogyakarta, ± 500 meters entering in the north of the Yogyakarta – Solo road. This place is included in the area of the Regency of Sleman, District of Depok, Sub-District of Catur Tunggal. The area of this center including its development is about ± 12 hectares.

The Kartini reactor was developed starting at the end of 1974. The implementer of the whole development was handled by experts of BATAN whereas in its implementation this was conducted by a group mentioned as the Reactor Development Team which formed in accordance to Letter of Decision of the Director General of BATAN No. 119/DJ/13/XI/1974 dated 13th November 1974.

The Kartini reactor reached its criticality condition for the first time on Thursday, 25th January 1979 at 17.40 hours, and officially inaugurated by the President of the Republic of Indonesia on the date of 1st March 1979.

The reactor operation has been conducted at a power level of 100 watts.

Atomic reactor

The atomic reactor is a place where a nuclear chain reaction could occur continually and under control. The nuclear chain reaction mentioned here is a fissile atomic reaction which is caused by neutron capture (On1). For the Kartini reactor the fissile atoms which are used are U235 and neutrons which causes the nuclear reaction are thermal neutrons.

The equation of the fission reaction in this case is :

U235 + 0n1 -------- fission results + (2-3) 0n1 + reactor (heat).

The thermal neutrons are obtained by slowing down neutrons from the results of fission through a reactor moderator. The design of the Kartini reactor is based on the pool reactor, which is a reactor whereas the fuel elements and core are within a tank filled with water.

The design of this type was selected because this type has advantages in the case of : simplicity, easiness in maintenance and – flexible for research purposes.

REACTOR

REACTOR TANK

The reactor tank is made of pure aluminum having a thickness of ± 6 mm, cylindrical in shape with a diameter of ± 200 Cm and a height of ± 600 Cm, filled with water of very high purity (specific resistance ± 500 K Ω/Cm), which functions as an additional moderator, coolant, and a vertical direction radiation shielding.

The horizontal direction radiation shielding uses Barium Sulphate concrete (specific weight of 3,3 tons per cubic meter), which is a mixture of cement, Barium Sulphate sand and rocks. This construction is capable to withstand radiation from the core which works on a power of 250 Kilowatts.

REACTOR CORE

The reactor core is situated at the bottom part of the tank, which is an array of fuel elements, control rods which are emplaced in holes of the horizontal plates according to a certain configuration and reflector. The plates consists of two parts which are the upper and lower plates, made of aluminum, each with a thickness of ± 1,5 Cm and 2 Cm respectively. The upper plate functions to regulate the distance of elements in the core, with the number of holes amounting to 90 and a central timble. The lower plates functions as a support of the above core elements. The two plates become a unity with the graphite reflector.

The Kartini reactor fuel element consists of a homogenous mixture of uranium zirconium hybrid (U Zr H ) in the form of an alloy, with the contents of uranium, 8.5% of weight and enrichment of the U235 of 20%. The active part has a diameter of ± 3,5 Cm and length of ± 35,6 Cm. At the two ends there is a thin Samarium (Sm) which functions as a burnable toxin, and also graphite with the same diameter and length of 10.2 Cm. This assembly is then inserted into a tube from aluminum or stainless steel having a thickness of ± 0,7 mm, closed and welded at the two ends, forming a fuel element. The weight of the U235 isotope of every element is about 37 grams.

There are 3 control rods, which are : safety rod, shim rod and regulating rod, in which all consist of a neutron absorption rod which is placed in the tube made of aluminum, as an absorption material boron carbide (B4C) powder is used. The three control rods could be moved in a vertical direction in the guide tube, through a servo motor driving system which is controlled from the control room. With the three control rods then the size of the neutron population in the reactor could be regulated, and the reactor could operate safely. Outside the core there is a graphite reflector with a radial thickness of 30,5 Cm which stands on aluminum supports. On the upper part of the reflector there is an irradiation facility F-1, F-2 and F-3, and outside the reflector there are 2 fission chamber (FC) detectors and 2 ionization chamber compensated detectors (CIC), which is used as a detector for monitoring the flux and power of the reactor.

SIDE SYSTEM

This consists of a cooling system and a reactor room ventilation system, and generally is seen like the figure at the side. In accordance to its function as a research reactor, the heat coming from the core economically cannot be utilized and must be disposed. Disposal of the heat is by natural convection to water coolant circulated through a heat exchanger in this case is the primary system, and at the heat exchanger the heat is transferred to a secondary system which further is disposed of around the cooling pool through contact with water and air. In order to maintain the high purity of the water in the reactor, towards radioactivity as well as from contaminants, the primary system is complemented with a demineralizer and filter.

The air circulation in the reactor room is conducted by air suction in the reactor room with a blower, then the air is run through a filter (pre-filter and absolute filter) before being disposed through a chimney with a height of ± 30 m.

INSTRUMENTATION SYSTEM

The reactor instrumentation system covers the reactor control system, the monitoring system and protection system, whereas each is hanging on to one another. The control of the reactor is none other than the regulating of the position of the control rods in such a way that the nuclear chain reaction occurs at the desired power level. This system consists of a control rod driving mechanism and manual switching which is complemented by 3 pairs of up and down push buttons, control rod positioning screen, manual scram, scram reset, and experiment indicator.

The measurement of the size of the neutron flux, reactor power, period, radiation exposure in several places in the reactor building, the coolant temperature and other important parameters is conducted by a monitoring system. The parameter data is shown through a meter and a part of it is noted by a recorder.

The power measurement channel consists of a linier power channel and a logarithmic power channel, the linier power channel obtains its input current from the CIC detector which gives a linier power indication. Whereas for the logarithmic power channel the input current comes from the FC detector, which gives logarithmic indication & power. The power change rate period is obtained from the differential of % logarithmic power. The reactor operation safety is assured by the protection system, this system among others are :

  1. The TRIP circuit, which will cause the reactor to scram if :
    1. The high voltage (HV) of the FC detector changes ± 10 % of the operation voltage (± 300 V).
    2. At the time of start up, the neutron source is outside the core (level 1).
    3. % of algorithmic power shows 110% (level 2).
    4. The period shows smaller than 7 seconds.
  2. The interlock circuit, which causes the reactor not to start up due to control rods unable to be moved.
    The Interlock consists of :
    1. PCB Interlock Card
    2. Interlock of testing facility which covers :
      • Calibration testing % of logarithmic power.
      • TRIP testing % of logarithmic power.
      • Calibration testing period.
      • TRIP testing period.
    3. Level 1 interlock.

FACILITY FOR IRRADIATION AND EXPERIMENT

The facility for irradiation and experiment which is present in the Kartini reactor among others are :

  1. NEUTRON BEAM CHANNEL
    This facility is used for the need of irradiation of samples of quite large sizes (diameter of 15,2 Cm) as well as to provide neutron beam for various experimental needs. The neutron beam channel consists of :
    • Two radial neutron beam channels
    • One piercing radial neutron beam channel
    • Nudging/touching neutron beam channel
  1. THERMAL COLUMN
    This is used for irradiation needs with thermal neutrons. This column consists of graphite measuring 1,2 m x 1,2 m and length of 1,6 m which is coated with boral and aluminum. This column extends from outside of the reflector to the other surface in the portal closure.
  1. CENTRAL CHANNEL
    This central channel is designed for irradiation needs or experiments with maximum flux. This channel is in the form of a tube with a diameter of 3.84 Cm and length of 6m which extends from the top until the core supports through the core center.
  1. IRRADIATION FACILITIES : F1, F-2 and F-3 which is above the reflector.
  2. BULK SHIELDING FACILITY.
    Bulk shielding is an open water tank measuring of length of 265 Cm width of 240 Cm and height of 380 Cm, which is connected to the thermalization column. The thermalization column is similar to the thermal column, but with smaller measurements. This facility is used for shielding experiments, and also for temporary storage of spent fuel.
  1. SUBCRITICAL DEVICE
    A subcritical device is a small reactor, where the nuclear chain reaction could only occur as long as there is a permanent neutron source outside the reactor. In order to obtain a permanent neutron source, the subcritical reactor is coupled to the Kartini reactor, through a radial neutron beam channel. The fuel used in this device is natural uranium (content of U235 = 0,7 %), and as a moderator water is used. This facility functions for reactor static parameter study needs of the configuration system of uranium – water .
  1. PNEUMATIC TRANSFER SYSTEM
    This system functions to insert and exit samples quickly from the core. The samples are place in a rabbit with a diameter of ± 2,5 Cm, moving within a pipe. The movement of the rabbit is based on the difference of pressure in the pipe, through a blower. The air of the pneumatic system is expelled through a filter.

SUMMARY OF DATA

REACTOR

Type

Pool

Fuel

U Zr H, 20 % U235

Moderator and coolant

Pure water

Power

250 Kilowatt

Average thermal flux

1,2 x 10 13 n/Cm2 second

Average fast flux

2,5 x 10 12 n/Cm2 second

FUEL ELEMENT

Type

Standard TRIGA 102 and 104

Total length

72,5 Cm

Outside diameter

3,7 Cm

Active length

35,6 Cm

Active outside diameter

3,56 Cm

Fuel composition

U Zr H

Weight of each U235 element

37 g

Content of U235

20%

Ratio of hydrogen with zirconium

1,7

Tube

Aluminum or stainless steel type 304

Tube thickness

0,7 mm

CORE

Form

Cylindrical, diameter 45 Cm. Height : 72 Cm

critical mass

2484 grams (U235).

Full load mass

2675 grams (U235)

Number of fuel

75 pieces

Number of control rods

3 pieces

Shielding

Barium Sulphate concrete and water

CONTROL RODS

1.   Security rod

Outside diameter

2,5 Cm

 

Total length

51 Cm

 

Absorption material

Boron carbide (B4C) powder

 

Reactivity value

2,535 $

2.   Compensation rod

Outside diameter

2,5 Cm

 

Total length

51 Cm

 

Absorption material

Boron carbide (B4C) powder

 

Reactivity value

2,6307 $

3.   Regulating rod

Diameter luar

2,5 Cm

 

Total length

51 Cm

 

Absorption material

Boron carbide (B4C) powder

FACILITY FOR EXPERIMENT

1.  Neutron beam tube

Piercing radial beam tube, 1 piece

 

Radial beam tube, 2 pieces

 

Tangent beam tube, 1 piece

2.  Central channel, 1 piece

 

3.  Irradiation Facilities in the core, 3 pieces

 

4.  Pneumatic transfer facility, 1 piece

Reactivity value : 1,882 $.