The reflector tank provides a large region of high thermal neutron flux and the excess reactivity is sufficient for experiments. The average burnup of the discharged fuel assemblies meets the design objective, greater than 50 a/o burnup of initial fissile material. The reactor operation cycle is 28 days. The reactor has inherent safety characteristics such as heat removal by natural circulation and reactor trip by gravity drop of shut-off rods.
   
...Reactors Specifications
      Type       Open-tank-in-pool
      Maximum thermal power       30 MW
      Coolant       Light water
      Reflector       Heavy water
      Fuel material       U3Si in aluminum matrix, 19.75 w/o enriched
      Absorber material       Hafnium
      Secondary cooling       Cooling tower
      Reactor building       Confinement
   
HANARO reactor pool, service pool, and spent fuel storage pool.
Neurton beam spectrometers arranged in the basement.
   

Core Characteristics

The core features a combination of light-water cooled/moderated inner core and light-watercooled/heavy-water moderated outer core. The inner core has 28 fuel sites and 3 test sites. Among them, 20 fuel sites have hexagonal shapes, and 8 fuel sites are for circular fuel assemblies, which are enclosed by 4 control absorber rod (CAR) shrouds and 4 shut-off rod (SOR) shrouds made of natural hafnium. 3 test sites are also in hexagonal shapes and used for capsules. The outer core consists of 4 fuel sites and 4 test sites, which are embedded in the reflector tank



   

Fuel Assembly

The fuel used in HANARO is low enriched uranium of 19.75 w/o in uranium silicide compound which is dispersed in the aluminum matrix. The aluminum cladding, which are finned to increase the heat transfer surface area, protects the uranium from corrosion and prevents radioactive fission products from escaping. The quantity of uranium in one fuel element is 69.1 grams in a standard core element and 51.4 grams in a reduced core element. The reduced core elements are introduced to have a uniform power distribution within a fuel assembly and located at the outermost ring of the hexagonal fuel assembly. There are two types of fuel assemblies required for HANARO - hexagonal fuel assemblies having 36 elements and circular ones having 18 elements.

   
 
Reactor Systems

The primary coolant enters the inlet plenum and flows upward through fuel channels for cooling. The coolant is gathered in the chimney, and then exits through two outlet
.nozzles. Each of the two loops has a 400
hp pump, a 14 MW plate-type heat
exchanger, and a check valve
........which is designed to close with a
.. ..... ..reverse flow.
.. .... ... ..The two loops combine at a
.. .... ... ........returning line into the core.
.. .... ... ..... ....... ..10% of the returning flow
.. .... ... ...... . .... ...... (bypass flow) is
                             branched to the bottom
.......................... of the reactor pool. A hot
... ....... ....water layer is formed at the pool
............ surface for the safety of workers
............ around the pool surface.
For the removal of decay heat, two natural circulation modes are available; loop and pool natural circulation. When the density driving force is not enough for the loop natural circulation, the core is cooled by pool natural circulation through two flap valves. The secondary coolant is cooled by a cooling tower with 4 cooling fans. The reflector tank surrounding the reactor core is made of zircaloy 4 and filled with heavy water which is pumped around in a closed circuit. It accommodates various vertical and horizontal experimental holes.



Four CARs are connected to the driver through a magnetic clutch and driven by four independent stepping motors. The reactor regulating system is controlled by a multi-loop controller in which the control algorithm is embedded. The reactor protection system is of a safety class system. The reactor is tripped by dropping four SORs. The SORs drop once the solenoid valves, which are attached to the hydraulic circuit of the shutdown mechanism, are opened.