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The Filter-1 pilot test facility is designed for the investigations aimed at assessment of the effectiveness of the anti-debris filters (ADF) of the fuel assemblies (FA) of the VVER -440 (1000) reactors with respect to the particles (foreign objects) present in the coolant. The thermo-hydraulic configuration of the test facility provides for creating and maintaining in the core simulator the prescribed flow rate in the range of 1 to 250 m3/hour at the temperature of 30 ± 5°Ñ.
The circulation circuit of the Filter-1 test facility consists of the core simulator, a pump, a module for water injection and flow rate measurement, temperature stabilization circuit and pump load controller. The core simulator of the test facility is an assembly, composed of the shortened mock-up of the VVER-440 (1000) FA, a flow stabilizing section and a loading system. The FA mock-up inner cavity fully mimics the inner cavity of the real assembly in terms of geometric dimensions (with the exception of the length of the bundle and case tube, which is 1/4 of the length of the real FA). The shortened casing tube has transparent windows, providing for the visual monitoring and video recording of translocations of the debris during experiments.
The FA mock-up is fully dismountable – the casing can be removed, anti-debris filters replaced, and the splint wire removed.
The module for water injection and flow rate measurement consists of:
- distribution pressure header;
- four pipelines of different diameters with isolation valves, regulating valves and measurement diaphragms;
- inlet pipelines.
Upstream of the core simulator, there is a fine purification filter, and downstream of it – a trap-filter for debris after core model. There are sylphons in the pipelines upstream and downstream of the core model in order to decrease vibrations.
The test facility is equipped with instrumentation, including sensing elements of flow rate in the test facility circuit, pressure and pressure differential in the core simulator, and temperature. For investigation of the processes of the debris transfer and of the effectiveness of the anti-debris filters , the test facility is equipped with a video monitoring system. A specialized software-hardware complex of the real time data processing system – is used as a research automation system.
Purpose of the Filter–1 test facility
- investigation of effectiveness of anti-debris filters;
- investigation of the processes of debris transfer by water and its jamming in the fuel assembly (FA);
- measurement of the hydraulic resistances of anti-debris filters.
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Layout of the VVER-440 FA mockup
1 – transparent window ¹ 1; 2 – transparent window
¹ 2; 3 – transparent tube ¹ 3 (location of the anti-debris filter)
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Core simulator of the Filter-1 testbed
1 – FA mockup; 2 – anti-debris filter; 3 – flow stabilization section; 4 – loading unit; 5 – sylphon, Ò – temperature measurement; PD and P – pressure differential and pressure measurements |
Filter-1
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Results
In 2003, an experimental study of the effectiveness of the annular conical ADF developed by OKB «Gidropress» and JSC «MSZ» for VVER-440 assemblies was conducted under the contract with JSC «TVEL». Considering the tests performed the six pilot FAs equipped with ADF of this type were installed in the core of KolNPP Unit-2 during the scheduled works for 2004.
In 2004-2005, the investigation of the effectiveness of ADF for VVER-440 assemblies was continued. Rating tests of ADF of different designs (22 options) on anti-debris efficiency, hydraulic resistance, strength, effect on the field of coolant velocities in FA were carried out.
In the results of the tests some most perspective options of ADF of conical type of different designs were selected.
The work of the experimental testing of design elements of the working cassettes of the VVER-440 with the high operational reliability for the purpose of given recommendations under the construction of the lower unit of the unshroud cassettes, provided: the minimum length of the cassette, the optimum hydraulic characteristics, anti-debris security and rigidity, was carried out under a contract with JSC «TVEL». As a result of complex tests the optimum execute of the lower unit of the cassette was suggested in 2006.
In 2003-2006, the investigations of the effectiveness of ADF of different designes developed by OKB «Gidropress», JSC «MSZ» and MIFI for VVER-440 assemblies (22 designes) on anti-debris efficiency, hydraulic resistance, strength, effect on the field of coolant velocities in FA were carried out under a contract with JSC «TVEL». As a result of these investigations two most perspective options of ADF of conical type of different designs were selected. The six pilot FAs equipped with the annular conical ADF were installed in the core of KolNPP Unit-2 during the scheduled refueling for 2004.
In 2008, after reconstruction of the test facility, the first stage of the investigations of the effectiveness and hydraulic resistant of ADF for the FA of the VVER-1000 developed by OKB «Gidropress» during flow rates up to 550 m 3 / h was carried out.
For the first time in the practice of our country in this field of the investigations the following results were obtained:
- the anti-debris efficiency of the FA of the VVER-1000 without ADF was estimated;
- the effectiveness of the ADF was estimated;
- pressure differences in the following places were measured:
- at the lower lattice of the FA without debris in water;
- at the lower lattice of the FA with debris in water;
- at the ADF without debris in water;
- at the ADF without debris in water.
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