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Nuclear Safety Cooperation

R2.08/95 Improvement Fission Product VVER

All Countries
Benefitting Zone
€ 222,279.33
EU Contribution
Contracted in 1997
Technical Assistance to the Commonwealth of Independent States


Type of activity

Design Safety



Contracting authority

European Commission

Method of Procurement

(FR2007) Restricted Call for Tender - External Actions


23/04/1997 - 23/08/1998



Project / Budget year

WW9508 Nuclear Safety 1995 / 1995


Considering investigation of severe accident consequences, fission gas trapping systems (filters) or also called “Fission Product retention System” (FPR) have been developed both in RF and in EU.
The aim of the project is to prepare:
A feasibility study, including an economical assessment of the filter system;
A proposal for the system to be implemented on the VVER 1000 units;
A conceptual design of the filter system addressing the main technical issues and interfaces with existing nuclear plants.
The protection of the containment integrity in case of pressure transients should also be addressed.


The FPR system has been designed taking into account the requirements and enveloping operational conditions for the system elaborated within task 4 and task 5A of the current project.
These requirements and operational conditions are summarized as follows:
Aerosol retention rate : 99.9 %;
Elemental iodine retention rate: 99 %;
Organic iodide retention rate: 90 %;
Aerosol load capacity: 200 kg;
Accumulated decay heat: 300 kW;
Aerosol spectrum (MMD): 0.5 m;
Flow rate at containment pressure of 5 bar: 7.5 kg/s;
Autarky period: 24 h;
Relief pressure : 5 bar (System operation possible up to 6 bar (abs));
Temperature of steam‑gas mixture 180C (superheated conditions).
The composition of the steam gas mixture released through the system at the moment of system activation at 144000 s.
It can be summarized as follows:
Steam 65 % vol.;
Sir 23 % vol.;
Hydrogen 10 % vol.;
Carbon monoxide 2 % vol..
The results are in line with the objective and features mentioned before.