The NASU Presidium meeting took place on the 8th of February 2017. One of the issues was dedicated to consideration of the state and perspectives of R&D support of transformation of the Shelter into an environmentally safe system. Mr. Nosovsky, Director of the Institute for Safety Problems of Nuclear Power Plants (ISP NPP) of the National Academy of Science of Ukraine, Professor (PhD in Technical Science), reported on this issue.
Mr. Nosovsky reported that during the whole Shelter lifetime the ISP NPP employees were involved in R&D and practical activities related to radiation monitoring of the emergency power unit premises in order to find places of accumulation of nuclear fuel residues and to specify their quantity, ensure safety, diagnostic and operation systems, and also develop the strategy for Shelter transformation into an environmentally safe system.
“Currently, the completion of the New Safe Confinement (NSC) is the main task in the framework of Shelter safety assurance to allow considerable reduction in the risk of possible radioactive contamination of the environment that would result from collapse of Shelter unstable structures. But it is not the final but initial stage of transformation of the Shelter into an environmentally safe system”, said the scientist.
Detailed analysis of activities related to transformation of the Shelter into an environmentally safe system allowed the development and justification of the “R&D Support Program for Shelter New Safe Confinement Commissioning and Operation”. The program, considering available and new knowledge, includes a list of activities that require R&D support.
The State Specialized Enterprise “Chornobyl Nuclear Power Plant” (SSE ChNPP) requested to develop this Program. ISP NPP experts, together with experts of the State Research Institute of Building Structures” (SRIBS), have developed this Program. The Program was discussed by the Research Boards of the above-mentioned scientific institutions and by Scientific and Technical Council of SSE ChNPP.
The Program covers the following areas:
in short-term perspective – prior to completion of the dismantling of Shelter unstable structures – R&D support of NSC commissioning and operation;
in long-term perspective – R&D support of implementation of further transformation of the Shelter into an environmentally safe system.
R&D Program consists of two independent parts. First part – reliability of structures – includes the following main areas:
- monitoring of the Shelter and NSC structures;
- geodesic observations over the state of structures;
- analysis of the monitoring scope for the period up to the early dismantling of unstable structures and analysis of readings from detectors of NSC structure monitoring system;
- development of operational documentation on monitoring of the technical state of structures in general, etc.
Second part of the Program – nuclear and radiation safety – includes:
- study of the impact of change in the state of fuel-containing materials (FCM) on nuclear safety, creation of an additional local system for local control of subcriticality of nuclear-hazardous accumulations;
- creation and maintenance of a common subcriticality control database, development of procedures for identification of subcritical deviations in readings of neutron detectors and temperature sensors;
- assessment of the efficiency of regular criticality control systems;
- control of neutron activity and FCM temperature during changes in NSC temperature and humidity conditions;
- study of the impact of new conditions of Shelter operation under NSC on radiation safety;
- study of the impact of change in FCM state on the dynamics of FCM degradation;
- study of spatial, angular and energy characteristics of radiation fields in NSC, considering uncovering of the Shelter due to dismantling of its unstable structures;
- assessment of radioactive aerosol releases to the space under NSC, analysis of the airflows and related changes in radiological situation due to dust migration inside the Shelter;
- assessment of changes in radionuclide and elemental composition of water bodies and bottom deposits, hydrological monitoring;
- comprehensive analysis of potential accidents, analysis of operation of NSC safety important systems and components and analysis of their interaction with current Shelter systems and components, etc.
“Implementation of the above-mentioned activities shall ensure respective scientific and technical support to Shelter transformation into an environmentally safe system and required level of nuclear and radiation safety”, summarized Mr. Nosovsky.
This topic was discussed by Mr. Krasnov, ISP NPP Head of the Division on Nuclear and Radiation Safety, Mr. Nemchynov, SRIBS Deputy Director (PhD in Technical Sciences), Mr. Kondratenko, SSE ChNPP Shelter Deputy Technical Director, and Mr. Kyrylenko, Member of NASU, Academic Secretary of the Division on Physical and Technical Problems of Energy.
After hearing and discussion of Mr. Nosovsky’s report, the Presidium of the National Academy of Sciences of Ukraine approved the “R&D Support Program for Shelter New Safe Confinement Commissioning and Operation” and also obliged ISP NPP to organize and coordinate the participation of NASU institutions in all stages of implementation of the above-mentioned Program.