DNRS: Nuclear Safety Department

Scope of work:

• scientific and technical support (expert estimate and forecast of state, development and implementation of scientific and technical proposal, preparation of reporting documents for the works associated with Shelter Object conversion into an ecologically safe system (e.g., decommission Cooling Pond, commission, testing and estimate of efficiency of modernized dust suppression  system etc.);
• estimate and forecast of Shelter Object’s nuclear safety state on results of accessible experimental data, modeling and variation calculations;
• development, implementation, update and operation of expert survey system to monitor neutron flux density and temperature within the area of localized potential nuclearly hazardous FCM cluster on sub-reactor slab;
• study of corium generation processes occurred as result of severe accidents at nuclear power Units and products of its interaction with structural materials in sub-reactor space; adaptation of results of experimental and calculation work to model these processes under conditions and generation specificity of potential nuclearly hazardous FCM cluster in Shelter Object to estimate its content and structure;
• improvement of monitoring efficiency of methods and means (monitoring and control) of subcriticality level of potential nuclearly hazardous FCM cluster («unorganized multiplying medium») in «bad geometry» survey conditions and absence of direct access; development of preventive measures (preventive suppression of criticality parameters) to exclude conditions needed for occurrence and support of self-sustained chain reaction;
• refinement and verification of mathematic and physical models for nuclearly hazardous FCM cluster, realization of calculations to estimate its neutron-physical characteristics, content and structure, and so on;
• investigation of material and energy sources of FCM clusters origination in sub-reactor rooms of Chornobyl NPP power Unit 4;
• scientific and technical support (update, repair, improvement of measurement efficiency, development and implementation of metrological calibration procedures and neutron abnormalities identification) of regular nuclear safety monitoring system (NSMS IAMS).
• statistical analysis of experimental data, correlation and regression analysis of results of measured neutron flux density and temperature integrated in databases prepared by the Department.

Results of scientific research activities:

1. Procedure (MP-ISP NPP-01-12) of exceptional verification of measuring channels of regular nuclear safety monitoring system of Shelter Object prepared within the framework of contract № SIP09-2-001-HOSR-017. It is implemented at Chornobyl NPP.
2. Feasibility report on Chornobyl NPP Cooling Pond decommission. It is implemented at Chornobyl NPP.
3. Summary material and energy balance at Chornobyl NPP Unit 4 accident’s last stage.
4. Remote control gear (RCG) to conduct heat physics researches of FCM clusters with possibility of placement on it of pyrometer, gamma-locator, dose rate meter and video survey system. Manufactured within the framework of agreement № 341/13 with NAS of Ukraine. It is implemented at Chornobyl NPP.

1. RCG for sampling lava-like FCM developed within the framework of RDW «Development of measures enhancing nuclear, radiation and ecological safety of Shelter Object and New Safe Confinement».
2. RCG for sampling radioactive aerosols, developed within the framework of research and development work (RDW) «Development of measures enhancing nuclear, radiation and ecological safety of Shelter Object and New Safe Confinement ». It is implemented at Chornobyl NPP.
3. Conceptual model of FCM cluster generation process with high mass share of nuclear fuel.

8. Material model of potential nuclearly hazardous FCM cluster in Shelter Object.
9. Procedure for preventive and emergency installations for Shelter Object’s nuclear safety monitoring system. It is implemented at Chornobyl NPP.

1. RCG for sampling and localizing radwaste, developed within the framework of RDW «Development of measures enhancing nuclear, radiation and ecological safety of Shelter Object and New Safe Confinement». It is implemented at Chornobyl NPP.
2. Standard of enterprise STP 3.031-2015 «Estimate of state of protective polymeric coating in sub-roofing space of Shelter Object for contract with Chornobyl NPP. It is implemented at Chornobyl NPP.

12. Three-dimensional model of nuclearly hazardous clusters in sub-reactor room 305/2 of Shelter Object.
13. Procedure for characterization of fragments of large-sized ferroconcrete and metal structures with surface contamination. It is implemented at Chornobyl NPP.

1. Structure and three measurement databases of Shelter Object’s nuclear safety monitoring system.
2. Program of scientific and technical support at NSC-SO complex commission and operation stages. It is implemented at Chornobyl NPP.

17. Refined mathematic model of self-sustained chain reaction kinetics during 1990 year neutron abnormality.
18. Technical proposal for re-arrangement ICS «Finish» and «Finish-R» systems with the aim to create expert survey system for local monitoring of subcriticality of potential nuclearly hazardous FCM cluster at Shelter Object. They were implemented at Chornobyl NPP.

1. Concept of RCG for sorting and packing radioactive waste within the framework of international cooperation with Chinese company Xianchu Energy Development Group Co, Ltd.
2. Program of safe work realization at Shelter Object for technical Task «Estimate of changes in dynamics of moisture evaporation-condensation in NSC Shelter Object, FCM behaviour within changed conditions, and estimate of dust generation changes ». It is implemented at Chornobyl NPP.
3. Procedure for identification of neutron abnormalities at early stage of hazardous changes in subcriticality level potential nuclearly hazardous FCM cluster.

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