Annual report of N Reactor operating experience pertinent to nuclear safety -- CY-1973

The initiation events analysis and evaluation were the beginning of nuclear safety analysis and probabilistic safety assessment, and it was the key points of the nuclear safety analysis. The main methods of the initiation events analysis are reference to existing lists and reports, operating experience, project evaluation and logic diagrams analysis. Currently, the initiation events analysis method and experiences both focused on pressurized water reactor but there are no general theories for Fluoride Salt-Cooled High Temperature Reactor (FHR). With FHR’s research and development, the initiation events analysis and evaluation was increasingly important. Based on the FHR’s design, the theories and methods of initiation events analysis would be researched and developed. From the FHR’s design, the systems, subsystems and components are divided to identify the safety functions of them. Base on the safety functions, the logical analysis and accident analysis calculation method would be combined to study FHR’s initiation events. The theory of analysis would be developed and the analysis method system would be discussed. Finally, the preliminary initiation events list of FHR will be discussed and researched. The results would help TMSR’s reactor designs and nuclear safety analysis.

Download Full-text

Cooperation between SSTC NRS and the EU in the Area of Nuclear Safety

Nuclear and Radiation Safety ◽

10.32918/nrs.2017.2(74).01 ◽

2017 ◽

pp. 3-8

Author(s):

H. Pauwels ◽

P. Daures ◽

Y.J. Stockmann ◽

J. Végh

Keyword(s):

Performance Monitoring ◽

Operating Experience ◽

Nuclear Safety ◽

Plant Performance ◽

Severe Accident ◽

Spent Fuel ◽

Assistance Programs ◽

Time Extension ◽

Changing Role ◽

The Eu

The paper first briefly outlines the main characteristics of the EU assistance programs aimed to enhance nuclear safety in the Beneficiary countries. Then EU assistance provided to the Ukrainian regulator (SNRIU) is detailed, with specific emphasis on projects enhancing the capabilities of SSTC NRS as technical support organisation (TSO) to SNRIU, including training and tutoring (T&T) activities. The changing role of SSTC NRS in the cooperation activities is described as well. The broad range of cooperation is then illustrated by some selected projects focusing on various technical areas (e.g. severe accident management and mitigation, radioactive waste and spent fuel management, NPP service time extension, plant performance monitoring and operating experience feedback). Finally, the paper briefly discusses the future perspectives of the nuclear safety cooperation between the EU and Ukraine.

Download Full-text

IRRADIATION EFFECTS ON ZR-2.5NB IN POWER REACTORS

CNL Nuclear Review ◽

10.12943/cnr.2016.00010 ◽

2016 ◽

Vol 5 (1) ◽

pp. 17-36 ◽

Cited By ~ 7

Author(s):

Carol Song

Keyword(s):

Mechanical Properties ◽

Operating Experience ◽

Zirconium Alloys ◽

Light Water Reactors ◽

Irradiation Effects ◽

Light Water ◽

Current State ◽

Structural Applications ◽

Water Reactors ◽

Reactor Operating

Zirconium alloys are widely used as structural materials in nuclear applications because of their attractive properties such as a low absorption cross-section for thermal neutrons, excellent corrosion resistance in water, and good mechanical properties at reactor operating temperatures. Zr-2.5Nb is one of the most commonly used zirconium alloys and has been used for pressure tube materials in CANDU (Canada Deuterium Uranium) and RBMK (Reaktor Bolshoy Moshchnosti Kanalnyy, “High Power Channel-type Reactor”) reactors for over 40 years. In a recent report from the Electric Power Research Institute, Zr-2.5Nb was identified as one of the candidate materials for use in normal structural applications in light-water reactors owing to its increased resistance to irradiation-induced degradation as compared with currently used materials. Historically, the largest program of in-reactor tests on zirconium alloys was performed by Atomic Energy of Canada Limited. Over many years of in-reactor testing and CANDU operating experience with Zr-2.5Nb, extensive research has been conducted on the irradiation effects on its microstructures, mechanical properties, deformation behaviours, fracture toughness, delayed hydride cracking, and corrosion. Most of the results on Zr-2.5Nb obtained from CANDU experience could be used to predict the material performance under light water reactors. This paper reviews the irradiation effects on Zr-2.5Nb in power reactors (including heavy-water and light-water reactors) and summarizes the current state of knowledge.

Download Full-text

Some questions on nuclear safety of heavy-water power reactor operating in self-sufficient thorium cycle

Nuclear Technology and Radiation Protection ◽

10.2298/ntrp0802022b ◽

2008 ◽

Vol 23 (2) ◽

pp. 22-27

Author(s):

Boris Bergelson ◽

Alexander Gerasimov ◽

Georgy Tikhomirov

Keyword(s):

Heavy Water ◽

Power Reactor ◽

Water Channel ◽

Nuclear Safety ◽

Water Power ◽

Fuel Assemblies ◽

Different Types ◽

Reactivity Increase ◽

Reactor Operating ◽

Thorium Cycle

In this paper the comparative calculations of the void coefficient have been made for different types of channel reactors for the coolant density interval 0.8-0.01 g/cm3. These results demonstrate the following. In heavy-water channel reactors, the replacement of D2O coolant by H2O, ensuring significant economic advantage, leads to the essential reducing of nuclear safety of an installation. The comparison of different reactors by the void coefficient demonstrates that at the dehydration of channels the reactivity increase is minimal for HWPR(Th), operating in the self-sufficient mode. The reduction of coolant density in channels in most cases is accompanied by the increase of power and temperatures of fuel assemblies. The calculations show that the reduction of reactivity due to Doppler effect can compensate the effect of dehydration of a channel. However, the result depends on the time dependency of heat-hydraulic processes, occurring in reactor channels in the specific accident. The result obtained in the paper confirms that nuclear safety of HWPR(Th) lies on the same level as nuclear safety of CANDU type reactors approved in practice.

Download Full-text