Administrator

NRSC՛s representative participated in consultancy meeting held in Vienna from 20-24 April 2015. During the meeting, experts reviewed and discussed events reported to IRS in the period from 2012 to 2014. Total number of considered events is 254. After the screening 136 most interesting events were selected for Blue Book development. Selected events were grouped based on the related topic (human performance, fire, seismic hazard, ageing, etc.). During the meeting for each topic experts presented brief description of the events reported, safety significance and lessons learned. As a result of the meeting the draft version of Blue Book was developed. It is planned to publish Blue Book in 2016 after the review to be done by IAEA staff and national IRS coordinators.

NRSC’s staff member participated in a workshop which took place in Los Alamos National Laboratory; the workshop was devoted to Criticality Calculations with the MCNP. The workshop mainly was focused on best MCNP application practices as how to perform criticality calculations for reactor physics and criticality safety applications by applying the MCNP. During the workshop the following topics were mainly addressed: criticality calculations by using Monte Carlo methods, geometry, including lattices and repeated structures, tallies and mesh tallies, cross-section data, statistical analysis, assessment of the convergence of Keff and the source distribution (Shannon Entropy), 3D depletion capabilities of MCNP6, and sensitivity analysis of Keff. NRSC uses MCNP to carry out independent analysis of criticality safety of dry spent fuel storage, the ANPP spent fuel pools and spent fuel transport cask for Armenian Nuclear Regulatory Authority’s decision-making. Furthermore, recently the NRSC started to apply the MCNP for 3D depletion analysis of WWER-440 spent fuel assemblies for further burnup credit, severe accident and radiological consequence analysis. 3D Depletion Model of WWER-440 Fuel Assembly developed by MCNP6

Second meeting of the VVER Regulators Forum Working Group on Regulatory Use of PSA took place in Helsinki, Finland from 11 to 13 February 2015. The meeting was mainly devoted to: Task 1 – Comparison of current EE PSA approaches & regulations, Task 2 – Fukushima lessons learned for PSA implementation and Task 3 – National risk-informed decision making framework. Within Task 1 PSA WG members made national presentations on national practices in the field of EE PSA. Presented information was discussed within the group and used during discussions on Task 1 questionnaire developed by AERB (India). Within Task 2 NRSC presented results of investigation of available international studies on Fukushima and allowed to come up with the list of PSA related problems associated with Fukushima. During discussions it was decided to create a questionnaire on Task 2 based on presented results. Within Task 3 STUK (Finland) prepared a questionnaire that was circulated between participants for comments. It was agreed that STUK will finalize the questionnaire based on participant’s comments and prepare final version of questionnaire with STUK answers by the next meeting. In addition, VVER Regulatory Forum observers presented topical presentations on Task 1 and 2 related issues: The Fault Sequence Analysis Method to Assist in Evaluation of the Impact of Extreme Events on NPPs (IAEA), Fukushima lessons learned from PSA. Overview of international activities (e.g. ASAMPSA_E project) (GRS).