Neutron Activation in the Metal Structures of an RBMK-1500 Reactor

Narkunas, Ernestas; Smaizys, Arturas; Poškas, Povilas

doi:10.13182/nt09-a9239

Cited by 5 publications

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“…The remaining 4 years of operation were divided into 25 shorter periods, taking into account all reactor shutdowns for more detailed representation. As was already mentioned, conservatively, maximal initial impurities content in GR-280 graphite grade (Narkunas et al 2013) was used at this stage.…”

Section: Methodsmentioning

confidence: 99%

Estimation of the inventory of¹⁴C and other key radionuclides in irradiated RBMK-1500 graphite based on limited measurements and full 3D core modeling

et al. 2018

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Ignalina NPP contains two Units with RBMK-1500 reactors. After shutdown, several Unit 1 systems and equipment were radiologically characterized and dismantled. The highest volume of reactor structures is attributed to the graphite stack of the reactor core, radiological characterization of which has not yet been performed. The stack can be visualized as a vertical cylinder 8 m high and 14 m diameter, made up of 2488 columns where each column is made up from several graphite blocks. The total mass of the graphite stack blocks is about 1700 tonnes. Therefore, the main goal of work reported in this paper was to estimate the inventory of 14C and other key radionuclides in the irradiated graphite by a combination of activity measurements and full 3D reactor graphite stack neutron activation modeling. Obtained results show that, based on the combination of modeling and measurement techniques, the total inventory of 14C in graphite stack is estimated at 3.22×1014 Bq at 9 years after Unit 1 reactor final shutdown. 14C activity is the highest among the analyzed radionuclides; the second highest is 60Co (~6 times lower).

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Section: Methodsmentioning

confidence: 99%

Estimation of the inventory of¹⁴C and other key radionuclides in irradiated RBMK-1500 graphite based on limited measurements and full 3D core modeling

et al. 2018

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“…The measured 14 C content in the Ignalina NPP reactor GR-280 grade graphite reported in (Mazeika et al 2015) is 1.67×10 5 Bq g −1 . Combining this data with the new model, estimation of the 14 C inventory in the graphite stack was made (Narkunas and Poskas 2017). It was reported that the average specific activity value of the 14 C in RBMK-1500 i-graphite was 1.9×10 5 Bq g −1 with the standard deviation of 36.7%.…”

Section: Methodsmentioning

confidence: 99%

Preliminary investigation of¹⁴C migration from RBMK-1500 reactor graphite disposed of in a potential geological repository in crystalline rocks in Lithuania

et al. 2018

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There are two units with RBMK-1500 type reactors at the Ignalina Nuclear Power Plant (Ignalina NPP) in Lithuania where graphite was used as a neutron moderator and reflector. These reactors are now being decommissioned, and Lithuania has to find a solution for safe irradiated graphite disposal. It cannot be disposed of in a near surface repository due to large amounts of 14C (radiocarbon, carbon-14); thus, a deep geological repository (DGR) is analyzed as an option. This study had the aim to evaluate 14C migration from the RBMK-1500 irradiated graphite disposed of in a potential DGR in crystalline rocks taking into account the outcomes of the research performed under the collaborative European project CAST (CArbon-14 Source Term) and to identify the potential to reduce the conservatism in the assumptions that was introduced in the lack of data and led in the overestimated 14C migration. The information gathered during the CAST project was used to model 14C transport in the near field by the water pathway and to perform uncertainty analysis. The study demonstrated that more realistic assumptions could reduce the estimated 14C flux from the near field by approximately one order of magnitude in comparison with the previous estimations based on very conservative assumptions.

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Updating of the public dose assessment approach for decommissioning related releases from the Ignalina NPP

Ragaisis

Poškas

Šimonis

et al. 2016

Annals of Nuclear Energy

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Neutron Activation in the Metal Structures of an RBMK-1500 Reactor

Cited by 5 publications

References 1 publication

Estimation of the inventory of¹⁴C and other key radionuclides in irradiated RBMK-1500 graphite based on limited measurements and full 3D core modeling

Estimation of the inventory of¹⁴C and other key radionuclides in irradiated RBMK-1500 graphite based on limited measurements and full 3D core modeling

Preliminary investigation of¹⁴C migration from RBMK-1500 reactor graphite disposed of in a potential geological repository in crystalline rocks in Lithuania

Updating of the public dose assessment approach for decommissioning related releases from the Ignalina NPP

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Neutron Activation in the Metal Structures of an RBMK-1500 Reactor

Cited by 5 publications

References 1 publication

Estimation of the inventory of14C and other key radionuclides in irradiated RBMK-1500 graphite based on limited measurements and full 3D core modeling

Estimation of the inventory of14C and other key radionuclides in irradiated RBMK-1500 graphite based on limited measurements and full 3D core modeling

Preliminary investigation of14C migration from RBMK-1500 reactor graphite disposed of in a potential geological repository in crystalline rocks in Lithuania

Updating of the public dose assessment approach for decommissioning related releases from the Ignalina NPP

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Estimation of the inventory of¹⁴C and other key radionuclides in irradiated RBMK-1500 graphite based on limited measurements and full 3D core modeling

Estimation of the inventory of¹⁴C and other key radionuclides in irradiated RBMK-1500 graphite based on limited measurements and full 3D core modeling

Preliminary investigation of¹⁴C migration from RBMK-1500 reactor graphite disposed of in a potential geological repository in crystalline rocks in Lithuania