Details

Autor(en) / Beteiligte

• Žohar, Andrej
• Snoj, Luka

Titel

On the dose fields due to activated cooling water in nuclear facilities

Ist Teil von

• Progress in nuclear energy (New series), 2019-11, Vol.117, p.103042, Article 103042

Ort / Verlag

Oxford: Elsevier Ltd

Erscheinungsjahr

2019

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Activated cooling water in nuclear facilities can present a significant radiation source around primary cooling system causing radiation damage to electrical components, increasing doses to personnel and in the case of fusion facilities additional heating to superconducting coils. This paper focuses on activation of oxygen isotopes in water and decay of this activated isotopes, i.e. 16N, 17N and 19O. An analysis of activation of water in pressurized water reactors and in fusion reactors was performed. Different evaluated nuclear data libraries were used in activation calculations (ENDF/B-VIII.0, FENDL-3.1b, JEFF-3.2 and TENDL-2015). The calculated activation rates with different nuclear data libraries agree well for the 16O(n,p)16N reaction and significantly differ for 17O(n,p)17N and 18O(n,γ)19O reactions. In fusion reactor the specific activity of activated water isotopes is in the order of 1013 Bq/m3/MW, which is five orders of magnitude higher compared to specific activity in a typical fission pressurized water reactor, amounting to 109 Bq/m3/MW. The results of specific activity of cooling water were used to perform parametric analysis of dose rates around pipes of cooling system and dose field around a steam generator in a pressurized water reactor as a representative of heat exchangers. The analysis of dose rates around pipes include pipes featuring 1 mm to 8 cm thick walls and from 0.5 cm to 60 cm water radius. Results can be used to estimate dose rates for all studied isotopes, provided the specific activity is known. For heat exchangers the decay of 16N contributes majority to the dose rates in the air surrounding them while 17N and 19O decay contributes together less than 0.1%. For a typical 2 GW thermal power two loop pressurized water reactor the dose rates in air surrounding the stream generator are in the order of several mSv/h. •Dose rates due to activated water in order of mSv/h for 2 GW fission reactor.•Water activity higher by 5 orders of magnitude in fusion than in fission reactor.•Activation rate of O17(n,p) and O18(n,γ) strongly depends on nuclear data used.•General methodology to calculate dose rates around any pipe is presented.•Major contribution ( > 99 %) to the dose due to N16.