|Type||H - High priority request|
|Quantity||SIG - Cross section|
|Incident energy||10 MeV - 20 MeV|
|Status||Work in progress|
|Latest review date||28-Apr-2022|
Dr Stanislav SIMAKOV at KIT, GER
IFMIF and DONES material test facilities, and fusion power plants
The 39K(n,p) reaction produces 39Ar with decay half-life of 269 years and makes the dominant contribution to the long-lived radioactive inventories in NaK. The latter is considered as a coolant of specimens in the accelerator driven irradiation facilities that are designed now for the fusion material testing (IFMIF , DONES  ...). Together with the competing reaction 39K(n,np)38Ar they also determine the total amount of Argon gas which impact on the thermal and mechanical properties of sealed specimens containers . The current poor knowledge of these two reactions questions whether NaK could be used in the IFMIF and DONES design. Additionally, since potassium is present in cement and concrete, the 39K(n,p)39Ar reaction impacts on the long-term radioprotection and shielding issues in IFMIF/DONES testing vaults and future fusion power plants.
The continuous Argon gas leakage through cracks in the welding of sealed containers or their accidental rupture is a complex process. Because of this complexity, the sensitivity analyses quantifying the required accuracy of the cross sections have never been done. However, considering the potentially high impact and the poor knowledge of these cross sections, a request for 10% accuracy is a reasonable requirement that will be practically achievable by utilizing the current techniques. This requirement is supported by the fusion and general nuclear data users.
At 14 MeV neutron energy 3 measurements by proton spectroscopy and activation [4-6] reported 3 times larger value for 39K(n,p)39Ar reaction cross section than measurement by AMS . For competing reaction 39K(n,np)38Ar the situation is vice versa. See Ref.  for more information.
The main evaluated libraries are similarly discrepant depending on which experiment they follow.
The new measurement is needed first at 14 MeV to resolve this contradiction.
Work in progress (as of SG-C review of May 2018)
Main recent references
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