There is a lack of reliable experiments aiming at the prompt fission neutron spectrum of ²³⁵U for energies higher than 10 MeV. The presented experiment performed at the LVR-15 light water reactor aimed at the measurement of very high threshold reactions spectral averaged cross sections such as ⁵⁵Mn (n,2n)⁵⁴Mn, ¹⁹⁷Au (n,2n)¹⁹⁶Au, ¹⁹⁷Au (n,3n)¹⁹⁵Au, ²⁰⁹Bi(n,3n)²⁰⁷Bi, ²⁰⁹Bi(n,4n)²⁰⁶Bi. ²⁰⁹Bi(n,3n)²⁰⁷Bi and ²⁰⁹Bi(n,4n)²⁰⁶Bi reactions were measured for the first time. ⁵⁸Ni(n,p)⁵⁸Co reaction was used as a monitor reaction. The experimental spectral averaged cross sections are derived from reaction rates measured by means of high purity Germanium spectroscopy at the well defined detector. The experimental spectral averaged cross sections are compared with calculations using either ENDF/B-VIII.0 or JEFF-3.3 ²³⁵U prompt fission neutron spectrum and IRDFF-II cross sections. The discrepancy is higher with higher mean response energy for JEFF-3.3 unlike ENDF/B-VIII.0, where the agreement is good within broad range of mean response energy. Moreover, due to the high thermal neutron flux in the reactor, the experimental reaction rate is compared with calculated ¹⁹⁸Au (n,g)¹⁹⁹Au reaction rate. The difference of −55.3% for double capture reaction was found in comparison with ROSFOND-2010 calculations.

缺乏可靠的实验来针对能量高于10 MeV的²³⁵ U的迅速裂变中子光谱。在LVR-15轻水反应堆上进行的本实验旨在测量非常高的阈值反应光谱平均截面，例如⁵⁵ Mn（n，2n）⁵⁴ Mn，¹⁹⁷ Au（n，2n）¹⁹⁶ Au，¹⁹⁷ Au（ n，3n）¹⁹⁵ Au，²⁰⁹ Bi（n，3n）²⁰⁷ Bi，²⁰⁹ Bi（n，4n）²⁰⁶ Bi。²⁰⁹ Bi（n，3n）²⁰⁷ Bi和²⁰⁹ Bi（n，4n）²⁰⁶首次测量了Bi反应。⁵⁸ Ni（n，p）⁵⁸ Co反应用作监测反应。实验光谱平均横截面得自在定义明确的检测器上通过高纯度锗光谱法测得的反应速率。将实验光谱平均截面与使用ENDF / B-VIII.0或JEFF-3.3 ²³⁵ U瞬变裂变中子光谱和IRDFF-II截面的计算结果进行比较。与ENDF / B-VIII.0不同，JEFF-3.3的差异更大，且平均响应能更高，后者在较宽的平均响应能范围内吻合良好。此外，由于反应堆中热中子通量高，因此将实验反应速率与计算得出的结果进行了比较¹⁹⁸Au（n，g）¹⁹⁹ Au反应速率。与ROSFOND-2010计算结果相比，两次捕获反应的差异为-55.3％。