Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: First Application of Large Reactivity Measurement through Rod Drop Based
  on Three-Dimensional Space-Time Dynamics   Reactivity measurement is an essential part of a zero-power physics test,
which is critical to reactor design and development. The rod drop experimental
technique is used to measure the control rod worth in a zero-power physics
test. The conventional rod drop experimental technique is limited by the
spatial effect and the difference between the calculated static reactivity and
measured dynamic reactivity; thus, the method must be improved. In this study,
a modified rod drop experimental technique that constrains the detector neutron
flux shape function based on three-dimensional space-time dynamics to reduce
the reactivity perturbation and a new method for calculating the detector
neutron flux shape function are proposed. Correction factors were determined
using Monte Carlo N-Particle transport code and transient analysis code for a
pressurized water reactor at the Ulsan National Institute of Science and
Technology and Xi'an Jiaotong University, and a large reactivity of over 2000
pcm was measured using the modified technique. This research evaluated the
modified technique accuracy, studied the influence of the correction factors on
the modification, and investigated the effect of constraining the shape
function on the reactivity perturbation reduction caused by the difference
between the calculated neutron flux and true value, using the new method to
calculate the shape function of the detector neutron flux and avoiding the
neutron detector response function (weighting factor) calculation.

2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga