Authors & Affiliations

Artemov V.G., Zinatullin R.E.
Alexandrov Research Institute of Technoloqy, Sosnovy Bor, Russia

Artemov V.G. – Head of the Laboratory, Cand. Sci. (Tech.), Alexandrov Research Institute of Technoloqy. Contacts: 72, Koporskoe shosse, Sosnovy Bor, Leningrad region, Russia, 188540. Tel.: +7(81369) 6-08-83; e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..
Zinatullin R.E. – Senior Researcher, Alexandrov Research Institute of Technoloqy.

Abstract

To monitor the subcriticality of the Leningrad NPP’s spent fuel storage the experimental methods are implemented. The method of neutron flux damping decrement determination, which is the modified Simmons-King method, is considered as the most advanced one.

The paper presents the results of the numerical investigations which allow establishing the relationship between the measured damping decrement and the parameters of spent fuel storage’s nuclear safety. The compacted fragments in the spent-fuel storage shall contain only spent fuel with the burnup depth not lower than the limiting value, when the nuclear safety requirements are still met. The limiting fuel burnup value is determined from the condition that multiplication factor in postulated accidents is not higher than 0.95.

The calculations are performed simulating the experiments with pulse neutron source for the spent fuel of different burnup depth. It has been established that increase of the fuel burnup depth linearly enhances the neutron flux damping decrement. The damping decrement limiting values corresponding to the limiting fuel burnup depth have been determined on the basis of the numerical calculations. On the basis thereof the following criterion has been formulated: if the measured damping decrement values are within the limits, the nuclear safety requirements will be met for the spent fuel storage.

The numerical investigations showed that the maximum value of neutron multiplication factor which can be achieved under emergency conditions and the damping decrement value measured in the fuel storage’s fragments under normal operating conditions are linearly dependent from one another. Using the results of measurements this relationship makes it possible to assess the neutron multiplication factor and to timely evaluate fulfillment of nuclear safety requirements in the storage facility. It is shown that the revealed relationship holds for the wide burnup area covering the actual nomenclature of spent assemblies in the storage facility.

Therefore, the obtained results confirmed that the pulse experiments are a sufficiently effective instrument to monitor the compliance with nuclear safety requirements in the RBMK’s spent fuel storage.

Keywords
RBMK’s spent fuel storage, pulse method, numerical modeling, nuclear safety monitoring, subcriticality, fuel burnup depth

Article Text (PDF, in Russian)

References

UDC 621.039

Problems of Atomic Science and Technology. Series: Nuclear and Reactor Constants", 2017, issue 2, 2:6