Authors & Affiliations
Artemov V.G., Zinatullin R.E.
Alexandrov Research Institute of Technoloqy, Sosnovy Bor, Russia
Zinatullin R.E. – Senior Researcher, Alexandrov Research Institute of Technoloqy.
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.
RBMK’s spent fuel storage, pulse method, numerical modeling, nuclear safety monitoring, subcriticality, fuel burnup depth
1. Pravila bezopasnosti pri khranenii i transportirovanii yadernogo topliva na ob"ektakh ispol'zovaniya atomnoy energii [Safety rules for the storage and transportation of nuclear fuel at nuclear facilities]. Rostechnadzor, Federal Norms and Rules in the field of the use of atomic energy, NP-061-05.
2. Somov I.E., Nikolaev S.A., Polevoy V.B., Nemytov S.A., Bespalov V.N. Raschetno-eksperimental'nye metody opredeleniya parametrov pri khranenii i obrashchenii s OYaT [Calculation-experimental methods for determining parameters during storage and handling of SNF]. Voprosy atomnoy nauki i tekhniki. Seriya: Fizika yadernykh reaktorov - Problems of atomic science and technology. Series: Physics of Nuclear Reactors, 2002, no. 3, pp. 15-25.
3. RD EO 0613-2005. Metodika kontrolya podkritichnosti khranilishch otrabotavshego yadernogo topliva Leningradskoy AES s pomoshch'yu ustanovki UIP-006 [The method for monitoring the subcriticality of the spent nuclear fuel storage facilities of the Leningrad NPP with the help of the UIP-006]. Moscow, Rosenegoatom Publ., 2004.
4. Kudryavtsev K.G., Kalyazin N.N., Bolotov D.V., El'shin A.V., Artemov V.G., Piskarev A.V. Kontrol' za razmnozhayushchimi svoystvami khranilishcha OYaT Leningradskoy AES s ispol'zovaniem kompleksa programm SAPFIR_95&RC i ustanovki izmereniya podkritichnosti UIP-005 [Control over the reproducing properties of the SNF storage facility at the Leningrad NPP using the SAPPHIRE-95_&RC program suite and the UIP 005 sub-criterion]. Available at: www.dysnai.org/Reports/2000-2004/2004/2004.rar (assecced 29.02.2016).