Published November 2015 | Version v1
Journal article Metadata-only

Improvement of a calculation procedure of neutron-flux distribution for radioactivity inventory estimation for decommissioning of nuclear power plants

Creators

  • 1. Tokyo Institute of Technology, 2-12-N1-9 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)
  • 2. The Japan Atomic Power Company, 1-1,Kandamitoshiro-cho, Chiyoda-ku, Tokyo 105-0004 (Japan)
  • 3. Genden Information System Company, 2-4 Chiyoda-ku, Tokyo 105-0004 (Japan)

Description

Highlights: •A calculation procedure of reliable neutron-flux distribution around the Reactor is shown. •Both 2D distribution calculation and 3D distribution calculation of neutron-flux were performed. •Measurements of neutron-fluxes (Fast, Epi-thermal and Thermal) around the Reactor using activation foils (Activation detector) were performed. •Comparison between calculations and measurements was made. Causes of discrepancy between them were investigated. -- Abstract: We improved a calculation procedure of neutron-flux distribution in the Primary Containment Vessel (PCV) to get reliable estimation of radioactivity inventory, which is crucial for specification of a decommissioning plan of nuclear power plants. We calculated two-dimensional (2D) distribution of neutron-flux in cylindrical coordinate (r–z) with a 2D discrete ordinate (Sn) code DORT by utilizing knowledge of the characteristics of neutron-flux distribution in the PCV of Tsuruga Nuclear Power Plant unit 1 (TS-1). The knowledge was obtained from measurements and three-dimensional (3D) calculation of neutron-flux distribution in cylindrical coordinate (r–θ–z) with a 3D Sn code TORT. The measurements were performed by using activation foils at 30 locations where the distribution characteristics could be observed in the PCV. The 3D calculation provided us better qualitative understandings about the characteristics of neutron-flux distribution in the PCV. An improved model of 2D calculation of neutron-flux distribution was generated by utilizing the knowledge from the measurements and the 3D calculation in the PCV. The reliability of 2D calculation was confirmed by comparing calculated fluxes with measured ones at locations where measurements were performed. The comparison between them showed that neutron-flux distribution calculated by the improved 2D model has met our criteria of the reliability. Therefore, the improved procedure provided a reliable 2D distribution of neutron-flux.

Availability note (English)

Available from http://dx.doi.org/10.1016/j.pnucene.2015.05.009

Additional details

Identifiers

DOI
10.1016/j.pnucene.2015.05.009;
PII
S0149197015300044;

Publishing Information

Journal Title
Progress in Nuclear Energy
Journal Volume
85
Journal Page Range
p. 254-270
ISSN
0149-1970

INIS

Country of Publication
United Kingdom
Country of Input or Organization
International Atomic Energy Agency (IAEA)
INIS RN
51027550
Subject category
S21: SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; S97: MATHEMATICAL METHODS AND COMPUTING;
Descriptors DEI
ACTIVATION DETECTORS; BWR TYPE REACTORS; DECOMMISSIONING; DISCRETE ORDINATE METHOD; NEUTRON FLUX; NUCLEAR POWER PLANTS; RADIOACTIVITY; THREE-DIMENSIONAL CALCULATIONS; TWO-DIMENSIONAL CALCULATIONS
Descriptors DEC
CALCULATION METHODS; ENRICHED URANIUM REACTORS; MEASURING INSTRUMENTS; NEUTRON DETECTORS; NUCLEAR FACILITIES; POWER PLANTS; POWER REACTORS; RADIATION DETECTORS; RADIATION FLUX; REACTORS; THERMAL POWER PLANTS; THERMAL REACTORS; WATER COOLED REACTORS; WATER MODERATED REACTORS

Optional Information

Notes
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