US 12,731,078 B2 · Probabilistic evaluation of fastener degradation in nuclear power plants

Abstract

A probabilistic method for determining an operability interval for fasteners in a nuclear power plant assembly includes providing a geometric distribution of a given initial condition of fasteners in the nuclear power plant assembly at an initial time T0; generating a plurality of random future fastener failure patterns by applying a fastener failure probability model to the geometric distribution at a given time T1>T0; inputting the plurality of random future fastener failure patterns at time T1 into a machine learning model and outputting stresses of the fasteners and displacements of the components; iterating, by a processor of a computer, the applying and inputting steps for a given range of time values T2, T3, . . . , Tx>T0 and determining a maximum future time Tmax at which a predetermined acceptable probability of the fastener failure patterns having acceptable values of the stresses of the fasteners and displacements of the components, thereby justifying the acceptability of the fasteners for continued operation of the nuclear power plant assembly; and determining the operability interval as being the maximum future time Tmax minus the initial time T0.

Claims10

Dependent claims

A probabilistic method for determining an operability interval for fasteners retaining components in a nuclear power plant assembly comprising:

providing a geometric distribution of a given initial condition of fasteners in the nuclear power plant assembly at an initial time T0;
generating a plurality of random future fastener failure patterns by applying a fastener failure probability model to the geometric distribution at a given time T1>T0;
inputting the plurality of random future fastener failure patterns at time T1 into a machine learning model and outputting stresses of the fasteners and displacements of the components;
iterating, by a processor of a computer, the applying and inputting steps for a given range of time values T2, T3, . . . , Tx>T0 and determining a maximum future time Tmax at which a predetermined acceptable probability of the fastener failure patterns having acceptable values of the stresses of the fasteners and displacements of the components, thereby justifying the acceptability of the fasteners for continued operation of the nuclear power plant assembly;
determining the operability interval as being the maximum future time Tmax minus the initial time T0;
and
installing replacement fasteners in the nuclear power plant assembly in accordance with the pattern of replacement fasteners having the greatest maximum future time Tmax,
the fasteners and replacement fasteners being bolts of a core barrel assembly, the bolts including:
baffle-former bolts connecting former plates to baffle plates,
core barrel-former bolts connecting the former plates to a core barrel, and
baffle-baffle bolts connecting baffle plates to baffle plates of a core barrel assembly.

8 more elements

A probabilistic method for determining an operability interval for fasteners retaining components in a nuclear power plant assembly comprising:

(a) providing a geometric distribution of a given initial condition of fasteners in the nuclear power plant assembly at an initial time T0;
(b) generating a plurality of random future fastener failure patterns by applying a fastener failure probability model to the geometric distribution at a given time T1>T0;
(c) determining stress of the fasteners and displacements of the component for each of the plurality of random future fastener failure patterns at time T1;
(d) determining a probability of the plurality of random future fastener failure patterns being acceptable as a population at time T1;
(e) applying the fastener failure probability model to the geometric distribution at a given time T2>T1 by taking into consideration the stress of the fasteners and displacements of the component for each of the plurality of random future fastener failure patterns at time T1;
(f) determining stress of the fasteners and displacements of the component for each of the plurality of random future fastener failure patterns at time T2;
(g) determining a probability of the plurality of random future fastener failure patterns being acceptable as a population at time T2;
(h) iterating, by a processor of a computer, steps (d) to (g) for a given range of time values T3, T4, . . . , Tx>T2 and determining a maximum future time Tmax at which a predetermined acceptable probability of the fastener failure patterns having acceptable values of the stresses of the fasteners and displacements of the components, thereby justifying the acceptability of the fasteners for continued operation of the nuclear power plant assembly;
(i) determining the operability interval as being the maximum future time Tmax minus the initial time T0;
and
(j) installing replacement fasteners in the nuclear power plant assembly in accordance with the pattern of replacement fasteners having the greatest maximum future time Tmax,
the fasteners and replacement fasteners being bolts of a core barrel assembly, the bolts including:
baffle-former bolts connecting former plates to baffle plates,
core barrel-former bolts connecting the former plates to a core barrel, and
baffle-baffle bolts connecting baffle plates to baffle plates of a core barrel assembly.

12 more elements

A probabilistic method for replacing fasteners retaining components in a nuclear power plant assembly comprising:

(a) providing a geometric distribution of a given initial condition of fasteners in the nuclear power plant assembly at an initial time TO, the given initial condition including a pattern of replacement fasteners;
(b) generating a plurality of random future fastener failure patterns by applying a fastener failure probability model to the geometric distribution at a given time T1>T0;
(c) inputting the plurality of random future fastener failure patterns at time T1 into a machine learning model, for example an artificial neural network, and outputting stresses of the fasteners and displacements of the components;
(d) iterating, by a processor of a computer, the applying and inputting steps for a given range of time values T2, T3, . . . , Tx>T0 and determining a maximum future time Tmax at which a predetermined acceptable probability of the fastener failure patterns having acceptable values of the stresses of the fasteners and displacements of the components, thereby justifying the acceptability of the fasteners for continued operation of the nuclear power plant assembly;
and
(e) performing steps (a) to (d) for a plurality of different patterns of replacement fasteners;
(f) selecting the pattern of replacement fasteners having the greatest maximum future time Tmax as fastener replacement strategy;
and
installing replacement fasteners in the nuclear power plant assembly in accordance with the pattern of replacement fasteners having the greatest maximum future time Tmax,
the fasteners and replacement fasteners being bolts of a core barrel assembly, the bolts including:
baffle-former bolts connecting former plates to baffle plates,
core barrel-former bolts connecting the former plates to a core barrel, and
baffle-baffle bolts connecting baffle plates to baffle plates of a core barrel assembly.

10 more elements

Dependencies are inferred from the claim text.

Probabilistic evaluation of fastener degradation in nuclear power plants

Life of this patent

Probabilistic evaluation of fastener degradation in nuclear power plants

Life of this patent

Abstract

Claims10