Abstract
Atucha I is a Pressure Vessel Heavy Water Cooled Heavy Water Moderator Reactor. In this kind of reactor the moderator tank is physically connected to the primary coolant. Since neutron economy requires the moderator to be as cold as possible, it is necessary that even when physically connected, it should have a separated cooling system, which in this case is also used as a feed-water preheater, and also heat mass transfer with primary coolant should be minimized. This condition requires that some reactor internals are designed in principle to last the whole life of the plant. However, in 1988 the failure of one internal produced a 16 month shut down. This incident could have been prevented but the idea that reactor internals would not have failures due to aging was dominant at that time avoiding the early detection of the failure. However, the analysis of the records after the incident showed that some process variables had changed previously to the incident, i.e., power exchanged at the moderator heat exchanger had increased. Since the station restart up some changes in the moderator process variables and a flow rate reduction of about 10% through the primary side of one moderator cooler were
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Berra, S;
Guala, M;
Herzovich, P;
[1]
Chocron, M;
Lorenzo, A;
Raffo Calderon, Ma. C. del;
Urrutia, G
[2]
- Central Nuclear Atucha I, Nucleoelectrica Argentina, Lima, Buenos Aires (Argentina)
- Comision Nacional de Energia Atomica, Buenos Aires (Argentina). Centro Atomico Constituyentes
Citation Formats
Berra, S, Guala, M, Herzovich, P, Chocron, M, Lorenzo, A, Raffo Calderon, Ma. C. del, and Urrutia, G.
Moderator behaviour and reactor internals integrity at Atucha I NPP.
IAEA: N. p.,
1996.
Web.
Berra, S, Guala, M, Herzovich, P, Chocron, M, Lorenzo, A, Raffo Calderon, Ma. C. del, & Urrutia, G.
Moderator behaviour and reactor internals integrity at Atucha I NPP.
IAEA.
Berra, S, Guala, M, Herzovich, P, Chocron, M, Lorenzo, A, Raffo Calderon, Ma. C. del, and Urrutia, G.
1996.
"Moderator behaviour and reactor internals integrity at Atucha I NPP."
IAEA.
@misc{etde_454201,
title = {Moderator behaviour and reactor internals integrity at Atucha I NPP}
author = {Berra, S, Guala, M, Herzovich, P, Chocron, M, Lorenzo, A, Raffo Calderon, Ma. C. del, and Urrutia, G}
abstractNote = {Atucha I is a Pressure Vessel Heavy Water Cooled Heavy Water Moderator Reactor. In this kind of reactor the moderator tank is physically connected to the primary coolant. Since neutron economy requires the moderator to be as cold as possible, it is necessary that even when physically connected, it should have a separated cooling system, which in this case is also used as a feed-water preheater, and also heat mass transfer with primary coolant should be minimized. This condition requires that some reactor internals are designed in principle to last the whole life of the plant. However, in 1988 the failure of one internal produced a 16 month shut down. This incident could have been prevented but the idea that reactor internals would not have failures due to aging was dominant at that time avoiding the early detection of the failure. However, the analysis of the records after the incident showed that some process variables had changed previously to the incident, i.e., power exchanged at the moderator heat exchanger had increased. Since the station restart up some changes in the moderator process variables and a flow rate reduction of about 10% through the primary side of one moderator cooler were observed. In order to understand the flow reduction and the overall behaviour of moderators parameters, two models were developed that predict moderator and moderator cooler behavior under the new conditions. The present paper refers to these models, which together with the improvement of process variables measurements mentioned in another paper presented at this meeting permits to understand current moderator behaviour and helps to early diagnostic of an eventual reactor internal failure. (author). 2 refs, 4 figs, 1 tab.}
place = {IAEA}
year = {1996}
month = {Dec}
}
title = {Moderator behaviour and reactor internals integrity at Atucha I NPP}
author = {Berra, S, Guala, M, Herzovich, P, Chocron, M, Lorenzo, A, Raffo Calderon, Ma. C. del, and Urrutia, G}
abstractNote = {Atucha I is a Pressure Vessel Heavy Water Cooled Heavy Water Moderator Reactor. In this kind of reactor the moderator tank is physically connected to the primary coolant. Since neutron economy requires the moderator to be as cold as possible, it is necessary that even when physically connected, it should have a separated cooling system, which in this case is also used as a feed-water preheater, and also heat mass transfer with primary coolant should be minimized. This condition requires that some reactor internals are designed in principle to last the whole life of the plant. However, in 1988 the failure of one internal produced a 16 month shut down. This incident could have been prevented but the idea that reactor internals would not have failures due to aging was dominant at that time avoiding the early detection of the failure. However, the analysis of the records after the incident showed that some process variables had changed previously to the incident, i.e., power exchanged at the moderator heat exchanger had increased. Since the station restart up some changes in the moderator process variables and a flow rate reduction of about 10% through the primary side of one moderator cooler were observed. In order to understand the flow reduction and the overall behaviour of moderators parameters, two models were developed that predict moderator and moderator cooler behavior under the new conditions. The present paper refers to these models, which together with the improvement of process variables measurements mentioned in another paper presented at this meeting permits to understand current moderator behaviour and helps to early diagnostic of an eventual reactor internal failure. (author). 2 refs, 4 figs, 1 tab.}
place = {IAEA}
year = {1996}
month = {Dec}
}