Report on result of special test of fast experimental reactor "JOYO"; Isothermal reactivity coefficient and flow rate reactivity coefficient

*; *; Yamanouchi, Sadamu; *; Enokido, Yuji*; Shibahara, Itaru*; *

PNC TN941 82-38, 57 Pages, 1982/02

PNC-TN941-82-38.pdf:2.35MB

The isothermal reactivity coefficient and the flow rate reactivity coefficient of the Fast Breeder Reactor "JOYO" were measured during the power ascension test of 50MW. After 4 years operation, the core configuration of "JOYO" was increased to 79 from 70 subassemblies. The present experiment was intended to search the age effect for the above reactivity coefficients. The results obtained were as follows. [Isothermal reactivity coefficient] (1)The present value measured ((-3.850.17)10% k/k/C) shows good agreement with the design value and the value measured previously. (2)The age effect and the effect caused by the anomaly of the power reactivity coefficient are not found. [Coolant flow rate reactivity coefficient] (1)The reactivity change caused by changing of the flow rates in primary sodium loop (100% to 20%) was (-8.2-10.7) 10%k/k. This value is about 1/10 of the design value and 1/3 of the measured value before the 75 MW power ascension test. (2)The detailed analysis is needed to search the relation between the anomaly of the power reactivity coefficient and the above change of this coefficient.

Resent status of decoupler development for MLF neutron source

Oi, Motoki; Inoue, Hiromi*; Teshigawara, Makoto; Harada, Masahide; Ikeda, Yujiro*

no journal, , 

J-PARC Material and Life science experimental facility (MLF) is a pulsed spallation neutron source. There are three types of hydrogen moderators. Two of the moderators are using neutron absorbing material around the moderator which called decoupler. The decoupler is made with Au/Ag-In-Cd alloy. The first moderator assembly is using in the MLF and we are planning to exchange it to the second one in 2023. And now we are manufacturing the 3rd moderator assembly for the future exchange. Recently, due to RoHS directive, it is difficult to make cadmium alloy in the world. Therefor we make Au/Ag-In-Cd alloy by ourselves. For the second moderator assembly, decoupler parts are cut after casting. For the third moderator assembly, NC milling machine is introduced, and surface of the casted parts are milled by the NC machine for good surface condition for good hip bonding. In this presentation, we will mainly report on the production of the Au-In-Cd decoupler for 3rd moderators and reflector.