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WP1: Definition of specifications and detailed work programme of Fast Spectrum Transmutation Experimental Facility (FASTEF) (SCK•CEN)


Building up on the former design activities accomplished in the previous FPs, namely PDS-XADS in FP5 and continued in FP6 IP-EUROTRANS, it is proposed to take as starting point the design work performed for MYRRHA/XT-ADS. The purpose of this work package is to analyse and review the MYRRHA/XT-ADS design choices made in view of the different objectives set forward for MYRRHA-FASTEF.
One major difference in objectives of MYRRHA-FASTEF compared to MYRRHA/XT-ADS is the fact that the FASTEF needs to be able to operate as a sub-critical system as well as a critical system. Both operation modes have to be foreseen in the design from the beginning.
The first objective of FASTEF is to be operated as a high-flux and flexible fast spectrum irradiation facility. Such a facility will therefore be able to host several experimental devices and loops, in support of material and fuel research for different innovative reactor systems and fusion material research and for the production of radio-isotopes for medical purposes. To respond to this objective, attractive irradiation conditions for the experimental devices and rigs need to be assured.
Secondly, MYRRHA-FASTEF needs to demonstrate the ADS technology for transmutation and demonstrate efficient transmutation in such a facility and in this way be able to serve as test-bed for transmutation.
Thirdly, MYRRHA-FASTEF, as it will be designed also to be able to operate in a critical mode, will contribute to the demonstration of the Lead Fast Reactor technology.
Given the different objectives, a detailed definition of characteristics will result from a critical analysis of how and to which extent one can respond to the different objectives for FASTEF. The global analysis of design choices will then be based on the detailed definition of the characteristics of the MYRRHA-FASTEF.

Description of work

This work package is divided in three separate tasks. The first is devoted to the input and review of design choices and its methodology for MYRRHA/XT-ADS. The second task is related to the design modifications due to the introduction of a critical operation mode. In the third task, an analysis will be made to which extent MYRRHA/FASTEF can respond to LFR demo objectives. At the end of this work package, a definition of specifications and design choices together with a detailed work programme for FASTEF will be present.

At the end of IP-EUROTRANS, an advanced design will be available of the core, the primary system and the spallation target. Other elements of the design will be rather at a conceptual design level, such as the secondary system and DHR system, the lead-bismuth conditioning and control system and the spallation loop. From MYRRHA Draft-2 to MYRRHA/XT-ADS, a number of design modifications have been performed and a number of initial design choices were confirmed. The rationale behind this analysis serves as an input for the global analysis.
Feedback from the safety analysis from MYRRHA/XT-ADS will also be taken into account into the global analysis of design choices.

T 1.2. Analysis of FASTEF to operate in a critical mode (ENEA, SCK•CEN, KIT, ANSALDO, AREVA NP S.A.S.,CIEMAT)
Since the objective of FASTEF is to operate both in a subcritical mode and a critical mode, an analysis will be performed to establish to which extent the design of MYRRHA/XT-ADS can respond to the objective to be operated in critical mode and which possible design changes have to be envisaged.

First of all it is clear that reactor scram systems have to be included in the design. A primary reactor shutdown system based on shutdown rods and a secondary shutdown system based on another type of system will need to be incorporated to guarantee not only redundancy but also diversification. Control rods will need to be included too. Also, an analysis will have to be performed to determine which further design changes might be induced by removing the spallation loop. Especially with regard to the operation of FASTEF in critical mode as a flexible irradiation facility. By removing the spallation loop, major changes of the design are to be expected for the reactor cover plate design, cover plate penetrations and impact on leak tightness requests and safety aspects related to unintended events putting safety functions of components on the reactor cover into question.

Working in critical mode will significantly modify the safety characteristics of the facility. Already, in this analysis, the implications of additional safety requirements to the design of the core and the installation will need to be taken into account.

T 1.3. Analysis of FASTEF to respond to LFR demo (SCK•CEN, ENEA, KIT, ANSALDO)
A third element in the global analysis of design characteristics is the degree to which FASTEF is able to contribute to the demonstration of the LFR Gen.IV system. First of all, a detailed list of desired characteristics and objectives of Demo LFR should be established. Secondly, an analysis has to be made to which extent a critical FASTEF can already respond to these objectives. Thirdly, to obtain a better synergy between FASTEF and LFR demo some initial design choices can be re-evaluated. However, such a re-evaluation has to take into account the other objectives set forward for FASTEF (being a flexible irradiation facility, an ADS demo and a test-bed for efficient transmutation) and may not jeopardize them. Also, timing, availability of technical solutions, operational flexibility and cost implications are clearly parameters to be taken into account in this analysis.

Possible topics to be addressed in this analysis are the reactor shutdown system (primary and secondary system), reactor control system, fuel pin characteristics, fuel assembly characteristics, coolant cleaning system, oxygen control systems, visualisation systems, choice of coolant (lead-bismuth or lead), type of heat exchangers/steam generators, type of primary pumps, prevention and mitigation of the steam generator tube failure accident, refuelling strategy, connection to the grid and demonstration of the possibility of ISI/replaceability of the reactor internals.


D1.1 Feedback from MYRRHA/XT-ADS (KIT) (M6)
D1.2 Analysis of MYRRA-FASTEF to operate in a critical mode (ENEA) (M6)
D1.3 Analysis of MYRRHA-FASTEF to respond to LFR demo (SCK•CEN) (M6)
D1.4 Definition of MYRRHA-FASTEF specifications, design choices and detailed work programme (SCK•CEN) (M7)