Core outlet temperature

In China and Japan, test reactors are under construction which will have the capability of achieving core outlet temperatures of 950°C for the evaluation of nuclear process... 

Reactor pressure vessel Core inlet temperature Core outlet temperature Coolant inlet pressure Coolant flow Core power density Average fuel bumup Refuelii interval Gas turbine cycle type... 

The gas turbine cycle pressure ratio corresponding to peak thermal efficiency remains nearly identical at around 2.0 for both the 850°C and 950°C core outlet temperature cycles. This is the basis for the baseline and growth cycles to employ a similar line of gas turbines, which is another topic to be discussed later in Section 4. 

Some subassembly core outlet temperatures in the sector of the reactor supplied by. PSP 2 began to rise but stabilised after about 1.5 days. An accelerated increase in PSP 3 filter pressure differential was noted (by now of course PSP 3 filter was the only one intact). The plant was under close observation when on 29 June the oil bearing on PSP 2 failed completely causing a further oil spill, and the plant was tripped. It was observed from flow and differential pressure readings that PSP 3 filter failed at this time. 

The gas turbine-inlet temperature of 1 050 °C used in design B of this study is just 100 K higher than the mean core-outlet temperature of the AVR, which was achieved already in 1974... 

Fig. 5 HTR-MODUL fuel design data, release versus temperature, mechanisms of the release, and THTR-300 ftiel data From these data it is concluded, that the core-outlet temperature can be increased to 1 050 °C for future HTRs with modem gas turbine technology.

The perspective for an increased value of the mean core-outlet temperature of the HTR with pebble bed core is the value of 1 050 C. This follows firom the information given in the above chapter 3.2. For this reason the evaluation of the HTR-GST-cycIe in chapter 2 has been done with the gas turbine-inlet temperature (being equal to the core-outlet temperature) of 1050 °C. 

In the Chinese HTR-10 project, two phases of the high temperature heat utilization are planned During the second phase, the reactor core outlet temperature is increased up to 950 C and a GT-ST combined cycle is planed to be constructed This paper presents the investigation results of GT-ST combined cycle in INET Two patterns of GT-ST cycles, i e a parallel GT-ST cycle and a series GT-ST cycle, are referred Based on the state-of-the-art technology, the current activities of HTR-10 GT-ST combined cycle focus on a parallel combined cycle in which GT and ST cycle are independently parallel in the secondary side... 

MW(t) reactor will produce core outlet temperatures of 850 C at rated operation and 950°C at high temperature test operation. It will be the first nuclear reactor in the world to be connected to a high ten rature process heat utilization system. Criticality is expected to be attained in 1998. The reactor will utilized to establish basic technologies for advanced HTGRs, to demonstrate nuclear process heat application, and to serve as an irradiation test facility for research in high tenq)erature technologies. The timely completion and successful operation of the HTTR and its heat utilization system will be major milestones in gas-cooled reactor development and in development of nuclear process heat applications. 

Calculations show that, if HPIS injection is not available, early start of secondary bleed is very important to avoid core damage in FR-C.l, especially in case without HA injection. If so, the secondary side depressurisation initiated at 370°C core outlet temperature can avoid extended core damage, although short term violation of cladding temperature limit could occur. 

There were 3 cases calculated using results of calculations of total loss of power. Primary B F was initiated at different core outlet temperatures (320°C, 500°C and 650°C). Results show that bleed and feed process was effective in all 3 cases. The overall conclusion that operator can wait until core outlet temperature begin to rise and primary B F should initiate at 300 mm in all SGs. 

One of these tests consisted in inserting control rods at SO and 80 % NP to qualify the prototype system for processing the core outlet temperature measurements (ALPES system, see also 8.3.1.1), while the others were measurements intended to reduce the uncertainty margins of the calculation tools ... 

Simplified thermal-hydraulic analyses, which were benchmaiked against GT-MHR data, indicated that for a fixed core outlet temperature of 1000°C for the coolant, the peak fuel temperature in the AHTR during normal operation will be 110-130°C cooler than for the prismatic helium-cooled NGNP design, and the average fuel temperature at the core outlet will be 30-50°C cooler. This is a direct result of the superior heat transfer properties of the molten salt relative to helium. This is significant because the failure rate of the coated particle fuel increases with increasing temperature. 

The reference AHTR concept uses a core outlet temperature of 1000°C for the molten salt in order to respond to the functional requirement specified for the NGNP. This will sometimes be referred to as the AHTR-VT (very high temperature) concept. However, references are also made in this report to the AHTR-IT (intermediate temperature), which has a core outlet temperature of 800°C. The AHTR-IT concept provides a nearer-term option, because the reduced outlet temperature substantially reduces deployment risk due to material qualification issues. While the AHTR-IT provides the same large thermal power [nominally 2400 MW(t)] as the AHTR-VT, the lower conversion efficiency reduces somewhat the sizable economic advantage anticipated for the AHTR-VT. Details of the various trade-offs are given in... 

The design of the reactor internals has not been addressed yet, but they likely will be made of graphite or carbon composites to accommodate the high-core outlet temperature required by the NGNP (1000°C). It is possible that carbon-insulated metallic alloy will be used for the core support structure, although this has not been evaluated yet. Control rods will be required to provide for reactor startup, normal operation, and shutdown. The munber and placement of control rods has not been evaluated yet, but the rods will be constructed from carbon composites for the drive shafts and absorber casing and boron carbide or other high-temperature absorber for the neutron absorber. The control rod drive mechanisms will be located above the reactor enclosure head. 

Cooler fuel temperatures. Conversely, the maximum fuel temperature for a molten-salt-cooled reactor will be lower than that for a gas-cooled reactor—assuming the same maximum core outlet temperature. 

This economic study considered two variations of the AHTR—an AHTR-IT version with a core outlet temperature of 800°C and an electrical power output of 1145 MW(e), and an AHTR-VT version with an outlet temperature of 1000°C and an electrical power output of 1300 MW(e). Table 8.1 siunmarizes the results of the cost analysis, showing the relative cost of the AHTR compared with the S-PRISM and GT-MHR. 

A space abo e the coolant le el inside the RPV is as a self - pressurized space ( inside the RPV is depends on initial partial pressure of nitrogen and saturate apoiir pressure corresponds to the core outlet temperature in the pressunzed water operation mode Due to the nitrogen partial pressure existing the coolant can be kept subcooling in the core outlet This is calledpressunzed water operation mode... 

Self-pressurized performance A space in the upper part of the vessel is used for the self-pressurized space. Total pressure in RPV is formed by both nitrogen partil pressure of 0..5MPa and saturate steam partial pressure of I. l7MPa which correspond to the core outlet temperature of IS6°C... 

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