Effective full-power years

The sodium cooled fast reactor JOYO has been operated more than 20 years (about 5 years of effective full power years) since its initial criticality and the cumulative reactor output achieved over 1.9E+5 MWd. Since JOYO has not yet experienced any operation with breached fuels, FP radioactive contamination has not become an issue in the plant system. To reduce the radiation dose from long-lived Na, all primary coolant sodium in the main circulating loops is drained into a storage tank during annual plant inspections. Under these conditions, the spatial gamma-ray dose rate distribution is dominated by the radioactive CPs deposited on inner surfaces of the primary piping and components. This means that most personnel dose was due to these CPs. 

Not less than once or greater than twice the peak operating period of 40 EFPY fiuence (E > 1 MeV). This capsule may be modified on the basis of previous tests. Values in this table show the schedule in terms of effective full-power years (EFPY) of the reactor vessel. The operating period is usually 32 EFPY, unless otherwise identified. 

At specified effective full-power years based on shifts in trans. temp, with last capsule as a standby... 

Whenever clearly identified by designers, the operation period between refuellings is in effective full power years the actual operation period will be that divided by a load factor (for example, for a load factor of 0.85, the given value should be multiplied by 1.18). 

Effective full power years fraction in the tMs is assumed to be 0.2%... 

The refuelling interval varies from 5.7 to 16.6 effective full power years for water cooled concepts the average discharge burn-up varies from 30 (MW(th)-day/kg IHM) for uranium dioxide fuelled concepts and up to -120 (MW(th)-day/kg IHM) for cermet fuelled concepts. 

All refuelling intervals specified in this chapter are in effective full power years. Both reactor concepts are abbreviated as FBNR. 

Long core life. The core life will be five effective full power years ... 

Module life >20 effective full power years... 

Once for life (>20 effective full power years (EFPY)) core along with no refuelling or fuel shuffling on site the entire ENHS module is replaced when the core reaches end of life. Very high availability is expected. Plant life target is on the order of 100 years. 

Table XXII-3 presents the design conditions and neutronics performance results. Figure XXII-8 shows the change in reactivity vs. exposure time - with a peak to minimum swing of less than 1 over 20 effective full power years (EFPY).

Such fuel being loaded to the CHTR core, the required power of 100 kW(th) can be generated during 15 effective full power years of continuous operation. In this, the Doppler coefficient of reactivity was found satisfactorily negative. The values for this fuel design, as well as for a case with no poison added to the fuel, as a function of burn-up, are shown in Fig. XXIX-4. 

The very long life CHTR core, needing refuelling only once in 15 effective full power years, is the feature, which could reduce the O M costs. The design of the CHTR, with its all passive features, is intended to make the plant capable of unattended operation. 

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