SAFPWR home page

Effect of increasing auxiliary feed flow in broken sg

(cf rtvunsym_5.dat )
Difference | reference case rtvunsym_2:
wyan1= 120 | 85 from sec= 20.

As anticipated, the change does not affect much the trend of the transient (chart 01) until sg1 is dry. The influence on the following "post accident" trend is however impressive:

Subcriticality cannot be reached even at sec= 2000 s, while
boron ppm (chart 03) reaches 300 and is still increasing.
The system evolves itself to another, semi-stationary regime, whereby the core returns to a low, but not null, residual power q2c= 30.6 e6.
The effect on reactivity of continued boron injection is then just counterbalanced by a slow decrease rate of tavc (chart 06).
Aoc and u2c7 (chart 07) return to their initial value.

The only way of shutting down the core completely is by reducing wyan to the 85 level.
wyan= 120 was here chosen arbitrarily.

Pressu response

Pressu refills completely (chart 02) and its vapor region becomes overheated (chart 03) (x2p > 1 and t2p - tl0 = 40. (chart 04)

At sec= 1000 heater is cut off (qyp=0) (chart 05) and pressu spray takes over.
Remember that qup, the contribution of heat exchange with wall was neglected here (oqyp= f).
Spray succeeds controlling the pressure p3 (chart 08) at about its nominal value, but does not succeed suppressing vapor overheating.
The contribution of condensation at water-vapor interface, neglected is this case, should be investigated with realistic correlations.