Review SAR, Chapter 15 – Loss of Feed Water flow (LOFW)

1. Review SAR, Chapter 15 – Loss of Feed Water flow (LOFW) VARANS Tung Duong

2. Categorization of PIE • The considered initiating event presents the design condition of category 2 and refers to the group of initiating events resulting in reduction in heat removal from the primary circuit.

3. Acceptance criteria • Pressure in the reactor coolant system and SG steam lines will be less than 115 % of the design value. • The minimum DNBR shall be not less than the assigned value for the assumed correlation with a confidence probability of 95%. The applied DNBR correlations shall be based on experimental results that correspond to the conditions of core cooling and to the given design of fuel. • Fuel pellets do not melt even locally (temperature is less than 2540оС for “burnt-up” fuel and less than 2840оС for “fresh” fuel). • Radially-averaged fuel enthalpy shall not exceed 586 J/g UO2 in any fuel pellet. • Acceptance criteria are fully listed. • Need to show information about CHF correlation used and the DNBR limit should be given by value with considering uncertainty

4. BICs • Main parameters, delay times, and set points are presented in section 15.4. • All feed-water pumps supply into SG are tripped. • Need section 15.4

5. BICs

6. Availability of components and systems Conservative are selected for each acceptance criterion

7. Computer codes and calculation procedure The LOFW calculation is made with the use of computer code DINAMIKA-97 included into the computer code package TRAP-97 described in section 15.3. The code package TRAP-97 is validated against large scope of domestic and international experimental data and certified by Russian regulatory body.  Acceptable

8. Results Initial power is not 110% nominal power

9. Results Minimum DNBR about 1,07 but information about CHF correlation is not included  not confirmed

10. Results Below 110% nominal power

11. Results Inconsistence of figure 5 and 6

12. Thanks for your attention