As the one of the steps in transferring state-of-the-art safety analysis technologies to the Rivne NPP personnel, a working meeting between representatives of the Safety Analysis Laboratory and RNPP was held from March 28 to April 1, 2005 in Kyiv in the context of activities related to the Rivne NPP Unit 1 In-depth Safety Assessment. The meeting was primarily focused on discussion of technical issues related to analytical justification of symptom-oriented emergency operating instructions (EOI). In particular, the following topics were addressed:
- general EOI structure;
- advantages of EOIs comparing to the traditional emergency instructions;
- rules of emergency response procedures application by the example of the RNPP Unit 1 EOI project;
- approach to a selection of initial events and development of representative calculation scenarios to analytically justify the EOI.
As a practical task, the calculation scenario “Leak from primary circuit to secondary one with an equivalent diameter of 2x 13 mm (steam generator tube rupture) with subsequent manual isolation of feed water supply to broken SG, closure of main steam header steam isolation valve and trip of all HPIS pumps” was developed by RNPP staff. Correspondent thermal hydraulic calculation was conducted using RELAP5 computer code.
In addition, a procedure to estimate core damage frequency (CDF) due to internal floods was considered during the meeting. To obtain practical skills in analysis of flood propagation scenarios RNPP personnel developed Cf2 flood area description (cross sectional electrical equipment hall).
In general, the meeting enabled RNPP staff to fulfill far more detailed consideration of the procedure on the EOI analytical justification and estimation of CDF due to internal floods, as well as to obtain necessary practical skills.