Systems Exam 6 - Intro to Accident Analysis Flashcards
(12 cards)
The purpose of accident analysis is…
…to demonstrate that the public is protected from the harm which could come to them as a result of a reactor accident.
Accident analysis assumes we’re operating within…
Tech Specs. FSAR Chapter 15 defines analyzed accidents.
Fuel centerline temperature limit basis
Un-irradiated UO2 melts at approximately 5080°F. The melting temperature decreases by about 58°F for every 10,000 MWD/MTU.
Tech Spec 2.1.1 Core Operating Safety Limits
In Modes 1 and 2, Peak fuel centerline temp. shall be maintained <5080°F at BOL, decreasing 9°F per 10,000 MWD/MTU Burnup.
DNBR Parameters (5)
1) Core Power
2) RCS Pressure
3) RCS Temperature
4) RCS Flow
5) By maintaining these parameters within limits we ensure DNBR of ≥1.16 is maintained
10 CFR 50.46 ECCS Design Basis criteria (5)
CLOTH
1) Core Geometry
2) Long Term Cooling
3) Cladding Oxidation
4) Cladding Temperature
5) Hydrogen Generation
10 CFR 50.46 ECCS Design Basis criteria: Cladding Temperature
<2200°F
Prevent loss of clad temperature
10 CFR 50.46 ECCS Design Basis Criteria: Cladding Oxidation
<17% of local clad thickness
Prevents excessive loss of local clad strength and ductility
10 CFR 50.46 ECCS Design Basis criteria: Hydrogen Generation
<1% of amount which would be produced if all zircaloy in the active core region reacted
Prevents excessive explosive mixtures of H2 and prevent non-condensable gas accumulation in Reactor Coolant System
10 CFR 50.46 ECCS Design Basis Criteria: Geometry
Core remains intact and coolable
Prevent cladding and fuel failures from blocking coolant channels
10 CFR 50.46 ECCS Design Basis Criteria: Long Term Cooling
Core remains in a configuration which can be cooled for a long period of time
Ensure that decay heat can be removed to prevent additional core damage
During Condition III Events (Infrequent Faults)…
→Radiation release may not exceed…
→DNBR shall be…
→10 CFR 20, but shall be a small fraction of the 10 CFR 100 limits (<25%)
→greater than or equal to design limit for most transients analyzed by Westinghouse (single rod withdrawal at power is an exception).
During Condition IV Events (Limiting Faults)…
→Radiation release does NOT exceed…
→the limits of 10 CFR 100.
