Safety Criteria

When analyzing emergency conditions and establishing safety measures, the RBMK -1500 design is based on the following safety criteria:

With the reactor at nominal power, breaking of the maximum diameter pipe with discharge of coolant from both ends is considered to be the design basic accident (DBA).

First design limit of fuel-element failure under normal operating condition:

• 1% of fuel elements with gas leakage-type defects and
• 0.1% of fuel elements having defects resulting in direct contact between coolant and fuel.

Second design limit on fuel failure:

• fuel cladding temperature less that 1200 C
• local depth of fuel cladding oxidation less than 18 % of initial clad thickness
• fraction of zirconium oxidation less than 1% of fuel cladding weight in one group distribution header channels (about 40 of such channels).

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