Constant STORAGE_CLEAR_REFUND 

pub const STORAGE_CLEAR_REFUND: u64 = _; // 12_480u64

Available on crate feature evm only.

Refund for clearing a storage slot (was 4,800 pre-EIP-8038).

Derived per the spec as (STORAGE_WRITE + COLD_STORAGE_ACCESS) * 4800 / 5000.