Right now 30-year U.S. treasuries are paying 3.03%, and historically companies might go bankrupt (thus voiding the "guarantee" part) more often than the U.S. government. So at least demand a premium over U.S. Treasuries.
How are you going to meet expenses if you spend $40k / year and plan to receive $24k / year?
If you're afraid of the stock market, I'd still allocate to it - just a lower amount. Deep in retirement, Vanguard's target date funds allocate 30% stocks. So I'd point to Vanguard's example and suggest you put 30% of the $900k in a total world stock investment to ensure the money keeps up with inflation. "Total World" means about half U.S. stocks, half international... an ETF like "VT" holds thousands of stocks from around the world, so it's the most diverse stock investment available.