Chicken money

I have been mostly invested in stock mutual funds and ETFs. I have been retired for about 10 yrs. Currently I have about 10% of my IRA in VANGUARD TREASURY MONEY MARKET INVESTOR CL. I plan on increasing short term money to about 15% of my holdings. My question is that fund close to the risk of buying treasury bonds directly? In context my pension and Social Security not only pays my basic expenses but I am investing about 20 % of it into my non retirement brokerage account. I am debt free and that makes me able to tolerate more risk.