MAJOR CUSTOMERS AND CONCENTRATION OF CREDIT RISK - Accounts receivable (Details) - Accounts receivable - Credit Concentration Risk	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Concentration Risk
Concentration risk percentage	100.00%	100.00%
Southern Nuclear Operating Company
Concentration Risk
Concentration risk percentage	42.00%	16.00%
Con Edison
Concentration Risk
Concentration risk percentage	12.00%
Tennessee Valley Authority
Concentration Risk
Concentration risk percentage		18.00%
Bruce Power
Concentration Risk
Concentration risk percentage		17.00%
Comprehensive Decommissioning International
Concentration Risk
Concentration risk percentage		10.00%
All Others
Concentration Risk
Concentration risk percentage	46.00%	39.00%