RELATED PARTY - Schedule of transactions (Details) $ in Thousands	3 Months Ended
Mar. 31, 2023 USD ($)
Related Party
Balance of funds remaining on deposit with General Atomics at end of year	$ 1,866
General Atomics
Related Party
Balance of funds paid under the Cost Share Agreement at beginning of year	6,700
Funds transferred to General Atomics during the year	1,000
Company's share of Demonstration Plant project costs during the year	(5,834)
Balance of funds remaining on deposit with General Atomics at end of year	$ 1,866

Receivables to be collected from (obligations owed to) related parties, net as of the balance sheet date within one year where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(k)(1))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Name:	us-gaap_RelatedPartyTransactionDueFromToRelatedPartyCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant