RELATED PARTY - Schedule of transactions - General Atomics (Details) - General Atomics - USD ($) $ in Thousands		12 Months Ended
May 16, 2024	Dec. 31, 2025	Dec. 31, 2024
RELATED PARTY
Balance of funds owing to (remaining on deposit with) General Atomics as a related party balance at beginning of year		$ 895	$ (3,435)
Funds transferred to General Atomics during the year			(8,500)
Funds returned by General Atomics during the year	$ 3,811		(3,811)
The Company's share of Demonstration Plant project costs incurred during the year		(2,509)	9,019
Balance of funds owing to (due from) General Atomics as a related party balance at end of year		$ (1,614)	$ 895

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481990/310-10-45-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c)(2)(i))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c)(2)(ii))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(g)(3))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

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