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v3.22.1

Accounts Receivable (Details) - USD ($) $ in Thousands | Mar. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | --- | ---
Accounts Receivable |  |  |
Deferred DOE cost share liabilities | $ 10,237 | $ 10,237 | $ 0

X
- Definition The carrying amount of deferred DOE cost share liabilities. + References No definition available. + Details
Name: | svsvu_DeferredDoeCostShareLiabilities
Namespace Prefix: | svsvu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- References No definition available. + Details
Name: | us-gaap_AccountsReceivableNetCurrentAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration