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  <xsd:element name="SubsequentEventsDetailsTable" id="df_SubsequentEventsDetailsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="PrivatePlacementPipeMember" id="df_PrivatePlacementPipeMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="PlacementAgentWarrantsMember" id="df_PlacementAgentWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="StockIssuedDuringPeriodSharesConversionOfDerivativeInstruments" id="df_StockIssuedDuringPeriodSharesConversionOfDerivativeInstruments" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="LegacyDeepFissionMember" id="df_LegacyDeepFissionMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="BusinessCombinationConversionNumberOfSharesIssuedPerShare" id="df_BusinessCombinationConversionNumberOfSharesIssuedPerShare" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="BusinessCombinationSharesIssuedAndOutstandingTableTextBlock" id="df_BusinessCombinationSharesIssuedAndOutstandingTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="LegacySurfsideShareholdersMember" id="df_LegacySurfsideShareholdersMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="AdvisorMember" id="df_AdvisorMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ProceedsFromDerivativeInstrumentFinancingActivitiesIssuance" id="df_ProceedsFromDerivativeInstrumentFinancingActivitiesIssuance" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ProceedsFromDerivativeInstrumentFinancingActivitiesSubscription" id="df_ProceedsFromDerivativeInstrumentFinancingActivitiesSubscription" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FairValueAssetsLevel1ToLevel2TransfersAmount" id="df_FairValueAssetsLevel1ToLevel2TransfersAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="FairValueAssetsLevel2ToLevel1TransfersAmount" id="df_FairValueAssetsLevel2ToLevel1TransfersAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="FairValueLiabilitiesLevel1ToLevel2TransfersAmount" id="df_FairValueLiabilitiesLevel1ToLevel2TransfersAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="SafeNotesMember" id="df_SafeNotesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="FiveYearsAfterClosingDateMember" id="df_FiveYearsAfterClosingDateMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ThreeYearsAfterSharesListedOnNseMember" id="df_ThreeYearsAfterSharesListedOnNseMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="EquityIncentivePlan2025Member" id="df_EquityIncentivePlan2025Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardAnnualSharesIssuanceIncrementalPeriod" id="df_ShareBasedCompensationArrangementByShareBasedPaymentAwardAnnualSharesIssuanceIncrementalPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardAnnualIncreaseInAuthorizedSharesPercentage" id="df_ShareBasedCompensationArrangementByShareBasedPaymentAwardAnnualIncreaseInAuthorizedSharesPercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="ValueOfDerivativeInstrumentIssued" id="df_ValueOfDerivativeInstrumentIssued" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="AdjustmentsToAdditionalPaidInCapitalWarrantIssuedIssuanceCosts" id="df_AdjustmentsToAdditionalPaidInCapitalWarrantIssuedIssuanceCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ClassOfWarrantOrRightTotalGrantDateFairValueOfWarrantsOfRightsIssued" id="df_ClassOfWarrantOrRightTotalGrantDateFairValueOfWarrantsOfRightsIssued" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="PreMergerEquityPlanMember" id="df_PreMergerEquityPlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ClassOfWarrantOrRightGrantDateFairValuePerShare" id="df_ClassOfWarrantOrRightGrantDateFairValuePerShare" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" />
  <xsd:element name="DeepIsolationNuclearIncMember" id="df_DeepIsolationNuclearIncMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="February2026WarrantsMember" id="df_February2026WarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="AdjustmentsToAdditionalPaidInCapitalRsuLiabilityAwardReclassification" id="df_AdjustmentsToAdditionalPaidInCapitalRsuLiabilityAwardReclassification" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="LesseeOperatingLeasePurchaseOptionContingentPurchasePrice" id="df_LesseeOperatingLeasePurchaseOptionContingentPurchasePrice" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ShareBasedPaymentArrangementPlanModificationFairValuePerShare" id="df_ShareBasedPaymentArrangementPlanModificationFairValuePerShare" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="ProceedsFromIssuanceInitialPublicOfferingNetOfUnderwritingDiscount" id="df_ProceedsFromIssuanceInitialPublicOfferingNetOfUnderwritingDiscount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ThresholdPeriodToPurchaseAdditionalShares" id="df_ThresholdPeriodToPurchaseAdditionalShares" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="UnderwritingExpense" id="df_UnderwritingExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="StockIssuanceCosts" id="df_StockIssuanceCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ClassOfWarrantOrRightNumberOfWarrantsExercised" id="df_ClassOfWarrantOrRightNumberOfWarrantsExercised" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="StockIssuedDuringPeriodSharesExerciseOfWarrants" id="df_StockIssuedDuringPeriodSharesExerciseOfWarrants" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="ProceedsFromExerciseOfWarrants" id="df_ProceedsFromExerciseOfWarrants" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="IssuanceOfInitialPublicOfferingCommonStockShares" id="df_IssuanceOfInitialPublicOfferingCommonStockShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="IssuanceOfInitialPublicOfferingCommonStockAmount" id="df_IssuanceOfInitialPublicOfferingCommonStockAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="UnderwritingDiscountsAndOfferingCostsRelatedToInitialPublicOffering" id="df_UnderwritingDiscountsAndOfferingCostsRelatedToInitialPublicOffering" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="IssuanceOfCommonStockForCashlessExerciseOfEquityComponentWarrantsShares" id="df_IssuanceOfCommonStockForCashlessExerciseOfEquityComponentWarrantsShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="IssuanceOfCommonStockToFormerSafeNoteHoldersShares" id="df_IssuanceOfCommonStockToFormerSafeNoteHoldersShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
</xsd:schema>
