Now turning to our consolidated annual results. For the full year 2023, consolidated Net Sales were $6.0 billion, down 11% from the prior year. This decline was driven by lower year-over-year volumes in TT and in our APM segment’s Advanced Materials portfolio, partially offset by stronger volumes and pricing in TSS. For the full year, GAAP Net Loss was $238 million, or $1.60 per diluted share, adjusting primarily for $639 million of after-tax litigation settlement charges. Full year Adjusted Net Income was $425 million, or $2.82 per diluted share, compared to $738 million, or $4.66 per diluted share, in the prior year. Full year 2023 Adjusted EBITDA was $1.0 billion, down 25% from 2022, attributable to weaker results in TT and APM.
Our full year consolidated Adjusted EBITDA figure includes a $40 million charge related to non-cash inventory write-offs for our Kuan Yin facility closure. I want to be clear about what this reflects. In our third quarter results, Adjusted EBITDA excluded the impact of a $36 million charge for non-cash inventory write-offs associated with our Kuan Yin facility closure. As you may have seen in our comment letter filings with the SEC, subsequent to the filing of the third quarter Form 10-Q, we agreed that it would be appropriate to classify all non-cash inventory write-offs associated with our Kuan Yin facility closure as cost of goods sold. As such, we have now included this $36 million impact in consolidated Adjusted EBITDA for the year ended December 31, 2023. For the full year, non-cash inventory write-offs associated with the Kuan Yin facility closure were $40 million, all of which are reflected in cost of goods sold.
Now turning to our business segments, starting with TT. In the fourth quarter, TT Net Sales increased 7% year-over- year to $651 million. This improvement was driven by a 12% increase in volume on stronger demand in all regions, except for the North American market. Prices overall were down 6% year-over-year. Prices declined for market- exposed channels, which was partially offset by price increases for our contractual volumes. Currency impact was a slight 1% tailwind for the quarter.
Fourth quarter Adjusted EBITDA for TT was $64 million, up 52% versus the prior-year quarter, resulting in a 10% Adjusted EBITDA Margin, or 300 basis points higher year-over-year. These increases were primarily driven by the growth in volume and cost savings from our TT Transformation Plan.
Moving now to our TSS segment. For the fourth quarter, TSS delivered a 17% year-over-year increase in Net Sales to $374 million. This result was driven by broad-based 10% growth in volumes across portfolios, with the exception of legacy refrigerant products, and a 6% increase in price, driven by pricing actions across legacy HFCs and in our Foam, Propellants, and Other Products portfolio. Currency impact also provided a 1% tailwind to growth. Fourth quarter Adjusted EBITDA for TSS reached $124 million, up from $54 million in the prior-year quarter. Adjusted EBITDA Margin was 33%, 16 percentage points higher year-over-year.
Now, turning to APM. For fourth quarter 2023, Net Sales for APM were $325 million, 15% lower versus the prior year. This result was attributable to 18% lower volume, partially offset by a 2% increase in price and a 1% currency tailwind. Softness was driven by a 27% Net Sales decline in our Advanced Materials portfolio, which covers more economically sensitive end markets. This was partially offset by an 11% increase in Net Sales for our Performance Solutions portfolio. For the quarter, Adjusted EBITDA for APM was $40 million, down compared to $61 million in the prior-year quarter. Adjusted EBITDA Margin was 12%, 400 basis points lower year-over-year. The declines were attributable to lower fixed-cost absorption given lower volume and an extended outage for maintenance and improvements during the quarter at one of our manufacturing sites, which is now back online.
Moving on now to our cash flow and balance sheet statements. In the fourth quarter 2023, we generated $482 million in GAAP operating cash flow, an increase of $321 million compared to the prior-year quarter. Fourth quarter Capex totaled $135 million, up from $67 million in the prior-year quarter. This increase in capex was driven by increased growth capital investments in our Performance Solutions portfolio in APM.
For full year 2023, GAAP operating cash flow was $556 million, compared to $755 million in the prior year. The year- over-year change was driven primarily by lower earnings and $66 million of outflows for PFAS litigation settlements, partially offset by working capital. Capex was $370 million, compared to $307 million in the prior year. This was lower than originally projected due to project timing.
As of December 31, 2023, Chemours had an unrestricted cash and cash equivalents balance of $1.2 billion. We also maintained $604 million in restricted cash and restricted cash equivalents held in escrow primarily related to the Chemours comprehensive settlement of PFAS-related drinking water claims announced in June of 2023. As we have previously disclosed, Chemours’ share of this settlement is $592 million and is already reflected in our restricted cash and restricted cash equivalents balance on the balance sheet as of December 31, 2023.
Disbursement of the restricted cash and restricted cash equivalents from escrow is pending the approval for the settlement becoming final in accordance with the terms of the settlement agreement. We also settled PFAS-related claims with the State of Ohio on November 28th, with our share of the settlement under the related MOU totaling $55 million. We expect this amount to be paid this year. Our total liquidity was $2.1 billion at year-end. This includes the $852 million available under our undrawn revolving credit facility net of outstanding letters of credit, but excludes restricted cash and restricted cash equivalents.
Turning to our capital profile. As of December 31, 2023, consolidated gross debt was $4.1 billion. Debt, net of our $1.2 billion of unrestricted cash and cash equivalents, was $2.9 billion. This resulted in a net leverage ratio of approximately 2.8x on a trailing 12-month Adjusted EBITDA basis at the end of the year. In 2023, we increased our aggregate borrowings by $400 million by amending and extending our U.S. dollar and euro-denominated term loans, providing additional flexibility to our capital structure. In terms of capital return to shareholders in 2023, we returned $218 million to shareholders in the form of $149 million of dividends and $69 million of share repurchases.