AM Best has assigned a Financial Strength Rating of B++ (Good) and a Long-Term Issuer Credit Rating of “bbb+” (Good) to Nuclear Industry Reinsurance Association (NIRA) (Luxembourg). The outlook assigned to these Credit Ratings (ratings) is stable.

The ratings reflect NIRA’s balance sheet strength, which AM Best assesses as strong, as well as its adequate operating performance, limited business profile and appropriate enterprise risk management.

NIRA’s balance sheet strength is supported by its risk-adjusted capitalisation at the strongest level, as measured by Best’s Capital Adequacy Ratio (BCAR). The mutual has limited financial flexibility to recapitalise in the event of a full limit loss; however, its available capital is sufficient to more than fully cover two full limit losses for nuclear accidents. The assessment is supported further by the mutual’s liquid investment portfolio with good asset quality.

NIRA has a track record of adequate operating performance with an average return on capital and surplus of 2.1% for the five-year period ending in 2025. The mutual reported a combined ratio of 439% in 2025, which was driven by unfavourable developments on two large claims tied to conventional non-nuclear energy third-party liability risks. Combined ratios in the preceding four years ranged between 35% and 66%. AM Best expects prospective operating performance to remain adequate, albeit subject to volatility due to the nature of the risks underwritten.

NIRA’s business profile assessment of limited reflects the mutual’s modest competitive position in the nuclear reinsurance market, as a small mutual reinsurer mainly providing third-party liability and material damage covers to its members. The mutual’s value proposition is enhanced by its provision of coverage for conventional non-nuclear energy property and liability risks. Strong demand for nuclear insurance capacity and suitable geographical diversification of reinsured assets partially offset the mutual’s limited profile and high-risk nature of the business underwritten.

This press release relates to Credit Ratings that have been published on AM Best’s website. For all rating information relating to the release and pertinent disclosures, including details of the office responsible for issuing each of the individual ratings referenced in this release, please see AM Best’s Recent Rating Activity web page. For additional information regarding the use and limitations of Credit Rating opinions, please view Guide to Best’s Credit Ratings. For information on the proper use of Best’s Credit Ratings, Best’s Performance Assessments, Best’s Preliminary Credit Assessments and AM Best press releases, please view Guide to Proper Use of Best’s Ratings & Assessments.

AM Best is a global credit rating agency, news publisher and data analytics provider specialising in the insurance industry. Headquartered in the United States, the company does business in over 100 countries with regional offices in London, Amsterdam, Dubai, Hong Kong, Singapore and Mexico City. For more information, visit www.ambest.com.

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