Nuclear Reinsurer Earns B++ Rating from AM Best
AM Best assigned Nuclear Industry Reinsurance Association a B++ Financial Strength Rating and a stable outlook.
Updated on Nov. 5, 2026 in Nuclear
AM Best assigned Nuclear Industry Reinsurance Association, a mutual reinsurer based in Luxembourg, a B++ Financial Strength Rating and a bbb+ Long-Term Issuer Credit Rating, both with a stable outlook. The agency cited strong balance sheet strength and the strongest level of risk-adjusted capitalisation as measured by BCAR.
Why it matters
The ratings signal that NIRA's available capital is sufficient to more than fully cover two full limit losses for nuclear accidents. Its 2025 combined ratio of 439%, driven by two large conventional non-nuclear energy liability claims, shows how volatile results can be for a small reinsurer covering these risks.
AM Best rates NIRA at B++ and bbb+, with a 2025 combined ratio of 439% versus 35% to 66% in the four prior years. Its five-year average return on capital and surplus was 2.1%, and the agency expects prospective operating performance to remain adequate but volatile.
The players
Nuclear Industry Reinsurance Association (NIRA)
A Luxembourg-based mutual reinsurer that provides third-party liability and material damage coverage for nuclear and conventional energy risks to its members.
AM Best
A credit rating agency that specializes in the insurance industry and assigns financial strength and issuer credit ratings to insurers and reinsurers.
The details
NIRA, a small mutual reinsurer providing third-party liability and material damage covers to its members, had its 2025 results pushed up by unfavourable developments on two large claims linked to conventional non-nuclear energy risks. AM Best assessed its liquid investment portfolio as having good asset quality and its capitalisation as the strongest level measured by BCAR.
Timeline
2025: NIRA reports a 439% combined ratio driven by two large claims.
Five-year period ending in 2025: NIRA averages a 2.1% return on capital and surplus.
November 5, 2026: AM Best publishes the rating assignment for NIRA.
Big Picture
NIRA's B++ rating rests on AM Best's BCAR framework, which measures risk-adjusted capital, and NIRA scores at the strongest level under it. The rating therefore reflects capital strength, even though NIRA's 2025 combined ratio of 439% shows that earnings can swing sharply for reinsurers covering nuclear and energy liability risks.
For readers following nuclear energy costs, the rating indicates NIRA's ability to pay large nuclear accident claims, which underpins liability coverage for operators. The stub gives no direct effect on premiums or policyholders.
The takeaway
Strong capital can offset volatile earnings when insurers cover catastrophic risks. Readers tracking nuclear insurance should weigh both a reinsurer's capitalisation and its year-to-year claim results.
Further reading
Explore more coverage in the Nuclear section.
Source note: This article includes information reported by Ambest.
