Nigerian research reactor operator committed to safety

12 August 2019

The operator of the Nigerian Research Reactor-1, known as NIRR-1, has shown a high commitment to safety following the conversion of the reactor core to use low-enriched uranium as fuel instead of high-enriched uranium, according to the International Atomic Energy Agency (IAEA). It made a number of recommendations to the Nigeria Atomic Energy Commission (NAEC) to further enhance safety.

The NIRR-1 reactor hall (Image: Ahmadu Bello University)

In December 2018, more than 1 kilogram of Chinese-origin highly enriched uranium (HEU) from NIRR-1 was returned to China in an operation involving the two countries, the IAEA and the US Department of Energy's National Nuclear Security Administration. Shipment of low-enriched uranium (LEU) fuel to NIRR-1 began last October and the reactor reached full-power operation using LEU fuel in late November.

An IAEA Integrated Safety Assessment of Research Reactors (INSARR) mission is conducted at the request of an IAEA member state. It is a peer review service that assesses and evaluates the safety of research reactors based on IAEA safety standards.

A five-day INSARR mission to assess the safety of the NIRR-1 reactor concluded on 9 August. The four-member team comprised experts from India and Jamaica, as well as the IAEA. The mission covered organisational and management aspects as well as technical areas including safety analysis, operation and maintenance programmes, radiation protection, and emergency preparedness.

"The reactor operator has effectively utilised experience gained from similar facilities to successfully convert the core from HEU to LEU fuel," said team leader David Sears, senior nuclear safety officer at the IAEA. "The operator is showing a high commitment to safety."

However, the INSARR team made recommendations to NAEC for further improving safety at NIRR-1. These include completing the revision of reactor safety and operating documentation to reflect the results of the commissioning of the reactor following the fuel conversion. It also said the development and implementation of an ageing management programme for the reactor should be finalised in a timely manner. Also, an integrated management system should be finalised to enhance safety and foster a strong safety culture.

NAEC Chairman Simon Mallam said: "We are committed to implementing the recommendations. The reactor's continued safe operation will assist our efforts to embark on a new project for a more powerful 10 MW research reactor and will contribute to education and training in view of Nigeria's nuclear power programme."

NAEC said it will request a follow-up INSARR mission by 2021.

NIRR-1 is a Miniature Neutron Source Reactor (MNSR) designed, manufactured and constructed by the China Institute of Atomic Energy, and has a maximum thermal power level of 30kW. Originally fuelled with 90.2% HEU, the reactor is designed for use in universities, hospitals and research institutes, mainly for neutron activation analysis, production of short-lived radioisotopes, education and manpower development. The NIRR-1 reactor was originally commissioned in 2004 at Ahmadu Bello University's Centre for Energy Research and Training.

China National Nuclear Corporation in the 1990s helped Ghana, Nigeria and other countries to build "micro-piles" like NIRR-1 to support nuclear science research and personnel training. In 2006, efforts began to convert Chinese-designed MNSRs from HEU to LEU fuel, enriched to less than 20% U235. Ghana's GHARR-1 was the first of five such MNSR reactors outside of China to become eligible for conversion and fuel return to China. Conversion of GHARR-1 to LEU was completed in July 2017, and its HEU fuel was returned to China the following month.

Nigeria has sought the support of the IAEA to develop plans for up to 4000 MWe of nuclear capacity by 2025. IAEA support has included two missions to Nigeria in 2015, which found the country's emergency preparedness and response framework to be consistent with IAEA safety standards. A ten-day IAEA Integrated Regulatory Review Service peer review mission in 2017 described the country's nuclear regulator, the Nigerian Nuclear Regulatory Authority, as a "committed" regulatory body working for the continuous improvement of nuclear and radiation safety.

Researched and written by World Nuclear News