Under the guidance of the Nuclear Science Committee (NSC), the Working Party on Scientific Issues of Reactor Systems (WPRS) studies the reactor physics, fuel performance, and radiation transport and shielding in present and future nuclear power systems. The working party also studies the uncertainties associated with the modelling of these phenomena, particularly the modelling of reactor transient events.

The WPRS's objective is to provide member countries with up-to-date information to preserve knowledge on and develop consensus in the following areas:

Fuel performance aspects include:

• reactor-based plutonium disposition
• experiments (International Fuel Performance Experiments [IFPE] database).

Reactor physics aspects considered include:

• reactivity characteristics and reactivity control
• core power/flux distributions
• fuel depletion
• advanced nuclear systems
• experiments (International Reactor Physics Experiments [IRPhE] Project).

Radiation transport and shielding aspects include:

• reactor vessel dosimetry
• reactor biological shielding
• accelerator and irradiation facility shielding
• experiments (Shielding Integral Benchmark Archive Database [SINBAD]).

Reactor core thermal-hydraulics aspects include:

• methodologies for modelling on different scales
• technics for high to low fidelity/resolution model data exchange (Hi2Lo)
• fluid structural mechanical interactions for normal and deformed cores
• preservation of experimental data

Uncertainty analysis aspects include:

• coupled neutronics/thermal hydraulics transient modelling
• benchmark comparisons
• sensitivity analysis.

Prior to the creation of the WPRS, a number of reactor physics benchmarks were undertaken.

Reactor types considered include, but are not limited to the following:

• present generation light water reactors (LWRs) with advanced and innovative fuels, evolutionary and innovative LWRs and heavy water reactors (HWRs)
• advanced reactor systems
• accelerator-driven (sub-critical) and critical systems for waste transmutation.

The WPRS liaises closely with other NEA working groups, especially those operating under the guidance of the Committee for Technical and Economic Studies on Nuclear Energy Development and the Fuel Cycle (NDC) and the Committee on the Safety of Nuclear Installations (CSNI) in order to ensure the respective work programmes are complementary and to provide advice and support where required and undertake common work where appropriate. Particularly close working relationships are maintained with the Working Party on Scientific Issues of the Fuel Cycle (WPFC), the Working Party on Multi-scale Modelling of Fuels and Structural Materials for Nuclear Systems (WPMM) and other relevant NSC working parties.