The first stage of both bodies' joint Generic Design Assessment (GDA) of new plants found "no shortfalls at this stage - in terms of safety, security or the environment - that would prevent any of them from ultimately being constructed on licensed sites in the UK".
The four designs cleared to progress are:
AECL's ACR 1000
EdF/Areva's European Pressurised Reactor (EPR)
General Electric-Hitachi's ESBWR
HM Chief Inspector of Nuclear Installations and Head of the HSE's Nuclear Directorate Dr Mike Weightman said: "As new nuclear power stations are being considered for the UK, it is vital for regulators to get involved with potential designs at the earliest stage - where regulatory assessments can have most influence - so that we can ensure that the existing high standards of nuclear safety and security in the UK are being maintained and improved."
The GDA process began in August 2007 and is expected to take three and a half years in total, at the end of which the HSE and Environment Agency will make recommendations on the best designs to allow to be built.
The first initial stage that has finished consisted simply of a fundamental safety overview by the HSE and preliminary review by the Agency.
It will now make way for a detailed design assessment and Agency head of Radioactive Substances Regulation Joe McHugh reminded firms submitting the designs that the process was far from over.
"We demand that any new nuclear power stations meet high standards of safety, security and environment protection," said McHugh.
"As we begin the detailed assessment step of GDA, the reactor vendors and the regulators have much work to do before we will be able to decide whether these designs can meet those high standards."
In the January 2008 Energy White Paper, the Government announced that if necessary it would run a prioritisation exercise to identify, in conjunction with reactor designers and operators, which of the four designs, subject to the regulators' initial assessment, is most likely to go through for licensing and construction.
Currently the Department for Business Enterprise and Regulatory Reform (BERR) is awaiting confirmation from all of the design companies that they wish to continue to the next stage of GDA.
If BERR does decide that it needs to undertake a prioritisation process, then at the end of that process the Secretary of State will make recommendations to HSE and the Environment Agency on the designs that should be given the highest priority for progressing through the next stage.