Design Assurance for Nuclear: How PDL is Raising the Bar for Valve Validation

As nuclear new‑build projects progress, the need to integrate commercial off‑the‑shelf (COTS) valves into safety‑classified systems is becoming increasingly common. Products originally designed and verified to industrial codes, such as ASME B16.34, may not inherently satisfy the extensive quality assurance requirements enforced within nuclear environments. Ensuring compliance, therefore, requires a structured and evidence‑based approach.

PDL’s Design Assurance team has been working at the forefront of this challenge. With over 25 years of experience supporting design assurance across large, safety-critical UK engineering programmes, the team brings a depth of understanding to deliver a structured and evidence-based approach that moves commercial valves into nuclear service with confidence.

PDL successfully achieves this by undertaking a comprehensive gap analysis between the manufacturer’s existing qualification - often aligned with ASME B16.34 or equivalent - and the nuclear code of interest, such as ASME Section III or RCC‑M. This detailed comparison highlights where compliance already exists (for example, hydrostatic test pressures may already meet nuclear expectations) and where further substantiation is required. Typical shortfalls relate to documentation, markings, weld traceability and design validation under nuclear load cases.

To close these gaps, PDL adopts a Commercial Grade Item Dedication (CGID) methodology. This structured assurance process provides reasonable confidence that a commercial component can perform its safety function under nuclear plant conditions. CGID often includes activities such as material verification through X‑ray fluorescence (XRF), weld quality examination, and checks on identification and certification records.

Where nuclear design rules require analysis beyond the manufacturer’s commercial documentation, engineering substantiation may be carried out. This may include 3D scanning of components, creation of CAD models, and Finite Element Analysis (FEA) assessments to demonstrate structural integrity under operational, faulted, and seismic loads as required by the nuclear standards.

Targeted testing is applied where required to ensure nuclear‑grade validation. This may involve reproducing or supplementing the manufacturer’s pressure tests to nuclear code acceptance criteria, alongside any additional non‑destructive examination or mechanical checks needed to satisfy requirements.

All evidence - documentation, analysis, test results and quality records – is consolidated into a single Confidence Building Measure document or equivalent assurance package. This enables operators, regulators, and end‑users to clearly understand how each component meets nuclear expectations and ensures that decision‑making is transparent, traceable and defensible.

With the growing demand for nuclear‑compliant valves, PDL’s structured design assurance provides a pragmatic route for manufacturers and operators seeking to safely incorporate proven commercial products into the next generation of power plants - without the prohibitive cost of bespoke nuclear‑specific designs. To learn more about PDL’s Design Assurance and nuclear validation capabilities, contact the team: designassurance@pdl-group.com 

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