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Application Guide

Valves for Nuclear Power Plants

Nuclear power plants demand the most stringent valve qualification programme in any industry — ASME Section III Class 1/2/3 design and fabrication rules, N-stamp third-party oversight, seismic qualification to IEEE 344, and MOV actuator qualification to IEEE 382. Vajra Industrial Solutions supplies ASME Section III Class 2 and Class 3 valves for balance-of-plant (BOP) systems — auxiliary cooling, spent fuel pool cooling, condensate, feedwater, and service water — with complete QA/QC documentation traceable to 10 CFR 50 Appendix B in international projects and AERB guidelines in India.

ASME Section III (Class 2/3)ASME B16.34IEEE 382 (MOV)IEEE 344 (Seismic)10 CFR 50 Appendix BAERB (India)NRC Regulatory Guides
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Recommended Valve Types for Nuclear Power Plants

Gate Valve (ASME Sec. III Cl.2)

Class 150 / 300 / 600 (ASME B16.34 ratings)

Why: Main isolation on auxiliary cooling, emergency core cooling (ECCS) suction, and spent fuel pool cooling

Materials: A351 CF8M (SS316 cast), A182 F316 forged (Class 2); WCB with SS316 trim (Class 3)

Standards: ASME Section III NB/NC/ND, ASME B16.34, ASME B16.10

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Globe Valve

Class 150 / 300

Why: Throttling and control on reactor auxiliary cooling, chemical dosing, and letdown systems

Materials: A351 CF8M SS316, A182 F316L for radioactive waste service

Standards: ASME Section III Class 2/3, IEEE 382 for motor-operated versions

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Check Valve

Class 150 / 300 / 600

Why: Back-flow prevention on ECCS injection lines, charging pump outlets, and feedwater systems

Materials: A351 CF8M (SS316), A182 F316 lift or swing check

Standards: ASME Section III Class 2/3, API 594

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Butterfly Valve

Class 150

Why: Large-bore isolation on service water, component cooling water, and turbine building HVAC

Materials: A216 WCB with SS316 disc and EPDM seat; rubber-lined for raw water service

Standards: ASME Section III Class 3, AWWA C504, IEEE 382

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Critical Requirements

ASME Section III Class 2/3 design: complete material traceability (Certified Material Test Reports — CMTRs) for all pressure-boundary components
N-stamp or NA-stamp: third-party ASME Nuclear Inspector oversight for Class 2 and above
Seismic qualification per IEEE 344 — valves on safety-related systems must withstand Operating Basis Earthquake (OBE) and Safe Shutdown Earthquake (SSE)
Motor-operated valves (MOVs) qualified per IEEE 382 — torque, voltage variation, and harsh-environment performance testing
QA programme per 10 CFR 50 Appendix B (USA) or AERB Safety Guide (India) — design control, procurement document control, inspection, and test records
No substitution of materials without NCR (Non-Conformance Report) and AERB/NRC approval — traceability is mandatory

Fluid & Service Challenges

⚠Primary coolant (reactor-grade water) — ultra-low chloride (<0.1 ppm); SS316L or Alloy 600 trim to avoid stress corrosion cracking
⚠Borated water — boric acid corrosion; SS316 or high-alloy materials mandatory
⚠Heavy water (D₂O) — CANDU/PHWR reactors; no moisture absorption; all valve internals must be compatible with D₂O chemistry
⚠Steam and feedwater — IBR certification mandatory in India; ASME B31.1 code compliance
⚠Service water (raw river/sea water) — rubber-lined butterfly valves or duplex stainless for seawater

Material Selection Guidance

Class 1 (primary boundary — Vajra does not supply): Alloy 600/690, SA-351 CF8M SS316. Class 2 (auxiliary systems): SA-351 CF8M for cast bodies; SA-182 F316 or F316L for forged/machined components. Class 3 (balance of plant): A216 WCB with SS316 trim acceptable; rubber-lined butterfly for raw service water. All Class 2/3 materials must have Certified Material Test Reports (CMTRs) from mill — no commercial-grade dedication without proper programme.

Typical Service Points

Spent fuel pool cooling — gate and check valves, Class 2 SS316 (passive safety system)
Emergency core cooling system (ECCS) — Class 2 gate valves on injection headers
Reactor auxiliary cooling water — Class 2 gate, globe, and check valves
Component cooling water (CCW) — Class 3 butterfly and gate valves
Service water (raw intake) — rubber-lined butterfly, Class 3
Turbine building feedwater/steam — IBR gate/globe/check in India; ASME B31.1 internationally

FAQ — Valve Selection for Nuclear Power Plants

What is ASME Section III and why does nuclear require it?
ASME Section III is the Boiler and Pressure Vessel Code for Nuclear Facility Components. Unlike ASME B16.34 (industrial valves), Section III imposes full design analysis, material traceability to mill certificates (CMTRs), N-stamp third-party oversight during manufacturing, and complete quality records. Class 1 covers the primary pressure boundary (reactor coolant), Class 2 covers safety-related secondary systems (ECCS, spent fuel cooling), and Class 3 covers other safety-related systems (service water). Vajra supplies Class 2 and 3 components for balance-of-plant applications.
What is the difference between nuclear Class 2 and Class 3 valves?
ASME Section III Class 2 applies to systems that could affect the safety function of the reactor coolant boundary — e.g., emergency core cooling, spent fuel pool cooling. Class 3 applies to systems important to safety but with a lower direct interface — service water, fire protection, component cooling water. Class 2 requires more rigorous design documentation, full material traceability, and N-stamp inspection. Class 3 has slightly relaxed requirements but still demands CMTRs and a documented QA programme.
Does Vajra supply valves for Indian nuclear plants (NPCIL/BHAVINI)?
Vajra supplies balance-of-plant valves meeting ASME Section III Class 2 and 3 requirements with full CMTR documentation for NPCIL PHWR projects and BHAVINI FBR applications. All valves comply with AERB Safety Guide requirements. We supply gate, globe, check, and butterfly valves for service water, auxiliary cooling, turbine island, and condensate systems with IBR certification for steam service. Contact us for NPCIL project-specific documentation requirements.

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Nuclear Power Plants

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Key Standards

ASME Section III (Class 2/3)
ASME B16.34
IEEE 382 (MOV)
IEEE 344 (Seismic)
10 CFR 50 Appendix B
AERB (India)
NRC Regulatory Guides

Products for This Application

Gate ValvesGlobe ValvesButterfly ValvesCheck Valves

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