As China’s self-developed third-generation pressurized water reactor, the HPR1000 is equipped with an independently designed control rod drive line, which acts as pivotal equipment for reactor reactivity regulation, power maintenance, and emergency shutdown. The drive line is the only movable integrated unit inside the reactor, and its performance directly governs nuclear plant operational safety. Compared with second-generation nuclear power units, the HPR1000 imposes more stringent technical requirements: a 60-year design lifetime, a 0.3 g seismic resistance criterion, and Class 1 nuclear safety grade for rod position detectors, along with innovative designs including an integrated pressure-bearing shell and double-tooth latch claws. Current studies mostly focus on individual tests rather than the systematic, full-lifecycle, comprehensive verification of the complete drive line. Given its novelty and insufficient engineering verification, full-scale integrated tests are urgently required. This study assesses the lifetime safety function, operational reliability, and seismic performance of the HPR1000 drive line; verifies the rationality of the structural design and the accuracy of theoretical simulations; reveals the influencing mechanism of thermal-hydraulic and seismic factors; and fills the technical gap in full-cycle verification for third-generation nuclear power drive lines.

A full-lifecycle comprehensive verification framework was established following a rational test sequence of individual equipment, cold- and hot-state lifetime performance, and formal seismic tests, supplemented by seismic precursor and ultimate lifetime exploration tests. For single equipment verification, a counterweight lifetime test of the control rod drive mechanism (CRDM) was implemented with 6 million stepping cycles to simulate actual high-temperature and high-pressure operating environments. Qualification tests covering functional inspection, aging, irradiation, mechanical load, and seismic assessment were completed for rod position detectors using structurally reserved scaled specimens. Using 1 : 1 full-scale prototypes identical to actual reactor components, cold- and hot-state integrated tests were carried out on a large thermal-hydraulic facility under four typical working conditions. Over 9.12 million stepping operations and 707 rod drop tests were performed, together with sensitivity tests covering variations in the main flow, reactor top bypass flow, misalignment, initial rod positions, and CRDM ventilation loss. A newly developed multi-point loading seismic test device was adopted to provide bidirectional multi-point excitation. Five half-safe shutdown earthquake (SSE) tests and one formal SSE test were conducted with conservative load margins. Comparative analyses were performed between horizontal-only and coupled horizontal–vertical seismic excitations, as well as between precursor and formal seismic tests using thermally aged prototypes.

All rod drop time indicators under normal and seismic conditions fully satisfied design limits with sufficient safety margins. The CRDM maintained stable operation throughout the lifetime test, and double-tooth latch claw wear stayed within the allowable range, whereas cavitation on magnetic isolation plates prompted optimization to nickel-based alloy materials. Rod position detectors passed all qualification tests and met Class 1 safety requirements. Main flow prolonged rod drop time by forming flow resistance, whereas top bypass flow exerted a slight opposite effect. A 5 mm design-limited misalignment barely increased friction and rod drop time, whereas excessive misalignment caused a sharp increase in friction. Even under complete ventilation loss, the CRDM coil temperature remained below the 200 ℃ design threshold. Post-test inspection confirmed prototype integrity, with all wear characteristics within expectations. Seismic tests showed that horizontal excitation dominates variations in rod drop time, whereas vertical seismic impact was negligible. Rod drop time of aged prototypes increased moderately compared with precursor tests due to elevated surface friction, rendering the evaluation more conservative.

The HPR1000 control rod drive line fully meets the design criteria of a 60-year lifetime, 0.3 g seismic resistance, and nuclear safety requirements, with excellent comprehensive performance. This study established a complete verification platform and mastered core test and analysis technologies. It quantitatively characterized the effects of temperature, flow rate, misalignment, and seismic excitation on drive line dynamic performance and effectively validated theoretical calculation and simulation models. The study also explored the ultimate service potential of the drive line and proposed targeted material optimization schemes. The findings provide technical support for the safe operation of HPR1000 units and offer a reliable reference for the design and verification of similar nuclear-grade key equipment.