如果把反应堆看作一台高速行驶的列车，那控制棒就是控制列车行进速度的刹车，每次停堆换料启动前，开展控制棒控制能力的验证，精确的校准“刹车”能力，是保证反应堆安全运行的基础。传统的控制棒价值测量方法，需要在反应堆临界后开展，即在已经行驶的列车上验证刹车功能，有意外“停车”的风险, 而次临界刻棒，则通过对反应堆内空间效应的模拟在“停车”状态下验证控制棒的功能，具有安全高效的特点。

刻棒技术是海南核电与核动力院强强联合研发的成果。核动力院于2014年成立科研攻关团队开始次临界刻棒方法研究，掌握了扎实的理论技术，亟待实践检验；海南核电拥有丰富的启动物理试验实践经验，理论和实践的完美结合，让次临界刻棒技术迈上了应用的征程。次临界刻棒技术也是贯彻落实习近平总书记“要坚持安全发展、创新发展，坚持和平利用核能，全面提升核工业的核心竞争力”指示精神的重要举措。联合研发项目启动以来，团队始终秉持着“严谨求真，创新敢干，合作共赢”的理念，强化团队整体·协同力度，破解项目进展重、难点问题。

项目历时三年，经历了理论计算、试验方法开发、模型建立、试验验证、安审对话、批复应用多个阶段，团队成员一步一个脚印，解决了次临界状态下中子波动干扰、控制棒价值空间修正、堆芯次临界度修正等多个难题，成功实现了次临界刻棒技术的研发。同时，通过开展周密的现场试验准备工作，从对规程的反复研习，到试验过程的详细推演，再到数据处理软件的不断调试，最终成功实现了次临界刻棒的工程应用。

If the reactor is regarded as a high-speed train, the control rod is the brake that controls the speed of the train. Before each shutdown and refueling start, the verification of the control rod control ability and the accurate calibration of the "brake" ability are the basis for ensuring the safe operation of the reactor. The traditional control rod value measurement method needs to be carried out after the reactor criticality, that is, the brake function is verified on the train that has already been running, and there is the risk of accidental "stop", while the subcritical rod cutting method verifies the function of the control rod in the "stop" state through the simulation of the space effect in the reactor, which has the characteristics of safety and efficiency.

Rod carving technology is the result of joint research and development of Hainan Nuclear Power Institute and nuclear Power Institute. In 2014, the Nuclear Power Institute set up a research team to study subcritical rod cutting methods, mastered solid theoretical and technical knowledge, and needed to be tested in practice. Hainan Nuclear Power has rich practical experience in starting physical tests, and the perfect combination of theory and practice has made subcritical rod carving technology step on the journey of application.  Since the launch of the joint research and development project, the team has always adhered to the concept of "rigorous truth, innovation and win-win cooperation", strengthened the team's overall coordination efforts, and cracked the difficult problems of the project progress.

The project lasted for three years, and went through multiple stages of theoretical calculation, test method development, model establishment, test verification, safety review dialogue, and approval application. The team members made step-by-step efforts to solve multiple problems such as neutron fluctuation interference in the subcritical state, control rod value space correction, and core subcriticality correction, and successfully realized the research and development of subcritical rod cutting technology. At the same time, through the thorough preparation of the field test, from the repeated study of the procedure, to the detailed deduction of the test process, and to the continuous debugging of the data processing software, the engineering application of the subcritical cutting rod is successfully realized.