In a major mishap a boiler explosion took place at state-run power major NLC India Limited’s power generation unit in July, leading to worker fatalities. The cause of the accident is still under investigation. However, the incident comes as a reminder to utilities to step up their safety measures in order to minimise the risks that technicians, operators and other workers are exposed to during power plant operations. This is even more so as the ongoing pandemic has put greater pressure on companies to protect employees from not just worksite hazards but also health hazards like Covid-19.
A closer look at the recent explosion incident, the current policy guidelines on safety, as well as possible strategies, solutions and corrective actions that can be taken by power plants to reduce or eliminate risks and prevent accidents….
On July 1, 2020, NLC India announced that at around 9.45 hours, a fire broke out in the boiler area of Unit 5 of Thermal Power Station-II (TPS-II), Neyveli, following an explosion while it was under shutdown and maintenance. This resulted in injuries to the NLC India maintenance team comprising one executive, two supervisors, three non-executive employees and 17 contract workmen.
TPS-II is a pithead lignite-based power project comprising seven units of 210 MW each, aggregating 1,470 MW. These units were commissioned in two stages (three under Stage I and the remaining under Stage II) between 1986 and 1993. The power generated at TPS-II is shared by Tamil Nadu, Kerala, Karnataka, Andhra Pradesh and Puducherry after meeting the needs of Mine II of the company. The project is located in Neyveli in Cuddalore district of Tamil Nadu. On a consolidated basis, NLC operates seven thermal power stations and solar/wind projects with an aggregate capacity of 6,044 MW as on December 31, 2019.
Of the 23 personnel injured, six workmen belonging to a contractor succumbed to their injuries on the spot (the total number of people who succumbed to their injuries increased to 13 as of July 9). The 17 injured were immediately rushed to hospitals.
A high-level inquiry, headed by P.K. Mohapatra, retired director (technical), NTPC Limited, has been ordered into the cause of the accident. Apart from this, an internal inquiry committee, comprising senior executives and headed by the director (power) of NLC, is looking into the incident.
In its reply to the Madras High Court’s notice, NLC has reportedly stated that the lignite dust deposited on the girders possibly led to the explosion. It further stated that the workers on the fateful day may have cleaned the lignite dust deposited inside the box girders holding the boiler using metal scrappers and a spark due to friction may have ignited the lignite particles, leading to the accident. The company said the executives, supervisors and non-executives involved in the operations and maintenance of the boiler of Unit 5 were well-trained in standard operating procedures (SOPs). They undertook refresher courses from time to time. The contractors’ workmen, who were deployed for maintenance works, were also trained in work and safety, NLC told the court.
Meanwhile, the National Green Tribunal (NGT) passed an order on July 9 directing NLC to deposit Rs 50 million as an ad hoc arrangement to meet claims for further compensation. The NGT has also constituted an independent committee comprising the Central Pollution Control Board, the Tamil Nadu Pollution Control Board, the district magistrate (Cuddalore), NEERI and IIT Chennai. It has directed the committee members to visit the accident site, ascertain the facts and submit an independent report.
In another update on the incident shared by NLC on July 8, 2020, it said that action was being taken by the company to ensure that all units, other than the affected unit, are operationalised at the earliest. All safety measures were being ensured before resumption of power generation from the units. Meanwhile, NLC has stepped up vigil in all its operating units and other projects.
Guidelines and advisory on safety
At the policy level, there are specific sections under the Electricity Act, 2003, which contain safety provisions for power plants. Section 53 contains provisions relating to safety and electricity supply. Based on these, the Central Electricity Authority (CEA) has framed the Central Electricity Authority (Measures Relating to Safety and Electric Supply) Regulations, 2010 and a subsequent amendment, Central Electricity Authority (Measures Relating to Safety and Electric Supply) Amendment Regulations, 2015, which are applicable to all installations across the country.
Under Section 162 of the Electricity Act, 2003, the central/state governments have their own electrical inspectorates to enforce the specified safety regulations in power installations belonging to or under the control of their respective jurisdictions. On the occurrence of an electrical accident, the appointed chief electrical inspectors/electrical inspectors conduct inquiries on a case-by-case basis and suggest remedial measures for prevention of such accidents.
In January 2019, the CEA also issued an advisory to all TPPs, which included key recommendations to be followed by power utilities. As per these recommendations, all systems and facilities including control and instrumentation, control loops, wall soot blowers and long retraceable soot blowers should be completed before the commissioning of the unit/plant. Further, the ash handling capacity of the bottom ash handling system, economiser ash handling system, air preheater ash handling system and electrostatic precipitator for the fly ash handling system should be designed keeping in view the likely maximum ash content of coal. The SOPs/local management instructions of the plant should be reviewed periodically. Further, the plant operating instructions should be in line with the original equipment manufacturer’s recommendations. The permit system for undertaking operations and maintenance (O&M) activities should be endorsed by the safety department in addition to the O&M department. Also, no maintenance work should be undertaken when the boiler is in operation. Besides, proper communication regarding maintenance work should be ensured in order to avoid risky operations. Persons working in the ash-handling area should be provided thermal wear that can withstand high temperatures. Flame-proof clothing should be provided to people working near the furnace area. The plant engineers deployed at different levels should have adequate and relevant experience.
Possible strategies and solutions
While power plant operations have become much safer now, safety is an area that needs continuous attention and improvement. “Thermal power plant operations involve exposure to a significant amount of high pressure and high temperature equipment. All safety aspects require proper, systematic care of the systems and careful adherence to maintenance practices,” says a senior NTPC official.
NTPC has comprehensive best practices in safety. These include regular plant inspections and review by business unit heads and the senior management. Internal safety audits of all sites by NTPC’s safety officers and external safety audits by organisations such as Du-pont, National Safety Council Mumbai and DMI Bhopal are carried out for each project and station. The recommendations of the auditors are regularly complied with. Cross-functional safety task forces are functional at all projects. To mitigate on-site emergencies, effective engineering controls are provided to indicate and handle emergency situations. Mock drills are conducted regularly to check system health. These activities are reviewed by the factory inspectors during their visit to the plant.
There are a number of areas that asset managers can focus on to improve plant safety, including adopting new and advanced technologies. According to Ashok Sethi, chairman, Tata Consulting Engineers, “The Covid-19 pandemic is appropriately accelerating the use of IT-OT by the power industry. The use of ICT to automate systems and processes is the need of the hour, and helps involve every individual, create convenience, and sustain and control systems and processes. The ICT industry is already providing enough options to digitalise processes and MIS, thus helping the industry to be proactive in addressing the noble cause of zero harm.” To achieve “zero harm”, companies need to focus on housekeeping and hazard area identification, competency building, SOPs, tools and fixtures, near miss reporting, action plans, job safety analysis, and workmen skill, health and behaviour. “There has to be commitment to this cause through safety training, resources, rewards and recognition and, above all, empowerment,” he notes.
The current pandemic is also changing the way companies think about safety. Power major Tata Power has worked out an extensive set of measures to ensure that its workforce has a secure and hygienic work environment, especially amidst the Covid pandemic. “We immediately implemented a rota system for employees, factoring in backups. We also have dry backup teams with people who can step in immediately if one of the teams on the rota system gets impacted. But many things about this crisis are different; so many of our responses too are new. We moved from a physical handover of operations between shifts to a virtual handover. We figured out new travel arrangements to ensure that our staff could get to the plants, adhering to all social distancing norms and other precautions,” stated PraveerSinha, chief executive officer and managing director, Tata Power, in a recent interview with Tata Review, April-June 2020 edition. The company’s robust and resilient business continuity system has helped the company to adapt quickly. “We have been able to run without a minute’s stop. Our plants have been working at full capacity, which for us means continuing a Six Sigma performance. We have ensured that our 11 thermal and hydro generation plants across six states continue to operate efficiently,” he adds.
Undeniably, safety in power plant operations is of paramount importance. More so, in today’s evolving situation, power plant managers are under significant pressure to achieve even more aggressive safety goals as they navigate complex risk environments. While power plants have integrated safety procedures and best practices into their operational activity, they must also focus on seeking out and re-evaluating potential hazards. Detected early, it would be possible to prevent these from erupting into major incidents, thereby ensuring the safety and security of the workforce. n