Several accidents at the power station reveal serious issues in maintenance, safety systems

In the past five years, two major accidents and a minor accident occurred at the Neyveli Lignite Thermal Power Station (NLTPS) a lignite-based thermal power station located near the lignite mines of Neyveli in Tamil Nadus Cuddalore district.

Another accident at the plant owned by Neyveli Lignite Corporation (NLC), an undertaking of the Union government revealed serious issues in maintenance and safety systems in the old units running at NLTPS, for which the senior management should be held responsible.

NLC has a history of management issues. There have been frequent strikes by workers over several issues over the years. These strikes may be one of the reasons for poor operational practices at NLTPS.

Continuous delays in the commissioning of new units forced NLTPS to run its old units, scheduled to retire between 2011-15. Efficient and safe operating life of thermal power plant is considered to be around 25 years. At NLTPS, however, a large number of units are 25-57 years old.

Unit 6, where the incident occurred, is more than 26 years old and is to be retired due to unavailability of space for pollution control technologies, according to the National Electricity Plan, 2018.

NLTPS has distinct phases, where new units are usually commissioned, with auxillary utilities (like coal handling, water treatment etc) being common for different units in each phase.Phase one consists of units 1-6 (50 x 6 megawatts or MW) and 7-9 (100 x 3 MW), commissioned during 1962-70. All these units were scheduled to be retired between 2011-15.

This plan, however, could not be executed due to a continuous delay in commissioning of the new capacity.

The present total capacity of the first stage is 500 MW (unit 7, with a capacity of 100 MW, was retired in 2019). The expansion of phase one included two units of 210 MW capacity each.

NLTPS phase two has units 1-7 (210 x 7 MW) commissioned during 1988-93. Stage two expansion has two units of 250 MW capacity, each commissioned in 2014-15.

Two new units of 500 MW each, that were scheduled to arrive in 2014-15, were continuously delayed. One of them was added in 2019 and the other is yet to come.

These two units were critical as retirement of the old plant was based on the commissioning of these units. The retirement of old units (40-50-years-old) was continuously delayed due to delay in the commissioning of new units.

Source: CSE

History of disorder

2011:It was planned for NLTPS phase one to be decommissioned between 2011 and 2014. In 2011, however, the period of operations was extended for five years and still has not been retired.

2013-17: Frequent strikes in NLC on dilution of stakes and wages issues, with the matter in court till February, 2020.

May 20, 2014: Blast at a pipeline of a boiler in NLTPS phase one unit seven (100 MW) killed two people and injured four others. An NLC probe committee blamed an engineer for the incident and said it was satisfied with the built-in safety protection available in the scheme. It was claimed that a life extension programme and periodical residual life assessment studies were conducted to ensure safe operation of the plant.

June 2019:One person was killed and two others seriously injured in an explosion of the safety valve at one of the units in NLTPS phase two.

May 5, 2020: Minor fire incident at the conveyor belt in NLTPS phase two.

May 7, 2020: The incident occurred in the NLTPS phase two, unit 6 boiler of NLC India's second thermal power station. The pressure build-up inside the boiler caused the blast. Eight people, who were working in the area, were injured and taken to NLC's hospital.

There may be many technical reasons including excessive accumulation of ash and improper fuel combustion for a blast in a boiler, caused by uneven heat transfer at certain locations, said Ashu Gupta, a former general manager at National Thermal Power Corporation Limited.

All these issues are handled by power plants in day-to-day operations andmaintenance, he said. This blast is clearly a result of a failure of built-in checks and safety systems that are in place in all the power plants, Gupta added.

Such incidents are the blatant failure of maintenance and operational safety interlocks and should not be linked to the novel coronavirus disease (COVID-19) outbreak, according to Amit Kumar Singh, a power sector consultant.

There might be various technical reasons for the blast, but the real reasons will be revealed after the investigation report comes out, according to several experts.

Over the years, Delhi-based non-profit Centre for Science and Environment (CSE) has been pushing hard to expedite the retirement of old units.

The execution of government plans for the retirement of old plants are continuously delayed. These old plants require significant investment for operation and safety, with poor management at the plant level making these units prone to such serious incidents.

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All is not well at the Neyveli thermal power station in Cuddalore - Down To Earth Magazine

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