With the passing away of Shri S K Sharma, former Chairman, Atomic Energy Regulatory Board (AERB) on December 16, 2014, India lost a distinguished scientist and an internationally acclaimed, outstanding nuclear engineer.

A graduate in Chemical Engineering from the Banaras Hindu University, Shri Sharma joined the erstwhile Atomic Energy Establishment, Trombay as a trainee engineer in 1963. He served the Bhabha Atomic Research Centre (BARC) in different capacities.

As the Director, Reactor Group, he had the responsibility to operate and facilitate utilization of APSARA.CIRUS and DHRUVA, the three research reactors at Trombay. Scientists and engineers have been using these reactors to produce radioisotopes for use in industry, medicine and research and for basic and applied research.

Shri Sharma was directly involved in implementing the Plan projects “Critical facility for Advanced Heavy Water Reactor & 500 MWe PHWRs” and “Design modification & refurbishing of Apsara”.

The development of the design of a pool type Multi-Purpose Research Reactor (MPRR) to be built at a new campus of BARC towards augmenting our radioisotope production capability and for providing enhanced research facilities in frontier areas of science was another assignment of Shri Sharma.

He was a member of the Design Safety Committee for PRP Project right from its inception and chaired it in 1994.

"What was the most interesting, challenging and memorable activity you had in your career?, this writer asked him, exactly over an year ago, while travelling with him to attend the 23rd Annual Conference of the Indian Nuclear Society at Trombay.

He thought for a moment; probably he had too many activities in his mind. He listed two important instances: the resolution of the vibration issue while commissioning the Dhruva reactor and the refurbishing of CIRUS.

During initial operation of Dhruva, the aluminum-clad fuel elements suffered from excessive flow- induced vibrations causing abrasions in the fuel cladding exposing the uranium element. It

caused aluminum turbidity and uranium contamination of the heavy water coolant. The fuel element vibrated excessively because of clearances between the fuel assembly and the guide-tube at the bottom where the coolant entered.

Shri Sharma explained that the natural frequency of the fuel assembly was close to that of the main coolant heat exchangers together with their support structure. This caused resonant vibration of the fuel assembly. The reactor designers rectified these deficiencies. Scientists removed the turbidity of the coolant by using a specially developed magnesium loaded ion exchange resin and a centrifuge system.

Shri Sharma was responsible for successfully carrying out extensive refurbishing of CIRUS, after this old facility had been in operation for over 35 years. CIRUS was brought back into operation at its rated capacity. He seemed to rate the refurbishing of CIRUS as more interesting.

The refurbishing job included large scale repairs and replacement of above ground and sub-soil piping, primary coolant heat exchangers, air-conditioning and ventilation equipment, remote repairs of leaks in inaccessible locations involving significant development effort, revamping of sumps and replacement and modernization of several electrical and instrumentation items.

Shri Sharma gave a graphic account of the entire project: safety upgrades, improved system for failed fuel detection, modification to radioiodine removal system in emergency ventilation exhaust, seismic qualification of safety related structures and components in this old facility, replacement of fogged radiation shielding windows of the isotope handling hot cells of CIRUS and Dhruva by new windows that were assembled in house etc

On December 18, 2010, the scientists and engineers in the Department of Atomic Energy (DAE) celebrated the Golden Jubilee of CIRUS and the Silver jubilee of Dhruva. Everyone who was associated with the two research reactors assembled. For many, especially for those who retired decades ago, it was an emotional homecoming.

Shri Sharma who was former Director, Reactor Group, BARC made an emotional speech.“I am truly heartbroken to learn that this old workhorse will be put to sleep at the end of this year for reasons that are anything but technical” his words truly reflected those of many others present.

“But then those are the ways of the world that we live in,” he consoled everyone (50 years of CIRUS: some unforgettable memories, The Hindu, December 23, 2010)Sharma assisted the International Atomic Energy Agency by participating in the Agency's expert missions, and in their Training Courses as a lecturer, He was associated with IAEA's Co-ordinated Research Programmes; he lent his experience and expertise to IAEA on innumerable occasions on assignments at Korea, Tunisia, and Egypt among others. He provided expert services for solving problems in research reactors and developing the Country Programme Framework and Regional Co-operative programmes for the Asia-Pacific Region. He was a member of the IAEA's Commission on Safety Standards, International Nuclear Event Scale

Advisory Committee and International Nuclear Safety Group (INSAG).Sharma contributed significantly to several senior level committees of AERB. He chaired the Safety Review Committee for Operating Plants, the Apex Committee for reviewing safety of all operating plants of the Department of Atomic Energy. He was the Vice-Chairman of AERB’s Advisory Committee on Nuclear Safety which advises AERB on generic matters of nuclear safety and carries out the review of all AERB safety documents. As Vice-Chairman of the Advisory Committee for Project Safety Review of Light Water Reactors, he participated in the safety review of the design of the 1000 MWe Kudankulam nuclear power reactors in Tamil Nadu. He was Chairman of the Board from 2005-2010.

Just over a week Post Fukushima nuclear accident, AERB set up a 10 member specialists committee to review the safety of Indian nuclear power plants against external events of natural origin with Shri Sharma as its Chairman. The Committee's report produced under his guidance and direction bears testimony to his insight covering all aspects of the accident and his unique ability to arrive at practical solutions from the recommendations of many specialist working groups.

He was one among the handful of nuclear engineers who dedicated their life for placing India in the nuclear map of the world.

*[Dr K S Parthasarathy is former Secretary, Atomic Energy Regulatory Board]