Prototype Fast Breeder Reactor reaches criticality

A key figure in India’s fast breeder nuclear programme has highlighted the significance of the Prototype Fast Breeder Reactor (PFBR) achieving criticality, calling it a major indigenous milestone that strengthens the country’s second-stage nuclear energy ambitions.

For four decades, SC Chetal worked solely on India’s fast breeder programme, an asset of the Department of Atomic Energy thatIndia worked diligently to keep outside the safeguards of International Atomic Energy Agency during the Indo-US nuclear deal. Asthe facility crossed a major milestone by reaching criticality, the former head of Indira Gandhi Centre for Atomic Research and akey figure in this accomplishment shares his insights exclusively with ET's Anubhuti Vishnoi. Edited excerpts:

On PFBR Criticality

PFBR achieving criticality is significant as it gives confidence that we can have a series of sodium-cooled fast reactors in India, a necessary second stage for our nuclear programme. It is a phenomenal development for India as it is a totally indigenous activity. I have been involved with thermal power reactors as well, but that technology is mostly foreign. In the case of PFBR, it is designed by India and manufacturing of all components has also been done in India. We had also done extensive work on manufacturing technology of key components prior to sanction of PFBR for building confidence.

ET Bureau
I would say PFBR is over 90% indigenous as we did have to import--mainly large-size stainless steel plates and sodium for PFBR. There were peculiar reasons for the same--mainly due to economy of scale where we do need to work. So, India is not gifted with large amounts of natural uranium. To make the best use of our limited natural uranium, we need fast reactors, as these have potential to generate 300GW against 10GW in PHWRs. We must frame our energy policy in general based on the resources we have. Sometimes, policymakers get guided by what happens in the Western world, but we need to be cautious.

On Plans Ahead

I understand that two more reactors will be established at Kalpakkam of similar design. These next-stage reactors would take less time to build compared with PFBR. So, we should be able to build the next reactors at Kalpakkam in 7 years from approval time. Once the PFBR goes into full power commercial operation (may be maximum of a year from now), its spent fuel will be reprocessed enabling the 'closed' fuel cycle system. This second stage is important because as we go further, we will be using thorium 232 blankets instead of uranium 238, as is the case in PFBR. Once we have the blankets in thorium, then we can convert the reprocessed blankets to U233 fuel. The ultimate target of the Indian fast reactors is planned to be based on 1000 MW metal fuel reactors from better breeding potential instead of the mixed oxide of plutonium and uranium used in PFBR.

On Commercial Op

Currently, we are at zero-power for low power operations at PFBR, as per the AERB consenting process. Since this reactor is a first of its kind in India, data must be generated and intimated to safety authorities on provisions linked with safety. We will have to go through several stages of operation-- at 20% power, 30% power, 50% power, 90% power, and full power. This is necessary so that the performance of various components can be checked on various parameters.

Power from PFBR to grid could start at 30% while commercial operation implies in general full power operation.

On N-Power Matrix

India has established the 700 MW PHWR with 3 units already in operation. So, our primary nuclear power production in the next, say 20 years, will be based on thermal reactors both indigenous and imported. Once PFBR goes to full power, we are going to have two units at Kalpakkam. It is also envisaged that we would have four more fast reactors at another site along with associated fast reactor fuel cycle facility. So, we first intend to introduce the fast reactors in a gradual manner and subsequently bring in reactors based on U233-thorium cycle reactors on commercial scale.

On PFBR Delays & Failures

I would say that we kept the quality assurance very high. There have been challenges, but I would not call them failures, as something of this nature was being done for the first time at such a large scale and to very stringent manufacturing requirements and, hence, delays in construction. Each unanticipated event during commissioning took more than a year to rectify. Commissioning has taken longer than anticipated but I am hopeful that the next reactors will not have the same issues and incorporate the lessons learnt.

On Tech Gaps

Our main problem is we do not dare to go largescale. China is able to think and make for the world. We are good at science and engineering, but we need to improve on economy of scale and technology. That is the gap. I will be happy when technology is denied to India. Then, you will develop it. We need to be more flexible in placement of contracts. Fortunately, in the atomic energy sector, this problem is not there as we see capability rather than prior experience. For PFBR, all major nuclear components were sought on a limited tender basis. India has all the infrastructure to do advanced technologies. What we need is push. In atomic energy, fortunately, the push is inured.

On Strategic use options

Our aim for PFBR is to make fuel for the next stage of future fast breeder system for power generation. For PFBR, we are going to reprocess the spent fuel at Fast Reactor Fuel Cycle Facility at Kalpakkam and going to refabricate the fuel also here. A closed cycle in real sense. We must look for solutions based on our resources. On energy front, why not produce hydrogen and other fuels from abundant coal in gasification plants. and also what role low-rated nuclear reactors of high specific capital cost SMRs have in power generation.Indigenisation Levels

PFBR is an entirely indigenous activity. The Department of Atomic Energy, realising the importance of fast reactors in the nuclear power programme, established BHAVINI, another PSU in its fold. For PFBR, design and R&D responsibility have been with IGCAR, and construction and operation are with BHAVINI.

In PFBR, we have a main vessel of 12.9 metres diameter. To build such a huge circular vessel is a big challenge but thanks to the Indian industry, delivered it meeting stringent tolerances and quality specified though it took longer time. To make a number of vessels of large size for the reactor, one needs large size plates to minimise the number of welds. So, we imported these plates from France.

Meanwhile, we have parallelly developed successfully the technology to make large size plates in India on an experimental basis to insure ourselves against sudden exigencies.

Similarly, we had to import 1600 tonnes of sodium from France. While we had the technology to do so in India as sodium for FBTR was produced in India, the company which was making it at that point as it could not match the price and import of sodium was allowed by then foreign trade office as sodium is also used in pharmaceutical industries. Economy of scale is a serious issue. We should target to have indigenously produced sodium for future fast reactors as sodium production is well proved but power intensive.

Apart from these, we had enormous support from BARC.PFBR fuel and enriched boron came from there. Nuclear Fuel Complex, Hyderabad produced very high-quality special grade stainless-steel tubes which encase the mixed oxide fuel, all the structural elements of subassemblies, and tubes of the steam generators to name a few cases.

India’s vast thorium reserves

We have thorium in abundance. However, there is a misconception that thorium is also a fuel, and we can generate power from that.

There are a couple of challenges.

Firstly, thorium has to be converted to U233 either in thermal or fast reactors. For thorium conversion to U233 in fast reactors, one needs to establish the technology. That will happen once we reprocess the thoria blankets from Fast Breeder Test Reactor (FBTR) over the next few years by IGCAR. This activity has picked up though earlier it was planned at the end of reactor life.

India has knowledge of reprocessing of spent fuel to produce U233 from thorium from thermal reactors but to take it to a commercial scale is still an advanced technology on which the BARC establishment is working.

Also, reprocessing is far more challenging than reactor design in my opinion. Once we are ready with the reprocessing of U233-Thorium cycle, we will have third stage commercial reactors.

The breeding ratio of PFBR mixed oxide fuel is such that the amount of excess fuel production is small. In fact, initial fast reactors will be coming up from the spent fuel of thermal reactors. We need to build more thermal reactors so we get more plutonium as starting fuel for second-stage reactors. Fast reactors will then generate excess fuel that can take us to U233-based reactors in third stage of our nuclear power programme.

PFBR and safety risks

All our reactors are designed with safety requirements in mind and Indian fast reactors and thermal reactors are safe.

PFBR safety concerns are different from those of thermal reactors as we are dealing with sodium. We have stringent safety norms. Several layers of safety mechanisms are in place ––from encasing primary sodium with another vessel/pipe with inter space filled with nitrogen and so on.

India follows all global safety norms. Our regulatory body AERB is in touch with IAEA and a few foreign regulatory bodies. Whenever any serious event takes place anywhere in the world, there is a relook into the event consequences and whether we need to take more precautions and our own safety upgrades.

The Shanti Act & Private Sector’s Role

PFBR is based on an entirely different technology of sodium-cooled reactors and involves plutonium that cannot not be shipped from one country to another unlike natural or slightly enriched uranium needed for power production. It stays a closed facility. Private sector participation can still be there and over time they can build fast reactors. It is more likely that over the next two decades, the private sector will be building several thermal reactors, especially the 220 MW reactors as design and experience is available. Under the SHANTI Act, DAE and NPCIL will give a supporting hand. Fast reactors cannot be built with natural uranium and enriched uranium based fast reactors do not fit in our nuclear power programme.

Industry’s Role

Several industries have contributed to PFBR and thermal reactors. For PFBR, It was the first time such a reactor was being set up. Now that PFBR has achieved criticality, the industries involved have got good experience. For our next two fast reactors, which are to be of identical design as PFBR, it should be targeted to reduce construction time by at least two years and we should ensure manufacturing preferably by the same industry.

The country has the knowledge to build such reactors, but it takes time as we currently have very few industries that can manufacture nuclear components. We need to ensure continuity in placement of orders and rope in more industries to reduce construction period.
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Source: EconomicTimes
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