https://www.researchgate.net/publication/391391289_Radiation_of_Quartz_in_Concrete_in_Structures_of_Nuclear_Power_Plants-Commercial_Opportunities_out_of_these_Maladies
Projections over the Research:
Eirwen Williams, a New York-based journalist at Sustainability Times, claims to spotlight in his reviews the intersection of activism, policy, and green technology with focus on climate policy, sustainable innovation, and environmental justice.
He has covered a science article based on the work at The University of Tokyo on the impact of radiation on the quartz particles. This article can be accessed at the following link.
His summarized projections over the findings of the Scientists at the University of Tokyo are as follows:
-
- The discovery observed that concrete can self-repair under nuclear radiation, extending its lifespan.
- The research focused on the regenerative properties of quartz crystals within concrete, using advanced X-ray diffraction techniques.
- This discovery could significantly reduce maintenance costs and improve the safety of nuclear infrastructures worldwide.
This has encouraged the scientists of INSWAREB, Visakhapatnam, India, who have reasonable knowledge on the material science of cement and concrete, to review the scientific rationale in the projections to benefit the students, researchers and faculty with facts and figures. Based on the earlier works at some research institutes, Reviewers have taken it for granted the impact of radiation on quartz crystals.
But the projection of nuclear radiation on quartz crystals to render self-repair at post-hardening stage of concrete is the point of concern, attracting this review.
Bibliographic reference to the claim:
The study conducted by Chinthaka M. Silva et al. (March 2018, ACS Publications) of Materials Science and Technology Division, Oak Ridge National Laboratory, United States, has thrown considerable light on transformation of quartz upon exposed to neutron radiation.
This work summarises, “quartz single-crystal samples consisting of α-quartz crystal structure were neutron irradiated at two temperatures (52 and 95 °C). The changes in the α-quartz phase as a function of these two conditions (temperature and fluence) were studied through instrumentation techniques. The results are presented in a single place for the first time. XRD studies showed that the lattice parameters of α-quartz increased with increasing neutron flux. The lattice growth was larger for the samples that were neutron irradiated at 52 °C than at 95 °C. Moreover, an amorphous content was determined in the quartz samples neutron irradiated, with the greater amount being in the 52°C irradiated sample. Complete amorphization of quartz was observed using XRD and confirmed by TEM characterization and Raman spectroscopic studies”.
In order to find the veracity of projections made by Mr Eirwen, the original work of Building Material Engineering Lab, The University of Tokyo, is accessed. The paper entitled, ‘Evaluation of Radiation-induced Amorphization of a-quartz in Concrete Aggregates using Ramon Spectroscopy’ offers transparent data, free from hyperboles as projected by Mr Eirwen. Moreover, a specific observation in the introduction of their paper is noteworthy as follows:
“The radiation-induced volumetric expansion (RIVE) of aggregates plays a major role in the development of damage in concrete subjected to neutron radiation.”
Contextual explanation to the synthesis of Concrete:
Concrete is the mix of cement (as binder) and aggregate (as filler) in association with water.
Cement is reactive mineralogical substance whereas aggregate is specified to be unreactive crystalline mineralogical product.
In cement, the dissociation of anhydrous mineralogy in the presence of water and exothermic heat, leading to association of compounds into hydrated mineralogy towards crystal growth, gives bonding strength to the inter and intra matrix of the concrete. Thus, concrete is enriched through hydration chemistry of cement, improving the prospects for densification and strength gain of concrete matrix. It is necessary to note that in the presence of lime, no silica is free in the cementitious matrix of concrete.
Aggregate, consisting of sand (fine aggregate) and stone (coarse aggregate), is specified to be non-reactive in order to ensure dimensional stability to the hardened concrete element. At post-hardening stage, if any portion of aggregate is reactive it may lead to deleterious effect such as ASR (alkali-silica-reactions) leading to weakening and spalling of the concrete. In this context, the Reviewers give an interesting analogy of concrete to ‘fully grown human body’ whereby aggregate of concrete is akin to bone with a few exceptions. In the human body, anatomically the changes in the muscle are acceptable but not in the bone. On the other hand, the synthesis of bone needs to be protected to avoid complications.
Other than sand which is the crystalline substance of silica, coarse aggregate also may contain quartz, brightening the chances for irradiation in nuclear reactors. It is the same issue with complementary cement inputs such as fly ash which do contain considerable portion of quartz.
The durability of concrete structures in nuclear power plants is crucial, and they are designed to withstand the harsh conditions of radiation exposure and temperature fluctuations. For this purpose low heat cements or blended cements are used with the least water to cement ratio in order to avoid even micro-cracks. Thus the chances for degeneration are minimised considerably right at the preparation and placement of concrete which are, nevertheless, unavoidable due to aggressive conditions in NPPs.
The comprehensive paper published by IAEA (Nuclear Energy Series No. NP-T-3.5) captioned ‘Ageing Management of Concrete Structures in Nuclear Power Plants’ discussed elaborately on the facets of ageing effect of concrete in NPPs. Here is the link for ready reference.
https://www-pub.iaea.org/MTCD/Publications/PDF/P1654_web.pdf
While cosmetic repairs are available on deteriorated concrete to satisfy the need, all those are a stop gap solace against the mandatory priority to synthesise concrete with:
-
- Least cement but more complementary cementitious inputs; minimising free lime in the hardened concrete to as low as possible;
- Aggregate content to as low as possible in order to minimise transition zone;
- Selection of aggregate free of reactivity;
- w/cm to as low as possible without hampering the placement criteria;
- Avoidance of cracks of whatsoever nature in the matrix of concrete;
- Absolute impermeability;
The Nano Concrete invented and patented by Reviewers (https://fal-g.com/wp-content/uploads/2022/04/Tech.-Note-on-NAC-Dec-2015.pdf) do satisfy all the above criteria subject to structural evaluation and placement criteria in the structures of NPP.
Review on the projections of Eirwen Williams:
In the background of above clarifications the following aspects are vulnerable for debate and need substantiation:
-
- While the concrete of nuclear reactors is supposed to be absolutely sound, free from whatsoever microcracks, where is the scope for self-healing?
- If at all there is self-healing, the claim may be new but the phenomenon must have been old enough and unnoticed since there was quartz (through aggregate) and radiation effect in reactor-concrete over course of time in the past.
- While the impact of radiation on transformation of quartz is established, how far this phenomenon holds good in protecting the concrete of NPPs at post-hardening state!
- What happens to the dimensional stability and soundness of the concrete while the aggregate is subjected to transformation at post-hardening state? Is it not akin to ASR that causes disaster to concrete soundness!
Response of University of Tokyo:
Meanwhile to the mail sent by Reviewers to the team of scientists at University of Tokyo seeking clarifications over the projections of Mr Eirwen, response is received within 9 hours from one of the authors of the work, with following salient statements:
“I know that sometimes, the title of the article is somehow attractive and catchy, but the word “self-repair” and “regeneration” seems misleading of our outcome.
I found that there is a healing mechanism that can compensate the damage in quartz by neutron irradiation. However, the “self-repair” and “regeneration” of concrete lead people to believe that the cracks in the concrete have healed. In this sense, I cannot endorse this article and ‘concrete’ should be replaced with ‘concrete aggregates’ in most cases, TO AVOID the situation people believe that concrete itself is healed by neutron radiation.”
Above observations have put at rest the controversies aroused out of the projections of article by Mr Eirwen. However, the healing mechanism claimed by Researchers to compensate the damage in quartz needs to be substantiated in holistic behaviour of concrete.
Commercial scope of Research Work:
The redeeming feature of the research findings in favour of cement-concrete is the conversion of quartz from crystalline (unreactive) state to amorphous (reactive) state through radiation. This aspect opens up commercial opportunity as follows:
By designing suitable reactors, the crystalline quartz could be converted at commercial scale to amorphous silica. If its reactivity is studied and established, such product could be used as complementary cement input to improve the quality of cement. This is more helpful where low grade limestone hampers the quality of clinker.
By processing high pure quartz, amorphous silica can be produced that may be akin to ‘silica fume’ in behavioural properties. This has to be established through due concrete studies. Subject to economic aspects, the value addition to cement and concrete could be potentially enhanced.
By subjecting the coarse fly ash and pond ash to radiation in commercial reactors, the crystalline fly ash could be converted to amorphous ash to the extent of quart content, rendering value addition to the inert ash. In the light of storage of over 2860 million tons of ash in ash ponds occupying about 65,000 acres of land in India, this may prove as the most sustainable avenue of exploitation in many aspects. The economic spin off is about Rs. 2.86 trillion in value addition of the product and Rs. 650 billion in reclaiming the land occupied by ash ponds.
Conclusions:
Hyperbolic projections over the research works are not acceptable in technical and scientific reviews, distorting the basic and truthful findings of the research. This is where the bibliographic survey is meaningful before continuing the research work of predecessors. There should be distinct demarcation in reports while dealing with findings-observations-postulations-assumptions, be it by research scholars or reviewers. But meanwhile the confusion can be avoided by the reviewers if they are accountable and diligent in their report.