Cancer risk estimates by WHO - Fukushima radioactivity releases

This has reference to the News Report (Fukushima Disaster raised Cancer Risk - WHO...) in Times of India dated March 1, 2013.

With all the due respect for the WHO and the team of experts who have done the risk estimations, it can be stated that: 

1. The releases from Fukushima are very much lower than the Chernobyl. 

2. The estimated number of cancer incidences from the Chernobyl releases, predicted using the similar line of calculations followed by WHO, never occurred and far from reality. 

3. The very concept of Linear No-Threshold (LNT) approach followed for the risk estimations is not  experimentally proved and hence should not be used for actual risk calculations. 

4. The LNT concept can only be used for general optimization of protection.  

5. The International Commission on Radiological Protection (ICRP), in its latest recommendations, clearly stated that: Risk factors for carcinogenesis calculated using LNT approach have a high degree of uncertainty. This is particularly so for the calculation of cancer risk by adding up of the calculated low levels of individual doses to the members of the public (which is a small fraction of the natural radiation dose received by all of us), in situations of environmental releases in accidents. This is exactly the situation encountered in Fukushima nuclear accident. 

6. The ICRP Recommendations (ICRP-103, page no. 313) is the backbone of Radiological Protection   world-wide, and it clearly states that the adding up of small estimated doses over large populations and calculating the cancer risk is using LNT approach is NOT A VALID PROCEDURE. 

Based on the above facts, it is not advised to give such a publicity to the news item, which will only harm the nuclear industry. 

For further reading pl see: 

http://healthcare.financialexpress.com/inimaging2011jul/inimaging2011july09.shtml  

Storage of Spent Nuclear Fuel, IAEA Safety Standards Series SSG-15 Subject Classification: Radioactive waste management, STI/PUB/1503, 110 pp. Language: English, Date Published: 2012.

This Safety Guide provides recommendations and guidance on the storage of spent nuclear fuel. It covers all types of storage facilities and all types of spent fuel from nuclear power plants and research reactors. It takes into consideration the longer storage periods that have become necessary owing to delays in the development of disposal facilities and the decrease in reprocessing activities. It also considers developments associated with nuclear fuel, such as higher enrichment, mixed oxide fuels and higher burn-up. Guidance is provided on all stages in the lifetime of a spent fuel storage facility, from planning through siting and design to operation and decommissioning, and in particular retrieval of spent fuel. 

Contents: 1. Introduction; 2. Protection of human health and the environment; 3. Roles and responsibilities; 4. Management system; 5. Safety case and safety assessment; 6. General safety considerations for storage of spent fuel. Appendix I: Specific safety considerations for wet or dry storage of spent fuel; Appendix II: Conditions for specific types of fuel and additional considerations; Annex: I: Short term and long term storage; Annex II: Operational and safety considerations for wet and dry spent fuel storage facilities; Annex III: Examples of sections in operating procedures for a spent fuel storage facility; Annex IV: Related publications in the IAEA Safety Standards Series; Annex V: Site conditions, processes and events for consideration in a safety assessment (external natural phenomena); Annex VI: Site conditions, processes and events for consideration in a safety assessment (external human induced phenomena); Annex VII: Postulated initiating events for consideration in a safety assessment (internal phenomena) (Source; www.iaea.org).

Stable iodine prophylaxis

Stable iodine prophylaxis is a protective measure of administration of stable iodine to block uptake and reduce accumulation of of radioactive iodine released in nuclear reactor accidents, in thyroid. The administration is done before, or promptly after, intake of radioactive iodine released in nuclear reactor accidents. Intake of radioactive iodine by inhalation begins when the radioactive cloud arrives at a location and continues during the passage of the cloud. Action to implement stable iodine prophylaxis, and thereby reduce the dose to the thyroid, will be required promptly. The decision will most probably have to be made in a situation when reliable data for calculating the potential dose to the thyroid are not available. 

Stable iodine could also be used as prophylaxis against ingested radioactive iodine from contaminated food. However, in such situations, the iodine prophylaxis will be required for a longer period of time, leading to a need for repeated doses. In such situations, food controls would be easier to implement and more effective in the long term in reducing the collective dose than stable iodine prophylaxis.

Spent Nuclear Fuel – A Waste or a Resource?

In any power plant, there is a need of fuel which needs to be burnt to generate heat which in turn is used to produce steam and ultimately to produce electricity. In fossil fuel based plants, the fuel is coal or gas. There are different types of fuels, such as heavy metal fuels like naturally occurring uranium, enriched uranium ²³⁵U, plutonium (Pu) or their appropriate mixtures can be used in nuclear reactors. The radioactive isotopes – ²³⁵U and ^239/240Pu are fissile materials, meaning that the radioisotopes can undergo fission reaction to produce energy, termed as nuclear energy. Very highly radioactive fission products (see the reaction below) are also produced in the fission reaction. The half-lives of these fission products vary from seconds to several years. In addition to the release of energy during fission reaction, the decaying fission produce in the fuel generates large amount of heat (termed as decay heat). The heat from the fuel is utilized to produce steam via suitable heat exchanger systems.

In nuclear reactors, this rate of fission reaction is controlled, by design, to ensure proper and safe utilization of the released energy.     

In the reactors, nuclear fission reaction is induced using a sub-atomic particle, neutron. For example, heavy metal, ²³⁵U absorbs a neutron in the reactor to become an unstable nucleus ²³⁶U, which splits into two lighter and highly unstable products fission products, three neutrons and a lot energy. The unstable fission products quickly decay to finally become ¹³⁷Cs (a beta-gamma emitter) and ⁹⁰Sr (a beta emitter) with half-lives of around 30 years.

The ²³⁸U isotope forms about 99.27% of natural uranium. In the nuclear reactors, due to the neutron absorption, a small percentage of the uranium isotope gets converted through nuclear reactions, to plutonium isotopes which are again good fissile materials and can be used in nuclear weapons, and as part of mixed nuclear fuel used in “breeder” reactors. The remaining portion of the spent fuel consists of depleted uranium (DU) where the percentage of fissile ²³⁵U is reduced due to the fission reaction in the reactor to below the existing level of 0.72% in natural uranium fuel.

After the useful life of the nuclear fuel in the reactor, the highly radioactive fuel is called Spent Nuclear Fuel (SNF). As such, SNF does not have further use as nuclear fuel.

In addition to the fission products, plutonium, depleted uranium, the SNF also contains minor actinides which include long-lived and relatively long-lived isotopes of neptunium (²³⁷Np), americium (²⁴¹Am and ²⁴³Am) and curium (²⁴²Cm, ²⁴⁴Cm). These are also useful radioisotopes. Efforts are underway to separate the fission product radionuclides chemically from the waste and use them as radiation sources in industrial applications of radioisotopes.   

In countries where nuclear power has a considerable share in electricity production and has adequate uranium resources, the SNF is considered as nuclear waste and is disposed of or stored safely in isolation from the biosphere.  In countries like India, where there is shortage of uranium and need plutonium as fuel for the future up-coming reactors, the SNF is the resource material which can be reprocessed chemically to separate the useful plutonium and depleted uranium from the spent fuel.  

It is reported that India now retains the right to reprocess the SNF in India, with all the safety aspects considered, from upcoming Kudankulam nuclear power plant instead of sending them away to Russia. 

IAEA Launches Database of Fukushima Radiation Information

The International Atomic Energy Agency (IAEA) on 7 September 2012 launched a database, Fukushima Monitoring database,  of radiation measurements collected in Japan following last year's accident at the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company (TEPCO). The database, prepared by the IAEA’s Incident and Emergency Centre (IEC), consists of data on radiation measurements collected both near and far from the power plant since the Fukushima Daiichi accident began on 11 March 2011. It is reported that the database will be upgraded as and when additional information is received from Japan (source: IAEA News).

International Cooperation is vital for Global nuclear security

Protection of nuclear material in transport and storage and the protection of nuclear facilities against acts of terrorism are important from global nuclear security point of view.

According to the IAEA Director General Yukiya Amano attending the Nuclear Security Summit in Seoul, South Korea, national governments continue to have primary responsibility for nuclear security. He pointed out that more than 100 countries are reporting incidents of thefts or other illicit activities involving nuclear and other radioactive materials to the IAEA Illicit Trafficking Database, which now tracks several hundred incidents every year. Mr. Amano urged all countries to continue to share information on illicit trafficking with the IAEA in order to ensure that the world has a comprehensive overview of the threat and can respond effectively.

On strengthening nuclear security, Mr. Amano also stressed the importance of the "human element". Strengthening nuclear security is not just about spending money on guns, gates and guards, he said. Training specialist staff and transferring know-how are of equal importance.

Aftermath of Indo-US nuclear deal

The deal virtually lifted the de-facto international ban on the trade of nuclear materials and equipments related with the nuclear industry. The deal and other related agreements were signed in October 2008. However, nothing much has changed in the Indian nuclear scenario.

India is still unable to buy nuclear fuel from nuclear material abundant countries like Australia. Indian nuclear facilities are not able to buy nuclear related equipments, monitoring instruments and systems from western countries.

Now, in a major breakthrough it is reported that US has permitted US firms to collaborate with Indian companies to manufacture nuclear related components. Even Australia which till now reluctant to sell uranium to India, is willing to sell uranium to boost its economy! Good for India, because price of uranium has fallen from $140 (2007) to $50 a pound after the Fukushima nuclear disaster.

The developments will help the seller countries to boost their sagging economies, and for India to buy the uranium fuel for the reactors and much needed equipments for the safe operation of nuclear fuel cycle facilities.