Safety status of nuclear power plants
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The radiation doses to the public were very low
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Photo: K. Gajendran
NEW LEASE OF LIFE: MAPS underwent safety upgradation recently.
THE ATOMIC Energy Regulatory Board (AERB) reported that during 2005-2006, the Nuclear Power Corporation of India Limited (NPCIL) has operated safely all its nuclear power reactors in the country.
The radioactive releases from the plants were well within the limits prescribed by AERB. The estimated radiation doses to the public at different stations were too low to be measured and were very small fractions of the permitted value.
The radiation doses to workers in all Units of the Department of Atomic Energy (DAE) were also in total compliance with the AERB limits.
Classified into seven levels
Of the 28 events reported from various nuclear power stations during the year, 26 were at level zero (deviations, no safety significance) and two were at level 1 (anomalies).
The International Atomic Energy Agency (IAEA), depending on their safety significance, classifies events occurring in a nuclear power plant into seven levels (1-7).
The Agency rated the accident at the Chernobyl nuclear power station at level 7, as it involved large-scale release of radioactivity and human health effects. IAEA calls the events at level 4 and above, accidents.
Up-gradations
NPCIL implemented the required safety up-gradations at Units 1 & 2 of the Tarapur Atomic Power Station, the oldest nuclear power reactors in the country.
The up-gradations included modification of emergency power supply, segregation of shared systems, addition of emergency control room, up-gradation of fire protection system, seismic re-evaluation and retrofitting as appropriate.
AERB renewed authorisation to the plants up to March 2011.
The Board renewed the authorisations to operate Unit 1 & 2 of the Madras Atomic Power Station up to March 2011; these reactors also underwent safety up-gradation.
The Board is carrying out safety review of reactors of new and diverse designs that are under construction. These included two water moderated water-cooled reactors (VVER) at Kudankulam, several Pressurised Heavy Water Reactors (PHWR), the Prototype Fast Breeder Reactor (PFBR) at Kalpakkam and Advanced Heavy Water Reactor (AHWR) at Trombay.
Scope for improvements
AERB continued to administer the provisions of the Factories Act 1948 in the Units of the Department of Atomic Energy. The overall status of industrial safety in various DAE Units was satisfactory; there was scope for further improvements.
Unfortunately, there were 13 fatalities due to industrial accidents during the year. Following one fatal accident, AERB suspended jobs involving work at heights at all NPCIL projects until it submitted a detailed report on measures taken to improve safety of workers working at heights. The Board lifted the restrictions after verifying that NPCIL had implemented such measures.
Indoctrination of workers
Continuous indoctrination of workers on safety measures and compulsorily showing them audiovisual programmes of case studies of accidents may be necessary to help prevent accidents.
AERB has started implementing the Atomic Energy (Radiation protection) Rules 2004 by issuing type approvals to radiation generating equipment such as Computed Tomography Units (16), medical accelerators (18) and baggage inspection systems (7), radiotherapy simulators (5) and 124 devices containing radioactive material. The Board staff inspected 450 institutions outside the DAE.
Unusual incidents
Two instances in which Indian firms exported steel products contaminated with cobalt-60 to the U.S. highlighted the need to install appropriate radiation monitors at ports and other entry points to prevent contaminated material from entering and exiting the country. The firms used imported scrap to produce the products.
Two incidents related to transport of radioactive materials (a molybdenum-99 generator and a package containing Y-90) used in nuclear medicine revealed avoidable procedural lapses. The incidents did not involve any radiation exposure to the public.
AERB assisted the customs authorities of Jawaharlal Nehru Port Trust to search and recover a low activity Am-Be neutron source from a shipping container of steel scrap.
This followed an alert received from U.S. customs. AERB investigated two cases involving theft of radiography sources.
AERB staff held discussion meetings on safety related topics with the staff of the US Nuclear Regulatory Commission in September 2005 and March/April 2006.
Other notable developments included the renewal of cooperation agreement with the French Regulatory Body for five years and the organisation of an IAEA meeting at Mumbai of the countries operating CANDU type reactors.
K.S. PARTHASARATHY
Former Secretary, AERB
(ksparth@yahoo.co.uk)
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