Technical aspects of improvingPresentation Transcript
Technical aspects of improving acceptance of nuclear power : dealing with catastrophe syndrome Anil Kakodkar* INSAC 2012 November 7,2012*With inputs from Shri H. S. Kushwaha & Dr. R. K. Singh
Key issues in public acceptance• Dealing with mind sets Small is beautiful Nuclear is evil Perceived external influence Trust deficit , NIMBY………• Catastrophe syndrome Consequences (real or perceived) larger than a threshold are unacceptable regardless of low probability TMI, Chernobyl and now Fukushima have created adverse impact on publicmind That Fukushima was caused by nature’sfury is an added factor
NEVER AGAIN• Both TMI & Chernobyl were triggered by internally initiated events• Several lessons learnt, improvements implemented and confidence restored• Signs of nuclear renaissance were visible• Chernobyl also led to valuable insights into consequences in public domain• Fukushima was triggered by an extreme external natural event• We must now ensure that an essential goal for nuclear safety is “NEVER AGAIN” should there be any significant off site emergency
Comprehensive approach to safety1. Reassess the design basis assumptions for both new and existing plants at two levels• plant shall be able to cope without significant radioactive releases and without irreparable damage• plant should be able to cope without requiring significant off-site emergency response2. Reassess plant response to severe accidents that cause extensive reactor damage3. Develop and implement effective on-site accident management strategies4. Reassess capabilities for off-site emergency management5. Approach to old and new nuclear power plants6. Reassess safety culture and quality of safety management7. Ways to strengthen the international safety regime8. Better ways to inform the media and the public on the severity of
Dual level design basis• Design basis No impact in (risk lowered to an public domain or acceptable level) irreparable damage to plant• Extreme event* No significant off-site (maximum potential) emergency *Extra margin between design and ultimate load capacity should be sufficient to cope with this• Note: Nuclear Power Plants are Designed to withstand the loading due to Natural and Man-induced external Events with low enough probability of occurrence. Some of the man induced hazard are ruled out using SDV Criteria.• On a similar logic one could identify maximum potential loading for specific engineered safety features / events at a site* and demonstrate them to be within the margin beyond design basis capacity.• *Core cooling capability, hydrogen mitigation, containment isolation, earthquakes, tsunami, etc.etc.
Potential Natural and Man-Induced Hazard Phenomena • ATOMOSPHERIC Cyclones Tornado Tropical Storm Lightening • SEISMIC Ground Shaking / Fault Rupture Liquefaction Tsunami• GEOLOGICAL Rock Fall Land Slide Debris Avalanches • HYDROLOGICAL Flooding Strom Surge Erosion and Sedimentation • Man-Induced Events Oil Storage & Refineries Explosion Missiles Air Craft Crash Terrorist Attack
BARC Containment (BARCOM) Test-Model (Design Pressure Pd 0.1413 MPa) at BARC-Tarapur Test Facility with details of Embedded Sensors and Cable Panels An overview of Sensors & Instrumentation Cable for concrete, rebar and tendonsPhase-II Test- Typical Response Pre-Test Predictions by Round Robin Participants
Jason-1 track 109 satellite (altitude 1300km) record and TSUSOL Predictions
Long term nuclear power development - The challenge of the numbers.• A per capita electricity use of about 5000 kWh/year appears to be needed for reaching a state of reasonably high human development. Considering the progressive depletion of fossil fuel reserves, and the urgent need for addressing the global warming related concerns, nuclear energy is expected to substantially contribute to meeting the future global energy requirements.• Assuming that at least half of the total energy demand may need to be met with nuclear, the world will need between 3000 to 4000 nuclear power reactors of different capacities for electricity generation. The number may at least double with the use of nuclear energy to provide an alternative to fluid fossil fuels.• A large number of these reactors may need to be located in regions with high population densities and modest technological infrastructure with their sizes consistent with local needs. 10
AHWR is a 300 MWe vertical pressure tube type, boiling light water cooled andheavy water moderated reactor (An innovative configuration that can provide low risk nuclear energy using available technologies)AHWR 300-LEU would enable realisation of these advantages with competitive Uranium use & without the need for concurrent recycle. This may be a necessity in many countries. Major objectives Significant fraction of energy from Thorium Top Tie Plate Several passive features Displacer 3 days operator grace Water Rod Tube period Fuel No radiological impact in Pin public domain AHWR can be Can address insider threat configured to accept a scenarios range of fuel types Lower proliferation including LEU, U- concerns Pu , Th-Pu , LEU-Th and 233U-Th in full Design life of 100 years. Bottom Tie Plate core Easily replaceable coolant AHWR Fuel assembly
Peak clad temperature hardly rises even with the extreme postulate of complete station blackout andsimulteneous failure of both primary and secondary shut down systems.
PSA calculations for AHWR indicate practically zero probability of a serious impact in public domain Plant familiarization & Level-3 : Atmospheric Dispersion With SWS: Service identification of design Consequence Analysis Water System aspects important to APWS: Active Process Water severe accident System Release from Containment ECCS HDRBRK: ECCS Header PSA level-1 : Identification Break of significant events with LLOCA: Large Break LOCA large contribution to CDF Level-2 : Source Term (within SLOC MSLBOB: Main Containment) Evaluation through SWS A Steam Line 63% 15% Analysis Break Outside Contribution to CDF Containment Level-1, 2 & 3 PSA activity block diagram 10-10 10 -10 Frequency of Exceedence 10-11 10 -11 -12 10-12 10 10-13 10 -13 10-14 10 -14 1 10 mSv 0.1 Sv 1.0 Sv 10 Sv -3 -2 -1 0 10 10 10 Thyroid Dose (Sv) at 0.5 Km Iso-Dose for thyroid -200% RIH + wired shutdown system Variation of dose with frequency exceedence unavailable (Wind condition in January on western Indian 13(Acceptable thyroid dose for a child is 500 mSv) side)
Generic Assessment Procedure for Determining Protective Actions during a Reactor Accident • Accident Assessment • Emergency Classification • Protective Action Decision Making• Assessment of Environment Data • Monitoring • Operational Intervention Levels (OILs)
LNT Model is Inaccurate The major cause of worry is the general public perceiving that radiation is harmful no matter how low the dose. Reality Real radiation danger levels Crosses show the mortality of Chernobyl firefighters (numbers died/total in each dose range ) .Colorado ,USA has a population over ( curve is for rats)5 millions residents. According toLNT model Colorado should have anexcess of 200 cancer deaths per yearbut has a rate less than the nationalaverage. . Ramasar ,Iran, residents receive a yearly dose of between 100-260 mSv. This is several time higher than radiation level at Chernobyl and Fukushima exclusion zone. People living in Ramsar have no adverse health effect , but live longer and healthier lives. . We also know that China , Norway, Sweden, Brazil and India have similar Above 4,000 mSv 27/42 died from Acute areas where radiation level is many Radiation Syndrome (ARS), times higher than 2.4 mSv/yr world not cancer. average. Below 4,000 mSv 1/195 died.
Projected health consequences from low doses to large sections of population are questionableIN CASE OF CHERNOBYLSOME ESTIMATED CONSEQUENCES Driven by overAN ESTIMATE IN 2006—93,000 WILL DIE DUE conservativeTO CANCER UP TO THE YEAR2056 ANOTHER linear noESTIMATE IN 2009---985,000 DIED TILL 2004 threshold principle (whichACTUAL CONSEQUENCE is notTOTAL DEATHS;62 (47 PLANT, 15 DUE TO THYROID CANCER ) substantiated byACUTE RADIATION SYNDROME; surveys in high134 (OUT OF WHICH 28 HAVE DIED) natural radiationINCREASED CANCER INCIDENCE; background AMONG RECOVERY WORKERSTHYROID CANCER; (CURABLE, WAS AVOIDABLE) areas) we tend to 6000 ( 15 HAVE DIED) create avoidable trauma in public
Looking back at Fukushima. It has become apparent at Fukushima that theevacuation from the “exclusion Zone” has beenexcessive. Some of the areas that have beenevacuated probably suffered so little contaminationthat they could be reoccupied. . As per WHO report most of the people in Fukushimaprefecture would have received a radiation dose ofbetween 1-10 mSv during first year. Two places thedose were between 10- 50 mSv still below harmfullevel. Almost all other places were below theinternationally agreed reference level for the publicexposure due to radon in dwelling (about 10 mSv).
Chernobyl Psychosomatic effects‘Besides the 28 fatalities among rescue workers and employees of the power station due to very high doses of radiation (2.9 - 16 Gy), and three deaths due to other reasons (UNSCEAR 2000b), the only real adverse health consequences of the Chernobyl catastrophe among approximately five million people living in the contaminated regions were the epidemics of psychosomatic afflictions. These appear as diseases of the digestive and circulatory systems and other post-traumatic stress disorders such as sleep disturbance, headache, depression, anxiety, escapism, “learned helplessness”, unwillingness to cooperate, overdependence, alcohol and drug abuse and suicides (Forum 2005). These diseases and disturbances could not have been due to the minute irradiation doses from the Chernobyl fallout (average dose rate of about 1 - 2 mSv/year), but they were caused by radiophobia (a deliberately induced fear of radiation) aggravated by wrongheaded administrative decisions and even, paradoxically, by increased medical attention which leads to diagnosis of subclinical changes that persistently hold the attention of the patient.Bad administrative decisions made several million people believe that they were “victims of Chernobyl” although the average annual dose they received from “Chernobyl” radiation was only about one third of the average natural dose. This was the main factor responsible for the economic losses caused by the Chernobyl catastrophe, estimated to have reached $148 billion by 2000 for the Ukraine, and to reach $235
. The Health Physics Societys position Statement first adopted in Jan. 1996, as revised in July 2010, states: In accordance with current knowledge of radiation risks, the Health Physics Society recommend against quantitative estimation of health risks below an individual dose of 5 rem(50 mSv) in one year or a lifetime dose of 10 rem (100 mSv) above that received from natural sources.. French Academy of Sciences and the National Academy of Medicine published a report in 2005 that rejected the LNT model in favour of a threshold dose response and a significantly reduced risk at low radiation exposures.
What do we need to do?• Realistic worst case assessment in public domain at each site taking margins beyond design basis into account• Pragmatic evidence based intervention levels ( not biased by LNT) to be articulated in advance• Credibly demonstrate best estimate impact in public domain (expected to be much lower)• Develop and deploy systems that do not cause any adverse impact in public domain