At Present there is a strong public agitation against the commencement of two nuclear reactors of 1000MW capacity at Kudankulam in the Southern Tamilnadu district of Tirunelveli. The agitation against this nuclear plant started way back 1989 but due to various reasons like the disintegration of Soviet Union into several states and the change of the Government in India the work on these reactors could not be commenced earlier. Subsequently the conditions of the agreement changed between India and the aid lending Soviet state after about a decade even the Union Government chose to continue to give life to the first environmental clearance given in 1988-89 so that its lease of life prolonged although under usual circumstances the validity of environmental clearance is only for 5 years for all industrial projects. The reports of the site selection committee and the environmental impact appraisal reports given by experts and the nuclear power project authorities were based on insufficient and improper data even by violating international standards on nuclear safety. The public were informed and they never involved in the preparation of the emergency preparedness plans and in chalking out evacuation schemes to protect public health and the environment in the case of a maximum credible accident like the one which occurred at Fukushima in Japan in March 2011 due to human failures. The public demands to make available the environmental Impact Assessment reports including the Emergency Preparedness Reports were not given to the public who requested them for the same and they were slowly coming out due to applications made by the environmental activists under the Right to Information Act. Even without making a scientific based mock drill for emergency preparedness and disaster management consequent to a potential nuclear reactor explosion the authorities are misleading both the public, the state and central Government authorities on the safety of nuclear power even by violating the environmental protection rules and regulations and the guidelines issued by the national Disaster Management Authority under the Chairmanship of the Prime Minister on the disaster management procedures to be followed for handling the consequences of a radiological emergency arising from nuclear power plants. In order to provide some basic idea about what kinds of emergency preparedness plans have been made for several reactors in several countries of the world are presented below so that a comparison can be made on the measures being taken by the state and central governments and nuclear power authorities for ensuring the safety of the people and their environment in case of the Kudankulam nuclear power plant. It is proposed to revise this presentation in the near future after receipt of construction suggestions from the concerned people.
1]UNITED STATES
Emergency Planning Zones for nuclear accidents as
per United States Standards (80kms Zone):
http://www.nrc.gov/about-nrc/emerg-preparedness/about-emerg-preparedness/planning-zones.html
http://www.nrc.gov/about-nrc/emerg-preparedness/about-emerg-preparedness/planning-zones.html
To facilitate a preplanned strategy
for protective actions during an emergency, there are two emergency planning
zones (EPZs) around each nuclear power plant. The exact size and shape of each
EPZ is a result of detailed planning which includes consideration of the
specific conditions at each site, unique geographical features of the area, and
demographic information. This preplanned strategy for an EPZ provides a
substantial basis to support activity beyond the planning zone in the extremely
unlikely event it would be needed.
The two EPZs are described as
follows:
Plume Exposure Pathway EPZ
The plume exposure pathway EPZ has a
radius of about 10 miles from the reactor site. Predetermined protective action
plans are in place for this EPZ and are designed to avoid or reduce dose from
potential exposure of radioactive materials. These actions include sheltering,
evacuation, and the use of potassium iodide where appropriate. For more
information, see Typical
10-Mile Plume Exposure Pathway EPZ Map.
Ingestion Exposure Pathway EPZ
The ingestion exposure pathway EPZ
has a radius of about 50 miles from the reactor site. Predetermined protective
action plans are in place for this EPZ and are designed to avoid or reduce dose
from potential ingestion of radioactive materials. These actions include a ban
of contaminated food and water.
2]JAPAN:
According to The Nikkei, disaster management zones will
cover a distance of up to 30km from nuclear
power reactors. In cases of accidents, areas within 5km will be considered
‘immediate evacuation zones’ while areas up to 30km away will be designated as
‘probable evacuation zones’. The current zones only reach as far as 8-10km. The
new established regulatory authority also urged emergency centers for disaster
response set up by central and local governments be located further away. Under
the new guidelines, idle reactors will only be restarted if local governments
are well-prepared for accidents, as approved by the regulatory.
3] INDIAN STANDARDS:
The AERB Code of Practice on Safety in Nuclear Power Plant Siting lays down desirable criteria for population for selection of a site as follows:
“Other desirable population distribution characteristics in plain terrain are:
i) Population centers greater than 10000 should not be within 10 km of the plant.
ii) The population density within a radius of 10 km of the plant should be less than 2/3 of the state average.
iii) There should be no population centres more than 100000 within 30 km from the plant.
iv) The total population in the sterilised area should be small, preferablyless than 20000.”
It may be reiterated that these are only desirable criteria and are prescribed to enable easy emergency planning.
For the purpose of planning for serious accidents, if any, an area of 16 km around the plant is considered as the Emergency Planning Zone. The AERB Code of Practice on Safety in Nuclear Power Plant Siting states:
During emergency, availability of transportation network means of communication, etc. which are of significance during emergency condition shall be checked. A radial distance of 16 km from the plant may be considered for this purpose.
The AERB Code of Practice on Safety in Nuclear Power Plant Siting lays down desirable criteria for population for selection of a site as follows:
“Other desirable population distribution characteristics in plain terrain are:
i) Population centers greater than 10000 should not be within 10 km of the plant.
ii) The population density within a radius of 10 km of the plant should be less than 2/3 of the state average.
iii) There should be no population centres more than 100000 within 30 km from the plant.
iv) The total population in the sterilised area should be small, preferablyless than 20000.”
It may be reiterated that these are only desirable criteria and are prescribed to enable easy emergency planning.
For the purpose of planning for serious accidents, if any, an area of 16 km around the plant is considered as the Emergency Planning Zone. The AERB Code of Practice on Safety in Nuclear Power Plant Siting states:
During emergency, availability of transportation network means of communication, etc. which are of significance during emergency condition shall be checked. A radial distance of 16 km from the plant may be considered for this purpose.
The AERB Code of Practice on Safety in Nuclear Power Plant Siting states: An exclusion area of appropriate size (at least 1.5 km radius from the reactor centre) shall be established around the reactor and entry to this is to be restricted to authorized personnel only. Thus the population falling within the exclusion zone, if any, is only resettled. The sterilized zone is the annulus between the exclusion zone and an area up to 5 km from the plant. The AERB code states in this regard:
“A sterilised area up to 5 km around the plant
shall be established by administrative measures where the growth of population
will be restricted for effective implementation of emergency measures. Natural
growth, however, is allowed in this zone”. Thus,
there is no displacement involved in the sterilized zone.
In fact, there are no restrictions on natural growth of
population in the sterilized zone. The administrative measures are put in place
to ensure that there is no large increase in the population due to say setting
up of an industry involving large labour force, etc.
http://www.npcil.nic.in/pdf/news_28sep2011_02.pdf
(From NPCIL publication on Frequently Asked Questions on Kudankulam Nuclear Power Project)
EMERGENCY PLANNING ZONES: NUCLEAR ACCIDENTS, IAEA
www-pub.iaea.org/mtcd/publications/pdf/method2003_web.pdf [see Page.91]
http://publications.jrc.ec.europa.eu/repository/bitstream/111111111/2756/1/reqno_jrc43311_final%20version%5B2%5D.pdf
The
document [4] requires that for facilities in threat category I or
II,arrangements shall be made for effectively making and implementing decisions
on urgent protective actions to be taken off the site within:
(a) a PAZ,
for facilities in threat category I, within which arrangements shall be made
with the goal of taking precautionary urgent protective action, before a
release of radioactive material occurs or shortly after a release of
radioactive material begins, on the basis of conditions at the facility (such
as the emergency classification) in order to reduce substantially the risk of
severe deterministic effects.
(b) an
UPZ, for facilities in threat category I or II, within which arrangements shall
be made for urgent protective action to be taken promptly, in accordance either
with international or national standards, in order to avert dose off the site.
The PAZ
and UPZ should be roughly circular areas around the facility, their boundaries
should be defined, where appropriate, by local landmarks (e.g. roads or rivers)
to allow easy identification during a response as illustrated in Fig. 4.1. It
is important to note that the zones should not stop at national borders. The
size of the PAZ and the UPZ should be consistent with the guidance provided in
Appendix II of [5].
(c) In
addition to PAZ and UPZ, there is also a Food Restriction Planning Zone(FRPZ), which is more often called Longer-term Protective
action Zone (LPZ).
This is an
area around the facility where preparations for effective implementation of
protective actions to reduce the long term dose, i.e. the risk of stochastic
health effects5 from deposition and ingestion of locally grown food, should be
developed in advance. The longer term protective action zone will of course
include the PAZ and the UPZ and extend to a further radius. On the bases of
severe accident studies, the United States Nuclear Regulatory Commission
(USNRC) for instance has adopted this zone of 80 km (50 miles), however, it
might be much larger, up to a couple of hundreds of kilometres.
On-Site: Internal zone, under control of
NPP operator
PAZ: Precautionary Action
Zone UPZ: Urgent Protective action planning Zone
LPZ: Long-term Protective Zone (Food
Restriction Planning Zone-FRPZ)
[12]. The
calculations assumed average meteorological conditions, no rain, ground level
release; 48 hours of exposure to ground shine, and calculates the centralized
dose to a person outside for 48 hours. The suggested sizes for the PAZ were
based on expert judgment considering the following:
UK
TABLE4 SHORT TERM EFFECTS OF EXPOSURE ON POPULATION HEALTH
AND THE EFFECTS OF EMERGENCY COUNTERMEASURES: FOUR EXAMPLES OF SELECTED
SCENARIOS (1)
Release type
|
Weather conditions
|
Wind direc-tion
|
No. of early deaths
|
No. of prodomal vomiting
(2)
|
Area evacuated (sq.km)
|
Max. distance (A)
|
people evacua-ted
(B)
|
shelter- Area (3)
(C )
|
persons sheltered (3)
(D)
|
UK1
|
FD
|
270O
|
725
|
2,300
|
255
|
35
|
22,000
|
820
|
205,000
|
Uk1c
|
D5
|
240O
|
0
|
2
|
17.5
|
8.6
|
5,350
|
325
|
155,000
|
Uk9
|
DR
|
210O
|
0
|
0
|
12.5
|
5
|
1,100
|
23
|
3,200
|
UK11
|
D5
|
240O
|
0
|
0
|
13
|
5
|
4,750
|
13
|
4,750
|
A) Max. distance of evacuation(km)
B) No. of people evacuated
C) Area of sheltering using NRPB’s
ERL-2 criteria
D) Total No. of persons sheltering
using NRPB’s ERL-2 criteria
(1): Results for all 36 scenarios can be found in Appendix1, Tables 3 and 5. Criteria for countermeasures described in Table 4.
(2) Not estimated by NRPB;
evaluated by using the ratio between early deaths and prodomal vomiting in each
type of release in NRPB –R137. The number of people suffering from
prodomal vomiting includes those who will die. Figures are estimated
after taking into account counter-measures implementation.
(3) Includes the number of people or
area which will be evacuated some hours afterwards (shown in above columns 8
and 6) as well as those people or areas for which no evacuation will take place
but for which the exposure dose is within the range defined in NRPB’s ERLs for
sheltering. The latter group taking shelter are not considered in
estimating early health effects.
KUDANKULAM
CONSEQUENCES OF RADIOACTIVE RELEASES FROM KUDANKULAM NUCLEAR STATION ON THE POPULATION:
Main results of the countermeasures scenario, using
the MARC model
( For weather conditions referred to the table presented
below)
TYPE
OF ACCIDENT:
UK1
Wind direction (Southern winds with slight variation on
either side)
|
Weather Conditions:
DR 240o
|
|
1. Consequences of emergency
counter-measures
- Potential Sheltering1:
Surface area2
Maximum distance from reactor
Population concerned
|
Sq.km
Km
Persons
|
3,000
170
30,00,000
|
- Evacuation:
: Surface area
Maximum distance from reactor
Population concerned
|
Sq.km
Km
Persons
|
800
85
15,00,000
|
2. Consequences of emergency
counter-measures
- Relocation of population
prior to decontamination:
Surface area
Maximum distance from reactor
Population concerned
|
Sq.km
Km
Persons
|
2,000
115
20,00,000
|
Decontaminated area still
not re-inhabited after 5 years :
Surface area
Maximum distance from reactor
Population concerned
|
Sq.km
Km
Persons
|
1,500
115
500,000
|
Decontaminated area still
not re-inhabited after 20 years :
Surface area
Maximum distance from reactor
Population concerned
|
Sq.km
Km
Persons
|
700
80
10,00,000
|
3. Health effects – as estimated
by NRPB3:
- early deaths
- late deaths (cancer)
|
3,000
50,000
|
(Approximate values have been presented due to
non-availability of latest population data)
NOTES FOR TABLE 3: 1. This ‘potential sheltering’ corresponds to the
application of NRPB countermeasures recommendations in ERL-2. In the
calculation of health consequences, sheltering is considered only in the
evacuation area, prior to evacuation. 2. ‘Surface areas’ in this Table are land
areas only. 3. These health effects have been computed by the
NRPB considering only evacuation as a counter-measure. Sheltering is
assumed to be required only for evacuated people, prior to evacuation. No
specific relocation model is used, but it is assumed that source after
evacuation (this implicitly corresponds, relocation).
METEOROLOGICAL CONDITIONS USED IN ESTABLISHING THE ACCIDENT
SCENARIOS
Code Name
|
Atmospheric stability
|
Duration (h)
|
Pasquill category
|
Windspeed1
(m s-1)
|
Mixing layer depth1(m)
|
Rainfall rate (mm h-1)
|
D5
|
Neutral
|
Total
|
D
|
5
|
800
|
0
|
FD
|
Stable
|
t < 4 h
t > 4 h
|
F
D
|
2
5
|
100
800
|
0
0
|
DR
|
Neutral (Rain)
|
Total
|
D
|
5
|
800
|
1.0
|
Note: The
Values assigned to the wind speed and mixing layer depth are
representatives values for the corresponding Pasquill stability categories and
have been taken from: R.H Clarke, ‘The First Report of a Working Group on
Atmospheric Dispersion: A model for short and medium range dispersion of
radio nuclides released to the atmosphere’, NRPB, Harwell, NRPB-R91, 1979.
Pasquill categories are used to classify the degree of stability of weather
conditions in order to distinguish the main atmospheric dispersion patterns of
clouds emitted from land-based source.
RISK ANALYSIS OF KUDANKULAM REACTOR ACCIDENT : REMEDIAL
MEASURES SCENARIO FOR TAMILNADU STATE
(Due to the reactor accident at Kudankulam the
following villages and towns will be facing the risks of poisonous radioactive
pollution)
Distance from reactor
|
Time taken to execute counter measures
|
Places effected due to UK1/DR/240
(For weather conditions see table above with the
modification that the wind direction is taken as South )
|
|
Sheltering
|
Evacuation
|
||
0 - 5 km
|
1 hr
|
2 hr
|
Ponnarkulam, Erukkandurai,
Nakkaneri, Panaivilai, Sanganeri, Vairavikinaru, Idintakarai,
ThilaivaranThoppu, Kudankulam
|
5 - 30 km
Zone-A
|
6 hr
|
12 hr
|
Nagercoil, Marungoor, Anjugramam,
Aralvaimozhi, Ramapuram, Therur, Rajavoor, Shankaranputhoor, Vadasery,
Thirupattisaram, Vellamadam, Kothaigrammam
|
30 - 85 km
(20 years)
Zone-A
|
6 hr
|
1 day
|
Kayathar, Ithikulam, Paneerkulam,
Thalayalnadanthankulam, Ayyanaruthu, Nellai, Kandheeswarampudur, Pallikottai,
Alavanthankulam, Thenkalam Pudur, Periyarnagar, Thathanuthu, Thalaiyuthu,
Senthimangalam, Thachanallur, Balabagyanagar, Tirunelveli, Vanarapettai, Palayamkottai,
Naranammalapuram, Kattudayar, Kudiyiruppa, Kurichikulam, Vengadasalapuram,
Kollankinar, Maniyachi, Gangaikondan, Savalaperi, Rayavallipuram, Melapattam,
Burkitmangaram, Reddiarpatti, Sivanthipatti, Panayankulam, Maruthakulam,
Caussanelpuram, Perinbapuram, Kandinthakulam, Tharuvai, Keeloomanallur,
Pannankulam, Nellaiyappapuram, Mulaikkaraipatti
|
85– 110 km
(10 years)
Zone-B
|
6 hr
|
2 days
|
Akhilandapuram, Sivagnanpuram,
Chettikurichi, Naickerpatti, Kattalankulam, Kalampatti, Sayamalai
Madhuthupatti, Kokkukulam, Karadikulam, K.Velayuthapuram, Meenthulli,
Valikandapuram, Kalugumalai, Vanaramutti, Alangulam, Zamin Devarakulam,
Vagaikulam, Alaganer, Azhakunachiapuram, Maruthankinaru,
|
110 – 140 km
(5 Years)
Zone-C
|
6 hr
|
2 days
|
Srivilliputtur, Sivakasi, Sattur,
Rajapalayam, Poolavoorani, Madathupatti, Samsigapuram, Thenmalai, Mamsapuram,
Ayyaneri, Venkatachalapuram, Ilayarasanendal, Elayiramapanni, Thiruvengadam,
Melachthiram, Sankaramurthipatti, Viswanadham, Meenampatti, Vadamalapuram,
Anaikuttam, Thiruthangal, Thlukankulam.
|
140- 170 km and above
(1 Year)
Zone-D
|
6 hr
|
2 days
|
Peraiyur, Vannivelampatti, Villur,
Thaaniparai, Watrap, Kallikudi, Sengapadi, Virudnagar, Kumapatti, Mangalam,
Amathur, Maharajapuram, Ayankarisalkuam, Kilankualm vandapuli,
Mallapuram,Karaikeni, Solaipatti, Maravankulam, Usilampatti, Madurai.
|
The details given above are
approximate because the relevant detailed maps are not available with the
author and they will be improved as soon as more details are received.
Note:
Intervals between evacuation and reoccupation of original houses and lands
after decontamination
Since the radio-active pollutants seriously pollute the
lands, buildings and equipment, the people duly evacuated and rehabilitated in
safer places, can return along with their cattle to their original homes in
their native places only
1) after one year upto 170km and above from the reactor
2) after 5 years upto 135km from the reactor
3) after 10years upto 120km from the reactor and
4) after 20 years upto 80km from the reactor.
Depending
upon the vagaries of the weather, some places may be more polluted than others.
DEFENCE IN DEPTH
http://www-pub.iaea.org/MTCD/publications/PDF/P082_scr.pdf
For animation purposes see website to see the nuclear plant in working condition
1. US ENVIRONMENTAL AGENCY PREDICTIONS ON DISASTERS BASED ON FUKUSHIMA ACCIDENT
For detailed narrative see website: http://www.nrdc.org/nuclear/fallout/
2. PUBLIC AGITATION AGAINST INDIANA POINT REACTOR,NEW YORK, DISASTER SCENARIO
For more detailed information on the predicted nuclear reactor explosion and its impacts see website:
http://www.nrdc.org/nuclear/indianpoint/files/NRDC-1336_Indian_Point_FSr8medium.pdf
For more detailed information on the predicted nuclear reactor explosion and its impacts see website:
http://www.nrdc.org/nuclear/indianpoint/files/NRDC-1336_Indian_Point_FSr8medium.pdf
3. PREDICTED AND OBSERVED RADIOACTIVITY LEVELS DUE TO CHERNOBYL ACCIDENT 1986
Table 5 gives the most important emissions due to the accident.
The released fractions correspond with the theoretical predictions of the
source term in case of an early failure of the containment of a PWR reactor.
Nuclides
|
Released fraction (% of
the core inventory)
|
Released activity
(PBq)
|
Xe-133
|
100
|
6 500
|
I-131
|
55
|
1 800
|
Cs-137
|
33
|
85
|
Cs-134
|
33
|
52
|
Sr-90
|
4
|
8
|
Pu-239
|
3.5
|
3 10-2
|
Table
5 : Most important emissions due to the Chernobyl accident.
The emission was composed of core fragments, fine aerosols and
volatile fission products (gas and condensation aerosols). Hot particles, or core fragments (UO2), or graphite fragments contaminated with
condensed semi-volatile fission products were found.
The high temperature of the releases led to a significant
increase of the effective height of the radioactive cloud (up to around 1 000
m). This led to transport of radioactivity over very large distances.
The main exposure routes were, in chronological order: exposure
to direct irradiation from the cloud, inhalation of iodine and irradiation of the soil and
other contaminated surfaces (5 to 10 mSv/h at Pripyat). The latter factor constituted the basis of
the decision for evacuating an area of 30 km around the power plant. During several days, the cloud
spread out over Europe and over the Northern Hemisphere. The deposition of iodine and
caesium and also the resulting contamination of food products were considered as being the
chief issues.
The countermeasures may be summarised as following [3]:
• evacuation
of about 110 000 persons during the first month;
• distribution
of stable iodine to several millions of persons;
• evacuation
of several tens of thousands of animals;
• prohibition
of consuming milk and fresh vegetables in a large part of Europe;
• construction
of barriers to avoid transfer of the contamination to drinking water sources;
• decontamination
and demolition of houses over a surface of 7 000 km²;
• decontamination
of roads, treatment of fields, etc;
• delayed
evacuation of 220 000 persons from their villages up to several hundreds of kilometres
from the power plant, considering a potential chronic exposure of more than 5 mSv/y
(in particular the villages contaminated by wet deposition).
http://books.google.co.in/books?id=LItzN3tYwBIC&pg=PA205&lpg=PA205&dq=%22Figure+5.28+shows+the+distribution+of+radiation+levels%22&source=bl&ots=JhiRndd461&sig=lN8bmB0i4pAej1Xl_IZMsTvSUXs&hl=en&sa=X&ei=p5iCUJLjLJCzrAfj_IDYDg&ved=0CB0Q6AEwAA#v=onepage&q=%22Figure%205.28%20shows%20the%20distribution%20of%20radiation%20levels%22&f=true
4. US GOVERNMENT EVACUATED VICTIMS UPTO 32Km (20 MILES) FOR REACTOR ACCIDENT AT THREE MILE ISLAND IN UNITED STATES BASED UPON ACTUAL OBSERVATIONS OF RADIOACTIVITY WHICH STOOD ABOVE THE PERMISSIBLE LEVELS TO ENSURE PUBLIC SAFETY
For more details on the reactor accident and disaster management see the website below:
1000 MW NUCLEAR PLANT - DISASTER SCENARIO(350Km)
DISASTER SCENARIO -1000 MW NUCLEAR PLANT SUBJECTED TO
NUCLEAR BOMBING (1350 Km)
5. ACTUAL ISODOSE MAPS OF RADIOACTIVITY DUE TO FUKUSHIMA REACTOR EXPLOSION
For more detailed information see the following website
Note: The following information is extracted in public interest from the NEI website cited below.
UNSAFE ASPECTS OF NEW RUSSIAN REACTORS (VVER 1000) AS PER ASSESSMENT OF
EXPERTS
Third-Generation VVER-1000 (Nuclear Reactors under construction at
Kudankuylam)
The
VVER-1000 design was developed between 1975 and 1985 based on the requirements
of a new Soviet nuclear standard that incorporated some international practices, particularly in the
area of plant safety. The VVER- 1000 design was intended to be used for many
plants, and 18 units now operate in two former Soviet republics. Of these,
two—Novovoronezh 5 andSouth Ukraine 1—are prototypes; three are Model
V338s—Kalinin 1 and 2 and South Ukraine 2; and all the rest—Balakovo 1-4, Rovno
3, Khmelnitskiy 1, South Ukraine 3 and Zaporozhye 1-6—are Model V320s. Russia
Balakovo 1-4 , Kalinin 1-2,Novovoronezh 5,Ukraine Rovno 3,Khmelnitskiy 1South
Ukraine 1-3,Zaporozhye 1-6
Two
VVER-1000 units were built outside the former Soviet Union:Bulgaria Kozloduy 5
and 6
VVER-1000 TYPE NUCLEAR PLANTS USED AT
KUDANKULAM WERE STOPPED IN OTHER PLACES:
Work was
stopped on two other VVER-1000 units in Bulgaria (Belene 1 and 2) after public
protests over claims of unsuitable soil and seismic conditions.
The
Hungarian government canceled Paks 5 and 6 in 1989.
Construction
of two VVER-1000 units at Stendal, in the former East Germany, was halted
following reunification with West Germany.
Two
VVER-1000 units under construction at Temelin in the Czech Republic are being
upgraded with Western instrumentation and control equipment and fuel.
A total of
25 VVER-1000 units are at some stage of construction in the former Soviet
Union—15 in Russia and 10 in Ukraine. But work on 12 of these units in Russia,
and six in Ukraine, has reportedly been canceled or deferred indefinitely.
Of the
VVER-1000 units earmarked for completion under the 1992 Russian plan, Kalinin
3—originally scheduled to come on line in 1995—is expected to be operational by
2000, according to a Ministry of Atomic Energy official.
Other units
expected to come on line by 2000 are Balakovo 5, a VVER-1000, and Rostov 1, a VVER-1000
that is reportedly 97 percent complete. A second unit at Rostov is said to be
95 percent complete, but there is local opposition to both projects. Russia’s
new energy law requires the approval of local authorities for plant
construction.
Ukraine is
seeking funding to complete the construction of two VVER-1000 units—Khmelnitskiy
2 and Rovno 4.
Principal
Strengths:
n Steel-lined,
pre-stressed, large-volume concrete containment structure, similar in function
to Western nuclear plants.
n “Evolutionary”
design incorporating safety improvements over VVER-440 Model V213 plants. The
Soviet approach to standardization was based on continued use of components
that had performed well in earlier plants.
n Use of four
coolant loops and horizontal steam generators—both considered improvements by
Soviet designers.
n Redesigned
fuel assemblies that allow better flow of coolant, and improved control rods.
n Plant worker
radiation levels reportedly lower than in many Western plants, apparently due
to selection of materials, high-capacity system for purifying primary coolant,
and water chemistry control.
DEFECTIVE SAFETY ASPECTS OF VVER-1000 REACTORS
PROPOSED AT KUDANKULAM
Principal
Deficiencies:
n Substandard
plant instrumentation and controls. Wiring of emergency electrical system and
reactor protection system does not meet Western standards for
separation—control and safety functions are interconnected in ways that may
allow failure of a control system to prevent operation of a safety system.
n Fire
protection systems that do not appear to differ substantially from earlier VVER
models, which do not meet Western standards.
n Quality
control, design and construction significantly deficient by U.S. standards.
n Protection
measures for control-room operators essentially unchanged from earlier VVER-440
Model V213 design, which does not meet U.S. standards. Unlike all U.S. nuclear
plants, and most in Western countries, VVER-1000s have no on-site “technical
support center” to serve as a command post for stabilizing the plant in an
emergency. Technical support centers were incorporated in U.S. and many Western
nuclear plants following the accident at Three Mile Island Unit 2 in 1979.
n Operating
and emergency procedures that fall far short of Western standards and vary
greatly among operators of VVER-1000 plants.
n Higher power
densities and the smaller volume of primary and secondary systems result in a
somewhat less forgiving and stable reactor.
VVER-1000 Derivatives
Even before
the breakup of the Soviet Union, derivative versions of the VVER-1000 were
under development.
In 1987,
design work was begun on the VVER-1800, a VVER-1000 upgraded for greater safety
and economy. The VVER-1800 design incorporated a lower-power reactor core,
annual refueling, and more reliable control and protection systems.
In 1989,
Finland and the Soviet Union jointly announced the start of development work on
the VVER-91, a VVER-1000 version that would meet stringent Finnish nuclear
plant design requirements. On paper, the Soviet VVER-91 design is among the
world’s most advanced light water nuclear power plants.
Development
of a new VVER-1000 design, the VVER-92, was expected to be carried out with
Western assistance. The VVER-92 incorporated what one Finnish nuclear expert
called “radically simplified” plant systems that included active safety
systems, a reduced-power reactor core, and a double containment structure
surrounding the nuclear reactor. However, the Ministry of Atomic Energy has
reportedly diverted some funding for VVER-
92
development to a pilot project for building a smaller advanced VVER, the VVER-640
or Model V407.
Classifying Nuclear Events
with the INES
Had the INES
existed at the time, these nuclear events would have been classified as
follows:
Chernobyl. The 1986
accident in Ukraine involved wide environmental and health effects and would
have been classified as a Level 7 “Major Accident.”
Three Mile
Island. The
1979 accident that seriously damaged the core of Unit 2 at this nuclear power
plant in Pennsylvania involved the release of very small amounts of
radioactivity outside the plant and would have been classified a Level 5
“Accident With Off-Site Risks.
” VVER-1000 Program on
Safety
In February
1992, the IAEA was asked to expand its safety program on the VVER-440 Model 230
reactors to other Soviet designs. Bulgaria, Czechoslovakia and Ukraine
separately requested that the agency initiate a more comprehensive safety
evaluation of VVER-1000 nuclear power plants. The VVER-1000 is a design that
shares similarities with Western plants, in terms of design philosophy, design
features and constructability. However, concerns remain about engineering
design solutions, quality of manufacture, and reliability of equipment. The
strategy for improving the safety of VVER-1000s is similar to the IAEA’s plan
to upgrade the VVER-440 Model V213s. The main elements of the VVER-1000 program
follow.
Steam Generator Collector
Integrity
Between 1986
and 1991, 24 VVER-1000 steam generators developed cracks in primary cold
collectors; cracking occurred after 7,000-60,000 hours of operation, and was
determined to be caused by environmentally assisted cracking at temperatures of
about 280 degrees C. Although cracked collectors were generally replaced, and
the cause identified, concern remains:
As of
November 1993, 19 operating VVER-1000s had been outfitted with 76 of the steam
generators in question.
The rupture
of steam generator collectors could initiate accidents of high safety
significance in two ways: The radioactive primary coolant could be discharged
to the environment through the main steam atmospheric dump; and the long-term
cooling of the core cannot be assured in the event of loss of primary coolant
water through the main steam atmospheric dump. In addition to the existing
corrective measures, the IAEA has suggested improvements related to detection,
inspection, repair, material, manufacturing processes, stress relieving,
accident mitigation, and operating conditions. A new, improved steam generator
design is under consideration at Gidropress, a Russian nuclear components
manufacturer. The following are other important future activities:
n All adopted
measures should ensure a low probability of a catastrophic break of the
collectors.
n The current
estimates of the safety consequences of a steam generator rupture accident
should be reviewed, with the aim of developing preventive and mitigative
accident management procedures.
n In the short
term, preference should be given to upgrading the main steam atmospheric dump
valves for discharging of steam-water mixture and to developing procedures for
better maintaining the water inventory.
Fuel Assembly Structural
Instability
Deformed
fuel assemblies were discovered at Balakovo and Zaporozhye 1. The problem was
observed after an irradiation of two years in the core. In addition, the
distance between spacer grids was no longer uniform. Preliminary results of a
post-irradiation examinations by Russia’s Scientific Research Institute of
Nuclear Plant Operations confirmed the deformation of whole fuel assemblies;
the institute continued its study in 1994, and is looking into whether the
cause is a design problem. The spacer grid movement may be the result of
inadequate loading.
While a root
cause analysis is under way, design modifications to make the fuel assembly
structure more rigid and to provide dimensional stability are being considered
by the Russian designer.
Control Rod Insertion
Reliability
During the
refueling of Zaporozhye 1 in late 1992, it was discovered that eight control
rod assemblies were not at the bottom position. Subsequently, the same problem
was seen at Balakovo, Kalinin, Khmelnitskiy, Rovno and South Ukraine. In
addition, an increased drop time exceeding the maximum design value was
observed. Most of the problems have occurred during the third year of operating
an assembly in the reactor.
Root cause
investigations are being conducted. A preliminary conclusion links the problem
to an increase in the friction between the control rods and their guide tubes
in the fuel assemblies due to shape changes of the guide tubes or possible
rubbed surface roughness. There appears to be a close correlation between the
control rod insertion problem and the structural instability of fuel
assemblies.
While the
IAEA stresses the importance of determining the root cause and implementing
measures to eliminate the problem, the agency notes that the final solution may
rest on the new improved design of fuel and control assemblies.
