Nuclear accidents

nacc

1. Laura Rodriguez
3°BB
English – Daniela Segui
2011
ITSP

2. A nuclear accident
or nuclear incident, depe
nding on the severity, is
known toinadvertent
releases of radioactive
materials,
accidental or radioactivit
y levels likely to
harm public health.

3. Is described as a nuclear
accident or incident according to its
severity and its impacton the
population and the environment.
Radiological accidents can happen at a nuclear
plant or outside, ie in a facility thatconducts
a nuclear activity (hospitals, research
laboratories ...) or due to the loss of a radioactive
source, or by spreading involuntary or voluntary radio
active substances intothe environment.
To measure the severity of an event, there is an
international scale: INES scale.

5. No safety significance.
Examples:
4 June 2008: Krško, Slovenia: Leakage from the primary
cooling circuit.
17 December 2006, Atucha, Argentina: Reactor
shutdown due to tritium increase in reactor compartment.
13 February 2006: Fire in Nuclear Waste Volume
Reduction Facilities of the Japanese Atomic Energy Agency
(JAEA) in Tokaimura.

6. Impact on the defense in depth. Greater exposure 
to legal limits annual member of the
public, minor problems with security elements
and components to defense in depthremaining an
d theft or loss of a source of low-level radioactivity.

7. Impact on people and the environment. Exposure 
of a member of the public to more
than 10 mSv and exposure of a worker in
excess of legal limits annually.
Radiological damage and control barriers. Radiati
on level in an operational area of more
than 50 mSv / h and radioactive
contamination within the facility is not prepared in
thedesign.
Impact on the defense in depth.
Example: Incident at nuclear plant Asco

8. Impact on people and the environment. Exhibition of
10 or more times the legal annuallimit for
workers and non-lethal effects produced by
radiation.
Radiological damage and control barriers. Exhibition
of more than 1 Sv / h in a work zone.
Impact on the defense in depth
Example: THORP plant Sellafield (United Kingdom) –
2005.
Paks Nuclear Power Plant (Hungary), 2003; fuel rod
damage in cleaning tank.
Vandellos Nuclear Power Plant (Spain), 1989; fire
destroyed many control systems; the reactor was shut
down

9. Impact on people or
the environment. Minor release of
radioactive material that may be
required, albeit unlikely, measures of o
pposition. At least one death by
radiation.
Radiological damage and control barri
ers. Molten fuel or
damaged and release significant
amounts of radiation with probability of
public exposure.
Example: Accident Accident Tokaimur
a nuclear reactor RA-2, Argentina

10. Impact on people or the environment. Limited
release of radioactive material
that mightrequire measures of opposition. Several 
deaths from radiation.
Example: Windscale Fire, 1 3 Goiânia.2 Radiologica
l Accident
Radiological damage and control barriers.
There is serious damage to the reactor
core and causes the release
of radioactivematerial in
a facility that generates risk of public exposure that
could result from acritical accident or fire.
Example: Accident at Three Mile Island.

11. Impact on people and environment
Significant release of radioactive material likely to
require implementation of planned countermeasures.
There has been only one such event to date:
Kyshtym disaster at Mayak, Soviet Union, 29
September 1957. A failed cooling system at a military
nuclear waste reprocessing facility caused a steam
explosion that released 70–80 tons of highly
radioactive material into the environment. Impact on
local population is not fully known. This is the only
accident to go over 5 on the scale besides
Chernobyl and Fukushima

12. Impact on people and
environmentMajor
release of radio-active
-material with
widespread health
and environmental
effects requiring
implementation of
planned and
extended -
countermeasures

13. There have been two such events to
date:Chernobyl disaster, 26 April 1986. A power
surge during a test procedure resulted in
a criticality accident, leading to a powerful steam
explosion and fire that released a significant
fraction of core material into the environment,
resulting in a death toll of 56 as well as estimated
4,000 additional cancer fatalities among people
exposed to elevated doses of radiation. As a result,
the city of Chernobyl (pop. 14,000) was largely
abandoned, the larger city of Pripyat (pop. 49,400)
was completely abandoned, and a
30 km exclusion zone was established.

15. Fukushima I nuclear accidents, a series of events
beginning on 11 March 2011. Rated level 7 on 11 April
2011 by the Japanese government's nuclear safety
agency.[2][3] Major damage to the backup power
and containment systems caused by the 2011 Tōhoku
earthquake and tsunami resulted in overheating and
leaking from some of the Fukushima I nuclear plant's
reactors. Each reactor accident was rated
separately; out of the six reactors, three were rated
level 5, one was rated at a level 3, and the situation
as a whole was rated level 7.[4] An exclusion zone of
20 km was established around the plant as well as a
30 km voluntary evacuation zone

17. There are also events of no safety relevance,
characterized as "out of scale".
Examples:17 November 2002, Natural Uranium
Oxide Fuel Plant at the Nuclear Fuel
Complex in Hyderabad, India: A chemical
explosion at a fuel fabrication facility.
29 September 1999: H.B. Robinson, United
States: A tornado sighting within the protected
area of the nuclear power plant (NPP).
5 March 1999: San Onofre, United States:
Discovery of suspicious item, originally thought
to be a bomb, in nuclear power plant.

18. The severity of effects increases with the
dose, duration and age of the person. In case of accident,
the doctor determined from the dose received medical
examinations.

19. Exhibition Severity Symptoms
Some millisieverts  only possible long-
term
Several hundred millisievertsNo immediate effect Possible temporary nause
a and slight fever
Between 1 000 and 2
000 millisieverts
remarkable
medical Effect
 vomiting, fatigue,
fever, risk of infection,
cancer
Between 2 000 and 4
000 millisieverts
serious medical Effect vomiting, fever, digestive
disorders, bleeding, hair
loss,
leukemia, other cancers
Between 4 000 and 10
000 millisievertsand
 probability greater
than 50% death,
property
damage neurological (di
zziness, disorientation) an
d cancers of many types
Excess of 10 000 mSv  safe Death