Soviet Report on the Chernobyl Accident.

705 Pages·2015·17.09 MB·English

FOC~FlAPCTBEHHbIR I{OMHTET
110 HCJ1OSrlb3OBAHIHO ATOMHOfl 3HEPFHH CCCP
State Commiittee for Using the Atomic Energy of USSR
ABAPHH HA. 'EPHOBMlJlbCKOfl A3C.
H EE IIOCJIE)1(cid:127)CBHH
THE ACCIDENT AT THE CHERNOBYL AES AND ITS CONSEQUENCES
HH(cid:127))opM a1(cid:127)HR, flo~rOTOBJ~eHxaR AVIR COBe~laHHR
aHcnep~?oB MArAT3
(25--29 aeryc'ra 1986 r. BEHA)
Data prepared for the
International Atomic Energy Agency
Expert Conference
(25-29 August 1986, Vienna)
WORKING DOCUMENT FOR CIIERNOBYL
POST ACCIDENT REVIEW MEETING
HOT FOR PUBLICATION
Anryer
1986Sr.
TRANSLATED FROM THE RUSSIAN
DEPARTMENT OF ENERGY, NE-40
AUGUST 17, 1986
OtTE(cid:127)S
Introduction
1. Descripticn of the Qhernobyl' ~AES with RPlvK-1000 Reactors
2. Chronology of the Development of the Accident
3. Analysis of the Process of Development of the Accident on a ?'.~t~heatical
Model
4. Causes of the Accident
5. Initial Measures to Increase Nuclear Power Plant Safety with REM Reactors
6. Preventing Development of an, Accident and Reducing Its Consequences
7. ?.n~itoring Radioactive Contamination of the Environmrent and the Health of
the Population
8. Rem dt~ions for Increasing the Safety of Nuclear Power Engineering
9. Developmrent of Nuclear PRm~er Engineering in the USSR
The information presented here is based on conclusions of the
Governme~nt Cczmmiss ion on the causes of the accident at the fo~urth unit of
the Qhernobyl' Nuclear PowJer Station and was prepared by the following
experts employed by the USSR State Commission Commnittee on the Use of Atanic
Energy:
Abagyan, A. A. Mysenkov, A. I.
Asmlov, V. G. Pavlovskiy, 0. A.
Gus'kova, A. K. Petrov, V. N.
Denin, V. F. Pikalov, V. K.
Ii'in, L. A. Protsenko, A. N.
Izrael', Yu. A. Ryazantsev, Ye. P.
Kalugin, A. K. Sivintsev, Yu. V.
Konviz, V. S. Sukhoruchkin, V. K.
Tokarenko, V. F.
Kuz'znin, I. I.
Kuntsevich, A. D. Khirulev, A. A.
Legasov, V. A. Shakh, 0. Ya.
M~aterials obtained fram the following organizations were used in
preparing the information: The 0 VV. Kurchatov Institute of Atomic Energy,
the Scientific Research and Design Institute of Powr Ecpuilz1_nt, the
V. G. Khl.opin Rdiumi Institute, the S.* Ya. Zhuk "Hydrodesign" Institute, the
AUl-Union Scientific Research Institute on Nuclear Power Stations, the
Institute of Biophysics, the Institute of Applied Geophysics, the State.
Committee on Nuclear Energy, the State Committee on hydrcireteorology
2
Ministry of Health, the State Carinittee on Nuclear Safety, the Ministry of
Defense, the Main Fire Protection Administration of the Ministry of Internal
Affairs and the USSR Academy of Sciences.
INTRODUCTIO(cid:127)I
An accident occurred at the fourth unit of the Chiernobyl' Nuclear Power
Station on April 26, 1986, at 1:23 AM with damge to the active zone of the
reactor and part of the butilding in which it was located.
TIhe accident occurred just before stopping of the powerplant for
scheduled maintenance during tasting of the operating imodes of one of the
trbo~gerierators. The powr o~tpuit of the reactor suddenly increased
sharply, which led to damage to the reactor and discharging of part of the
radioactive products accunmulated in the active zone into the atnsphere.
The nuclear reaction in the reactor of the fourth puerplant stopped in
the process of the accident. The fire which broke out was extinguished, and
Soperations were begun for containing and eliminating the consequences of the
accident.
The popalation was evacuated from areas immediately adjacent to the
area of the nuclear power plant and fran a zone with a radius of 30 kmn
around it.
In view of the extr(cid:127)r character of the accident which occurred at
Cherrobyl', an operations gr~oup headed by Prime Minister of the U.S.S.R.
N. I. Ryzhkov was organized at the Politblxo(cid:127) of the Oz CPSU (Central
Ca~inittee of the Cammunist Party of the Soviet Union) for coordinating the
activity of ministries and other gouierrxnt departments in eliminating the
consequences of the accident and rendering aid to the population. A
'Goveriet Cariission was fonrme and entrusted with studying the causes of
2
the accident and carrying ou.t the necessary emergency and reconstruction
me~asures. The necessary scientific,. technical and econaomic capabilities and
resources of the country were provided.
Representatives of MrAGATE were invited to the USSR and given the.
o~portunity to familiarize themselves with the state of affairs at the
Qheznobyl' Nuclear Pc~rplant and measures for overcoming the accident.
They informed the world catuunity about their asses(cid:127)Tent of the situation.
The goverr~ts of a number of countries, many goverretal, social and
private organizations and individual citizens fram various countries of the
w~rld appealed to various organizations of the USSR with proposals
concerni~ng participation in overcoming the after-effects of the accident.
Somre of these proposals were accepted.
In the thirty years of its development, nuclear power engineering has
occupied an essential place in wo~rldwide p~er production and, on the whole,
has displayed high levels of safety for man and the environmrent. One cannot
imagine the future of the world econamy without nuclear power. However, its
further development ruist be accarpanied by still greater efforts on the part
of science and engineering for ensuring its operational reliability and
safety.
The accident at Chernobyl' was the result of coincidences of several
events of low probability. The Soviet Union draws the proper conclusions
from this accident.
3
Rejecting nuclear power sources wo~uld require a considerable increase
Sin prcduction and combuastion of organic fuels. This would steadily increase
the risk of hiuman diseases and t~he loss of water-and forests due to the '
continuous passage of harmful chemical substances into the biosphere.
The development of the world' s nuclear power resources brings with it,
in addition to gain in the area of the energy supply and the preservation of
natural resources, dangers of an international character.* These dangers
include transfers of radioactivity across borders, especially in large-scale
radiation accidents, the problem of the spread of nuclear weapons and the
danger of international terrorism, and the specific danger of nuclear
installations under conditions of war. All this dictates the fundame~ntal
necessity of deep international cooperation in the field of develoumnt of
*nuclear power systems and ensuring of their safety.
Such are the realities.
The saturation of the n(cid:127)dz world with potentially dangerous
industrial processes, in significantly intensifying the effects of military
operations, places the question of the senselessness and unacceptability of
war under modern conditions on a new plane.
In a speech on Soviet television on May 14, M. S.*G orbachev stated:
'flie indispitable lesson of (2hernobyl' for us lies in the fact that under
conditions of further expansion of the scientific and technical revolution,
questions of the reliability of equipment and its safety and questions on
4
discipline, order ard organization take on primary importance. The
strictest requirements are needed everywhere.
Furthermo~re, we consider it necessary to nave toward a serious
deepening of cooperation within the framework of the International Agency on
Atomnic Energy."
CHAPTER 1i. DESCRPTION OF THE CHERNOBYL' NUCL.EAR POWqER ST~ATION
"WITH RBK-1OOO REACTORS
1.1 Design Data
The planned poe of the Qiernobyl's Po(cid:127) Station (ChAES), was 60140,
and cn January 1, 1986, the power of four units of the AES was 4000140. The
third and fourth units belong to the second phase of the ChAES and to the
second generation of these Nuclear Power Stations (AFS).
1. 2 Description of the Reactor Installation (RU)
of the Fourth Unit of the ChAES
The basic design features of RBMK reactors are as follows:
1) vertical channels with the fuel and the heat-transfer agent, which
penmit local reloading of fuel with a working reactor;
2) fuel in the form of bundles of cylindric fuel elemnts of uraniumt
dioxide in zirconiu~m shell tubes;
3) a graphite mo~derator between channels;
4) a low-boiling heat-transfer medium in the forced circulation
rrcirculation mo~de (KMFTs) with direct feeding of steam to the turbine
0
These design decisions in combination condition all the basic features
of the reactor and the AES, both advantages and shortcomings. The
advantages include: the absence of reactor vessels, which are awkward to
produce on the powerplant maxizmum capacity and on the production base; the
absence of a complex and expensive steam generator; the possibility of
~cntnosreloading of fuel and a good neutron balance; a flexible fuel
cycle, which is easily adapted to variations in the fuel market conditions;
2
the possibility of nuclear superheating of the steam; high thernodynamnic
reliability of the thermal equipent and viability of the reactor due to the
controlling of the flow rate for each channel separately, uonitoring of the
integrity of the channels, m~nitoring of the parame~ters and radio activity
of the heat-transfer medium of each channel and replacemrent of damaged.
channels while running. The shortcomiings include: the possibility of the
developme~nt of a positive void coefficient of reactivity due to the phase
change in the heat-transfer agent which deten es the transient neuilronic
behavior; high sensitivity of the neutron field to reactivity disturbances
of different kinds, necessitating a complex control system for stabilizing
the distribution of the release of energy in the active zone; complexity of
the inlet-outlet piping system for the heat-transfer agent of each channel;
a large amtount of thermnal energy accu.mulated in the metal structures, fuel
elements and graphite block structure of the reactor; slightly radioactive
steam in the turbine.
The PBMK-1000 reactor with a power of 3200 (cid:127) (thermal) (Fig. 1) is
equidpped with two identical cooling loops; 840 parallel vertical channels
with heat-releasing assemblies (TVS) are connected to each loopo.
A cooling loop has four mteain parallel circulation pxrps (three working
pumps feeding 7000 t/h of water each with a head of about 1.5 MWa, and one
back-up pump).
Thie water in the channels is heated to boiling and partially
evaporateso The water-steam mitue with an average steam content of 14% by
imass is bled thrcugh the top part of the channel and a water-steam line into
two horizontal. gravity separators. The dry steam (with a mocisture content
less than 0.1%) separated in them passes fram each separator at a pressure