ML20138Q198
| ML20138Q198 | |
| Person / Time | |
|---|---|
| Issue date: | 11/07/1985 |
| From: | NRC OFFICE OF PUBLIC AFFAIRS (OPA) |
| To: | |
| Shared Package | |
| ML20138Q140 | List: |
| References | |
| FOIA-85-481 PROC-851107, NUDOCS 8511180029 | |
| Download: ML20138Q198 (190) | |
Text
_ . _ . . -. .
.- UNITED STATES NUCLEAR REGULATORY COMMISSION j OFFICE OF PUBLIC AFFAIRS p REGO A>
- s" 8 ,j V
'I+*e w /
NUCLEAR- POWER l
AND
- RADIATION l
WORKSHOP MANUAL
!!A22Sgig9 esito7 HANAUER85-481 PDR 7f A7 m __
UNITED STATES NUCLEAR REGULATORY COMMISSION OF lCE OF NSPECT.ON AND ENFORCEMENT gg REGug '
gh O s ,
s REACTOR CONCEPTS :
G -
100 L
1
TABLE OF CONTENTS
,q Pace
\ Nuclear Power for Electrical Generation........................... 1-1 The Fission Process and Heat Production........................... 2-1 Ra d i a t i o n Te rm i n ol o gy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 1 Exposure and Dose Measurements.............................. 3-11 International System of Units............................... 3-23 Radiation Sources................................................. 4-1
, Natural Background Radiation Sources......................... 4-2 Man Made Radiation Sources................................... 4-7 Radiation Sources at Nuclear Plants............................... 5-1 Biol ogical Effects of Raciation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 C el l ul a r D ama g e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 - 4 Radiation Syn'drome.......................................... 6-10 i NRC Dose Limits............................................. 6-12
\., .
- Acute Radiation Dose........................................ .
6-14 Ca nc e r Ri s k Es tima te s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-17 Sens i ti vi ty Facto rs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .* . . . . 6-22 Methods for Protection Against Radiation and C o n tami n a t i o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 - 1 Minimize Time................................................ 7-3 Maximize Distance............................................ 7-5 .
Maximize Shielding........................................... 7-7 Protection Agains t Contamina tion. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-10 BWR Systems....................................................... 8-1
- P W R Sy s t e m s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 1 Radioactive Waste Disposal........'............................... 10-1 R e a c t o r Eme r g e n c i e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 - 1 The Three Mil e Isl and Acci dent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-1
_____ ___ w
i
! r ~.
l NUCLEAR POWER FOR
! ELECTRICAL l
GENERATION 1 l
i l
l .
i The purpose of a Nuclear Power Plant is not to produce or release
" Nuclear Power" but to generate electricity. It should not be surprising j then that a nuclear power plant has many similarities to other elec-i trical generating facilities. It should also be obvious that nuclear ,
- plants have some significant differences from other plants. Some of l
{ these differences could lead to an adverse effect on public health and l
\ l
- safety. '
.l I 1 .
l 1-1
sT/ TIONARY Coll DRIVE SHAFT _
fg q /., a ; ym % ROTOR
\ ggUsh %
h '
)
b j FLANGE k f, ]E ECTRIC AL p
N
\_ GENER ATOR HOUSING p____y ELECTRICAL GENERATOR I I l non l
///
l': =
l l w, i l / ,*o- Bectron ,
I i
- Flo w L _ _ _ _ _ _ _ _ _ _ _ .2 ELECTRICAL .
GENERATOR Of the several known methods to produce electricity, by far the most prac-tical for large scale production and distribution involves the use 1,# an
" electrical generator." In an electrical generator, a magnet (rotor) revolves inside a coil of wire, creating a flow of electrons inside the wire. This flow of electrons is called electricity. Some mechanical device (wind turbine, water turbine, steam turbine, etc.) must be avail-able to provide rotation.
1-2
1 TURBINE METAL FLANGE HOUSING BLADES
~
b 1 -
N:
- Wi}'rnm====ae am g3 m
-} .- *Mi i * ' ' "
0 l h 4l U; ygh'&Y' l)') "QW$$ 3 i
N TURBINE GENERATOR When a turbine is attached (flanged) to the electrical generator, the kinetic energy (i.e. , motion) of the wind, falling water, or steam pushes against the fan-type blades of the turbine, causing the turbine, and the attached rotor of the electrical generator to spin and produce electricity.
1-3
HYDROELECTRIC PLANT
!MCd"' f o'n 7
V E W TR B
/ Cl J
/J ......
DA W ,
a In a hydroelectric power plant, water flowing from a high level to a lower level travels through the metal blades of a water turbine, causing the rotor of the electrical generator to spin and produce electricity.
1-4
'( \.
THROTTLE VALVE STEAM TURBINE r- .- ..
m .!:
l.
9 nnn i:!' jj D !! if:! ((i I
> shf ~ y&~ ~p '.-
- . .. . .:. i.. .:
-3 .
ll l v vj
.- o o
- ELECTRICAL
- . - ' 'M:i. GENERATOR d
I 1 I x
, l 4 hf [ l BOfLER '
FEEDWATER C : ;J PUMP FOSSIL FUEL STEAM PLANT In a fossil-fueled power plant, heat from the burning of coal, oil or natural gas converts (boils) water into steam (A), which is piped to the turbine (B), where it travels through the blades of the turbine, which spins the electrical ger.erator (C), resulting in a flow of electricity.
After leaving the turbine, the steam is converted back (condensed) into water in the condenser (D). The water is then pumped (E) back to the boiler (F) to be reheated and converted back into steam.
L .,
1-5 J
THROTTLE VALVE
,7;. M.
EY.it nnn s e e .. I I J
[ .
i!!!!Ei!
I
// I I I
NUCLEAR TURBINE
- - /""/ o 3
. ELECTRICAL STEAM \;O:ij 'i!P;ii GENERATOR CONDENSER SUPPLY e
i
~
SYSTEM PUMP NUCLEAR FUEL STEAM PLANT In a nuclear power plant, many of the components are similar to those in a fossil-fueled plant, except that the steam boiler is replaced by a Nuclear Steam Supply System (NSSS). The NSSS consists of a nuclear reactor and all the components necessary to produce high pressure steam for the production of electricity.
1-6
s..
O Fission I
- O
\ l 1
i Like a fossil-fueled plant, a nuclear power plant boils water to produce '
electricity. Unlike a fossil-fueled plant, however, the nuclear plant's energy does not come from the combustion of fuel but from the fission (or splitting) of fuel atoms.
- N..s 1-7
ENRICHMENT
(% U-235) en GT3 '
ie na '
c6ha y
c D rA -5 f/ &
C , ,-
URANIUM FUEL NUCLEAR ORE PELLET WEAPON
.7% 3.5 % >97%
[
Most power reactors (capable of producing electricity) in the United States use a "slightly enriched" uranium fuel. " Enrichment" refers to the percentage of the easily fissionable U-235 atoms present in the fuel to the less fissionable U-238 atoms (which are far more abundant in nature). " Weapons Grade" Uranium is very highly enriched (greater than 97% U-235).
l 1-8
<m 70
\
s\
l M N Spacer i
Upper Spring .
Spacer -
b I
e l[ "
l Spacer l
Fuel Pellets Lower Spring Spacer Babcock & Wilcox 4
Once fabricated, ceramic uranium dioxide (UO 2
) fuel pellets, each about 3/4 in. diameter and about 5/8 in. long, are inserted, one on top of the other, into 12-foot long, slender metal tubes. The tubes are generally made of zirconium alloy, aluminum, or stainless steel. The tube material is known as " cladding." When a tube is filled with the uranium fuel pellets, pressurized with helium gas and sealed, it is referred to as a
" fuel rod."
1-9
B Upper End Fitting End Cap
.g.g r.
Fuel Pellet h\ \ , ,
Spacer Crid g! -
u cuid. Tud. ' -
g&
L -
A . .
Fuel Rod ill -
h
' lll l l g Lower End Fitting Babcock & Wilcox At the fuel fabrication facility, fuel rods are bundled together into
" fuel assemblies" or " fuel elements." Spacer grids separate the indivi-dual rods to allow for the necessary flow of coolant water between them.
The number of fuel rods per fuel assembly varies, depending on the type and size of the reactor.
l
, 1-10
I 1
i REFUELING
/ BRIDGE N
N N N REFUELING N
' CANAL N N (WATER)N g@
CORE REACTOR VESSEL
.l 1
At the nuclear power plant, the fuel assemblies are inserted vertically into the reactor vessel (a large steel tank filled with water). The fuel is placed in a precise grid pattern known as the reactor " core."
1-11
REACTOR THROTTLE VESSEL VALVE TEAM LINE
. &. . w
. ~
Mot $TuRE E::,
SEPARATOR r ij.yi, ^n ^
k i;t, M::
- TuReint
- '!iy:: '
!!! ,,:.!f
..5.
REA.T R CORE
- N!d,
/ "' ;
j!. l!; . b^
e e *
- ELECTRICAL 7y , ;i GENERATOR g
JET y CCNCENSER
. PUMP
_g g-g PEEDWATER q
~ T RECIRC q y REC 1RC ( e.--
a r PUMP H PuM, PuMe i
BOILING WATER REACTOR PLANT (BWR)
The Boiling Water Reactor (BWR) operates in essentially the same way as a fossil-fueled generating plant. Inside the reactor vessel (A) heat from the fission of uranium fuel in the reactur core (8) boils coolant water into steam. The steam travels through a moisture separator (C) and is piped (0) to the turbine (E), which turns the electrical generator (F).
The steam is condensed back into water in the condenser (G). The water is then pumped (H) back to the reactor vessel to be reboiled. The recir-culation pumps (I) and jet pumps (J) take a portion of the coolant water and reinject it into the reactor vessel to increase the mixing and flow of reactor coolant. Boiling water reactor systems are manufactured in the U.S. by the General Electric Company, San Jose, CA. BWR's make up about 1/3 of the power reactors in the United States.
1-12
M.""
.m ~
.y' >:;
"nn
(" ,,,,,,, !@:. .
E;!!f[Ei ""
l// / I n:- l','s^L,o n -
lh '
lQ 5 m s.u.
{L ';9: _.
):a fjf En%">M
_ .~,..
v l
, y t . _ ....
3g D
n y= -)v%-- 0,uo, 4 ru.t
,,,c,,, PRESSURIZED 9 WATER
]' REACTOR y
gy a'>c'o,"::a"~'
PLANT Q,~ (PWR)
The Pressurized Water Reactor differs from the Boiling Water Reactor in that steam is produced in the steam generator (B) rather than in the reactor vessel (A). The pressurizer (C) keeps the reacto" coolant (water) under very high pressure (about 2200 pounds per square inch) to prevent it from boiling, even at operating temperatures of about 600 degrees F. Pressurized water reactors make up about 2/3 of the Power Reactors in the U.S. PWR's are manufactured by the Westinghouse Electric Company, Pittsburgh, PA; Babcock & Wilcox Company, Lynchburg, VA; and the Combustion Engineering Company, Windsor, CN.
1-13
THROTTLE VALVE He . .Y_,,
- . STEAM N... A A /'i CIRCULATORGENERATOR [j;: :
O FUEL O ?? -
~ #
TURBINE ,
j y' y' j o ags
- 3
'b[ ::n:: j'j ELECTRICAL
, .. GENERATOR V Q --- ; j CONDENSER CCNCR ETE REACTOR I l[ J VESSEL FEEDWATER h T
(: s PUMP HIGH TEMPERATURE GAS-COOLED REACTOR PLANT
( HTGR )
Another type of reactor uses helium gas instead of water as its coolant.
The only High Temperature Gas Cooled Reactor (HTGR) in the U.S. is the Fort St. Vrain plant in Colorado. The plant was manufactured by General Atomic Company of La Jolla, CA. HTGRs are widely used in other countries.
I 1-14
i i
's 1
i Fission
< Proc uct Decay:
O RADIATION DECAY HEAT f
k_
Since nuclear power plants produce electricity by fission rather than combustion their byproducts are very different than those associated with fossil-fueled plants. "Fissien products" are highly radioactive atoms produced by the splitting of the larger uranium atoms. Because of the intense radiation associated with fission products a system of " barriers" has been developed to prevent these atoms from escaping into the environment. The rapid rate of decay of most fission products causes a significant amount of energy to be generated inside the fuel pellets.
This energy is called " Decay (Residual) Heat" and unless removed could result in damage to portions of the barrier system, or even to the fuel pellets themselves. " Radiation," " Decay Heat" and " Fission Product Barriers" are all discussed further in subsequent sections of this manual.
1-15
Stearn 6--*-
,'5
" ^^
Turbine J. :
1 i i
.!! [:i,{.-i! /i, 3 i v' u j o
/
.: : . .. . J : .- 3
- .g Mcal Generator Conde .
VlY
['
1 k
-e-- 0 Feed Pump T
( '
( ~~.---
A b: - Cire. Water Pump
.-.- 3 CIRCULATING WATER SYSTEM To operate properly all steam plants whether nuclear or fossil fueled, need a circulating water system to remove excess (waste) heat from the steam system and transfer that heat to the environment. The circulating water system pumps water (A) from the environment (river, lake, ocean) through thousands of thin metal tubes in the plant's condensor (B).
Steam exiting the plant's turbines (C) rapidly cools and condenses into water when it comes in with contact the much cooler tuces. Since the tubes provide a barrier there should be no physical contact between the steam and the environmental circulating water. Because the condenser's operation produces a vacuum, any tube leakage in this system will produce an " inflow" of water to the condenser rather than an " outflow" to the environment.
1-16
I 1
l i
Turbine Generator m
1 \ /
\ / Condenser
/' h m
< s I
.i i ) -
F Discharge
! T '
i, 3 Ocean 4 -
r
/
l ' "~' inteke l
( l l , ~ ~ ~ '\
Circ. Water Pump / _
4
_j l' '
i ._
i i
j 1
I Power plants located on the ocean (or other large bodies of water) will
- often discharge their circulating water directly back to the ocean under strict environmental protection regulations. Water is taken from the I ocean, pumped through the thousands of small tubes in the condenser to j remove the plant's waste heat and is then discharged back into the ocean.
- The expected temperature increase from circulating water inlet to outlet is about 5-10 degrees F.
J l,
f 1-17
l i
i l
Turbine Generator
~
4
$ / Forced Draft
\
- \ / Condenser Tm r .%
r '
1
- < , ,1 L , h j
i Paa*-U UUUU U
, s .
---*, k ? b i
i
~
I
(
) ) :
) )- W Cire. Weter Pump i
l l Most nuclear power plants not located on the ocean need cooling towers to
! remove waste heat from the circulating water system. One type is the forced draft cooling tower, in which circulating water from the condensor is permitted to splash _ downward through the cooling tower transferring some of its heat into air. Several large electrical fans located at the 4
top of the cooling tower provide forced air circulation for more effi-cient cooling, l
1-18 t
e~,
(s..
Turbine Generator
\l) ,
I d
\
M
/ Condenser N
Natural Convection Cooling Tower s s b
I/ /j lh \ \
r )
Circ. Water Pump The taller, hourglass shaped natural convection cooling towers do not require fans to exhaust waste heat from the circulating water system into the air. Rather, the natural tendency of hot air to rise removes the waste heat as the circulating water splashes down inside the cooling tower.
i 1 1-19
COLD DRY RELATIVE AIR HUMIDITY { M T ((
35-30- '
gms 25' # WARM H2O 20
- wEr METER per 3 15'
/ AIR AIR 1a .
30 50 70 90 l lg F
The " steam" vented from the top of a cooling tower is really luke warm water vapor -- and it's not radioactive. As the warm, wet air from inside the cooling tower contacts the cooler, dryer air above the cooling tower, its ability to hold moisture is reduced. The released cloud of water vapor is visible only until it can be dispersed and absorbed by the air. The graph above shows air's ability to hold water as air temper-ature changes.
1-20
e ' N, TYPICAL REACTOR PLANT LAYOUT q ( PRESSURIZED WATER REACTOR )
S/G S/G m Mm
=1 W N!!LP Gen.
- ~ 9 i dlnthdlIsl' i r G4( . { f, f .
r ,Q~ g / (
bm%
h fIw h}g'L h((w,y Ge.
~
Q Aumrery conenment Tureirw suading suksng suading The major structures at a pressurized water nuclear plant are the containment building, which houses the reactor and its high pressure
- steam generating equipment; the turbine building, which houses steam turbines, condensers and the electrical generator; the auxiliary l building, which houses normal and emergency support systems (such as the Residual Heat Removal System, fuel handling and storage equipment, laboratories, maintenance areas and the control room. Depending on the plant location, there may or may not be a cooling tower to remove waste heat from the facility.
1 4
1-21
TYPICAL REACTOR PLANT LAYOUT (Boiling Water Reactor)
RX Pnmary Containment m
(DWO MSR m __
lh h LP Gen.
C l11l
~
C lll 1
,ti, , .
muc- - '
' ~
i $
hD D t \= - - , i u ond ump
- RHR I - - ,
i c - Cooling Cire. Pump Tower Reactor Building Turbine (Secondary Containment) Building The major structures at a Boiling Water Nuclear Plant are the Primary Containment (Drywell), which houses the reactor and recirculation pumps, the Reactor Buildino (Secondary Containment) which surrounds the Primary Containment and serves many of the functions of a PWR's Auxiliary Building and the Turbine Building. Depending on the plant location there may or may not be a cooling tower to remove waste heat from the facility.
1-22 h
l
,%- l t! I THE FISSION PROCESS
! AND i
l HEAT PRODLICTION l i
! l
! i i
l t l
f i
l l
i i
f A nuclear power plant converts the energy within atomic nuclei into elec- l l trical energy. This section discusses the release of nuclear energy by
- the fission of uranium atoms and the methods used to control the rate at i
which energy is released and power is produced.
I i
2-1
Electron Proton O+
V
,H Hydrogen Atoms are composed of positively charged protons in the nucleus and nega-tively charged electrons orbiting the nucleus. The simplest atom is hydrogen, composed of one proton and one electron. Its atomic number, derived from the number of protons, is 1, 2-2
1
+ i+ l 2He Helium More complex atoms have more protons and electrons, but each unique com-bination of protons and electrons represents a different chemical element. Helium, for example, with two protons has an atomic number of two.
2-3
PERIODIC TABLE OF THE ELEMENTS H He LiBe B C N O F Ne NaMg Al Si P S Cl Ar 4
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Gage As Se Br Kr 2, . . . .. ., . . . ., . . ,, ,, ,, ,. -
- Rb Sr Y -Zr NbMo Tc Ru;Rh Pc Ag Cd in Sn Sb Te I Xe OsBa La Hf Ta W Re Os Ir Pt Au Ho Tl Pb Bi Fb At Rn Fr RaAc " " " " " - " " " " " "
4 Ce Pr No Fh1Sn Eu Gd Tb Dy Ho Er inYb Lu Th Pd U Np PuArOn Bk Cf EsiRpMd No:Lw i
i Each element has been assigned a chemical symbol. Elements are listed by increasing atomic number and grouped by similar chemical characteristics
- on the Periodic Table of Elements.
. 2-4
.---._,-.---.sy-- +,,------,--e-w, c-,,,,__ - - -g.,,.e.,_. p-, ->- -,,- , ,,,w-.. ..mme,-.r-- - .- ---,% wg, ,-, - *.-y.,*--,-----
w
i
@< Like Charges Repel Opposites Attract O = =
Electrostatic Force Since all protons are positively charged, and since like charges repel, electrostatic force tends to push protons away from eact. Other.
2-5
Neutrons Provide g Nuclear Attractive l
Force !
- No l
4 Electrostatic Repulsion l Hold Larger Atoms
! Together .
i j
Neutrons, with no electrical charge, provide the attractive nuclear force to offset electrostatic repulsive forces and hold atoms together. All atoms found in nature (except the the basic hydrogen atom) have one or more neutrons in their nuclei. ..
2-6 l
Hydrogen Isotopes DEUTERIUM RITIUM iH iH
( 1H HYDROGEN l
l l
I .
A chemical element can have several different combinations of protons and
. neutrons in its nuclei. Hydrogen, above, has three naturally occurring combinations (known as " isotopes"); Basic hydrogen (one proton, no neutrons); deuterium (one proton, one neutron) and tritium (one proton, twoneutrons).
2-7
AT@MIC NUMBERS i 1 o
IH 2 He 3 Li 80 1
! r i l i
27 CO 79AU 92 U
- I
! i The number of protons an element has (atomic number) determines its l chemical characteristics. Atomic numbers are always related to the same element (hydrogen-1, cobalt-27, gold-79, uranium-92). l When used in technical literature, the atomic number is usually written to the lower lef t of the chemical symbol (as shown above). Of ten the l
atomic number for an element will be omitted from technical writings l since this number will never change for the element under discussion.
t i
2-8
. l l .
Naturally Occurring
'sC ': C .
':C 6 Protons 6 Protons 6 Protons 6 Neutrons 7 Neutrons 8 Neutrons s
Since chemical elements can have different numbers of neutrons,the use of isotopic numbers (or mass numbers) is nece sary to distinguish one iso-tope from another. Naturally occurring isotopes of the element carbon are shown above. The isotopic number (shown co the upper left of the chemical symbol) is the sum of the number of protons and the number of neutrons in the nucleus of an atom.
l l
l j 2-9
Naturally Occurring Copper l
- Cu :: Cu 29 Protons 29 Protons 34 Neutrons 36 Neutrons P
The commonly found isotopes of copper are shown above. Although the placement of the isotopic number in the upper left is technically
- correct, many variations are encountered. For example
l 63 63 CU, CU, CU , CU-63, copper-63 All refer to the same isotope of copper.
l l l
l l l
/
2-10 j
Naturally Occurring Uranium
- U : U :: U 92 Protons 92 Protons 92 Protons 142 Neutrons 143 Neutrons 146 Neutrons !
- ( ;
Power reactors in the United States use uranium as fuel. The naturally occurring isotopes of uranium are shown above. About 99. 3% o f all uranium atoms are the isotope U-238. About .7% are U-235. Trace amounts (far less than 1%) of U-234 can be found. Another isotope, U-233 does not exist naturally but can be manufactured and used to fuel some types of reactors.
l l
l l
l 2-11 ,
(r k}
3 ' - -
h C /rji %
Lj
(/ w -- - u URA \llUM FUEL ORE ~
PELLET
.7% 3.5 %
ENRICHMENT '
<< % U-235) 6 Uranium-235 (enriched from .7% abundance to about 3.5%) is the fuel for most. power reactors in the United States.
2-12
i Fission G
(vf h _G
- Aasoration l
o Uranium-235 is useful as a reactor fuel because:
(1) it will readily absorb a neutron to become the highly unstable isotope U-236.
1 (2) U-236 has a high probability of fission (about 80*' of all U-236 atoms will undergo fission)
(3) The fission of U-236 releases energy (in the form of heat)
- wnich is used to produce high pressure steam and ultimately electricity.
(4) The fission of U-236 releases two or three additional neutrons which can be used to cause other fissions and establish a
" chain reaction."
l 2-13
l l
l Fissions > Heat Rate of Rate of ,m Heat l
Fission Production o
l t
1 i
Every fission releases a tiny amount of heat. Trillions of fissions per second are necessary to produce high temperature, high pressure steam for f electrical power production. The rate at which uranium atoms are fissioned determines the rate at which heat (and power) is produced.
2-14
.- s
. N .g *.
'k' ' N# .
l
. g /*
- [
- Ns -
Fission *.
Chain ~ ,- /**/ '
Reaction j/ N.
3 Since neutrons are necessary to cause the fission reaction and since e ach fission releases neutrons, there is the potential 56 set up a self-sustiining chain reaction (if there is a sufficient quantity of fis-sionable material and the material is snaped to decrease the chance of neutrons escaping).
2-15
l l
Criticality
% l Steady Rate of Power Generation Criticality is the term used to describe the condition of " balance" in a reactor. When the number of neutrons being produced by fission exactly equals the number of neutrons being absorbed by all materials (uranium, structural components, shielding, etc.) the reactor is said to be
" critical." In a critical reactor the number of neutrons present, the number of fissions occurring and the heat being produced are all steady over time.
2-16
For Criticality:
l 1. Neutrons Must Lea <
Out of the Core ;
I I
- 2. Neutrons Must be Absorbed by Poisons .
i i
Because more neutrons are released by fission than are needed to produce a steady rate of fission, there is always a surplus of neutrons whenever the reactor is operating. To mai7tain the " critical" balance needed for 2
a constant reactor power level, some of these excess neutrons must be allowed to " leak out" or escape the fuel area where they cannot cause further fission. The remaining surplus must be absorbed by non-fissionable materials in the reactor core. These neutron absorbers are called neutron " poisons."
1 2-17
SHIELD
/ / =
T
/
/ ht r+
=
- 7 \ Fuel
/
W
/
'- Control Rod
/
/
w m
p g. ..'
dt
/ + .
s >.~.
/ $ ' '
/ m c yl l
/ -
x Water
/ u -
/
/
4:-(.
z -
5 ....
Moderator b ;, -.y hl.
/ -
_/ -
g.- .- _
/y/
3 .
-a . . - - .- .
a Reactor
'/
y 9.;, .
Vessel
/
/ % *n s>
Wall
/
Some of the neutrons released by fission will " leak" out of the reactor core area to be absorbed by dense concrete shielding around the reactor vessel. All the remaining neutrons in the reactor core area will be absorbed by some material (U-235, U-238, water, steel, control rods, etc.)
~
( .
l l
f 2-18
'I T NEUTRON POISONS CONTROL RODS SOLUBLE BORON l FISSION PRODUCTS URANIUM-238 l i STRUCTURAL COMPONENTS
(
i l
Any material that absorbs neutrons and does not fission is a " poison" to the fission process. The reactor vessel, structural components and the reactor coolant all absorb neutrons. Several fission products absorb neutrons (especially xenon-135 and samarium-149). Uranium-238 sometimes fissions, but when it does not, it acts as a poison. Reactor operators can manipulate the total amount of poisons in the reactor by moving control rods and (in PWR's) changing the concentration of boron in the reactor coolant water.
i l
l 2-19
CONTROL RODS IN -
FEWER NEUTRONS POWER DOWN OUT -
MORE NEUTRONS POWER UP l
Control Rods are concentrated neutron absorbers (poisons) which can be moved into or out of the core to change the rate of fission in the reactor. Rod insertion adds neutron poisor, thus fewer neutrons are i available to cause fi s si on', fission rate decreases, heat production
- decreases and reactor power goes down. Pulling control rods out of the core removes poison, thus more neutrons are available for fission and reactor power goes up. '
2-20 l
) I ] ]
1r1rifif PWR
(
Rapid insertion of Control Rods to Shutdown the Fission Chain Reaction A reactor " scram" (or " trip") is the rapid (two-four seconds) insertion of control rods to stop the fission chain reaction. In a boiling water reactor, control rods are inserted from below the core. In a pressurized water reactor, control rods are inserted from above the core. Although a reactor scram does not stop all 'ission in the core, the " chain reaction" is immediately broken causing a significant decrease in reactor power in a few seconds.
1 e j 2-21
Thermalization Birth
?-
/ *N*
8 .
Q mo m %..
Absorption 3
Neutron Life Cycle Fuel Pellet '
Fuel Rod Moderator lI l
The water.used in a BWR or PWR reactor coolant system has two important functions. As a coolant, water carries away heat from the reactor fuel rods (maintaining temperatures in the core within specified limits).
I Water's other major function is to control the fission process by slowing down and reflecting back high energy neutrons so that more fissions can occur. This " slowing down" process is called "thermalization" or
" moderation."
l 1
i 2-22 i
i
TEMPERATURE DE\lSITY I' RELATIONSFIP OF WATER W ater v -
Temp f -
.- . . Density 1 -
v '
Neutron Leakaget -
Power V '
Output!
s, Moderator Temperature O .
The use of water as a neutron moderator helps produce a steady rate of reactor power. If the reactor coolant temperature increases, the water becomes less dense and less effective as a neutron moderator. This tends to reduce the power level of the reactor. Conversely, if the reactor coolant temperature decreases, it becomes a better moderator, thus tending to increase the number of fissions that occur in the fuel. This temperature - density relationship is a major factor in controlling the fission process and heat production of the reactor.
2-23
00 0 '
oog 0
0 ' 0 0
Voids 0 0 (Steam Bubbles;i 00 Ob
' ' r Very 0%o foo (Low Density; p,
ho I,q h, w s jg More Voids-9, ya More Leakage-
!! !! Power 1
!. e IY / I Moderator density changes are important factors in controlling the fission rate and power production of a reactor. In boiling water reactors, the conversion of water into steam produces a dramatic change in moderator density from the bottom to the top of the core. Water at the bottom of the core is far more dense (and moderates neutrons far better) than does the water-steam mixture at the top.
l '
l l
l l 2-24
1700*F v j/
(~;
v A 34 1400 F l-i:.
- l 750 F w 2 ::
p:
l: -
650 F
!!\
li. w s gi 600 F O
- ll l.
Q 3 Q
!! /f !l l TYPIC AL FUEL ROD
/
g ,7 </l :l AND COOLANT TEMPER ATURES When a power reactor is operating, these are the approximate normal temperatures in the reactor core and reactor coolant system: 1700 degrees F in the center of the fuel pellets where many of the fissions occur, 750 degrees F at the outer surface of the fuel pellets , ,[ 650 degrees F at the cladding tube and 600 degrees F in the coolant water.
The average fuel pellet temperature under normal operating conditions is about 1400 degrees F. Melt temperature for the ceramic fuel pellet material is about 5200 degrees F. Fuel clad damage will start to occur above about 1800 degrees . F. Significant fuel damage can be expected at sustained temperatures above 2200 degrees F. Reactor emergencies and their consequences are discussed in section eleven of this manual.
i I
l v
I 2-25 i
l f
RADIATION TERMINOLOGY i
l This section discusses the terms and concepts which are necessary for any meaningful discussion of radiation, its sources and its risks.
I l
l 3-1
~
ENERGY Radioactive Atom o
PARTICLE l
A " radioactive material" contains atoms which are unstable due to some excess of energy in their nuclei. In an attempt to become more stable,a radioactive atom disintegrates (or decays) by ejecting particles or elec-l '
l tromagnetic energy (photons).
i i
l I
3-2 i
Energy
+
M i Racioactive Racia: ion Atom o
Particle I
(
Radioactive material ejects particles and/or photon energy as it decays.
The particles and/or energy emitted are " radiation."
f a
3-3
1 CURIE:
1400 Lbs 1gm
_ 238U 92 1/1000 gm ECO 2 *Ra 3.7 x 1010 Disintegrations per second Radioactivity is measurea in " curies." One curie is defined as the amount of any radioactive material (radioisotope) that will decay at a rate of 37 billion disintegrations per second (the rate of 1 gram of Radium-226).
3-4
p200 ILJ E
\,
HALF LIFE I 3 '
O
- w ',
' IN THAlfLl!E PER1005
> > 100 THE RAD /CA CTIv/TY Of D 's, rxE wreniA . x> s
> DECAYED r0 LESS THAN IN 5
O
< \' '.' .
O o .g 50
" ' , 5 out ,4 ,q, ,
+ uAvure n nnioo <~2.....",el.\%,g to. , o %,
........,,j-...........,,..g..........,,%'
i l i I l l l l
~ - - ,w n , ,
1 2, 3 4 5 i [
(~ TIME
(.
The rate of nuclear decay is measured in " half lives." The half life of any radioactive material is the length of time necessary for one half of the atoms of that material to decay to some other material.
Half lives range from millionths of a second (for highly radioactive fission products) to millions of years (for long lived materials such as naturally occur-ing uranium).
l 3-5
4 4
l
\
/ f ~~ s % /
/
/ \ /
/ fss N '%_ -
@\
l l . .
l U .
] .
l IONIZATION 1
l I
Nuclear power plants produce ionizing radiations. " Ionization" is the process of stripping or knocking electrons away from their oroital paths creating chemically active ions. This process can cause chemical changes in the material where it occurs. If chemical changes occur in the cells of our bodies some cellular damage may result. The biological effects of l
radiation exposure are discussed in section six of this manual.
l l
l l
3-6
i 1
@ f i
c ALPHA :
l l
(
i l
Alpha radiation is a particle made up of two protons and two neutrons.
l Alphas are low speed, low penetrating particles which can only travel one
! or two inches in air. Alphas are easily shielded (stopped) by thin
! sheets of paper or the body's outer layer of skin. Alphas are considered to be an " internal hazard" due to their ability to cause a large number of ionizations in a small area if the radioactive atom can get inside the body. Outside the body, alphas present little or no hazard.
l l
l l
3-7
h .
BETA e
i l
l l
t l
i I
i i
Betas are high speed, high penetrating particles which are usually nega-tively charged. About 1/1800 the mass of a proton or neutron, the beta can easily penetrate the skin and is considered both an " internal" and an
" external" hazard. Betas are best shielded by thick metals and plastics.
l l
l 3-8 l
.m
/
h GAMMA
, N l
l l
l l
Gamma radiation is electromagnetic energy (no mass, no charge) similar in
- many respects to visable light (but far more energetic). Gammas can travel thousands of feet in air and can easily pass through the human body. Gammas are best shielded by very dense materials such as lead, concrete, and uranium.
Note: X-rays are similar to gammas but are produced by changes in electron position rather than nuclear decay or fission.
I l l
l 3-9
l l
- NEUTRON r i
I l
l -
i -
P o -
~ .
Neutron radiation is the high speed, high energy neutrons emitted by
- nuclear fission and by the decay of some radioactive atoms. ?16atrons ce '
i travel hundreds of feet in the air, can easily penetrate, the ' human body .
and are best shielded by materials such as water, polyethylene and . ,
concrete. .
r em l
3-10
l l
EXPOSURE AND DOSE MEASUREMENTS
- ROENTGEN i
RAD REM I
i 6
I t
ik l
l When radiation interacts with a material it causes ionizations. These ionizations can be measured and their effects estimated.
The commonly used units for radiation exposure and dose measurements in the U.S. are the roentgen, the rad and the rem.
1 L..
3-11 l
ROENTGEN l
n,--,-,,---------_--
/ ,
/
Gamma l'----- T T l 1 Dyne
_=1_, = 7>.
Ray ;, ; Force l s' y ------s e -
, ,.- 4- y; m? __,,-
- 1 Esu/Cm 3 Dry Air s
The roentgen is a measure of exposure to X or gamma radiation. One roentgen will deposit enough energy to strip 'about two billion electrons out of their orbits in a dubic centimeter of dry air.
i t
3-12 t 1,
. ~ _.
4 1 RAD 1
/s i / \ \
gam ** Q __ b ban 100 Ergs / gram (Any Material?
s_
i The rad is a measure of absorbed dose (the energy deposited in a material). One rad is the deposition of one hundred ergs of energy in one gram of any material due to ionization from any type of radiation.
(One erg is about one ten billionth of a btu). Rad is an acronym for
" Radiation Absorbed Dose."
I 3-13
t Rem Damage Equal l To 1 Rad l l of Gamma Radiation i in Body Tissue l t
)
The rem is a measure of biological damage caused by ionization in human tissue. One rem equals the biological damage that would be caused by one rad of exposure to gamma radiation in the body. Rem is an acronym for
" Roentgen Equivalent Man."
l l
l 3-14
_ _ _ _ _ _ _ . _ . _ _ _ _ _ . _ - _ . _ _ _ _ _ ..__ _ _ - _ _ .. ~ - _
r-FOR GAMMA i
( AND X-RAYS )
i
. 1 Roentgen I
1 Rad l 1 Rem. '
t r
I
(
(
l l
J l
l I
i i
For gamma and X radiations, one roentgen of exposure is (about) equal to one rad of absorbed energy which equals one rem of biological damage in l
humans.
h 3-15
I l
K . h -
\
n f\
?
b- -
>\ g .
1 Rad Alpha 1 Rad Gamma Particulate radiations such as alphas and neutrons have been found to cause more biological damage than do gamma or X-rays for the same energy depositdd. For example,100 ergs deposited by alpha can be expected to cause about twenty times the damage caused by 100 ergs deposited by gamma. This difference in ability to cause damage is called the
" Relative Biological Ef fectiveness" (RBE).
3-16 l
I l
)
I m
DOSE Energy vs. Damage 1 Rad Gamma = 1 Rem i 1 Rad Beta = 1 Rem 1 Rad \leutron = 10 Rem 1 Rad Alpha = 20 Rem REM = Rad x Quality Factor
\
i To account for Relative Biological Effectiveness, a group of " Quality Factors" has been developed which convert the energy deposited (rads) into an equivalent biological damage in rems.
I i
3-17
REM VS. MILLIREM
- 4=mx
{}{ : :'jQ'{'sfM@3A num : - : s :: -~ : ~ .
p n m:#
e::e : : : :
s s
s;s; # s s
s%w 1 Rem = 100C m Rem 1 m Rem -
1/1000 Rem All the units used in a discussion of radiation and radioactivity may be prefixed to indicate fractions (or multiples) of the standard unit. The table below lists the most common prefixes for scientific use.
PREFIXES d deci (= 10 1) da deka (= 10) c centi (= 10 2) h kecto (= 102 )
m milli (= 10 3) k kilo (= 103 )
p micro (= 10 8) M mega (= 108 )
n nano (= 10 8) G giga (= 108) p pico (= 10 12) T tera (= 1012) f femto (= 10 15) a atto (= 10 1s) 3-18
DOSE RATE y X Measure of the- r. .
Strength of M A I N Na Radiation ! .
' Field V
-(
The dose rate is the amount of radiation exposure (or equivalent biologi-cal damage) that a person would receive in a particular length of time.
It is a measure of radiation intensity (or field strength). Commonly used dose rates are:
mrem /hr, rem /hr, mrem /wk , rem /wk, rem / quarter, rem /yr
)
. 1 3-19
l Dose- Dose Rate x Time
- 25 m Rem 50 mrem x 1/2 Hour
!i HR i
i I
I.
i The dose is equal to the strength of the radiation field (dose rate)
I multiplied by the length of tirr.e spent in that field. The example above indicates a person could expect to receive a dose of 25 mrems by staying in a 50 mrem /hr field for thirty minutes.
3-20 l
l
STAY TIME Dose Limit / Dose Ra::e 100 m Rem / 50 m Rem /
H r= !
2 Hour !
Stay Time
(
i r
The " stay time" is the length of time a person can remain in a radiation field before exceeding some " dose limit." In the example above, a dose limit of 100 mrems has been established. The dose rate is 50 mrem /hr. ,
The stay time is calculated by dividing the dose limit by the dose rate.
1 1 1
e 3-21 l
Contamination xx i b n s.
j
/tdN \ . ,
/ '
AWcw
. s s./>
g__ M.
Radiation Contamination is generally referred to as some material in a location where it is not intended or desired to be. Radioactive contamination is radioactive atoms that have escaped the systems or structures that nor-mally would contain them.
Additionally, if a worker must enter a " container" (for example, to per-form steam generator repair on a PWR or turbine repair on a BWR) we say that worker will enter a " contaminated area." Methods of protection against radiation and contamination are' discussed in section seven of this manual.
.A 3
~
I N TER'N A~~, ' O N A'_ SYS-~ V Or UN S SI UNIT OLD UNIT BECOUEREL CURIE COULOMB ROENTGEN KILOGRAM RAD GRAY SIEVERT REM C
The United States has yet to fully implement the use of the internation-ally accepted system of units and measures (SI). The SI units shown above are expected to gradually replace the curie, roentgen, rad and rem in technical literature.
I I
l 3-23 I
. x 10" DIS.
1 CURIE :
SEC.
1 DIS.
1 Bq. :
SEC.
1 Bq. : 2.7 x 10 'Ci.
One curie is defined as the amount of any radioactive material that decays at the rate of 37 billion disintegrations per second. One bec-querel equals one reciprocal second (sec'1). Therefore, we can say that one curie equals 37 billion becquerel.
. )
3-24 L
-4 COULOMB 1 ROENTGEN : 2.58 x 10 KILOGRAM i
i 1 COULOMB : 3876 ROENTGEN KILOGRAM
(
t 4
The roentgen will not have a designated SI equivalent unit, but the force produced by a roentgen can still be expressed. The correct representa-
~1 tion of coulomb / kilogram is coulomb kilogram .
3-25
1 1 RAD = GRAY 100 1 GRAY = 100 RAD The gray will replace the rad as the unit of absorbed dose.
One rad equals 1/100 of a gray.
One gray equals 100 rad.
/
3-26
p ""%
1 1 REM : SIEVERT 100 1 SIEVERT : 100 REM l
The sievert will replace the rem as the unit of biological damage to human tissue.
l One rem equals 1/100 sievert.
One sievert equals 100 rem.
3-27
l l
! l
~
- l Radiat'on
! Sources
@ a 1
i l
t i
l l
[
I i
This section discusses the sources of radiation exposure to the general Both naturally occurring and man made radiation j
_ U.S. population.
sources are discussed.
l i
a l 4-1
1 NATURAL BACKGROUND RADIATION SOURCES '
OUTER SPACE AIR WATER ,
. GROUND MINERALS
! FOOD / TOBACCO PRODUCTS BODY TISSUES i
i I
I Our bodies are penetrated thousands. of times each second by naturally 4 occurring radiations. Natural Background Radiation comes from the Sun and other stars and the decay of naturally occurring radioactive elements in the ground, air, water, plants, and animals and inside our own bodies.
i
~
4-2
- BACKGROUND SOURCES COSMIC RADIATION 4
PROTONS NEUTRONS 1
BETAS GAMMAS X - RAYS i
l, 38 - 75 m REM / YEAR ;
\
l Activity on our Sun (and other stars) and the Earth's magnetic fields cause the upper atmos;;here to ce bombarded with high speed particles and l
! photons. While the Earth's atmosphere shields us from much of this !
- direct radiation, we are still exposed to some of this " primary" radiation. Interactions in the upper atmosphere release " secondary !
radiations" which are the source of most of the cosmic radiation which i reaches the earth.
l 1 l
l .
4-3 l -. _ _ _ - - _ - - - . . . . - - - . - .
i TERRESTRIAL RADIATION Granite, Soil, Minerais, l
Ground Water, Etc.
l H , "6 C 3
- K , 19 222 86 R n 3 22 era , 222 Th 88 90 1
228 g 92 1
l 15 -14D mrem / Year i
I i
l Terrestrial radiation comes from the decay of naturally occurring radio-I active materials which can be found in varied amounts '.broughout the world. Srme of the most abundant natural radioisotopes are listed above.
(
4-4 ,
}
I INTERNAL SOURCES 14 40 226 6 i 19 i 88 ,
i 15-20 m Rem / Year I
l l 1
I l
l 1
l l
l l I
l l
1 All of us have some radioactive material inside our bodies. Three of the l
l most abundant internal radiation sources are listed above.
I i
.I 4-5
I l NATURAL BACKGROUND RADIATION l
l COSMIC 38 - 75 m REM / YEAR TERRESTRIAL 15 - 140 m REM / YEAR i INTERNAL 15 -20 m REM / YEAR
! AVERAGE : 100 m REM / YEAR l
l
)
The average American receives a dose of about 100 m Rem each year due to background radiation.
i l
l 4-6 1
1
_..------..----w-w.-,-,.n.,,.,-,--- e.,,,_-_____,n_,__,.,,---,-n., .n,, n_..,.,,n. , , _ _ ..
l MAN MADE RADIATION SOURCES l MEDICAL EXPOSLIRES 90 m REM / YEAR
! BUILDING MATERIALS &
CONSUMER PRODUCTS 5 m REM / YEAR ,
WEAPONS FALLOUT 5 m REM / YEAR 1 AVERAGE : 100 m REM / YEAR l
! l l! i l
i l
l Medical procedures (both diagnostic and therapeutic) are the largest j
source of man made radiation exposure to the general public. The use of ,
I building materials containing trace amounts of natural radioactivity, i some consumer products, and fallout from nuclear weapons add slightly to the total man made radiation dose.
i 4-7 ,
CONSUMER PRODUCTS :
l l
TV SETS LUMINOUS WATCHES SMOKE DETECTORS i
- AIRPORT X-RAYS l NATUR AL GAS ;
- INCANDESCENT MANTLES FOOD / TOBACCO PRODUCTS i
! i l
The consumer products listed above either contain small amounts of radio-active materials or generate high speed particles or photons in the course ;
of their operation. .
l b ,
I 4-s
s GENERAL U.S. POPULATION :
i
! NATURAL BACKGROUND 100 m REM / YEAR 1
l I
f (' t i
i l I l
The average U. S. citizen receives a total annual dose of about 200 m Rem
- as a result of naturally occurring and man made radiations.
i 4-9
COMPUTE YOUR OWN RADIATION DOSE :
Your Annual Commen Source of Radiation Insentcry Locaeon: Ccsm:c raciat:en at sea level 26 For your e!evaton (in feet) - add this number cf mrem . .
Eevaton - mrem 10042 4000-15 7000-40 20C45 50C0 21 800G53 WHERE 30049 6000-29 9CCO.70 YOU E'evaton of some U1 ctes (in feet): Atlanta 1050. Ch4cago 595. Cailas LNE 435. Denver 5280. Las Vegas 2000. 2nceapolis 815. Pttseurgh 1200.
St. Louis 455. Salt Lake City 4400. Spokane 1890.
(Coastal ctes are assumed to be :ero. or at sea level)
Cround: US average . .. ... .. .. . . 26 House Constructon - For stcne. concrete or masonry building. add 7 .
WHAT YOU Food Water US awage 24 EAT. DRINK.
AND BREATHE Weapons test fa: lout . . . . . . . . . . . . . . . . . ... . . ... .. .. 4 X ray and radio pharmaceutical diagnosis Number of chest x rays x10........................
HOW Number of lower gas *roctestnal tract x rays x 500 . . ..
YOU Number of radiopharmaceutcal examinations x 300 . . . . . . . . .
g (Average dcse to total U1 populaton = 92 mrem)
Jet plane traveh For each 2500 mites add 1 mrem . . . . . . . . . . . . . . . . . .
7V Wewing: For exh hour per day x 0.1 5 . . . . . . . . . . . . . . . . . . . .
My total annual dose in rnrem a f 'l A s -
\ ) \l @
One mrom per year is equal to: Moving to an elevation 100 fact higher.
Increasing your diet by 4Y..
Taking a 4. to 5-day vacation in the Sierra Nevada Mountains.
4-10
h RADIATION SOURCES s.
t AT NUCLEAR PLAN;TS ~
s g
)
Nuclear Fuel Decay Fission Process l Fission Product Decay !
Activation Products -
Calibration Sources .
This section discusses the sources of radiation found at power reactors.
5-1 .
~
Nuclear Fuel Natural Decay 238 Process 235 l l 92 i 92 V G l
1 i
i i Uranium-238 (about 96% of the fuel) and uranium-235 (4%) are naturally radioactive and decay by the emission of alpha particles and gamma rays.
Beta particles are released by the fuel as uranium's daughter products continue the natural decay process toward a stable form (lead). Since
,' the fuel is sealed inside airtight fuel rods, there should be little or no alpha radiation problem at the nuclear plant unless there is some fuel rod damage.
l 5-2
i
~
9 s
l Fission F* Process ;
i
/l e I
I k .
I t
4 During the fission process uranium atoms split into two or three smaller atoms (called fission products). Powerful gamma rays and high speed neutrons are released during (and immediately following) the fission process.
s
.g .
9 5-3
I l
l 5
J Fission Product f
Decay
/
l The new atoms produced by fissi'on (fission products) are intensely l radioactive. Most will decay rapidly but several decay very slowly.
Fissio,n products generally decay by beta and gamma emission.
1 5-4 l
7 FISSION PRODUCT BARRIERS i
i l
1 CERAMIC PELLET
~ ~
- FUEL ROD
/ -
REACTOR VESSEL CONTAINMENT l
Since a significant fission product release could seriously jeopardize public health and safety (and the environment) a system of fission pro-duct barriers is a part of every power reactor design.
5-5
A > -
{
. g ~
. Activation of Water
% J and Corrosion Products w
7
}
$ (CRUD)
. 2 '
5
.. Contamination w j I r &
During the fission process, some of the f ~'p \g
~
materials in the vicinity of the reactor
- core will absorb neutrons and be changed \
') b from a stable form to a non-stable (radio-active) form. These materials (called .
activation products or " crud") are not contained inside the fuel rods (as are I most fission products) and are easily ,
transported by the reactor coolant system. ) i Crud is the source of most radioactive 0 contamination at nuclear power plants. d,
% ff W - )
, ~ , - _
g
~
l l
5-6 l
l
[
- 1. --
1 l
l MATERIAL RADIATION HALF LIFE I l
7 Krypton-85 Beta 10 years !
Gamma Strontium-90 Beta 28 years lodine-131 Beta 8 days Gamma Cesium-137 Beta 30 y2ars Gamma Carbon-14 Beta 5770 years Zinc-65 Beta 245 days Gamma Cobalt-60 Beta 5 years Gamma iron-59 Beta 45 days Gamma Tritium Beta 12 years (Hydrogen-3)
Above is a partial list of radioactive materials produced either by fis-sion (fission products) or neutron absorption (activation products).
These materials are of particular interest because of:
- 1. Their relatively long half-lives
- 2. Their relative abundance.in the reactor (or)
- 3. Their ability to chemically interact in biological systems 5-7
INSTRUMENT CALIBRATION )
V I
i 1
A SOURCES 1
Small quantities of radioactive material (sources) are stored on the plant site to allow instrument technicians to properly test and calibrate radiation detection devices. These sources are completely sealed and are stored in isolated areas when not in use.
5-8
, . - - .- ,w .e-, w - - ,.m.--
E 7 BEiological Effects of Radiation '
l l
4 l I .
/
gffs_,,.... *#l
-~
- This section discusses the expected short term ,
i and long term effects of radiation exposure on s,,
biological systems. ,
N
- L
! 6-1
__ _. .._ . __ _ _ ___ _ _. _ . _ = __
Radiation Causes O
lonization
./ . .
- N.
Decomposition
- \
- of H O
.J i
l O
e In L2 ell i
i Radiations such as alpha, beta, gamma, x-ray and neutron can deposit enough energy inside human tissue to knock or strip electrons away from their nuclei. Since a large percentage of the body is water, most,of the Some of radiat'sn induced ionizations will involve water molecules. !
these molecules may be decomposed (hydrogen separated from oxygen). The water molecules involved may or may not recombine into H20. If a large number of water molecules are ionized, a certain number can be expected to form into other combinations. (Example: 2H2 0*H2+H0)'
22 6-2
l 4
3
~'s .
I Damage To DNA From lonization Inside the cell nucleus, the. DNA molecules represent a relatively small (but very important) percentage of the whole body. Ionizations occurring in these molecules may result in the transfer of incomplete (or in-correct) genetic information to the cell's offspring during reproduction.
e av 6-3
CELLULAR DAMAGE:
- 1. lon.ization OO
\_ _,
- 2. Chemical Recombination LJLJ-
\ [O i
Radiation can cause cellular damage by ionization and by the potentially harmful effects of forming new chemical compounds as a result of the ionization process.
6-4
POSSIBLE CELLULAR PROCESSES
- 1. Normal Repair of Damage '
1: Normal Reproduction,'
F @3 a b I
3 3
. =
@a j
a b i
At low levels of radiation (such as normal backgrornd) the affected cell can usually repair (overcome) any damage resulting from the exposure.
6-5
POSSIBLE CELLULAR PROCESSES
- 1. Normal Repair of Damage
- 2. Cell Dies From Damage 3 '
i
- i .
I
> g i
1 l
At high levels of radiation, cellular damage may ultimately result in the death of the affected cell or in the indbility of the cell to reproduce, i'
! 6-6
POSSIBLE CELLULAR PROCESSES i
l
- 1. \orma Repair of Damage
- 2. Cell Dies From Damage ,
- 3. Daughter Cells Die i
c
- C ?
l l
If genetic damage occurs, the cell may reproduce, but the resultant t
daughter cells may not live (or may live but be incapable of further l
reproduction).
6-7
t i POSSIBLE CELLULAR PROCESSES i
- 1. Normal Repair of Damage !
, 2. Cell Dies From Damage
! 3. Daughter Cells. Die
- 4. No Repair or Non-Identical ;
i Repair Before Reproduction Y? As
- . =f@ n 1
L @a ,
A small portion of DNA changes are reproducible. The resultant changes, (or mutations) may range from non-detectable to life threatening.
}
6-8
..s RADIATION EFFECTS ACUTE CHRONIC UNDETECTABLE AT DOSES BELOW 5 - 50 REMS EXPOSURE l'
The effects of radiation exposure on living tissue can be short term (acute) and long term (chronic). Acute radiation exposures can cause i sickness and even death at doses of 300 - 1000 Rems. Acute exposures below 5 - 50 Re.as should cause no short term ill effects.'
i
- The chronic effects of radiation exposure are considered to have no thres-hold for risk. Although very small (compared to the total cancer risk, a person faces) the risk of a radiation induced cancer increases with each l additional exposure.
6-9 0
RAD AT ON SYNDROME 1
Nausea
- Fatigue i
Loss of Appetite ;
! Vomiting l
l i
Acute radiation sickness (the radiation syndrome) can be expected if a person receives a dose of 50 - 200 Rems or more over a short period of time. The onset of symptoms and the severity of the illness are related to the total dose received, the duration of the exposure and several other factors. Most people exposed to radiation doses below about 300 Rems can be expected to ultimately recover from these short term effects.
6-10
i RADIATION l^ SYNDROME Ultimate Effect !
l- Can l Be c
Death
! l The ultimate effect of any exposure to a hazardous material can be death.
The likelihood (risk) of death increases as the dose increases.
i 6-11
NRC DOSE ,
LIMITS l 10 CFR 20 DOSE STANDARDS IN RESTRICTED AREAS:
QUARTERLY YEARLY WHOLE BODY (REM) 1.25 5 HANDS & FEET (REM) 18.75 75 SKIN OF WHOLE BODY (REM) 7.5 30 3 REM / QUARTER IF EXPOSURE HISTORY IS KNOWN (NRC FORM 4)
AND LIFETIME EXPOSURE DOES NOT EXCEED 5(N 18)
N= AGE IN YEARS The NRC radiation exposure limits shown above are designed such that no worker at a nuclear facility will receive an acute whole body radiation exposure sufficient to trigger the radiation syndrome. The risk .of cancer (although not zero) should be no higher than the risk of cancer from other occupations.
t
/
6-12 i
l 1
NRC DOSE '
LIMITS 1
~
10 CFR 20 UNRESTRICTED AREA:
2 m Rem /HR 100 m Rem /7 Days l
The NRC limits all licensees in the handling and use of radioactive materials such that no member of the public (or worker outside the re-l stricted area) will receive a radiation dose of 2 millirems in any hour, or 100 millirems in any seven consecutive days. Additionally, the NRC has provided design objectives for power reactor licensees to keep off-site releases as far below the 10 CFR 20 limits as is reasonably achievable. These guidelines can be found in 10 CFR Part 50. See page 10-7 of this manual for more information on design objectives.
6-13
-_ - _ _ _ , . _ . _ - - - _ - _ . _ _ _ . . _ _ _- - _. _ . _.- _ _ .._ ____-. _ -._--._ .~._ -_ .
ACUTE RADIATION DOSE O-5 Rem No Detectable Effect l
5-50 Rem ' Slight Blood Changes :
50-100 Rem Blood Changes, Nausea, Fatigue '
100-200 Rem Above Plus Vomiting,1% LED 200-450 Rem Hair Loss, Severe Blood Changes, Some Deaths in 2-6 Weeks 450-700 Rem Lethal to 50% of Those Exposed Within 1 Month -
700-1000 Rem Probable Death For 100% of Those Exposed in 1 Month 5000 Rem Immediate Incapacitation Death Within 1 Week i
l The table above lists the expected effects from an acute whole body radiation exposure. The duration of the exposure is assu::ed to be short (24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or less). 1% LED is the lethal effective dose for one percent of a group of individuals exposed to a dose of 100 - 200 Rems.
I 6-14
99.99 -
i m 99.3 .
l PERCENT 99 .
~
95 .
MORTALITY i
90 .
go ,,
A. WITHIN 70 -
6 . e 50 60 DAYS 40 .
I
! 30 C
! 20 ,
l 10 .
5 -
2 ,
! l .
O.5 .
0.2 , !
l j( i 0.05 .
l 0 ' ' ' ' ' ' ' '
200 400 600 800 1000 1200 DOSE (REM)
Curve A -
Minimal Medical Treatment
- Curve B -
Supportive Medical Treatment Curve C -
Heroic Medical Treatment i i
l I
l The grafts above indicate how supportive and heroic medical assistance i can significantly reduce the effects of the acute radiation syndrome, 1
j The 50% mortality line lies at about 300 Rems for minimal assistance, I
about 450 Rems for supportive (normal) assistance and abcut 1000 Rems for I
heroic / extensive) assistance.
l 6-15
AS DOSE INCREASES:
i l i
I Risk of Cancer increases l
[
]
i l
l ,
The chronic effects of radiation exposure are considered to have no l threshold for risk. In other words, there is no level of exposure which i
is completely safe. The risk of a radiation induced cancer is considered to be very low (but not zero) compared to the normal incidence of cancer in the population (one person in four). >
l t
6-16 l
l ._ - -_ - _. - . - - _ - - - -_. _ - _ ______ _.________ -
s, CANCER RISK ESTIMATES
- 1. ADDITIONAL CANCERS -
t
- 2. REDUCED LIFE EXPECTANCY 4
Two commonly used methods to evaluate risks are decreased life expectancy
! and increased probability of cancer related to certain activities. The National Academy of Sciences' Advisory Committee on the Biological Effects of Radiation (BEIR), the International Commission on Radiation Protection (ICRP), the National Council on Radiological Protection (NCRP), the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), and many other national and international scientific bodies have studied and continue to study the risks of radiation exposure.
l 6-17 l
l
I RADIATION INDUCED CANCERS i
i RISK INCREASES ABOUT .03 % ;
i FOR EACH REM l
i
.016 .045 % BEIR , 1980
.1
.02 % ICRP, 1977
.015 .035 % UNSCEAR, 1977 i
l f
l .
l The normal incidence of cancer in the U. 5. is about 25P. (one person in four). Out of 10,000 people, 2500 can be (xpected to develop a cancer. l If all these people were to receive a dose of one additional rem we can i
estimate between 1 and 4 additional persons will develop a cancer. '
. I i
i 1
o 8-18
h RADIATION INDUCED CANCERS DECREASED LIFE EXPECTANCY I
SUBTRACT ONE DAY FOR EACH REM Estimated Loss of Life Expectancy from Health Risks a s
Estimates of Days of Several stud.es have compared the projected Life Expectancy Lost.
"* ' " ^ * *8' decrease in life expectancy resulting from exposure to radiation and other health risks. Smoking :0 cigarettes / day 2370(6.5 years)
Overweight (by 20"c) 985 (2.7 years)
The additional risk associated with radiation All accidents combined 435 (1.: years)
^"*
exposure has been calculated to be a reduction g coho n mption (U.S. average) of life expectancy by about one day for each rem. Home accidents 95 Drowning 41 Natural background radiation, 8 calculated Medical diagnostic x rays (U.S. 6 average), calculated All catastrophes (earthquake, etc.) 3.5 1 rem occupational radiation dose., I calculated (industry average for the higher dose job categories is 0.65 rem /yr)
I rem /yr for 30 years, calculated 30 physfci,' N I67vk s'E 9." "' ^ ' '" "
6-19
RISK OF CANCER A RADIATION EXPOSURE IS NOT A GUARANTY OF CANCER MOST PERSONS EXPOSED WILL i NOT DEVELOP A CANCER suT l
I EVERY EXPOSURE SLIGHTLY INCREASEE THE RISK OF A CANCER t The risk of cancer related to radiation exposure is under continuing study. The statements above can be used to summarize the results of most of the scientific findings in this area.
l 6-20
NATIONAL CANCER INSTITUTE'S SEVEN STEPS TO AVOID CANCER j
- 1. DON'T SMOKE OR USE TOBACCO AT ALL ,
l
- 2. EAT LESS FAT l
- 3. DRINK LESS ALCOHOL l
- 4. FOLLOW INDUSTRIAL SAFETY RULES j
- 5. AVOID UNNECESSARY X-RAYS i 6. PROTECT YOUR SKIN FROM THE SUN
- 7. AVOID UNNECESSARY ESTROGEN TREATMENTS l 1
l 5
The National Cancer Institute recommends the above precautions to markedly reduce the risk of cancer. ,
+
9 6-21
.f SENSITIVITY FACTORS
~
- 1. Type of Radiation
- 2. Amount of Raciation
- 3. Type of Cell Involved ll 4. Stage of Cell Division
- 5. Age of Individual s 6. General State of Health
- 7. Part of Body Exposed
- 8. Percentage of Body Exposed i .
- 9. Duration of Exposure i
l Different individuals exhibit different sensitivity to radiation. Some of the factors affecting radiosensitivity are listed above.
)
6-22
. - + - - , - , -,---,.-..--+,.,.-.,,.,-mp ,, ,,g,,y-.-,--.-y,.---- - - . - - . - ,*w. ...w-,-w,-% .-,_-,--.s-,,.. ..-m, -,,,%.m-,,., - - , ,--,y-- --w- --u, ., -e-- .w--,-.c. .y-g
MOST LEAST
^
SENSITIVE SENSITIVE Blood Ceis Bone Ce'Is Bone Marrow Musc e Ce s Eye Lens Nerve CeIs Reproductive Ceis
(
The different cells of the body exhibit a wide range of sensitivity to radiation. Some of the most and least sensitive cells are listed above.
6 l
Methods For Protection
- Against Radiation and Contamination
(
- 4.A !
a CAUTION I RADIOACTIVE l MATERIAL This section discusses the methods used *o protect individuals from the harmful effects of radiation and contamination.
7-1
PROTECTION AGAINST RADIATION
- 1. Time 1
j
- 2. Distance ,
l
- 3. Shielding
)
i i
i l
l '
Reducing the dose from any external source of radiation involves the use of three protective measures:
.. Reduced time Increased distance
! Use of shielding l ;
I ,.
7-2
MINIMlZE TIME
^
i DOSE RATE x TIME DOSE i
MINIMlZE DOSE i
'( ,
l i
The length of time spent in a radiation field is directly related to the dose received.
7-3
MINIMlZE TIME
%4
/
I 1
\
N 5 Rem /HR s
- Field V
r y///A
,5 ,m , yj -
I l
In a five Rem /Hr field an individual would receive a dose of:
100 mRems in 1.2 min.
1.25 Rems in 15 min.
3 Rems in 36 min.
5 Rems in 60 min.
I l
l 7-4
l MAXIVilZE DISTA\'CE F
Y E
= i 100 m Rem / Hr.
%# b at 1 foot I
! b 1 m Rem / Hr.
6.25 m Rem / Hr. at 10 feet at 4 feet
, VilNIVilZE DOSE
(
Mar.y radiation sources are " point sources" (appear to come from one spot some distance away). The radiation dose from these sources can be signi-ficently reduced by applying the protective measure of " distance" as demonstrated above.
7-5
MAXIMlZE DISTANCE I
i N
J x 5 Rem s
1 HR
))<
\ bkN
/ k Moving a few feet further away from a source of radiation can signi-ficantly reduce the dose rate and significantly increase an individual's stay time in a radiation area.
- 7-6 I . . _ _ _ . . . _ - - _
MAXIMlZE SHIELDING I
Y E
'f *
%._.. ........ 10 0 m R E M
%g 1/2 Thickness l Shield MiHALF E VALUE SHIELD LAYER 50 m REM HR MINIMIZE DOSE
(
Shielding is another effective way to reduce radiation exposure. The example above shows that the installation of a one half-value layer (half-thickness) of shielding will reduce the dose rate by a factor of two at a set distance from the source of radiation.
1 I
4 7-7 1
MAXIMlZE USE OF SHIELDING I
\
) sh x .3 REM
~
h s
0 HR
)/ s d:$' %\\N .06 REM
/ ( (j ...
(q x sR
(
Installing several half-value layers of shielding can significantly lower radiation dose rates and allow much longer stay times than could other-wise be possible.
Y 7-8 l
h i
.m. Relative Efficiency Of Various Shielding Materials CONCRETE WATER
--_. .7
- !.\d;.' .W.O.'.'W"W, %
!$ 7.*/ .*. 9& .'. . . . . * , . ? '.:;*g. #
. 7
.! . l:.'.' ... : 5 '; -i "
~I $.**f.(- .f: . .:.?.'-l,.?E f
. : **' . .],*.'; f&)
':s /
- t ... _.'... .-: :* :- .: -y -
//
/ /
/ 4 4 --geU,d,,, - W s p<_
2 _
/,
bg \ -
--y r
1 I
,i Materials differ greatly in their ability to shield (absorb radiation).
I The example above shows the relative efficiency of four common shield materials for gamma radiation.
i l
l 7-9
PROTECTION AGAINST CONTAMINATION
- 1. Minimize Leakage
- 2. Frequent Surveys
- 3. Good Housekeeping l
- 4. Access Control l l 5. Protective Clothing ;
- 6. Respiratory Protection i
- 7. Bioassays ,
i
\ ~ lil E
,y, 7'
{. t-l The protective measures listed !
I \ '.
\,.,6 l -
ab,ove are used to prevent, detect '
hs '
ra
[ j.[ ,
co,t,m /m'e"tlco .
y i 1- ;, % -
4
'/ j) ~
k]
_ - l '
[
\ .b- : 3 L ri ;
)
7-10
1 l
~
CAUTION - CAUTION l de e a a HIGH RADIATION AREA RADIATION AREA l
RWP REQUIRED FOR RWP REQUIRED FOR ENTRY. ENTRY.
DOSE HATE AT THIS POINT IS DOSE RATE AT THIS POINT IS MR/HH DATE POSTED _BY MR/HR DATE POSTED _BY 4.4 s
CAUTION HOT dea SPOT s .
CONTAMINATED AREA FULL ANTI-CONTAMINATION CLOTHING REQUIRED g
EATING, DRINKING AND CAUTION :
RADIOACTIVE l SMOKING PROHIBITED MATERIAL l l
l Some commonly used radiation / contamination warning signs and labels 4 e shown above. The international symbol for radioactive material is a '
magenta or purple three b!aded design on a yellow background.
7-11
j 's t
- i. :
l I !
l BWR !
l i
SYSTEMS l
4 i
l i.
! i l l l
- I 1
l j i f
l l
}
r
- i
. t 1
f This section discusses the purposes of the major systems and components ;
l of Boiling Water Reactors. ;
i i
l I
l
- l 8-1
a VES EL THROTTLE TEAM LINE VALVE MCIStuRE -
SEPARATOR b.:
k . iENEi _
,, i ^"^
W C .
i!!!!)ii i
, A REACfoR - *
- 3 CORE i:d'OQ.. f 3,., , -
3
!! !! - .!j i d i .
fii!
N',,,
d S
o ELECTRICAL M
, pyyp $ CONoENSER GENEMATCR I fll~
d j PEEDWATEM u nEcinc g nECinc
- T T
y
& c_
u, , ump H
,uo, I
BOILING WATER REACTOR PLANT (BWR) 4 Inside the Boiling Water Reactor Vessel (A) a steam water mixture is pro-duced as coolant water removes heat from the reactor core (B). The steam-water mixtures moves upward and into the moisture separator (C), where water droplets are removed before the steam is allowed to enter the steam line (D). The steam turns the turbine (E), which turns the electrical generator (F). The steam t'han enters the condenser (G), where it is condensed into water. The water is pumped by the feedwater pump (H) from the condenser back into the reactor vessel. The recirculation pump (I) and ,
jet pump (J) allow the operator to vary the coolant flow rate (and thus change reactor power), i
)
8-2
REACTOR BUILDING TURBINE BUILDING x
STEAM RELIEP V
MCISTURE SEPARATOR / RENEATER S STEAM THROTTLE 4 ISCLATCN VALVE l
yngygg ,, 9 OR M ELL M. - --
- *
- TUReiNE t It .il i. t 3 1 6
'4l 6' i O
" =nt; "t -
PRE $RE}}}} }}}}}} / M HEATER CONDENSER ELECTRICAL g e 2 g i 7 j \ GENERATOR [% 1, , ,, , . . , )
- - 1 = U 9 9 i
GG t e i s FEE 0 WATER PUMP
~
g
}
9 REACTOR CIRC CIRC VESSEL LOW WATER WATER PRESSURE
\ HEATER A CONDENSATE l l
PU#' ' WATER 1
*ECL
] Sv'STEI l
A boiling water reactor's coolant system consists of the reactor vessel, steam turbines, condensers, condensate and feedwater pumps, the reactor's recirc system and the pipes linking these components. 8-3
BWR REACTOR WATER CLEAN UP SYSTEM REACTOR CONTAINMENT VESSEL /
~ .
% - -* STEAM
- a FEEDWATER
\
0 A l I
'k, . .) h G t l f REGENERATIVE HEAT EXCHANGER NON-REGENERATIVE REClRC d
[ HEAT EXCHANGER PUMP : '
/ ~ "
[ - - - A [ t FILTER / REACTOR WATER CLEAN UP PUMP - DEMINERALIZER n o REACTOR BUILDING CLOSED COOLING WATER The reactor water cleanup system provides a means for the removal of corrosion and wear products and chemical impurities from the recirc system and the bottom of the BWR vessel. 8-4 i
BWR RESIDUAL HEAT REMOVAL SYSTEM (SHUTDOWN COOLING) REACTOR VESSEL
--+ ~ STEAM
- - FEEDWATER t
- i. J e ~
l RECtRC t PUMP
- CONTAINMENT RESIDUAL HEAT
~ REMOVAL HEAT RESIDUAL HEAT EXCHANGER REMOVAL PUMP f SERVICE y WATER The BWR's Residual Heat Removal System is used during reactor shutdown to transfer the core's decay heat away from the fuel to the environment. 8-5
BWR REACTOR CORE ISOLATION COOLING
- TO MAIN TURBINE lh -
o f % ISOLATION VALVES
]l ~
I
=
-- ~
-FEEDWATER LINE
=
f CONDENSATE STORAGE TANK f CST h f s'RCIC
~y C
RCIC (I r- TURBINE PUMP j " CONTAINMENT The BWR's Reactor Core Isolation Cooling System is used to supply water for decay heat removal when the normal source of coolant (feedwater) is not available. 8-6
BWR EMERGENCY ^ S COOLING SYSTEMS CONTAINMENT SPRAY s .. e CST STEAM LINE UR8tNE CONoENSATE STORAGE
= -
e TANK ces -- tu'a i" ""[ I J i
~
RHR HX D$) _ CONTAINMENT i t SERVICE A I 1 SPRAY g g WATER 0.. . P.. i L . . . . ._ . ._ ; onywatt L........ . WATtR f PUMPS PUMP
,oeg t aa!! LPCI l
The BWR Emergency Cooling Systems are designed to supply water to cool the reactor core and the Containment in the event of a loss of coolant accident (LOCA). 8-7
BWR STANDBY LIQUID CONTROL SYSTEM O CORE
'i.....I n - POISON g ;
m h W TANK EXPLOSIVE { (BORON) VALVE PUMP CONTAINMENT 9 The BWR's Standby Liquid Control System provides a method to stop the fis-sion process and maintain th' s reactor in a shutdown condition even if there is no control rod movement. 8-8
i K l 3 .g C "*'" "' F. @1 o 1 o
/~ 'e l
'. 8' 1
tie n$s e .. 4 p av n c6 oe. e fa u
\vg o 'I o t
q e '\ v M 'I. :2':,7.
' s,.e a n. $r aoos
'*'t.2.
.- . ,; ~.m. ,
t l I.: etAos I 6e . e,e s.,e h I t
,,,,,$,3 t
~
.one *.ca l ., Y .
- !; m
~
p ,,
;- aa=ou 9
o 4 GENER AL & ELECTRIC ;/ M EU,ii'." w ,
'U'07 \ a.s These cutaway drawin95 Show the major components of a BWR fuel assembly and control blade (rod),
8-9
1 7 Imj s
. xv m.
.?' P; s . , . . - .. . . BWR 6
' REACTOR ASSEMBLY II .
1 ,
, f4 / ==~~ annut c nuerme , ,,, ,, N i
g l J, f ..-... ...
, , , ji -L , , , - . ~ . . . .
, {y , D
""':::n*;; -- 50 < M -...
;k , ,, ?ll 4 m ll 4 mg ! = ' ~ ~ ~
Q l V - - ~ - _. __.. ;ri W -- j 'l ; = = .
- - = .. . = . >
i. l..i'.p.q1A. t j/,
* " ~ ~
. - ... / &h-Y) ~ - ..
.- 3
' N ._ .
N gN y
) <
.~ iA.
~,
These cutaway drawings show the ""'"*$?; %, 4 w major components of a BwR's reactor vessel and recirculation system. '
, j:i k y g,,..
p s _a
, ,t s' -
.u -o. . . .
'~ ;
* '*** M
.. , I
'.%.. ~
.. di 4 .,
8-10
,W" .
y $f
,r:- y l
,A -
% ( .
3 I* 5 l,. .,f, A ~ sll 1 2
-o-s 7/ ,
- I - ,
w .,g. n
., ; I k 4 i f w " .- .
i %7 o, ,,, _ , , y- "* == v a. m . 1
. - 6 s ;
- g ,
l(< DRYWELL TORUS ed l l l' $ \ CINIR AL $ tLICTRig . l J Preau,.sooo,. .np .
' N ,
( I These drawings show the layout and major components of a Mark I (Orywell - l i Torus) Containment. I i 8-11
t
'I
~& 7t[ ,
'a'-= f
/3'?"; l- i l
=
! : H i
'l k
g I
ew BWR CONCRETE CONTAINMENT GENER AL Q ELECTRIC t These drawings shcw the layout and major components of a Mark II Containment. l l 8-12
i l x, = e;. , v I '4,1 h. t [f' C',.'.
- h. r 1
o[ [
- m. ,-
-::.=: ,
_. ( ;t ; x-~ ( t, ._ g- j 1 ; _.. f- . L ,r
'_ &. -pyZ> = ~ .
I k i I f.I L
- g
< ' i
- U c ; ? '.
! 1 j 5 1- h l b 5 ,, , 1
. .esN iA 1 l j ,,. . , . _ ~
? 5'?
~~ ' ~ "
MARK lli CONTAINMENT ' REACTOR BUILDING
- [ St Sw ht GEN ER AL h ELECTRIC l 1 Polar Crane ,
f
- 4. Refuehng Platform l l S. Upper Poot
- 6. Acactor Water Ckanup j 7. Reactor Vessel i 8. Steam One
! 9. Shed Wad ! 10. Feedwater Une ! 11. Drywesi
- 12. ReCarculattert loop 11 Wmr Wad l 14. Hontental Vent
- 15. Suppresson Poos
{
- AuxluARY BUILDING IheSe dT3 Wings Sh0W the layout
S u
- i, ,,,, and major Components of a Mark III ia man Snt*"
l Containment. FUEL BUILDING
- 19. Fuel Transfer Ordge 1 20. Fuel Transfer Tube
- 21. Cask Harcieng Crane
- 22. Fuet Storage Pool
- 23. New Fuet Vauft 24 Cask Loadw; Pool 21 Spent Fuel Shipping Cask
- 26. Fuel Cask Skd 8-13 e
I 1 i. l ! l l I PWR !1 SYSTEMS l l I I i i .I , i
?
l ? l l l l This section discusses the purposes of the major systems and ccmponents of Pressurized Water Reactors. , l 9-1 l 1
/-
-p Q Turbine ,
. . - ekI ei
- 1 '
.ix :: onn, .
Steam C 1.k :
;I -
Generator 's vj -
~
m - $ Electrical Pressurizer b _ {!l d:5 lli[ Generator v , 7 a J Condenser { ,
)) g Feed s
v A ( N - [' U'[ -- {J Pump l Reactor vw , PRESSURIZED WATER ~ j REACTOR
--=~~ 3 L PLANT
. b Reactor Coolant Purnp The pressurized water nuclear steam supply system consists of two closed loop water systems. The primary system transfers heated water from the reactor vessel through the steam generator tubes (where heat is removed) to the reactor coolant pump, which forces the water back :nto the reactor vessel to remove more heat. The secondary system is the steam that exits the steam generator, turns the turbine and electrical generator, and enters the condenser. The secondary system also includes the condensed water pumped by the feedwater pump back to the steam generator.
~
9-2
- y
.J
Moistura sIO.rtto' Rehe.tif l \@ " pelief Throtti, d V. eves V.sv. Q f - y- ,, : f gre , m u. <, s i.- / u.- ... , r,. ,,e ,. .,i . . a .. r.. .. . n. .i .. ... dd see [/
/
isnit iisist o ,.. e ...r.. che# / _ [. Xi _s* Lh
+ 1:. f i- m ..
I 1T . {i." [ [ HP Conden-s.t 1r ye '/ / H..t.r cire. w.,- cire.
/ a w. .,
v [ 4 I
= if....,
z , f T cr..,, u. f u. He.ter System T [/
/ ,
Pump
. . , b come. Pump
//
PWR SECONDARY SYSTEM (STEAM / CONDENSATE /FEEDWATER) (~ G. A pressurized water reactor's secondary system consists of the steam, condensate and feedwater systems. Since physically separate from the contaminated primary system (by the steam generator tubes) the secondary system water should contain little or no radioactive material. 9-3
PWR CVCS SYSTEM
//,.
Coo 4% Reactor 1 Water Coolant Filter _ Lf _
~ - C 1 Demenerosaer Tanks
- _ ~-- - .s.
Regenerstrve n Heat Exchanger p. .isy..m
. ;:3t
; p. ;# n..m n
Wat Es%er Qggjj 3p[.' Pure Boric a Wa te- Acid
"; PZR p{.'j, ggff _ g
- 1 f- -
- 5 w.-
y . Wl' < , n (p
*i Volume contros iD n
('- h.'.~~,:e
~~
? Tank a sh '.
- Chemicas -
s
'^~
~'
tm Q Mg
-3 r~ gy-o T Pure water RC __J Pumo 6
Reector cooient system Pwn,e~ ts " ^umo 4 i The Chemical and Volume Control System provides filtration, chemical cleanup, chemical addition and waste removal for the PWR's reactor coolant system. The CVCS also responds to demands for volume changes in - the reactor coolant system due to temperature changes and minor leakage. l
.Y 9-4 l
I
@o TO ENVIRONMENT !
SERVICE E$c*na"n*g*e'r WATER 3 SYSTEM (~ sw pumo l ccw pumo COMPONENT
-mge s c ". (- COOLING
+ : a V
o I EW3 WATER SYSTEM
~
e s () u - ass n.. b, . l RHR Pump RESIDUAL HEAT Exchanger Rx j REMOVAL l((ll o U nce . SYSTEM C -
=
. ..c,c, c-... s *'-
PWR RESIDUAL HEAT <7 1 REMOVAL The Residual Heat Removal System (RHR) provides a heat exchange method for the transfer of decay heat from the reactor core to the environment. RHR is only operated after the reactor fission process has been stopped and the reactor coolant system has been partially cooled and depressurized. 9-5
PWR
### AUXILIARY FEEDWATER SYSTEM C
J
~ 4 Cx23 L':::w.
a O J5 From
,- PZR [.;.g g').
4 , y a y i System ff .
> b d Water nun e Storage O ~
Tank
" q
-3 r gy- ,
; WD l1111ax - :
V "c"
! T b
b= Ausdiary Feedwater Reactor Cooiant System # W//////////$$$#///$/AW////4?fWE/h The Auxiliary Feedwater System provides feedwater from a stor ge tank to the steam generators during reactor startup and shutdown. Aux Feed can ' remove the reactor's decay heat and (as steam) transfer that energy to the main condenser or out steam relief valves to the environment. l 9-6
#+f PWR EMERGENCY CORE m COOLING SYSTEMS O
Boron Water .,e -- T. Core Floodeg Tank ~ BIT
~
Insection Tank Storage if Tank ,
.- e.,- e.
'I C
V.lfy ,'
~
/
- s.[
~ 3 h % *
(C d A V Hegri Head o - l Safety in,ection System (Chargegt n n:SG:Y a ~ h p 4
.E' Cooling C O
g Wate, intermedste 1 Head Safety ,J 6 Y 1 Y Infection a 3 1 System " r ,
~
+- A k RHR Heat Exchanger Low Head IIIII RX ,, Safety infection RCP System (RHR) a T
Reactor Coolant System 2 i Contamment
- Sump lI - :
In an emergency, a PWR might need additional neutron poisons (to insure a safe reactor . shutdown) or additional water (to makeup for rapid changes in volume due to leaks and decreasing reactor coolant temperature). The PWR's emergency safety systems must be capable of injecting Boric Acid and a large quantity of water to the reactor under a wide variety of emergency conditions. 9-7
PWR CONTAINMENT SPRAY Soray Ring . SYSTEM s
, o ',
Wh k h M ?*-
,4-b s-; ;
tr. a W ater - O PZR nk ~@ n.:SG U -
,3
^
T;P Q 5 i n
-) 'r g.
i Containment Spray Pump T RX - (t - g RCP
- T h
Reactor Coolant System I
- P Containment Sump lI -
The PWR--Containment must be able to withstand the stress of a complete depressurization (leak) of the reactor coolant system. One system in-- stalled to reduce containment pressure is the Containment Spray ' System which pumps water to the top of the building and sprays the water over the steam which would result from a large Reactor Coolant System leak. - 8 i
~
r .... u ,,,,, ., QD . kO l11111J Babcock &Wilcox
!LT4 j '
, [' '! .
(q a ; g
~k
. l 3 h t' '
l These drawings show the basic laytut of components for the three PWR vendors in the h United States.
,3
!lf t
% g 9-9
( i
- h. ,k' g ,
. ROD TRAVEL
, HOUSING I
CONTROL ROO I l lI l DRIVE MECHANISM , I. . I J ,l l f. INSTR UM EN TATION i I d PORTS l , j I UPPER SUPPORT PLATE
!l ! l! l
, l.
. l THERMAL SLEEVE INTERNALS 1 ,1 SUPPORT .,
LIPflNG LUG LEDGE CLOSURE HE AO M #88I""Y CORE BARREL SUPPORT COLUMN
, o, ah . c i HOLOCOWN SPRING 04 l
- o. . 5)
UPPER CORE , ,
*~#-
g.
*O *a CONTROL ROO PLATE D j .
x GuiOE Tust (. i, gr y3v" ,s OUTLET NO22LE A I O - iss pe CONTROL ROO t . T i 2 . ORIVE SHAPT
' ' ' ~
~~~
SAPPLE RADIAL - I
/m' INLET NOZ2LE SUPPORT f7 d
( E,d r h.f s
//
3 APPLE --y i E CONTROL ROO i
./ CLUSTE R IWITHOR AvvNi CORE SUPPORT I .,f; .I', " {- .
COLUMNS e i w l lf ' INSTRUMENTATION THIMSLE CulOES ACCESS PORT REACTOR VESSEL ( RA08AL SUPPORT ,
!!!0 f LOWER CORE PLATE CORE SUPPORT ~ n .. ,
\ m u Y
Westinghouse i This cutaway drawing shows the major components of a typical PWR reactor vessel.
]
9-10 r
e, skdas D1 a~s.,sa,,
' "0L3 88"" 8"'"4 no. CLusTtt C. aft.L w..
T.e nozzte , h ,17,,t*t? N,m .
.... ... qy g~ ,
--fkimatt Tutt rl ui. 'g -
i. l
- " . g l g, ,p, p, .iii.. . .
m., ..1 . gy;;.e m[ l sis.nr insion
,j ., s %lj g ski
- QA $ ll
,,,,,,,,,,a - .i m , se. .
Westinghouse This cutaway drawing shows the major components of a typical PWR fuel assembly. 9-11
. /<*"yn f
- %, . ~:::: ... K- ,,.
u - -~ a
, t
, , f - --- n
~. ~_ -
( .:3r m 1% (. - ir
,a .
w
._ _.N .
1
,n r' ~-
+ - , .3 i
*
- i
% ~ ~a
-. ~. \ h ....n n -$
l8.;ij. l - <_
-- = % M -a .s i !
I "M __ { -
, ; of ca "
t, - N _m a=_
. - - - . trl s
_ r ,. N sE-g;fp-_ l
; . i i.
l r.r =- -
. . ../ w'\n\ -
i . y<e . . .~mm
'~
i . , [ N hii! l-
~.d
.p ::y- - , . ;
Q g.i g .,.eu t_f.! l;b
-- - c,.,,,,, &*
ms- co
,,,,,,,,,, s I m
, i_ 1 I i, i -
s ' d...ls - = < ' -
, iri a " '.v"" . 7,M
~~ s .
@ , , _ g. , ../ M' _ -
L-IF" ' b \..
~ ..
'k' ,
_ ._ p - -- , , , , , , ,
=- %
f.St:7' ---n ---- 1 #iC * *1*W
,Mv.41 4
N J.k. .. Westinghouse gg SYSTEMS POWER
-o. . . o Babcock & Wilcox These cutaway drawings show the basic steam generator designs of the three PWR vendors in the United States.
)
J l 9-12 l [
9
\ "
,LWMitL ,
A UPett RADIAL 8tAtlRG tp , Tutu 17 tutinG 2 , f E p /' g TMRUST stARI.s OIL Li,7 PuuP MOTOR STATCt
,ucigg "l3J"l 4 ~
L wit RA0lAL - "
' vp+%
~'"
=,=;>r f
StAtl G s , _ J :, '
, m .......
m ,Tv ... m uu .,,
...,,m / d
- g c
h *dy *":d;""" '""""
'""'l, /
, ,,7
.mi.. wuo i.uT sIfyj_ _ -n;guia'a
,,,c.,,, i, - _ '"""'Mf:0!'"'
am' eni . l ( / tweg;Ltt SUCTice - R0l%LE h Westinghouse This cutaway drawing shows the major components of a typical PWR reactor coolant pump. l 9-13
Speaf noi:Lt 8tLit8 Saf t?Y 422;t eC: L1 - T1-N ...... (tI I u,.it .ta, lusituktnistics 9C2 .1 Litties g u 18o..... (LO&e lasts) l l j . I 5" ELL LCwtt utas statti SUP90tf ultigw(s
' l , g ., til j e y hi/ :781 CAL ntA?tt SUP*2tf $sitt -
54431 at::;t Westinghouse
-This cutaway drawing shows the major components of a pressurized water reactor's pressurizer vessel.
3
.}
j
- 9-14'
l l 1 m o p l
- i
_l ' l _ . _ _ _' l . i_' ,6_
~
Q {, Q '=='}-
" ' ~ - -
=5
=5 ._ _ s =;. _
rii -- e
,-- - m-
~~~
-~
L-- 4 ,, t _ _- a w =ry --
-e Y,a_~ 22-
__ - , y 7-- , O : !
. M ,
. _=g ir = g - : . - - - - ,_
j g 4=-4 4 J .
'r- L. fw1 ~
1 i
=
Q7:=- ll:- g ==. e- , _, :
.( 'A h "
~Q_. '[ --- - ,
, 'wo . .,h 2: Y :o a;
[=. l.i _~: ,.2 m M w
-- r i . ~.- . - -
i
-w i . .
; =., ,
V
~
*_ l i l I
~
~ ~y
/~_,A ,
A iE --- - i ,5 M l1
"- :-- =. - Yl 5 ~
~
~~~ -
7 - These cutaway drawings show the general layout gg y , of major components inside a PWR containment ll j ; j;
" 's building. m' !E m -~
p / l 1, _ l ~:~ " Z" 1 9-15 '
Reactor Building Handling [._ Bridges
- c. .,
; Handling
[,, . L<.!. ) .- : Bridge s " [,
.s..
'W '*
.vf, ..
Fuel b l .' I- g ; a h St e W
- t. , t., 2 g
. :n., - t.". i-1.I
. Reactor L
~%
') '. k f.
l.I Core .' '. " ', N' * * -
-E r.] hi -
. . .. f, _
[; .; j -
,s.-
N {. - . . , . ,
,g /
Transfer . . ; Mechanisms ** y p'
..,[
C POWER SYSTEMS CG***A'Oe t*ahtes.on x This cutaway drawing shows the major components involved in fueling /re-fueling a pressurized water reactor, t 1
.s Y l
l 9-16 I
I L_ _!
< 4 i s. r sybybpWhphyb, . . _ _ "" "*"*/
g
, _ = _ _ .
g
...... .%%g , L - ,
.. ; Nw& .
)
yd a% ME'a- 3
'r._. ,
_ _. .. ..]_ 1
- 1' l
1- l" 1 n, v[ en e .v.
"2" __b /NI N- li ; .,[lk -.8 j M f'
- ooo I
[# ( '
'i LJ - .0memaGr.oJai
,_g -
_ h . . .Q- f [p00** p,' ;, .. . < - n..
*h p
g I % frT4 %
%.. ., a a # *Si t.O * * , . .5 L-m ny -
N.n - li\Y u. - e fG7g a.y
.ms' Westinghouse i
/ ( This cutaway drawing shows the general arrangement of buildings at a Pressurized Water Reactor nuclear plant. - 9-17
RADIOACTIVE WASTE GASEOUS EFFLUENT N AR POWER PLANT ; ph i?5b d LIQUlO Essqr; 5$$'.k g EF LUENT
==
k g_
?-
TRANSPORT DISPOSAL I i This section discusses the sources, handling and ultimate disposal of radioactive wastes generated by Nuclear Power Plant operations. l 10-1
HIGH-LEVEL R A DIO A CTIVE WASTE FUEL HANDLING BRIDGE lW
/
/
% ,a - -
1 l, ( ', _ g 1 ,1 . ,,,: ;D f- , < .3 ' ' ~ b U ~ ' , , h_ , -__ ., , , ., 5,l' .,,Q M ,f^ .a- ': .L'; ,x ,b,;;l' c ,76">'
,7 _ ~ 7 . ,
'T'- ^-- ' ','. 5 c 5 {5 5^ 21,k'
~
^'
/p ,s
^
U ,&- . ;, ;, qq ' 2, , , q'((5f_{(5' ',y' FUEL STORAGE
/ RACKS SPENT - b FUEL POOL SPENT FUEL ASSEMBLIES
( FISSION PRODUCTS ) l - l l High Level Radwaste (fission products) are sealed inside the spent fuel rods. They are presently being stored in spent fuel pools at nuclear plants and at some o'f site temporary storage facilities. J 10-2
LOW LEVEL WASTE SOURCES . L I Q U I D:
- 1. EOUlpMENT LEAKOFF POlNTS
- 2. EOUIPMENT VENTS AND DRAINS
- 3. FLOOR DRAIN SYSTEM
- 4. RELIEF VALVE DISCHARGES
- 5. SOLID WASTE SYSTEM ( DE-WATER )
S O LI D:
- 1. CONTAMINATED AAGS. TOOLS.
CLOTHING, ETC.
- 2. SPENT FILTER C A R T R 10 G E S
- 3. SPENT DEMINERALlZER RESINS G A S E O U S:
- 1. EOUIPMENT VENTS
- 2. LIOUlD WASTE SYSTEM
( EVAPORATOR GAS STRIPPER ) The principal sources of low level radwaste are the reactor coolant (water) and the components and equipment which come in contact with the coolant. The major constituents of radwaste are activation products (crud) with a very small percentage of fission products. 10-3
WASTE FROM CVCS
*%/,,
Coohng Reactor : SOLID RADWASTE Water Coonant Fdter F-
~U~ WASTE
~ '
f u Demenerakse, GAS
.__1 Tanks TO Non-Regeneratne -
7% r-) b WGDT
* - -- Heat Exchanger rN jf- Comp'eT ser H Ec
~
er
~
'?
'^
.Y.Y
't, Pure Borec Water Acid
,L n
R Q
*[ , ~gG yt
,, t rqa 4 /
cui3 8
- h?
g T Cherrucal a= Tank a
*M y*:S Ay e -
pgp T Pure Water i
. s t
Charging (t Reactor Coolant system Pump Vo Ac4
'HH/HMH/OM//4 The drawing above shows some of the sources of low level radwaste from a pressurized water reactor. In the Chemical and Volume Control System solid particles (some of which are radioactive) are removed by the Reactor Coolant Filter and Demineralizers. Gases are removed in the Volume Control Tank. Liquids can be pumped to storage tanks for sampling and reprocessing as necessary.
10-4
. _ ._. - - m . . _ .
'* i ION LIQUID ;
ION (0 CAY)
,,, FILTER --# --* AND m AND RADWASTE souos "-""' EXCHANGEa SAMPLE OfSCHARGE m TANK A
a
, canvaioo . m
[m.tCYCttamoe.,, TYPICAL oans - evA,oaAToa LOW-LEVEL t ....... . m . m . a . . '" e - " RADWASTE on-wavea souOiriCATioN HANDLING
,aOCEss SYSTEM I SOLID maan. voets. etorwn oc. Opp. SITE R A D WA STE
( 8URIAL ) camenioans c a n v aioo t s
'L ' "
GASEOUS (DECAY)
*
- PILTER M COMPRESSOR --* AND --+ FILTER --* AND RADWASTE SAMPLE TANK OlSCHARGE l
l l The block diagram above shows the layout for a simple radwaste handling system. Solids, liquids and gases are first separated from one another and then processed individually. All solid low level wastes will be shipped to licensed burial sites. Liquids and gases will be held up to allow most of the short-lived radioactivity to decay off and then will be diluted and released into the river / lake / ocean (for liquids) or the atmosphere (for gases). 4 f 10-5
l GASEOUS EFFLUENT NUCLEAR POWER PLANT y Q W LIQUID 32 ,s EFFLUENT 1 I i I fs
?
i '\ d,g o, Detect k=s { g . Irradiation 6 g / FUEL TRANSPORT
~
h 'b?.%'.? sherro.n, g to ~~ N$~.' l
\c& '
-m.C9&a... db88 /
g,. %,, __ 5 % w s 4
~..
{ l Y~ s.,z NT - l
~
~~
-. /A
/ -
N 9= % fs- _ 1 l l The drawing above shows many of the possible pathways for radiation l exposure to a member of the general public. l 1 10-6
10 CFR 20 DOSE STANDARDS ' 2 m REM IN ANY HOUR l l 100 m REM IN ANY 7 DAYS l 10 CFR 50 DESIGN OBJECTIVES - 3 m REM / YR TO WHOLE BODY 10 m REM / YR TO ANY ORGAN 1 GASES ( 15 m REM / YR TO SKIN i SOLIDS & l
- IODINE The licensee must not release radioactive material so that any member of l j the public receives a dose of 2 m Rem in any hour or 100 m Rem in any
.I seven consecutive days. Additionally, the NRC has issued numerical design limits for each reactor unit for exposure to releases into water i and air which are considerably lower than the limits published in 10 CFR 20. l 10-7
A REACTOR l ! EMERGENCIES i i i 1 This section discusses some of the possible events which could lead to a , significant release of fission products from the reactor core and the emergency systems, structures and components designed to prevent these accidents or mitigate their consequences to protect p;blic health and safety. l l 11-1 l _ - - - - - - - - _ , - - - - - - _ . - _ . _ - - - , - - . - - - _ - . . . - - - - - - - - - - - . . _ - - - , - - - . , - , - - - - , - ~ - - - . . - - - - , - , , . -
REAC- O9 ENERGEhCIES OVERHEATING FUEL RODS MECHANICAL DAMAGE TO RODS
/
/, ,
GAP
,&xa:/ CLAD
\ \MM r '/ ,
FUEL ROD W,23%'7 f ,w!+ / j;,f4;7 FUEL PELLET r N' /
- Fission product release can be a result of overheating or mechanical shock to the fuel rods. An abnormally high rate of fission or lack of decay heat removal can result in overheated fuel. Mechanical damage could be caused by a fuel handling accident, spent fuel pool damage or industrial sabotage. --
l \ 11-2
E V ERG E \ CY SA=E- Y SYSTE V S
= PROTECT FUEL RODS .
=
PROTECT RCS
=
PROTECT CONTAINMENT
= PROTECT THE PUBLIC
{ i All power reactors must have specially designed safety systems to insure the reactor can be shutdown and the fuel cooled under a wide variety of emergencies. The reactor safety systems are designed to protect or miti-gate the consequences of damage to the fuel rods, the reactor coolant system and the containment structure. The overall goal is to protect public health and safety from the consequences of an accident. 11-3
REACTOR EMERGENCIES REACTOR RADIATION SCRAM / TRIP EXPOSURE SIGNAL TO PUBLIC IF NORMAL \ IF CORE COOLING l EMERGENCY ( MODERATING PR EPAR EDNESS SYSTEMS Fall SYSTEMS Fall
/
E Eh y START RELEASE TO ENVIRONMENT
' [ IF REACTOR \
N IF CORE COkf l i COOLANT SYSTEM I l [ CONTAINMENT } ( MODERATING INTEGR TY SYSTEMS FAIL INTEGRITY. FAILS
\ \
FUEL RELEASE F M DAMAGE RCS i i I ! A combination of several low probability failures must occur for a signi-ficant amount of fission products to be released from reactor fuel into the environment. If these failures combine with an inadequate emergency preparedness system the released radioactive materials can cause an ex- ! posure to the public. i l l l .' 11-4
s STEA\4 GENERATOR TUBE RUPTURE Moisture Separator / Reheater
//
& a
=n- ~
Relief Throttle
/[ vaives Valve Xr =
HP u j ,j
}}j LP LP y,ol8 tion
- = tor v en. :: = u ::~: ::q -
c
/ @ IIIIII Illlli Efectnc ceneraio, Pressun.zer 6 T
/Gisic . ry '.'
TSWdb.'
/
/ _ / h HP e u
> ~. j e.te.
- e. .r , ,.,.,
D %..M " I TD fT ---- _- /,
/
a Reactor
/
/ : 3 Vessel u [,,,, 3
; Feedwater Condensate Pump Pump T /
(. h , Reactor Coolant Pump In a PWR, a steam generator tube rupture could lead to releases of radio-cative material due to increased steam line pressure. The operator's main goal in this situation is to provide an orderly shutdown and cool-down of the reactor coolant system so that the leaking steam generator can be completely isolated and the steam relief valves will not open. 11-5 0
/ MMme/ ,
l, // - l CONTROL ROD h MALFUNCTION a . fjj ?e OR ROD
- g. q "
e; t - o a'VSGM E J E CT-lO N g, p ~n 2' SAFETY-k* ax INJECTIO N 8 olt SYSTEM . 8 Reactor Coolant System { j
\
/
- 1. ,
A control rod malfunction or ccatrol rod ejection may require'the inser-tion of additibnal n'e'utron poisons. Both PWR's and BWR's have systems which can pump a boron solution into the , reactor to provide the 'necessary neutron poisons for reacto: shutdown. _'
./ "
s. 11-6 ,.
.1 . - . . - - - .
i STE A \A LINE BREAK- l SAFETY INJECTION SYSTEM
~
a Moistu o Separatori Aeneater 2
,/j'
// A A pen,, Throttie .L vaives Valve p/j j y
~
'/.' [uwv] (p (p olation yp
/ }4j Steam Generator
[
/
Main Turbine t,. la'
.,i
'a It, . tl pi 'il t._
ir
,11 il r i llllll IIIIII Electnc Generator Pressurizer j6
, , / ~ -> ,
u i
, y' ,
/ I a vain Conden.
ser o l/.
. ::. HP l \' '/ /
7
/
Heater Cire. Water y Cac. g ,,,, O / { ( R r' l Reactor Vessel u=- l t f// I
~
( 3 LP ___ /f V Feedwater M*8t" ~ Condensate
~
i /f Pump Pump
, /f
~;L - //
Reactor Coofant Pump In a PWR, a steam line break can cause a rapid temperature drop in the reactor's coolant system. As coolant temperature decreases, more neu-trons are moderated and reflected back into the reactor core causing more fissions and higher fuel rod temperatures. This situation requires a rapid reactor shutdowa which may include the injection of boric acid solution to ensure the reactor remains shutdown. 11-7
V' LOSS OF COOLA\T ACCIDENT
$$p PZR msSG OS k (*
g L L EMERGENCY _3 f v
~~
ax - CORE COOLING O RCP
*= SYSTEMS, Gc' ffh seacim coorant system ;
CONTAINMENT SY,ST E M S
\
i l A loss of coolant accident decreases the reactor coolant system's' ability to transfer decay heat away from the reactor core. The plant's emergency core cooling syster. v.ust be able to provide the necessary ' volume of water to prever* ' 6 e nage.
/
l ,
- -, )
L 11-8 , 3
PWR EMERGENCY CORE COOLING SYSTEMS
~ D
~
O BIT Boron injection W ater Storage
,3 w - -
~ 7 p{wf,3 T Core Flooding Tank _ _
Tank Tank y.yN.g lbf.:
'S -
- 3
- h High Head Safety injection System (Charging) ,,
;;j @:SGhp T
" hat intermediate Head Safety i j t injection 7 1 System y,
-m rb J ( - - ,
kM RHR Heat Exchanger Low Head Safety RX ,, injection V RCP System (RHR) a
- T Reactor Coolant System 3 Containment Sump The above drawing shows a simplified version of a PWR Emergency Core Cooling System which can inject borated water into the primary system under a variety of accident conditions.
l 11-9 l
l
\
J BWR EMERGENCY COOLING SYSTEMS l CONTAINMENT SPRAY
. ,is j L__... ,__
CST HPCl I STEAM UNE TURBINE CONDENSATE I STORAGE
---- +-- "
_ TANK 1
........ ,m PU
~
,i" !
I RHR HX b$) _ CONTAINMENT *t
}
SERVICE t 4 I i SPRAY 8 WATER 1 . , . - - _ - - - - - - '
- - e
-e--- l i .
oRvwEu.
- h f g f PUMPS MP
- aa LPCI I
The above drawing shows a simplified version of a BWR's Emergency Cooling Systems. These systems can inject pure water into the reactor vessel (and provide containment cooling) under a variety of accident conditions.
.)
11-10
COhTAINNENT BULLDING q
= ISOLATION SYSTEM
= SPRAY SYSTEM
. AIR COOLING SYSTEMS
= AIR PURIFICATION SYSTEMS Should serious fuel damage occur, fission products will be released from the fuel rods into the reactor coolant system. The primary function of the containment structure is to block the escape of this highly contami-nated fluid. The containment must bt properly isolated, cooled and de-contaminated in order to minimize fission product release to the environment.
11-11
y /, CONTAINMENT SPRAY Sorav Ria. SYSTEM 4 . O
~
u,- . hOOO
- fir.$.%g !.y. my L,.i. -
a water h lb - Q- PZR p.;:SG @9
" 5 A>~~~-
P Yi T 0:1P
'n y
- g containment Spray Pump
~
T gx - RCP
- T Reactor Coolant System
- containment Sump The drawing above shows a simplified version of a PWR's Containment Spray System. Containment Spray is one method available to cool and depres-surize the PWR containment in the event of a loss of coolant accident.
)
.J 11-12
EMERGENCY ACTION LEVELS UNUSUAL EVENT ALERT INCREASING SEVERITY SITE EMERGENCY GENERAL EMERGENCY l The Emergency Action Levels (shown above) have been established to pro-vide prompt notification of minor events which could lead to more serious consequences or which may indicate more serious conditions which have not yet been fully realized. 11-13
UNUSUAL EVENT ECCS ACTUATION HIGH COOLANT ACTIVITY SAMPLES ABNORMAL COOLANT / FUEL TEMPERATURES VALVE / PIPE FAILURES POWER FAILURES (0FF SITE) FIRE OR DEGRADATION OF FIRE PROTECTION LOSS OF MONITORING / COMMUNICATION SYSTEMS SECURITY THREAT ABNORMAL NATURAL PHENOMENON AIRCRAFT / TRAIN ACCIDENT ON SITE The Notification of Unusual Event indicates that there is a potential degradation in the level of plant safety. The notification:
- 1. Provides current plant status information. ,
- 2. Assures that the first step in any later response found to be necessary has been carried out.
- 3. Provides a test of emergency communication systems.
}
l 11-14 i
N. ALERT SEVERE CLAD DAMAGE RELEASE 10 TIMES GREATER THAN TECH SPECS SIGNIFICANT PRIMARY COOLANT LEAKAGE LOSS OF AC OR DC POWER SUPPLIES INABILITY TO COMPLETELY SHUTDOWN /C00LDOWN FUEL HANDLING ACCIDENT FIRE POTENTIALLY INVOLVING SAFETY SYSTEMS LOSS OF ALARM / ANNUNCIATOR SYSTEMS SEVERE NATURAL PHENOMENA ( AIRCRAFT / EXPLOSION DAMAGE TO FACILITY ANTICIPATED OR ACTUAL EVACUATION OF THE CONTROL ROOM ON G0ING SECURITY COMPROMISE The Alert classification indicates that events have occurred (or are occurring) which involve an actual or potentially substantial degradation of plant safety. This notification:
- 1. Assures emergency response personnel will be available if needed.
- 2. Provides an updated plant status report.
- 3. Provides a test of emergency response centers and personnel.
1 11-15
SITE EMERGENCY SIGNIFICANT CORE DAMAGE - LOSS OF COOLANT (BEYOND MAKEUP CAPACITY) LOSS OF AC OR DC POWER FOR 15 MINUTES MAJOR DAMAGE TO SPENT FUEL FACILITIES NATURAL PHENOMENA BEYOND DESIGN LEVELS DAMAGE TO SAFETY EQUIPMENT BY FIRE / IMPACT / EXPLOSION EVACUATION OF CONTROL ROOM WITH NO LOCAL CONTROL ESTABLISHED IMMINENT LOSS OF PHYSICAL SECURITY The Site Emergency classification indicates that events are occurring (or have occurred) which involve actual or likely failure of major plant functions necessary to insure public health and safety. This notification:
- 1. Assures response centers are staffed.
- 2. Assures response teams are dispatched.
- 3. Provides all response organizations with current plant status
, information.
- 4. Provides a test'for loca', state and national response organizations.
j 11-16
GENERAL EMERGENCY MAJOR INTERNAL / EXTERNAL EVENT (OR COMBINATION OF EVENTS) WHICH WOULD CAUSE: LOSS OF 2 0F 3 FISSION PRODUCT BARRIERS FAILURE OF ECCS TO SHUTDOWN AND C00LDOWN REACTOR-0FF SITE DOSE RATES: 1 REM / HOUR WHOLE BODY (' 5 REM / HOUR THYROID The General Emergency classification indicates that events are occurring (or have occurred) which involve actual or imminent substantial core damage with the potential loss of containment integrity. This notification:
- 1. Provides current and continuous plant status information to all response organizations.
- 2. Initiates predetermined actions for the protection of the public.
- 3. Initiates other protective measures as indicated by the situation.
l t l 11-17 l 1 -
THE THREE MILE ISLAND ACCIDENT 1 CCNTRCL ACO
/ . ,
i l hl 60 $7005 ANo NUTS
, (20 TCNSI REACTOR HEAO j SERvtCE STRUCTURE ,
,p
~
CCNimCL RCO OmivE W l
; GulCE TuSES
" 4 i CCNTAINING LE AD REACTOR PRESSURE VESSEL HEAQ SCREWS (3 LEAo (81 TCNS) k"" / , J. % SCREWS REMOVEDI vv _1 h (TO 8E STALLED:
y & ', k $Y'$ sp$ng gn' h '\ f , CANALFLCCR
\, j eW :
a, ,' g
-up*ER *tENuu ASSEV8Lf UTTLE i
j i 4 l ig f -l DAMAGE APPARENT I" $I
- i. i [EE S
\, , UPPER CAD FutL ADHE*'NG TC
, {f.
i
,5 FEET l
'~~
; f;p$ &" }
r t! -- RuSSLE SEDiMis 14' cE*TH: 2 I ,! ,;l 1.jh' I ' l CCRE SUP*CRT STRUCTURE t 12 5 TCNS) [r f. y'[ .[ ll l P' p . CCRE AREA.
]8) e' l I CON 0lTION UNKNOWN
, ,g ,
h 3 bf plCWER GRtc. CONCITt0N UN(NCWN
'b "'8 FLOW C.STR,8UTCR.
\b ##
'!}I t CONott:CN UN(NCWN
. ,f g-? /
i%5& This section discusses the core damage and the release of radioactive material resulting from the Three Mile Island accident. l l 12-1 l
l i l THREE MILE ISLAND HEACTOR BUILDING (CONTA!Nr.1ENT) AUXIUARY ' BUILDING C00UNG TUWTH
'l -
; g)r .-
so.., w= .g
-Q . v
- w r*=
c 6 M e.
....@4 -
a.a
== e / TURB!NE BUllDING
,-. - - g . -@ ,
La( ,I
-=. . .
e . m.
- .*~ -
r
=.--
=.v,yL, eJ (a- .
1,4'
~d-- -
- - = -
6.i e i-I g*,*,,,*
- c. c d'"W _ lG D Ip *e@ **Ty* (k *H=v
@ t.: -
4 " , j 6~
, _ . , - e _.
- p. .
d.l,,3E ' e5
- e. _
"j-- [_ ' , _ j'I . - -r s- - -
mm m a-* '-*
. - . = = . . c.Ie m, a ./. x m.
O
@. i l
l l This drawing shows the general layout of structures and components at Three Mile Island Unit Two. l l 12-2 1
i g$ . D \W 4) 4O STEAM GENERATOR . 3; n . - =
~,j d
CO ANT p R SURIZER ( s a G^R X REACTOR VESSEL This drawing shows the major reactor coolant system components at Three Mile Island. 12-3
~ . . , ,
~
% Wh x 1 /
s e M+__
- _ . _ -~f y T
khtj U hh
, i t .
~~
_. ~ I N gaang se.s.s. swr m./. I
\s ,,
Q m, l e l l
- r Yl~ =.-
\l g i \- l
- 7
]pr{
==
=
~ "'
_ _ g 1 = r
/r m...-
f -1 5: 'V ied [ T _
. . ,N '=
i I
, , l=l
.. U I fial /
TMI REACTOR BUILDING ( CONTAINMENT ) l This cutaway drawing shows the layout of components inside the TMI Reactor Building. l l
}
12-4 l I . _ . .
TMI PRESSURE CONTROL, VOLUME CONTROL AND WASTE SYSTEMS d ' b yALvg PLANT M Rv BLOCM VENT STACK
- .. P.33. .
CENERATOR SIEAM b == 'I't v nc9
.- n
( _ muu
~
#ENI COMPRESSOR PRES $unIgn ,
L' I TA K OEWINEAALIZEnS} f CORE VCT , E3HL WQD7-P"' Suu, cuanomo ruun M Suu, _ h)k kbkdkb - !b bh i o / CONTAINMENT A UXILI A R Y l BUILDING BUILDING t i The major systems involved in the TMI radiation release are the Reactor Coolant System, the Pressurizer and its's relief valves, the Chemical and Volume Control System, the Waste Gas Handling System and the Auxiliary Building Ventilation System. I i 12-5 l
. 1 TO PRT TMI LOSS OF COOLANT 9
RELIEF 8 Z VALVE SPRAY kE STEAM BU8BLE
- -t
.=. u .
HO 2 ,- l c: :- ,,c.
, f. .P.> ~ .- .i: ci'.;.iM!:
il
' ~ ~
- . $S: ?-
~
r-RCP (.f'c.'6behilf.{h l/ . . . ;. , M;
~~
~~
e
~~
-~
5 g .
)
t STEAM
.\ ,
, "y 1
)_) ' '
.,. ~ n n - ~ - n j- t i '
HOT LEG
} ; m , . ;
( _ .--- REACTOR SG , 1 FEED w
^
El HO 2 y 2 COLD LEG Following a relatively common reactor scram, a pressurizer relief valve stuck open causing a gradual loss of coolant pressure. Automatic safety equipment started as designed but was stopped in order to prevent the pressurizer from overfilling with water. (The rate of water pumped into the Chemical and Volume Control System was increased for this same reason). The resulting low pressure and high temperature caused the coolant water to boil. The low coolant pressure also caused the reactor coolant pumps to be shutdown. With little or no cooling av.111able to remove decay heat, the reactor fuel rods started to crack and breakdown. Some radioactive fission products (mostly gases such as Xenon and Krypton) were released into the reactor coolant. Later, when the stuck open relief valve was isolated, the reactor coolant pumps were restarted. This caused cold water (which had been away from the reactor) to be pumped onto the now very hot and very brittle fuel rods causing severe core damage. 12-6
(___-___-__ TMI RADIATION RELEASE PATH
* ':G .
.!# $D.I'.I N *: .
- ;.j .p. .....:..-.#
, ' * . ,* '+ '
') , . ,
.j,,',e s .'
. ,l L ~ . . .* .
- ,,-) y'..
- .,, . jI !<.'. .w, ,~. li,,,v,.: . .
*' .:t ':. M.(:M.
.;.n.9. a, t*/ Fg SAFETY f)',.........
VALVE j PLANT PCnv 8 LOCK
.*p i VENT STACK
. i .. . . ..o. ' T, PRESSunl2En [
t' STE AM STE AM A
.s CENERATOn Q[4 nw out ,-
[. . a
= 4,g_ i.
. .?: M '
'* RC9
'e l*= ' * *.g *' '.E. .. '.
..->.c CL r1 x" V : .'.,.. .
t,
*;*,'n'
- r. .*,s & . ~$','*f,',' . *; f
- p' =* ,.'. ,** ,. OA3 NRHit
*, ' , #[l'1%. [!((.I ggz
*7 PRESSURIZEa
$ b* T" I' ' 3= '
IVENT'
- REUEP W H LM
; TANK l..
~ ~ " DEMINERAlllEn3 J
- 3. CORE-
* *" CT ,;gy
, . , a )-
.,e f.'.**'.'.
REACTOR a.,
;.t -
..(..y v 9M..c.
. :.,s. 2",; O vaSSEt . : .; . ~
c.;VS61 e si: . ! ' 9 e di! M i h m h L* ' " enAnomo cour. h h bkMikhkkkd[kth Nhkk$$k$khfh)hl$ CONTAINMENT AUXlLi AR Y BUILDING BUllDING Fission products (mostly gases) escaped from the damaged reactor core into the reactor coolant. Reactor coolant was moving through the Auxi-liary Building and through the pressurizer. Leakage from the ; aessurizer relief tank severely contaminated the Reactor Building. The concen-tration of fission products in the Auxiliary Building piping caused that building to be evacuated. Some of the fission product gases le3ked from the Auxiliary BJilding piping and Were picked up by the Auxiliary Building Ventilation System and blown out the plant vent stack. 12-7
TMl CAMERA y-INSERTION I ,j A-an* ~ r '>7 ll ,j \.
/ .....
h
?s l g.. IN i :. ;.
e;mp gC.:..;;. At
.ha :
l,
i G$3 - Uf;
_l,
'q- i ,_ - ff l
.tQd{ N
[ l l-l .!. : N -.., A W )h o, ) unna n_.
~F (.un. tan I
[9,-))2j jd l .,
,, runw. ,I ..
i r. .,,. .
'I .:
4 FSAi- . ...D ($XI ; j @*t I p,.
..e O \ I,i g!g. .:..
e .f i( \ N. """ D ,'
,,y,,,.g m..sI[a~us.s.,
As m.c, r. ._..... su* tua.. n . .c., n... REACTOR VESSEL SHowtNG DAMActo pygL AND CAvlTY l l l l Television cameras lowered into the TMI core indicate a large void area at the top half of the core and a bed of rubble (fuel pellets, fuel rod j debris, etc. ) on top of the remaining lower half. The exact condition ( of the lower portion of the core has not been determined.
/
12-8 l
4 l TMI CONSEQUENCES 1 MAXIMUM PROJECTED OFF-SITE DOSE: LESS TH AN 100 m REM AVERAGE DOSE TO POPULATION:
$== 1.4 m REM / P ERSON PROJECTED ADDITIONAL CANCERS:
0-1 Fortunately the environmental and public health consequences of the TMI accident were very small (compared to other industrial accidents) but the psychological effects and the impact on the nuclear industry were (and continue to be) enormous. f i I l 12-9 l -. - - . .. _ -
. .. . - - _ - _ . -- .. . - - .}}