ML20045H958

NRC Regulator of Nuclear Safety

ML20045H958
Person / Time
Issue date:	06/30/1993
From:	NRC
To:
References
NUREG-BR-0164, NUREG-BR-0164-R01, NUREG-BR-164, NUREG-BR-164-R1, NUDOCS 9307220172
Download: ML20045H958 (26)

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NRC l NRC-REGULATOR OF NUCLEAR SAFETY The U.S. Nuclear Regulatory Com-WHY REGULATE? mission (NRC) was formed in 1975 to regulate the various commercial and in-The nuclear industry is strictly regu-- stitutional uses of nuclear energy, in. lated because of the potential hazards cluding nuclear power plants. The involved in using radioactive materials. agency succeeded the Atomic Energy These radioactive materials give off Commission, which previously had re-sponsibility for both developing and regulating nuclear activities. Federal re-search and development work for all en-ergy sources, as well as nuclear weap-ons production, is now conducted by the Department of Energy. $pg O Under its responsibility to protect the 7[

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public health and safety, the NRC has ... ~ e,, three principal regulatory functions: (1) / i establish standards and regulations; (2)

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issue licenses for the facilities and users i... of nuclear materials; and (3) inspect fa-cilities and users of nuclear materials to g m assure compliance with the require-g M_A', g 4' ments. These regulatory functions re-e late to both nuclear power plants and to %%_,_[LM y 'M [%g other users of nuclear materials-like nuclear medicine programs at hospi- ,,,b.e. t %$.Q.?,. g g d 1 tals, academic activities at educational e institutions, research work, and such in-(\\ dustrial applications as gauges and g'g f( ( testing equipment. The NRC places a high priority on b* v-

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keeping the public informed of its work. 1 Through such activities as public docu- ,f ment rooms across the country, public

1. ' s-hearings, public meetings in local areas, and discussions with individuals and organizations the agency recog-fn*an"y'so*[0ces"2c"o"sNe r*a"di ir ror sae a-nizes the interest of citizens in what it diation from radioactive elements in soll and rock, 4

and radiation from medical and dental x-rays and does. other medical procedures. 1

NRC radiation, which can be hazardous to tion, the NRC requires users to take people if they are exposed to it in signifi-steps to keep exposures well below the cant amounts. The extent of the risk de-limits. pends on the type and amount of radia-tion emitted by the radioactive material, the distance between the source of the NRC ORGANIZATION radiation and a person, and the length of time a person is exposed to the radia-The NRC is headed by a five-mem-tion. ber Commission with Commissioners appointed to five-year terms by the-The risks can be lessened by reduc-President of the United States with the ing any or all of these factors. The haz-confirmation of the Senate. A Chairman ard is less if there is a shielding material is designated by the President. like lead or concrete to block some of the radiation, if a person moves farther The NRC staff numbers approxi-from the radiation source, or if the expo-5ately 3,300 with a budget of over $500 sure time is reduced. million. Some tyfo-thirds of the NRC em-playees work in the agency's Head-if radioactive materials are properly quarters in Rockville, Maryland, or - handled and regulated, they do not nearby offices. The remainder are lo-pose a significant risk to the public or to cated in five regional offices throughout workers. the country or at resident inspection of-fices at each commercial nuclear power Radioactivity from natural sources is plant. present throughout the world. People are continually exposed to low-level radiation from radioactive materials in NRC REGULATIONS the earth and from cosmic rays from space. Exposure to natural radiation The NRC sets the rules that users of can be affected by geography as well as radioactive materials must follow. lifestyle. For example, radiation levels These rules are intended to protect the are higher in the mountains, and travel persons using the radioactive materials by airplane contributes additional expo-and the general public from the poten-sure because of increased cosmic tial hazards of radioactivity.- Many NRC radiation at high altitudes. Most people regulations have been established or also receive some radiation exposure changed, as necessary, based on the from medical and dental x-rays and recommendations of the NRC staff, other medical procedures. Members of the public and interested organizations can also request changes The NRC's regulatory program es-in regulations.The views of the public, of tablishes limits for radiation exposure to the industry being regulated, and of workers and the general public as a re-other interested parties are usually so-suit of the various uses of radioactive licited before new rules or changes are materials licensed by the NRC. In addi-adopted. 2

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TROJ X g TX* k.. E WDMW @? x rxxeshu cwce r%3r%srTINMvJ C4f1CE e The NRc Headquarters is located in Rockville, M aryland, outside Washington, D.C. There are five regional offices and also resident inspection offices at e ach nuclear power plant. REGULATORY RESEARCH materials must obtain a license. The use of very small amounts of radioactive As part of its regulatory program, the materials-lik.e the tiny radiation source NRC conducts an extensive research inside many smoke detectors-is ex-program to provide independent empt from licensing or is authorized by information and expertise to support its a general license, which does not re-safety decision-making and to assess quire active control to assure safety. potential technical issues. This NRC re-However,forthe manufacturing of these search is performed by government and similar items a specific license laboratories, universities, and other re-involving regulatory control is required. search institutions. Topics of inquiry in-clude such subjects as the durability and integrity of reactor components, Licenses for nuclear power plants the impact of natural phenomena like and their operators are issued by the earthquakes and tornadoes on nuclear NRC. Licenses for other uses of radio-facilities, radioactive waste disposal active materials are issued either by the technology, and how workers react to NRC or by State governments under instruments and systems in nuclear fa-NRC-approved regulatory programs. cilities. 3 There are about 8,500 licenses for LICENSES radioactive materials under the jurisdiction of the NRC and 15,000 un-Any organization or individual in-der the jurisdiction of those States tending to possess or use radioactive known as Agreement States which 3

NRC regulate certain radioactive materials Combined licenses also incorporate a under agreements with NRC. program of tests, inspections and re-lated acceptance criteria which are nec-States also have regulatory jurisdic-essary and sufficient to show that the tion over certain radioactive substances plant has been properly built. These cri-which occur naturally (primarily radium teria must be met before operation can and radon) or are produced by

begin, machines called particle accelerators.

This process provides for public hearings on the certification of the stan-The NRC or State license specifies dard design. There would also be public the types and quantities of radioactive hearings on the site approval and on the materials that may be possessed and ssuance of a combined construction used as well as any specific restrictions and operating license. As the plant on their use. Typically, licenses will de-nears completion, a public hearing scribe the location of use, the training could be held if there is a significant and qualifications of workers, specific question on whether the criteria of the procedures for using the materials, and combined construction and operating t any special safety precautions required, license have been met. The license holder must follow the spe-cific license requirements as well as the The licenses for nuclear power more general NRC regulations. plants are issued for a 40-year period. Licenses for currently operating plants will begin to expire after the year 2000. POWER PLANT LICENSES The NRC has developed criteria to be used if utilities seek to have the licenses For nuclear power plants,there have been two types of licenses-a Con-extended for an additional period. struction Permit, which allows the facility Licenses for nuclear power plants to be built, and an Operating License, can be amended and updated as the re-which permits operation of the facility sult of operating experiences at that once it is completed. plant or at other plants. When neces-sary, the NRC can impose new regula-In 1989 the NRC adopted a stream-tions or require changes in operating lined licensing process which encour-procedures or equipment to improve ages the use of standardized and pre-the safety of nuclear power plant opera-approved designs for any future plant tions. proposals and provides for the issu-ance of a combined construction permit in addition to licensing the facility, and operating license. Another feature the NRC also licenses the individuals of the streamlined process is possible who operate the controls of the reactor. i early approval of sites for nuclear plants. There are two categories of licenses-This combined licensing process pro-Reactor Operator and Senior Reactor vides for the early resolution of virtually Operator. The second type is for all issues before construction begins. supervisory positions. Before Operator 4

i NRC Licenses are issued, individuals must The core of the NRC inspection pro-complete an extensive training program gram for nuclear power plants is per-conducted by the utility' and pass formed by the resident inspectors, with license examinations administered by. at least two inspectors assigned to each ~ NRC examiners. Once licensed, the op-site. erators continue to receive training and are periodically tested to show they re-main qualified to operate the plant. [ l ci Q } m~ /,. INSPECTIONS I lIN i F i (b All NRC-licensed facilities are peri-a 4 Y ((a odically inspected to assure that their --- --J activities comply with NRC regulations 7 I [4 and the terms of their licenses. These in-j, spections vary with scope and fre-U- q O A t quency according to the relative hazard h)I~' pO__ s - {, l I of the authorized activities. Throughout the construction and operating life of a E6& g. nuclear power plant, for example, nu- / T' merous inspections are conducted each year. A small medical or research QQ s\\d ~ facility, using limited quantities of radio-P active materials, might warrant an in-k- N /

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y $' ' Q~ /l spection every few years. r- /\\ For a nuclear power plant, the NRC inspection program includes work by /g % D (h n y s N c's ;;C 6 3 /====== l NRC resident inspectors, who are sta-Q [ tioned at the nbciner piants on a full-time basis; inspections by specialists based in regional offices and NRC headquar-1 ters; and special team inspections, per-( i formed by teams made up of personnel from the regional offices and from NRC headquarters. Normal inspections con-sist of examination of a sample of the work being performed by a utility. If evi-unc resident inspectors are assigned to each dence of problems is found, the inspec-nuciear power prant with additionalinspections tor will focus on that work area in more performed by specialists from emc regionai of-fices and headquarters. gg 1 5 l

e NRC e OTHER USES OF RADIOACTIVE MATERIALS t .o.. N b b~) lN r - ---- r l e E'EEIt .) r=> \\ g{f} Q = _ _ / {. g, bN (h. c M/'g) \\ [ N,

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ff.. jII ~ '=h, l '*0 . $.75 ~ + {f ]yq gi </* f N f g "/ j 3 ,n vhyj ~ q - -v _5-b_ i (] ~ 14 3 Radioactive materials are used Other commercial and industrial in a wide variety of applications be-uses, including testing devices and sides fuel for nuclear power plants. gauges to measure such charac-teristics as soil density or levels of a These applications include: substance in processing equip-Medical radiation' therapy and ment. i diagnostic tests using radioac-tive pharmaceuticals. Var;ous research activities. Consumer products like smoke Each of these uses requires an detectors, gas lamp mantles, NRC cr Agreement State license, and static el,m, nation devices, and ii the activities are periodically inspected luminous watch dials. by NRC or state personnel. Violations of Industrial radiography, using NRC requirements are subject to the sealed radiation sources to same enforcement options as nuclear make x-ray-like pictures of power plants, although the level of fines heavy metal objects like pipes imposed are normally substantially and valves. lower. 6

4 NRC-The inspection specialists, based in For more serious violations or repeti-regional offices, review plant security, tive ones, the NRC may fine utilities and emergency

planning, radiation other licensees up to $100,000 a day for protection, environmental monitoring, each violation.

- periodic testing of plant equipment and in cases where there are serious systems, fire protection, construction activities, and other more specialized questions about the safety of NRC-licensed activities, the NRC may issue areas' Orders requiring that licensed activities be halted or an individual removed from During the course of a year, there w rk involving NRC-licensed materials. may be 10 to 30 of these routine inspec-NRC Orders also may modify, suspend, tions by NRC specialists at each nuclear r revoke a license. power plant, depending on the activities underway at the plants and problems Licensed activities,if halted, may not which may occur. be resumed until the safety and man-agement problems are corrected, and The special team inspections may the NRC approves the resumption of focus on a specific plant activity, like work. maintenance or security, or a team may Alicensee orindividualwho chooses be sent to the plant to look at a specific operating problem or accident. to contest a fine or an Order has the right to a hearing before the NRC. All inspections and the findings by The results of the NRC inspection -the inspectors are documented in in-program for each nuclear power plant spection reports. These reports are are periodically compiled with other sent to the facility to inform the utility of agency evaluations in a review called a the findings. Inspection reports are also Systematic Assessment of Ucensee maintained for public review in a public Performance (SALP) report. These re-library near each plant site and at the ports, issued every 12 to 24 months, are NRC Public Document Room in Wash-public documents and are reviewed ington, DC. (Certain sensitive informa-with the utility in a meeting open to the tion-principally on nuclear facility se-public. curity-may be withheld from public disclosure.) The NRC occasionally receives alle-gations of wrongdoing involving mis-When the inspections disclose viola-conduct by licensees or their contrac-tions of NRC requirements, the agency tors. Allegations of possible criminalac-has a range of enforcement actions. tivities are handled by the professional The basic step is a Notice of Violation, investigative staff of the NRC Office of in-which requires the licensee to correct vestigations. These investigations may .) the problem and take steps to prevent a result in civil enforcement action or recurrence of the violation. This re-criminal prosecution against licensees,. sponse must be acceptable to the NRC. individuals, or others. 7 ,1 ]

.. ~. _~_ l NRC' fBaccur N0GEUS S h MM /e/ NUGEOS g 1 O - .--. g 'n T \\ .j \\e'N@- Energy is released when an atom splits into smaller pieces. These smaller pieces strike other atoms, releas-f Ing more energy. This continuing splitting of atoms in a reactor is called a chain reaction. HOW A NUCLEAR The turbine is connected to a gen-If POWER PLANT WORKS erator. As the turbine shaft spins, the generator turns and produces' electric-i Power plants change one form of ity. This electricity is then carried by energy into another. Electrical generat-wires to the homes, businesses, and in-ing plants convert heat, the energy of stitutions which use the electricity. wind or falling water, or solar energy into (Electricity is one of the few forms of electricity. energy that can easily be moved from. one place to another. Electrical energy Anuclearpowerplantisone of those can be produced in large quantities at j plants that converts heat into electricity. one location and transported by wires to Other types of heat conversion plants many different places.) burn coal, oil, or gas for a heat source which is used to produce electricity. We can see coal, oil, or gas burn-_ ing-and we know from experiencethat The heat-no matter what the it produces heat. This is the same sort of j source-is normally used to heat water energy many people use to heat their to the boiling point and produce steam. homes. Some furnaces heat air, which. 1 This steam is then carried by pipes to a is blown through ducts into each room; I turbine-which has a series of fan others heat water which is piped blades on a shaft. The force of the throughout the house into radiators steam pushes against the blades, turn-where the water gives off _some of the ing the turbine. heat it absorbed from the burning fuel. 3 8 ,.-~. -

~. NRC REAcr0R m ssoee veset m. - Nuclear energy-as it is used in a 4 .. M ', hyji um nuclear power plant-cannot be seen. There is no burning of fuel in the usual i 1. mw 'f l sense. Rather, energy is given off by the na resun ,- m L nuclear fuel as certain types of atoms L split into pieces. This energy is in the {* g form of fast-moving particles and invis-L ible radiation. As the particles and radia-f tion ' move through the fuel and sur- } rounding water, the energy is converted into heat. The heat is the useful energy result-4 ing from the splitting of atoms. The ra-wse diation energy itself can be hazardous T pg l and requires special precautions to pro- ~ tect people and the environment. To understand this process let's ~ look at a nuclear reactor-which is a. i Md. large water-filled vessel containing the l 'N nuclear fuel. Water in the reactor is

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l heat is carried off to spin the turbine. REL g, y -~ EFACTCE 5 URANIUM FUEL g e6 1 The fuel of a nuclear plant is ura-De fuel r ds in the reactor contain hundreds of nium, but only a certain type of uranium ceramic pellets of uranium fuel. Each rod is atom can be easily split to produce en-sealed to prevent radioactive byproducts from ergy. This type of uranium atom-called entering the cooling water which surrounds the uranium-235-is less than 1 bercent of fuel. The fuel rods are grouped into bundles or asserrblies. Control rods in the reactor regulate uranium as it is m.ined. To make fuelfor the energy being produced. reactors, the uranium ore is purified and then processed to increase the percent-age of uranium-235 to 2 to 4 percent of Uranium fuel is formed into small the uranium. This percentage is enough cylindrical pellets, about the size of a for a continuous splitting of uranium at-finger tip. These pellets are then loaded oms-but much less than the percent-into metal tubes about 12 feet long. l age.necessary for a nuclear weapon These tubes, called fuel rods, are which requires almost 100 percent pu-sealed and assembled into bundles or i rity of uranium-235. The low percentage assemblies. The fuel assemblies are j of uranium-235 in reactor fuelis orie of produced at several commercia! ' the reasons a plant can never explode facilities for shipment to the nuclear i like an atomic bomb. plants to be loaded into the reactor. l 9 i

l NRC When a uranium-235 atom splits-or " fissions," to use the technical term - it gives off energy in the form of radiation i g% ;h and also fast-moving pieces of the origi- + r-7 a. c:. L^N nal atom. One of these piecer, which is Ek }M called a neutron, can collide with an-j [L3M other uranium-235 atom and cause it to i split, too. A continuing series of these l w mc1 E..%L g m YC -+ atomic splits, each triggering another { r 7 f 7 {(H e;}' a one, is called a chain reaction. iV Uranium-235 will split, or " fission," j ] spontaneously, but these spontaneous I atomic splits aren t frequent or reliable hp enough to use as an energy source.The pieces fly away too fast and don't cause the fission of another atom to occur.The A pressurized water reactor (PWR) circulates water through the reactor under prassure. The pieces need to be slowed dowi to that heated water goes to a large cylinder called a they can collide with another ura-steam generator where it heats another water nium-235 atom and continue the chain system to make steam. This steam spins the tur-bine-generator to make electricity. Several types of materials can be used to slow down the atomic particles, two-thirds of the reactors are pressur-j but most nuclear power plants (includ-ized water reactors with one-third being ing all of those now operating in the boiling water reactors. United States) use water as the " mod-The pressurized water reactor is a erator"-the material which slows the two stage system which keeps the particles down to a!!ow the chain reac-water in the reactor under high pressure ~ tion to continue. so that it does not boil. Piping carries To control the chain reaction-and this heated water to large cylinders called steam generators. The heated re-to stop it once it is started-reactors have control rods which can be inserted actor jvater flows through thousands of into the reactor to absorb the neutrons tubes in the steam generator. The tubes as they are given off, thus slowing or are surrounded by a secondary water stopping the chain reaction. supply that boils and produces steam } which is carried away by pipes to spin the turbine generator. TWO REACTCR TYPES The reactor cooling water then re-turns to the reactor to be reheated and There are two main types of reactors circulated back to the steam generator in operation in the United States-the again in a continuous loop. f pressurized water reactor (PWR) and The boilirg water reactor is a single the boiling water reactor (BWR). About stage system which allows the water in 10

NRC the reactor, but only through the con-denser tubes to cool the steam after it sTrA x + goes through the turbine. There is no ~.......:, contact between the condenser cooling .i, water and the reactor cooling water or g,,.[4.3 ... %(g m y the reactor components themselves. l l .w This outside cooling water, heated 1 ~ q on _j as it passed through the condenser, is )J _p c-returned to the source lake, river, or (/ ('C . M ocean. Many nuclear plants as well as 1 ' 4-- other types of power plants or industrial facilities use cooling towers, cooling m takes or ponds, or other techniques to reduce the effects of discharging heated water directly back into the river, A bomng water reactor (BWR) sends steam from lake, or ocean. With cooling towers the the reactor directly to the turbine-generator to provide electricity. After passing through the tur-Water, onco cooled,.is usually pumped bine the steam is cooled, becoming water again. baCk into the condenser to be used This water is then pumped back to the reactor to again to Carry off heat. Only a small por- '*"**'*d' tion c ~ the water is returned to the natu-ral water source. the reactor to boil and produce steam Once the steam is produced, the which is then piped directly to the tur-process and equipment used to gener-bine generator. ate electricity is similar in both nuclear in both types of reactors, once the power plants and fossil-fueled power steam loses its energy in spinning the plants. Fossil-fueled plants also dis-turbine, it flows into a condenser. Be-charge heated water to the environment cause not all the heat energy in the or use cooling towers or other rneans to steam can be converted into electricity, cool the water from the condenser. the leftover heat must be carried away by cooling water which is pumped RADIOACTIVE BYPRODUCTS through the condenser. The condenser contains thousands of tubes carrying Because the fission reaction pro-cool water which causes the steam to duces radioactive materials which can condense back to water. The water is be hazardous, nuclear power plants are collected in the condenser and pumped equipped with safety systems to protect back to be reheated, either in the reac-workers, the public, and the environ-tor itself for a BWR or in the PWR steam ment. generator. Radioactive materials require careful The condenser cooling water is use because they produce radiatinn-a drawn from a lake, river, or ocean. This form of energy which can damage hu-water does not actually pass through man cells and, depending on the 11

NRC amount and duration of the exposure, Although the effects of very low levels of can potentially cause cancer over long radiation are difficult to detect, the NRC periods of time. There are two possible limits are based on the conservative as-ways a person can beexposed to radia-sumption that radiation exposuies to tion. Internal exposures occur if a radio-members of the public should only be a active material is inhaled or ingested small fraction of what they receive from and remains deposited in the body. natural environmental radiation. External exposures can result from a Experience has shown that nuclear person being close to a radioactive nia-plants typically release only a small por-i terial without adequate shielding. tion of the NRC limits during normal op-In the reactor, most of these hazaro-erations. A person spending a full year ous radioactive substances-called fis-at a nuclear plant boundary would re-sion by-products-are trapped within ceive a radiation exposure of less than 1 the fuel pellets themselves or the sealed percent of the radiation exposure every-metal tubes holding the fuel. Small one receives frorn naturally occurring amounts of these radioactive fission radiation. (Natural environmental radia-byproducts, principally ga.ms, how-tion exposures average 300 millirems ever, become mixed with 1 water per year while the year-round exposure passing through the reactor. Uher im-at the plant boundary is 1 to 2 millirems purities in the water are also made ra-or less.) dioactive as they pass through the reac-The NRC also sets limits for radiation tor. The water is processed and filtered exposure to individuals working at nu-to remove these radioactive impunties clear plants and other facilities using ra-and then returned to the reactor cooling dioactive materials. Because these indi-system. Some small quantities of radio-viduals receive the radiation exposure active gases and liquids are ultimately as part of their employment and be-released to the environment under con-cause they receive special training on i trolled and monitored conditions. radiation protection, the occupational Radioactive materials lose their ra-limits are higher than those permitted dioactive properties over time-some for the general public. Radiation work-are short-lived and become non-ers must wear devices to measure the radioactive forms in seconds or min-radiation they are exposed to. utes. Other radioactive elements take The environmentalimpact of routine much longer to lose the,r radioactivity. i operations at a nuclear plant is very This process is called radioactive de-small. But because of the radioactivity cay. remaining in the reactor fuel, there must The NRC has established limits for be effective safety systems to prevent the release of radioactivity during rou-an accident that would lead to a large tine operations. These limits are based amount of that radioactivity being re-on guidelines set by the Environmental leased from the plant. The likelihood of Protection Agency and by national and such an accident is remote, but the pos-internetbnal standard setting groups. sibility that one could occur leads to i 12

NRC i I 1. A method to quickly shut down a re-N V actor and stop the fission chain re-4 .N N action-D MEWATER.- A[2. COOWN6 4 -' Numerous systems to control reac-g)wgg tor pressure and to centinue cool-yg ggg ing the reactor fuel-that is, to carry away the heat that continues to be j generated even after the reactor is / I shut down. \\- XF 3. Electrical, control, and instrument systems for the safety sysiams and l h' \\ %X 7 to monitor reactor conditions. 4. Methods of containing radioactivity N j-1 if it should escape from the reactor / fuel in an accident. i NTN/D AINUARYS0lLDIN6 SHUTDOWN SYSTEMS l (CCMTAlNMENT) l Each reactor has a system to insert the control rods into the reactor core A nuclear power plant includes the building hous-Ing the reactor and cooling system components; P e i Ba& the auxiliary bui; ding with the control room and im-tion. This immediate shutdown-called portant safety equipment; and the turbine building a reactor " scram" or reactor " trip"-Can where electricity is prodt.ved. M any nu. plants also have cooling towers to cool water which has be triggered by a reactor operator or by been used to condense steam passing through automatic controls which protect the the turbine. Water for this condensing function reactor from any unusual Conditions in comes from a river, lake or ocean-and does not pass through the reactor itself. the plant. COOLING AND PRESSURE CONTROL SYSTEMS special care in design, construction, When a reactoris operating,the heat and operation of nuclear power plants. energy from the fission reaction is car-ried off in the cooling water. That energy REACTOR SAFETY SYSTEMS is used as steam to spin the turbine generator, making electricity. A reactor Anuclear power planthasfourmajor shutdown stops the fission reaction, but types of safety systems to prevent acci-there is still heat being generated by the dents and reduce their effects if one radioactive fission by-products which should occur: have built up in the reactor fuel. There is 13 1

~- NRC much less heat being created than SAFETY SYSTEM POWER when the reactor is operating, but the heat is still sufficient to damage the fuel if Most of the safety systems are pow-it is not cooled. As time passes after the ered by electricity, although some reactor shutdown, the amount of heat -pumps do use steamto drivethemin or-being produced in the fuelin the reactor der to have an alternate source of-core decreases. Continued cooling of - power. Because of this reliance on elec-_ the fuel remains necessary, however. trical power, nuclear plants are required There are both normal cooling systems to have trultiple sources of electricity. and emergency cooling systems available. Each system has at least two A nuclear plant uses a portion of the parallel parts so that if one fails, the p wer it generates to run plant equip-ment. A plant also must have at least other part of the system would still be two connections to the utility's electrical availab!e to continue to cool the reactor, distribution system so that it can imme-diately shift to offsite power sources if a shutdown occurs. Should there be a The Emergency Core Cooling Sys-fa lure,n the offsite power connections, i tem (ECCS) consists of pumps and e h plant has emergency diesel gen-valves and pipes which are independent erators installed onsite with sufficient ca-of the normal cooling system. The pacity to supply electricity to the critical ECCS includes equipment that can safety systems. pump at high pressure to inject water into the reactor when the pressure in-The controland instrument systems side is at the high levels maintained dur-normuy use direct current (DC) elec-ing operation. There are also low pres. tricity, the kind of power found in batter-sure systems to pump water at lowe,- ies. For these systems there are large pressures, such as might occur if 'anks of batteries to provide DC power cooling water pipe broke and allowed ' ere is an interruption in the normal rces of electricity. t pressure inside the reactor to drop. The reactor systems also include CONTAINING RADIOACTIVITY valves which can be opened to reduce pressure by releasing steam. These re-lief valves open automatically if pressure There are three principal barriers to gets too high in the reactor system. prevent the release of radioactivity-the se led fuel rods, the reactor vessel and Some of the valves can be opened us-ing controls in the reactor control room. ssociated components, and the struc-ture housing the reactor, called the re-These pressure reduction systerns can actor containment. also be used to reduce reactor pressure so that the low pressure cooling sys-A serious reactor accident could tems can function. damage the fuel rods, which form the 14

NRC t first. barrier, if adequate cooling does CONTAIMMFJ17 not occur. Overheated fuel rods can i leak or break apart and eventually melt. [_ i Possible damage to the reactor cooling (N j i system piping could breach the second M M -barrier. N / /E \\( ~ f Even with the failure of these first two s barriers, the reactor containment is de-i signed to hold radioactive material that - might otherwise be released to the out-h N( e side environment. One type of reactor containment is a large cylinder-shaped building made out of reinforced con-Q b ' d, crete with a steel lining. It is designed to N I withstand the pressures that might build y N' D,w q up inside as steam and gases escape y (G from the reactor during an accident. An-N v ks} \\ other type of containment, called a ,/ x j pressure suppression containment, / g has a large water-filled pool to cool the steam and reduce the pressure buildup WACTBR VE5SEL. in the containment. l The reactor containment is a sealed reinforced concrete and steel structure which surrounds i The NRC requires that the reactor the reactor. It is designed to hold in radioactive containment be periodically tested to gases that rnight be released by a pipe break or th * ""'I "' '** ' * * * * * " l show it meets requirements to prevent leakage from inside the structure. of radioactive gases through seals and While reactor containments were gaskets around the containment. The designed to cope with many types of se-molten fuel could also damage the con-i rious reactor accidents, they may not crete base of the containment, leading - withstand the conditions that result from to a possible release of radioactivity. an extremely unlikely accident in which Even_ in these cases' however, most of I ^ all cooling capability is lost in the reac-the long-term hazardous radioactive tor. Under these circumstances, the en-material would remain inside the con-' ergy produced by the radioactivity re-tainment structure. maining in the fuel could cause the fuel in the only major commercial power ' l to melt. Melting of the fuel could eventu-reactor accident in the United States, ally lead to a pressure buildup in the the Three Mile Island accident in 1979, containment that could cause leakage' there was extensive fuel damage. ll .) 15

NRC-Radioactive gases and contaminated been prepared and the operators have cooling water filled the containment. been trained in their use, in addition, Although there was some release of ra-most nuclear power plants use com-dioactivity to the atmosphere by an indi-puter-based simulators for training in rect route, the containment itself per-both routine and abnormal situations. formed as designed and kept the radio-These simulators are laid out just like the I activity safely bottled up inside. The ef-plant's control room with all of the con-fectiveness of the containment was the trols and instrumentation. Computers major factor in preventing release of let the operators practice dealing with large amounts of radioactive materials to the environment. emergencies as they occur in the ator's mntrol m in 1986 a much more serious accident occurred at Chernobyl in the The Three Mile Island accident also Soviet Union. This plant used a much pointed out the need for improved plan-different type of reactor from those in ning by Federal, State, and local gov-t the U.S. It had no containment system ernments to deal with possible reactor like that of U.S. plants. The Chernobyl accidents. The NRC now requires that accident severely damaged the reactor emergency plans be prepared for core, releasing large quantities of evacuation or other actions to protect radioactivity to the environment. Radio-the residents in the vicinity of nuclear active contamination was deposited in plants. These plans usually cover an nearby countries and was even detect-area about 10 miles in all directions able at very low levels in the U.S. around each nuclear plant. The utility has its own emergency plan to notify government officials of a possible emer-WHAT IF? gency and to provide them with infor-mation and recommendations. State and local governments have detailed Although a major reactor accidentis plans for sheltering and evacuation of unlikely and each plant is equipped with residents if necessary. Federal emer-safety systems to prevent or cope with gency plans !nclude Federal personnel, an accident, additional measures help equipment, and resources needed to protect the public heath and safety. respond to a nuclear power plant acci-The first is special training given to dent. The NRC would closely follow the the reactor operators in the handling of handling of an accident by a utility and emergency situations. One of the investigate the causes of the accident. lessons learned as a result of the Three Mile Island accident was that reactor op-These emergency plans are tested erators needed to practice how they through emergency exercises whic'i would handle emergencies. Detailed simulate a serious reactor accident. Utr.- emergency operating procedures have ity personnel and government officials 16

NRC I NUCLEAR INSURANCE i

I, b lC t

.[ N Congress has established a system '\\ c'. of "no-fault" insurance to provide liability /. . 'I, ? ;/. coverage in the event of a major reactor f accident. This insurance program, b_,) ( b_ / known as the Price-Anderson Act, com-1., bines commercial insurance and self- ![ I.' 3., insurance by the nuchr industry. .c

• /

Large nuclear plants are required to f have the maximum amount of liability in-

1. ;,;

1 ( surance which is commercially avail- ., f ,;, 1 g able, currently $200 million. In addition, y each licensed reactor is liable for a $63 c., 1.' million assessment to provide funds in ( j@ the event of a major accident at a piant in E the U.S. (No reactor would be assessed Q=. more than $10 million in any one year.) Each nuclear plant has a warning system to notify With more than 110 nuclear power nearby residents of emergency conditions.1 '- plants in the U.S., the combination of structions in the event of an emergency would be provided by state and local officials using the commerCialinsurance and industry self-emergency broadcast system. insurance exceeds $7 billion. This is the total liability limit for an accident under follow their emergency plans in gather-the Price-Anderson Act and no claims ing information, consulting with each are required to be paid in excess of this other, and issuing instructions to the amount, but Congress will consider the public. These emergency exercises need for providing an additional source sometimes include small-scale evacu-of funds should $7 billion prove inade-ation drills for schools, nursing homes, quate. or other institutions. The Price-Anderson Act provides The NRC must determine that there liability insurance coverage for actual is reasonable assurance that evacu-ation or other steps can be taken to damages incurred by anyone affected ) protect area residents in the event of a by a major reactor accident. Besides major reactor accident. To make this the coverage for offsite public liability determination, the NRC reviews the claims, the NRC requires that utilities utility's plans, conducts inspections, maintain $1 billion in onsite property j and considers the assessment of State damage insurance to provide funds to and local planning by the Federal Emer-deal with cleanup of the reactor site after gency Management Agency. an accident. ~ 17

NRC RADIOACTIVE WASTE pools at each reactor site and at one DISPOSAL storage facility in Illinois. From one-fourth to one-third of the reactor fuelis During normal operations, a nuclear removed and replaced during refueling. power plant generates two types of ra-Reactors are normally refueled every 12 dioactive wastes-used fuel (usually to 18 months. called spent fuel), which is considered high-level waste, and low-level wastes, Spent fuelis highly radioactive since which include contaminated equip-it contains the fission by-products that ment, filters, maintenance materials, were created while the reactor was and resins used in purifying water for the operating. One characteristic of radio-reactor cooling system. Other users of active material is that it decays or loses radioactive materials also generate low-its radioactivity at a set rate. Each radio-level wastes. active component has a different rate of Each type of waste is handled differ-decay called its half-life-the time it takes the matenal to lose half of its ently. radioactivity. Some fission by-products have a half life of a few seconds, while HIGH-LEVEL WASTE others have half-lives of hundreds or The spent fuel from nuclear power thousands of years. plants is currently stored in water-filled When fuel is first removed from the reactor, the short-lived radioactive

1. C..

f / .s ~> 0 ~ Q w,. *' ** ~ ~ y p/ ... + Most of the highly-radioactive spent fuel removed from civilian nuclear power plants is stored in specially designed water basins at the reactor sites. When a Federat high-level waste site becomes available the used fuel will be moved there for permanent disposal. 18

NRC materials are still present. But over time, The Department of Energy (DOE) is these substances decay, leaving the developing plans for a permanent dis-longer-lived materials as the principal posal facility for spent fuel from nuclear substances for disposal. These materi-power plants as well as for the high-level als include cobalt-60 (5-year half-life), waste which has been produced by the cesium-137 (30-year half-life), and plu-nation's nuclear weapons production tonium-239 (24,400-year half-life). activities. Special procedures are needed in Congress has directed DOE to fo-the handling of the spent fuel, since the eqs on a proposed site at Yucca Moun-tain in southern Nevada for this waste radiation levels can be very dangerous without proper shielding. The water in disposal facility. Site studies are still un-the spent fuel storage pool provides derway to determine if the site is ade-adequate shielding for the radiation to quate for long-term disposal of the high-level waste. protect workers in a nuclear plant. At socne plants spent fuelis also stored in DOE would design, build, and oper-heavy metal or concrete containers ate the facility, which would be regu-placed on concrete pads adjacent to lated by the NRC. The NRC must ap-the reactor facility. prove the site and design for the facility as well as inspect it during construction Although most of the spent fuel re-and operation. mains stored at individual plants, there has been some shipment of spent fuel Although some nuclear plants have to offsite storage facilities. One offsite adequate capacity to store the spent storage facility operates in Illinois. fuel they generate until a DOE site is These shipments have used heavy available for disposal, other plants, par-shielded shipping containers which are ticularly the older ones, may run out of designed to withstand the conditions storage space in their spent fuel pools in that might occur during a shipping acci-the 1990s. DOE and the nuclear indus-dent. Spent fuel shipments have been try are considering various options to both by rail and by truck. The NRC certi. store additional spent fuel, including dry fies each shipping container that meets storage in large iron, steel, or concrete Federal requirements, and the Depart-casks, constructiori of additional offsite ment of Transportation sets the rules for storage facilities, and techniques for actual transportation of the spent fuel. storing more fuel in the existing spent fuel storage pools. Several utilities have Some of the components in spent recently begun using dry cask storage. fuel remain hazardous for long periods of time. Permanent disposal of spent LOW-LEVEL WASTE fuel therefore requires a disposal facility which provides reasonable assurance Low-level radioactive

waste, that the waste will remain isolated for whether from a nuclear power plant or thousands of years.

from other users of radioactive material, Y 19 i

~- NRC E WA l V4,MA MN tJY ID W yr get N N 91) g r }dk od -it ()7 Co CA KS NO W g ~ Ttl V. g ' T HM Ac w AL 6A g g3 N TX FL Through the years, commerciallow-level radioactive waste has been buried at sites in six states-Washing-1on, south Carolina, Nevada, Illinois, Kentucky and New York, sites in the latter three states have been shut down for rnany years and the Nevada site ceased operation on the first day of 1993. is shipped to licensed commercial dis-tional disposal facilities are expected to posal facilities where it is packaged and be in operation in the 1990s. placed in burial trenches and covered with soil. Less than half of the waste vol-ume is from nuclear power plants and TRANSPORTATION i the remainder is generated by hospi-tals, research institutes, and other users About 3 million shipments of radio-of radioactive materials. active materials are made each year in-the United States-by highway, by rail-In 1980 Congress provided that road, by aircraft, and by ship. Regulat-each state is responsible for assuring ing the safety and security of these ship-the availability of disposal capacity for ments is the joint responsibility of the commercial low-level waste produced U.S. Department of Transportation and l in the state. States could either provide the Nuclear Regulatory Commission. for disposal individually or by joining to-gether in a regional agreement. The in-The federal regulatory system pro-dividual states or state groups are in the tects transport workers and the public process of selecting new burial sites, or by setting performance standards for in some cases they'll use the facilities the packages and by setting limits on that have been operating. The addi-the radioactive contents and radiation 20

= -.. - ~ l i J NRC y ^ ^ Q 1 4._%_. - -.. f fl I. m* 1 g - og i 4 ts n I 3 t. + x T- ] Spent reactor fuelis carried in specially designed shipping containers that are designed to withstand-accident conditions without releasing their radioactive contents. i levels for packages and vehicles. Infor-tive materials each year. These ship-mation on radioactive shipments is pro-ments use packaging (classified as-vided by package marking and label-Type A) that is expected to withstand ) ing, vehicle placards, and shipping pa-the rigors of normaltransportation with-- pers describing the materials, out damage. The Department of Transportation The containers for larger quantities (DOT) has regulatory jurisdiction over of radioactive materials are designed to radioactive shipments while the material withstand accident conditions without j is in transit. DOT also establishes ship-releasing their ' contents. These pack- 'f ping categories, sets the standards for ages, designated as Type B, are used i labeling of radioactive shipments, and for shipping industrial irradiators, medi-establishes criteria for containers used cal radiation therapy devices, and some for smaller quantities of radioactive ma-shipments of radioactive wastes. The terials. The NRC, which licenses the or-' accident evaluation criteria for these

ganizations shipping and receiving the containers include impact, puncture, radioactive materials, assures that its li-heat, and submersion in water.

l censees meet the Department of Trans-AspecializedType B containeristhe portat,on shipping requirements. The i spent fuel shipping cask, which is used NRC also establishes the requirements to transport used fuel from nuclear reac- ? for. design and manufacture of pack-tors. These large shipping casks are ages for larger quantities of radioactive carried on trucks or rail cars. Like' all I materials. Type B containers, they are sealed to 1 Typical _ of small quantity ship-prevent leakage and heavily shielded to ments-using packages meeting DOT minimize the radiation levels. 1 requirements-are radioactive. materi-The NRC also imposes security re-j als. for medical diagnostic tests and quirements on spent fuel shipments -

therapy, and on shipments of larger quantities of -

These shipments comprise the ma-highly enriched uranium or plutonium. jor portion of all shipments of radioac-These security measures include route - 21 -l

NRC evaluation, escort personnel and vehl-These regulations apply to nuclear cles, communications capabilities, and power plants and to other facilities emergency plans. which handle radioactive materials in forms that may require cleanup proce-State governments are notified in dures when the facility is closed. Careful advance of spent fuel shipments and radiation surveys must also be per-those large quantity shipments of radio-formed before the site can be released active waste which require Type B con-for other uses.- tainers. During the operating life of a nuclear The regulatory system for transpor-power plant, many plant components tation of radioactive materials has been associated with the reactor become ra-successful in minimizing the safety im-dioactive, either through contamination pact from accidents involving the ship-or as a result of the radiation from the fis-ments. There have been few accidents sion reaction. Therefore, care is needed involving shipments of radioactive ma-in the handling of decommissioning terials (averaging less than 50 a year out work, and contaminated materials will of 3 million shipments). Only a small have to be shipped to a low-level radio-number of those accidents have in-active waste disposal site for burial. volved any release of the radioactive contents. In these instances, radioac-The NRC hasidentified two principal tive contamination has been generally plans for decommissioning a nuclear minor with no public safety conse-power plant-immediate dismantling or quences. safe storage for a period of 30 to 50 years followed by dismantling. A third DECOMMISSIONING ption, called entombment may also be available in some cases. This would in-v ive sealing ff radioactive compo-Decommissionin9 s the term used i nents with concrete and steel. Entomb-for ending the operation of a nuclear fa-ment would require less maintenance cility. Nuclear power plants are licensed and security provisions than the storage for a term of 40 years. Some plants may option. be closed before that time elapses, while others may seek an extension of the license period. The storage and entombment meth-ods allow for a reduction in the levels of A few small nuclear power plants radioactivity over time. NRC studies have been decommissioned in the past have shown that after 50 years, the vol-and several others are currently await-ume of radioactively contaminated ma-ing decommissioning. The NRC has terial would be reduced to one-tenth of adopted extensive regulations for deal-the original volume as a result of radio-ing with the technical and financial is-active decay. Delay in dismantling a sues associated with decommission-plant would also result in lower radiation ing. exposures to the workers involved. b 22

NRC Cost estimates for decommission-decommissioning of their plants, ing a large nuclear plant are $100 million Similar financial procedures are also or more, plus the cost of demolition of required for other types of nuclear facili-non-contaminated materials. The NRC ties, including plants which prepare fuel decommissioning rules require utilities for nuclear power plants or process to establish funds to pay for the future radioactive materials. For' additional information,. . contact: Office of Public Affairs U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 (301) 504-2240 l Regional Public Affair's Offices Region ! 475 Allendale Road Region ill 799 Roosevelt Road King of Prussia, PA 19406-1415 Glen Ellyn, IL 60137 5927 (215) 337-5330 (708) 790-5500 Region IV 611 Ryan Plaza Drive Suite 400 Arlington, TX 76011-8064 Region 11 101 Marietta Street Suite 2900 Region V 1450 Maria Lane Atlanta, GA 30323-0199 Walnut Creek, CA 94596-5368 (404) 331-4503 (415) 975-0200 i 23 ( -__-___-_-_____-___-__--__-______-A

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