section d7.1 – introductionepr-reactor.co.uk/ssmod/liblocal/docs/v3/volume 3... · fundamental...

CHAPTER D SECTION: D.7.1

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FUNDAMENTAL SAFETY OVERVIEW VOLUME 3: ENVIRONMENTAL IMPACT CHAPTER D: POTENTIAL ENVIRONMENTAL AND

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SECTION D7.1 – INTRODUCTION

1. INTRODUCTION

This section describes the estimated Health Effects (Radiological) of the radioactive discharges from the UK EPR. It covers the requirements 2.1 to 2.10 in the Environment Agency’s Process and information Document for Generic Assessment of candidate Nuclear Power Plant Designs.

The document is laid out in the approximate order of the EA Requirements listing, dealing firstly with the sources of the radioactive materials, the types of waste. It describes BPEO aspects of the design that are implemented to reduce waste arisings and minimise the impacts of those wastes that do arise. It then deals with the discharges of liquid, gases and solid wastes, the annual arisings of these and their impact on Human Health. It also deals with impacts on the terrestrial and marine environments of these discharges.

This current Introduction (D7.1) gives definitions and main sources of radioactive wastes and especially the liquid and gaseous effluents that are discharged from the proposed EPR. The next section (D7.2) gives an estimate of the wastes and describes in more detail the methods used for abatement. Healtheffects and effects on the marine and terrestrial environments are presented in D7.3. A further assessment of mitigation measures is given in D7.4. Finally, D7.5 provides further detail on monitoring methods in plant and Environmental Monitoring. The figures presented throughout section D7 are representative of the Flamanville 3 EPR and are not specific to an UK EPR.

2. DEFINITIONS AND TERMS USED

The EPR is a pressurised water type reactor. As a result of all stages of its operation, during start up, operation at power and shutdown for refuelling, it produces:

• Liquid radioactive waste

• Gaseous radioactive waste

• Solid radioactive waste (in the form of fuel and also other solid materials).

The wastes originate from the operation of the primary reactor circuit. These radioactive materials are in the form of fission products in the fuel and also arise from activation of the primary reactor circuit components and the liquid coolant. Once in the coolant, they are transferred around various parts of the primary reactor coolant circuit and can also pass into the various reactor support systems in liquid and gaseous form.

For all these types of waste, the effluent-management process may be broken down schematically as follows:



FUNDAMENTAL SAFETY OVERVIEW VOLUME 3: ENVIRONMENTAL IMPACT

CHAPTER D: POTENTIAL ENVIRONMENTAL AND HEALTH EFFECTS

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Collection Processing Storage Disposal

Figure D7.1-a: overview diagram of the arrangements for processing and storing effluent from the EPR.

A summary diagram showing the collection, processing, storage and disposal facilities within the EPR for the liquid and gaseous effluents is shown overleaf.

The following sections describe in detail these types of waste and their collection and management.

3. LEGISLATIVE BACKGROUND

3.1. LEGISLATIVE REQUIREMENTS

The following is a précis of the main areas of legislation that impact on radioactive discharges from nuclear sites in the UK and the associated human health effects.

The Radioactive Substances Act 1993 provides the framework for controlling the generation and disposal of solid, liquid and gaseous radioactive waste so as to protect the public and the environment. Under Section 13 of RSA 93, no person may dispose of radioactive waste unless it is in accordance with an authorisation issued under the Act, except where the waste is excluded from control under the Act or exempted from provisions of the Act by an Exemption Order. In addition, premises occupied by the Crown for defence purposes are exempt from the Act. However, discharges from these premises are made in accordance with approvals which apply the same standards as authorisations. The environment Agencies are responsible for determining applications for authorisations made by producers of radioactive waste and for reviewing those authorisations on a regular basis.

The Euratom Basic Safety Standards Directive provides for the implementation of the 1990 recommendations of ICRP within the European Union. Many of the Directive’s provisions are implemented by the Ionising Radiations Regulations and with respect to the control of radioactive waste have been implemented within England, Wales and Scotland through Regulations amending RSA 93 and Directions to the Environment Agency and SEPA. Regulations to implement the Euratom Basic Safety Standards Directive are currently being made in Northern Ireland. The principal aims of the Directions are to require the Environment Agencies to ensure, when exercising their duties and functions under the RSA 93, that:

• All public ionising radiation exposures from radioactive waste disposal are kept ALARA.

• The sum of the doses arising from such exposures does not exceed the individual public dose limit of 1 mSv a year.

• The individual dose received from any new discharge source since 13th May 2000 does not exceed 0.3 mSv a year.





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• The individual dose received from any single site does not exceed 0.5 mSv a year.

The Nuclear Installations Inspectorate (NII) within the Health and Safety Executive (HSE) is responsible for regulating sites licensed under the Nuclear Installations Act 1965 and is a statutory consultee in the process of determining authorisations. On sites for which a nuclear site licence has been granted by the NII, commonly referred to as ‘nuclear sites’, the accumulation of radioactive wastes are regulated via conditions attached to the licence. The HSE regulates the exposure of workers using radioactive substances under the Ionising Radiations Regulations (undertaken by the NII on nuclear sites).

3.2. INTERESTED PARTIES

Public Dose limits

There are a number of advisory bodies involved in the regulatory process. On 1st April 2000, the Food Standards Agency (FSA) became responsible to Government for providing advice on food safety, including the safety of radionuclides in food. FSA is a statutory consultee in the process of determining authorisations for nuclear sites and its advice is sought for the determination of authorisations for other premises. The FSA conducts radiological monitoring of food in England, Wales and Northern Ireland and its results are published annually, jointly with the radiological monitoring of food and the environment undertaken in Scotland by SEPA. FSA publishes food monitoring data on its web site.

The Health Protection Agency has a statutory role to give advice on the acceptability and the application in the UK of standards recommended by international or inter-governmental bodies. The functions of the Board are to give advice, to conduct research and to provide technical services in the field of protection against both ionising and non-ionising radiations.

Other advisory bodes involved in the regulatory process include:

• The Radioactive Waste Management Advisory Committee (RWMAC) – An independent body of experts drawn from a wide range of backgrounds including nuclear, academic, medical, research and lay interests. It is responsible for providing a source of independent advice to government on matters of civil radioactive waste management.

• The Committee on Medical Aspects of Radiation in the Environment (COMARE) – Created in 1985 to assess and advise the Government on the health effects of natural and man-made radiation in the environment and to assess the adequacy of the available data and the need for further research.

• Radiological Protection Criteria for Public Exposure

The following criteria are dealt with by these bodies:

• Dose Limits

• Site and Source dose Constraints

• Optimisation of low doses.

Other parties:

Other parties involved in the regulatory process relating to radioactive discharges and public doses and those on other biota include





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• English Nature / Countryside Council for Wales: Government advisory body and regulator responsible for the conservation of wildlife and wildlife habitats in England and Wales.

• Food Standards Agency: Government advisory body and regulator responsible for the protection of food sources, quality and standards.

• Relevant Sea Fisheries Committees: Regulator and interest group in the conservation of and promotion of sea fisheries.

• Department for Environment, Food and Rural Affairs; Ministerial division of the UK Government. Executive body of the EA, FSA and a number of other regulatory and advisory authorities.

• Relevant Port and Navigational Authorities; Regulators of coastal areas used for recreational and commercial use. Navigational channels are regulated by them and in some areas they may issue navigational or port passes. Statutory consultees for a number of environmental authorisations.

Other scientific interest groups and local user groups may also be consulted in order to fully scope the impact assessment.

4. RADIOACTIVE LIQUIDS

4.1. SOURCE OF RADIOACTIVE LIQUID EFFLUENT

Liquid radioactive effluent includes:

• Activated corrosion products: These consist mainly of the activated corrosion products of structural transition metals such as iron, nickel, cobalt, chromium, manganese that make up the main structural materials in the primary circuit

• The main source of these transition metals is from leaching and minor corrosion of the steam-generator U-tubes (but minimised using Inconel 690). The corrosion products (iron, nickel, cobalt) circulate and are carried and then deposited in the reactor’s primary cooling system. The primary cooling fluid contains these corrosion products in soluble or particulate form. When they pass through the reactor core, they are activated by neutrons. The activated corrosion products formed are mainly cobalt-58 (from nickel-58), cobalt-60 (from cobalt -59), silver-110 (from silver-109), manganese-54 (from iron-54), and antimony-124 (from antimony-123). They may appear in solution or go into suspension when the water is physically or chemically changed, e.g. when the Unit is shut down, and thus move around the primary circuit. The main method for removing these activation products from the Primary coolant is by a continuous bleed of the coolant into the Chemical and Volume Control System (RCV [CVCS]) where they can be removed from the coolant by ion exchange resins and a set of filters (and converted to solid waste).

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As well as the demineralisers in the Chemical and Volume control system, liquid effluents from other stages in the operation of the EPR are treated in other plants by additional decontamination methods such as evaporation, degassing, filtration etc. These provide abatement prior to any release into the environment. These are described in further detail later.

• Activation products from chemicals in the primary coolant. To assist in reactivity control in the primary circuit (additional to that from the control rods) boric acid is added to the coolant. As the cycle progresses, the boric acid is diluted to compensate for fuel burn up. To control the pH of the coolant due to this boric acid, small amounts of lithium-7 hydroxide (containing less than 0.1% Li-6) are also added to the coolant. Neutron flux in the reactor on these chemicals and on the water produces: carbon-14 (produced from oxygen-17 in the molecules of the primary cooling water, and from any dissolved nitrogen-14), and tritium, (produced by neutron action on boron 10 and lithium 6). These two activation products are generated in proportion to the reactor neutron flux and therefore reactor thermal power. They are not retained by the resins in the Chemical and Volume Control System (RCV [CVCS]). However, they do pass in liquids passed from the primary circuit into down-line systems and plant and thence in to the gaseous phase.

• Volatile fission products (caesium-134, caesium-137 and iodine-131), normally in a form soluble in the primary cooling water. These originate in the fuel. Fuel cladding is designed to contain these materials in the fuel as far as possible, but a small number of fuel pins always unavoidably have a small number of minute leaks through which these fission products can escape (the so called “failed fuel fraction”). Like the activation products, these fission products are removed from the coolant using the ion exchange resins in the Chemical and Volume Control System with volatile ones being removed in the volume control tank. Tritium produced by fission is almost entirely retained in the fuel cladding, even if the cladding is defective.


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HEALTH EFFECTS -

Figure D7.1-b: Overview diagram of the arrangements for processing and storing effluent from the EPR

Primary circuit

APG

NUCLEAR AUXILIARY BUILDING CLEAIRES

(BAN)Residue

sumps BTE

Chemical sumps BTE

Floor sumps BTE

EFFLUENT TREATMENT BUILDING (BTE)

TEU Residues

TEU Chemicals

TEU Floors

PROCESSING

Sumps

REACTOR BUILDING (BR)

Secondary circuit

TURBINE

HALL

Residue sumps

Chemical sumps

Floor sumps

APG

TEP

TEU

RCV

REN sampling

(REN + APG)

Retardant beds (TEG)

Non-recyclable samples

Recyclable samples

Recyclable leaks

Non-recyclable leaks

Unidentified leaks

Ventilation DWN

Continuous check for β in chimney

Vacuum pumps (CVI)

To the on-site T (KER) tanks

To the on-site Ex (SEK) tanks

CORE

RCV REA TEP

Recombination

Other possible

EPR Units Use of these circuits is not routine & requires permission from the regulator.

To the on-site S (TER) tanks

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HEALTH EFFECTS -

4.2. NATURE OF RADIOACTIVE LIQUID EFFLUENT

There are processing systems in place to restrict the discharge of radioactive liquid or gaseous effluent. These receive and process the effluent before discharge, in accordance with the principles of BPEO and waste minimisation, centring on, reduction at source, collection and segregation, treatment, reuse/recycling and finally, residual materials are monitored and discharged to the environment.

Liquid radioactive effluent falls into one of three categories, as shown in the following diagram:

Figure D7.1-c: Nature of liquid radioactive effluent

These three categories are described in the following paragraphs.

4.2.1. Recyclable Primary circuit liquid effluent

Primary aqueous liquid effluent is comprised of:

a) liquid leaked or drained from the primary coolant water. This contains only chemicals added to the primary circuit viz boric acid and lithium and is not otherwise contaminated by other chemicals or oils etc.

b) water from circuits containing the primary coolant, and discharged to downstream treatment systems in response to requirements to dilute boron through the fuel cycle (for neutron reactivity control additional to that provided by the control rods).





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Both these sources of primary reactor coolant consist of borated water containing dissolved lithium hydroxide. Primary reactor coolant from the primary circuit during operation at power also contains dissolved hydrogen; that drained from the circuit during periods at shutdown contains dissolved oxygen. At all stages the drained water contains dissolved and particulate activation products, dissolved and particulate fission products and dissolved gaseous fission products, as already described.

Primary liquid effluent from these sources is collected separately to other effluent sources and then sent to the Primary Effluent Treatment System (TEP [CSTS]) where it is decontaminated and the boric acid and water separated using an evaporator-degasser.

Boric acid concentrates (4% solution) and distillates from the TEP [CSTS] evaporator-degasser, may be reused as supplementary boric acid and water for the primary circuit coolant Any primary effluent that cannot be recycled in this way is sent either to the on-site storage tanks (T) before monitoring and discharge (distillates only) or to the Spent Effluent Treatment System (TEU [LWPS]).

4.2.2. Non-recyclable spent liquid effluent

This is of three types:

• process drain (DR): this is polluted primary coolant drained or leaked from systems or equipment after flushing. Recycling to the primary circuit may be precluded by the presence of other impurities (chloride, sulphate, oil etc) but even if this is not the case, low concentrations of boron make recycling and recovery uneconomic. Normally, its pollution level means it may be processed in a different way to chemical drainage or floor drains arising from other parts of the plant (see below).

• chemical drain (DC). This is produced in the Nuclear Auxiliary Building (BAN), and consists of water that is more polluted than water from the DR (above) or that from, for example, the REN [NSS] laboratory and the primary-coolant decontamination systems.

• floor drain (DP). This is of three types:

o Floor drainage 1 (DP1). This is potentially contaminated and comes from leaks from equipment carrying primary coolant and from washing the floors; sumps are installed in areas of the premises that contain equipment transporting primary coolant to collect this floor drainage.

o Floor drainage 2 (DP2). This is potentially uncontaminated and comes from leaks, floor washing and draining equipment (feedwater or RRI [CCWS]); sumps are installed in controlled areas of the premises to collect this drainage.

o Floor drainage 3 (DP3). This effluent is produced only outside the controlled area. Normally it is uncontaminated and comes from leaks, from floor washing and from draining equipment (feedwater or RRI [CCWS]).

Apart from DP3 which is sent to the SEK [CILWDS] tanks, the spent liquid effluent is either sent to the Spent Effluent Treatment System TEU [LWPS], or given treatment specific to its nature. Normally this is demineralisation for residual drainage, evaporation for chemical effluent (using a specific evaporator in the TEU [LWPS]) and filtration for floor drainage. After processing, it is collected in on-site storage tanks before discharge (T tanks).





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4.2.3. Steam generator blowdown systems

Blowdown water from the steam generators is largely made up of feedwater. In the event of small primary to secondary leaks (or more major tube failures), this blowdown may contain low levels of tritium from the primary circuit coolant.

This effluent source is normally directed to the steam generator blowdown treatment system where it is filtered and demineralised, then recycled to the main turbine condenser. Exceptionally, when recycling is not possible, the blowdown is sent to the T Tanks [storage tanks] before monitoring and discharge.

4.2.4. Water drained from the turbine hall

Water drained from the Turbine Hall comes from leakage, and from draining and emptying the secondary circuit, but excluding blowdown from the steam generators. This effluent steam is sent directly to the Turbine Hall storage tanks (Ex Tanks), and then sent for discharge.

4.3. TREATMENT OF LIQUID RADIOACTIVE EFFLUENT

A diagram showing an overview of the arrangements for processing and storing liquid effluent is given in Figure D7.1-b (Overview diagram of the arrangements for processing and storing effluent from the EPR).

Liquid effluent, segregated at source is treated in different systems, depending on its characteristics, to allow it either to be reused and recycled or discharged as required. Treatment methods employ best practical means to ensure that as much of the effluent as possible can be reclaimed and reused and, where this is not possible, discharges of dissolved and radioactive materials to the environment and their impacts are as low as reasonably practical.

Primary liquid effluent is treated in the Primary Effluent Treatment System TEP [CSTS]. The spent liquid effluent is treated in the Spent Effluent Treatment System TEU [LWPS] installed in the BTE for recycling.

The drainage water from the Turbine Halls is either processed in the system that processes blowdown water from the steam generators (APG [SGBS]), or sent to the on-site storage tanks for drainage water (Ex tanks) for discharge.

These treatment systems are described in the following paragraphs.

4.3.1. Treatment of primary liquid effluent

An overview of the treatment of primary liquid effluent is shown in the following diagram:





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yes

no

Recyclable Distillates

REA boron

TEP

TEU

yes

no

Primary liquid effluent

Demineralization, evaporation and

degassing

Recyclable Concentrates

KER (TER) on site

Figure D7.1-d: Treatment of primary liquid effluent

Primary liquid effluent is treated in the Primary Effluent Treatment System TEP [CSTS]. The main function of this system is to treat the primary effluent so that, as far as possible, the boron and water may be recycled through the primary reactor circuit.

In conjunction with the TEG [GWPS] for gaseous effluent, the TEP [CSTS] system processes all the primary liquid effluent, whether it contains dissolved hydrogen or dissolved oxygen.

The installation comprises:

• six reservoirs that may be used for demineralised water, distillates or primary coolant,

• a system for purification by demineralisation,

• an evaporation and degassing station,

• a degasser for the discharge from the RCV [CVCS] system

The entire TEP [CSTS] system is installed in the Nuclear Auxiliary Building (BAN).

The filtration-decontamination system comprises:

• a mixed-bed demineraliser containing resins that reduce the activity of the primary effluent,

• a filter, that prevents fine particles of resin escaping into the rest of the treatment system,

• a feed line to the downstream evaporation and degassing station,

The evaporator separates the primary coolant into a bottom concentrate containing boric acid concentrate (4%) and the distillates containing distilled water and any volatile constituents carried over in the distillation process (such as tritium). The separate degasser treats distillates from evaporation and also fresh demineralised water from the water treatment plant to produce reactor quality make up supplies.





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The degasser for discharge from the RCV [CVCS] system extracts the gases produced into the gaseous radwaste system (TEG [GWPS]) for treatment of the off gas (that is also, as far as possible recycled, see section 5.3.1).

4.3.2. Treatment of spent liquid effluent

The following diagram gives an overview showing how spent liquid effluent is treated:

Spent liquid effluent

Filtration (TEU)

Demineralisation (TEU)

Evaporation (TEU) KER (TER)on site)

Chemical effluent

Floor drains

Process drains

Figure D7.1-e: Treatment of spent liquid effluent

The spent liquid effluent is treated in the Spent Effluent Treatment System TEU [LWPS]. This system is sized for two EPR Units and its purpose is to limit the activity of spent effluent before it is transferred to the on-site storage tanks prior to monitoring and discharge (T tanks). Its treatment is specific to each category of spent effluent.

The spent liquid effluent is segregated at source, then stored in three sets of two front-end tanks, each set assigned to one type of effluent:

• process drain (DR): two 100m3 tanks,

• chemical drain (DC): two 160m3 tanks,

• floor drain (DP1-3): two 75m3 tanks,

Each set of two tanks has a sparging system, so that the contents of the tanks can be homogenized for sampling. The effluent treatment is determined based on the results of that sampling and involves:

• demineralisation for active effluent that has little chemical pollution (process drainage),

• evaporation for active effluent that is chemically polluted (chemical effluent)

• filtration for effluent that has little activity (floor drainage).

Process drain:

Process drain is sent from the front tanks where it is stored and then passed to the demineralisation plant, where it passes through:

• an initial fine 5 µm filtration to remove suspended solids from the spent effluent,





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• three demineralisers containing resins to reduce the activity of the spent effluent. The beds are strong anion and cation and a mixed bed to optimise removal of ions from the effluents.

• a secondary 25 µm filter, that prevents fine particles of resin escaping into the rest of the treatment system.

There are two successive stages in the demineralisation operation:

(1) Recirculation: the spent effluent processed in the demineralisers is sent back to the front tank from where it came,

(2) In open circuit: when the activity has been controlled, the treated spent effluent is sent to the storage tanks (T tanks) for monitoring and discharge.

Process effluent may also be treated by evaporation in an evaporator unit (separate to that used for primary coolant in the TEP [CSTS]).

Chemical drain:

Chemical drain is sent from the front end tanks where it is stored, coarse filtered and then sent to the evaporation plant. This comprises:

• 25 µm filtration station

• An evaporator to separate the spent effluent into distillates (only weakly active and/or chemically polluted) and concentrates (contain most of the activity and soluble and particulate chemical components).

• A storage tank for distillates.

The concentrates resulting from evaporation are sent to the system for Treating Solid Effluent (TES [SWTS]). The evaporation distillates may be sent, depending on the activity of samples:

• Back into the evaporation system, for treatment again,

• To the on-site storage tanks prior to monitoring and discharge (T tanks).

Floor drain:

Floor drain is sent from the front-end tanks where it is stored to the filtration plant. This comprises a filter to remove suspended solids. The filtered effluent is then sent to the on-site storage tanks before being monitored and discharged (T tanks). Floor drainage may also be treated by using the evaporator.

4.3.3. Treatment of blowdown from steam generators

The diagram below shows an overview of how water drained from the steam generators is processed:





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Figure D7.1-f: Treatment of blowdown from the steam generators

The blowdown from the steam generators is processed by the APG [SGBS] blowdown system. This circuit is specific to each EPR Unit and is intended to purify the blowdown water before it is recycled in the secondary circuit.

The purification plant for the steam-generator blowdown comprises:

• two parallel filters that remove a proportion of the solids suspended in the drained water,

• two parallel demineralisation lines, each with two resin-filled demineralisers, plus a secondary filter that prevents fine particles of resin escaping into the rest of the treatment system.

After purification, the purified blow down is sent to the main turbine condenser circuit where it is recycled. If analysis shows that it remains unsuitable for re-use (for example the tritium is too high) or the secondary circuit is not available, the treated effluents from the blowdown system may also be sent to storage tanks awaiting monitoring and discharge (T tanks).

If the APG [SGBS] system is not available, blowdown may be sent directly to the storage tanks before monitoring and discharge (via T tanks).

4.3.4. Treatment of water drained from the Turbine Hall

All activity associated with any small leaks from the primary to the secondary circuit is confined to the steam generator blowdown system, that has already been dealt with (see above). All other effluents from the Turbine Hall originate from leakage, and from draining and emptying the secondary circuit. These effluents are sent directly to the storage tanks for water drained from the Turbine Hall (SEK tanks; [CILWDS]) and therefore undergo no filtration or other processing.

Figure D7.1-g: Treatment of water drained from the Turbine Hall

4.4. STORAGE OF LIQUID EFFLUENT

Liquid effluent undergoes treatment in the KER [LRMDS] system that depends on its source:





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• primary effluent,

• spent effluent,

• water drained from the Turbine Hall.

All effluent passed to the KER [LRMDS] system passes through a final 5-micron filter

It is then passed to three separate sets of tank for interim storage, pending monitoring and discharge:

• T tanks (KER circuit [LRMDS]),

• S tanks (TER circuit [ExLWDS]),

• Ex tanks (SEK circuit [CILWDS]).

4.5. LIQUID RADIOACTIVE DISCHARGE

Liquid radioactive effluent includes:

• Activated corrosion products, mainly from corrosion in the steam-generator tubes,

• Activation products from chemicals in the primary coolant,

• Volatile fission products, from small but quantified minute leaks in the fuel assemblies and which increases in shutdowns and start-ups (fission product spiking).

The liquid radioactive effluent produced by the process is described in previous sections. At Flamanville, it is proposed that the KER [LRMDS] storage system from which the effluent is discharged would be common to the existing Units and the EPR Unit. These circuits discharge out to sea via the sea and cooling water outfalls (described later). The discharged radionuclides in the aqueous liquid discharges can be divided into four groups:

• Tritium,

• Carbon 14,

• Iodines,

• Other fission or activation products.

For each of these groups, the next parts of the current document show for the UK EPR:

• The expected discharges for normal operation. These are “realistic discharges” with no significant margin for normal operational contingencies/events.

• The maximum estimated discharges that include margins for a range of contingencies (but excluding faults and design basis accidents).

The detailed methods and source terms used to derive these discharges are described in more detail elsewhere (in section D7.2). However, the overall results and discharges through the various discharge routes obtained are summarised below





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4.5.1. Expected realistic performance for liquid discharges excluding contingencies

The table below gives the expected normal operating liquid discharge activities excluding contingencies:

Category Expected annual performance (excluding contingency) for liquid radioactive discharge

Tritium 52,000 GBq/ Carbon 14 23 GBq

Iodine 0.007 GBq Other fission or activation products emitting beta or gamma radiation 0.6 GBq

Table D7.1-a: Expected annual performance (excluding contingency) for liquid radioactive discharge

The distribution of the overall activity of 0.6 GBq between the different radionuclides in the group “Other fission or activation products” has been estimated using the averaged discharges from all 1,300MWe Units in France over the period 2002-2004. The 1,300MWe category has been chosen as the reference, since information about it is readily available, and its design, materials etc, are as similar to the proposed UK EPR as any existing design (though the EPR expected to show improvements in a number of respects).

Radionuclide Expected performance Ag 110m 0.0342 GBq

Co 56 0.1242 GBq Co 60 0.18 GBq Cs 134 0.0336 GBq Cs 137 0.0567 GBq Mn 54 0.0162 GBq Sb 124 0.0294 GBq

Te 123m 0.0156 GBq Ni 63 0.0576 GBq

Sb 125 0.0489 GBq Cr 51 0.0036 GBq

Table D7.1-b: Distribution of fission and activation products in radionuclides discharged in liquid form (expected performance)

4.5.2. Maximum liquid discharges

The figures for the maximum discharge of radioactive liquids from the EPR Unit includes normal operating contingencies, and is intended to provide a bounding case for the various situations in normal operation that the Unit could encounter. These do not relate to design basis incidents or accidents (as defined in relation to safety). The differences between maximum and expected performance values is an operational margin or maximum headroom that provides operators with some operational flexibility, whilst still meeting the various regulatory conditions with respect to ALARP operations and minimising discharges and environmental impacts. Maximum discharges are taken into account in defining the discharge Authorisations.

Category Maximum annual liquid radioactive discharge

Tritium 75,000 GBq Carbon 14 95 GBq

Iodine 0.05 GBq





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Other fission or activation products emitting beta or gamma radiation 10 GBq

Table D7.1-c: Maximum annual liquid radioactive discharge

The distribution of the overall activity of 10 GBq between the different radionuclides in the group “other fission or activation products” is again determined using the averaged discharges from currently operating 1,300MWe Units, over the period 2002-2004. No feedback data is available for the EPR Unit; the 1,300MWe category has been chosen as the reference, since information about it is readily available, and its design is, in overall respects, similar to that of the EPR.

Radionuclide Maximum annual activity Ag 110m 0.57 GBq

Co 58 2.07 GBq Co 60 3 GBq Cs 134 0.56 GBq Cs 137 0.945 GBq Mn 54 0.27 GBq Sb 124 0.49 GBq Sb 125 0.815 GBq Ni 63 0.96 GBq

Te 123m 0.26 GBq Others 0.06 GBq

Table D7.1-d: Distribution of fission and activation products in radionuclides discharged in liquid form (maximum values)

4.5.3. Chemical discharges associated with radioactive effluent

Primary coolant contains boric acid and lithium hydroxide. Secondary coolant contains ethanolamine and other secondary circuit conditioners. These chemicals accompany the trace radioactive constituents in the various liquid effluent treatment systems.

Boric acid and lithium hydroxide from the primary circuit are mainly retained in the evaporator bottoms and sent to solid radwaste. Other sources of boric acid and lithium hydroxide effluents are directed to the various liquid storage tanks prior to monitoring and discharge.

Secondary circuit chemicals pass mainly to the secondary circuit tanks and after monitoring are discharged directly.

The maximum values of the additional annual flux of chemical discharges are determined to enable:

• The circuit conditions specified in the various Chemical Specifications for the systems to be fully adhered to.

• A margin to allow for transient conditions in normal operation,

This approach means that the documentation gives realistic values for the discharges corresponding to expected performance (excluding significant contingency); and maximum values that are reasonably likely to encompass the amounts of chemicals discharged in the various situations that could be encountered at the site, as for liquid radioactive effluent.

The table below shows the expected performance excluding contingency; and the maximum amounts of chemicals associated with radioactive effluent that will be discharged:





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Chemicals Expected performance excluding contingency

(kg)

Maximum additional annual discharge

(kg) Boric acid (H3BO3) 2,000 7,000

Lithium hydroxide (LiOH) Less than 1 4.4 Hydrazine (N2H4) 7 14

Morpholine (C4H9ON) 345 840 Ethanolamine (C2H7ON) 250 460

Nitrogen (expressed as N) excluding hydrazine, morpholine and ethanolamine 2530 5,060

Phosphate (PO43) 155 400

Table D7.1-e: Expected performance excluding contingency and maximum annual additional discharge for chemicals associated with radioactive effluent

The table shows that for the EPR:

• Boric acid: the proposed treatment of the primary water facilitates greater recycling. The use of boron enriched with boron 10 significantly reduces discharge in normal circumstances.

• Morpholine: forms ethanolamine by thermal decomposition. This in turn, is decomposed in a series of reactions, finally forming glycolates, formiates, acetates and oxalates. The estimated maximum annual amount discharged for each of these substances is given in the following table:

Acetates Formiates Glycolates Oxalates Annual amount 1.53 1.9 0.19 0.127

Table D7.1-f: Annual flux of the degradation products of morpholine and ethanolamine (in kg)

• Nitrogen: nitrogen (excluding hydrazine, morpholine and ethanolamine) in the secondary-circuit water is present only in the form of ammonium ions. When collected in the sumps and transferred to the storage tanks, it may be converted into nitrates (or possibly nitrites) on contact with atmospheric oxygen. In the environment, it is stable in the form of nitrates.

• Because the discharge environment is seawater, the sodium level associated with phosphates is not specified: it is discharged in concentrations that are negligible compared with the concentration in the receiving environment.

• The distribution of all metals in the KER [LRMDS] and SEK tanks [CILWDS], based on the proportions found in Units 1-2, is as follows:

Al Cu Cr Fe Mg Ni Pb Zn 8.95% 0.70% 14.10% 59.30% 5.60% 0.75% 0.50% 10.10%

Table D7.1-g: Distribution spectrum for all metals





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5. RADIOACTIVE GASES

5.1. SOURCE OF RADIOACTIVE GASEOUS EFFLUENT

Gaseous radioactive effluent includes:

• Noble gases, formed by fission, and comprising mainly xenon-133 and xenon 135, with a lower proportion of krypton-85. These pass into the primary coolant. During normal operation, a portion of this coolant is let-down into the Chemical and volume control system and thence to the RCV [CVCS] tank. In the later, the fission product gases pass into the tank headspace which purges into the delay beds in the Gaseous Effluent Treatment System (TEG [GWPS]). The majority of these fission product gases have short half-lives and undergo radioactive decay on the beds. This minimises subsequent discharges to the environment through the gaseous effluent stack. In preparation for a shutdown refuelling, there may be increased release of these fission products from the fuel and coupled to increased let down and clean up of the coolant, this may increase the amounts discharged.

• During normal operation, Argon-41 is formed in the reactor building air and if there is any venting of this to the outside, very low levels of this noble gas may occur in the vicinity of the plant. Its half-life is under two hours and it therefore appears only transiently and in circumstances of reactor building venting.

• Tritium, formed by fission within the fuel and by activation of the boron added to the primary coolant. Tritium is also formed from traces of lithium-6 that are present in the Li7OH used to control coolant pH. The Zircaloy fuel cladding retains the bulk of the tritium formed by fission in the fuel and tritium in gaseous effluent comes mainly from activation of boron and lithium in the coolant. It is present in the different reactor tanks and fuel pools as tritiated water. It is transported by the ventilation systems. There are no cost effective methods for abatement of tritiated water vapour and the BPEO at all nuclear power plants is to discharge most via the stacks serving the various areas where tritiated water vapour arises.

• Carbon-14, formed mainly by the activation of oxygen and nitrogen dissolved in the reactor coolant water and then released from this by outgassing. It is present in atmospheric discharge, particularly as methane, and also, to a lesser extent, as carbon dioxide. It follows the same path as the noble gases (via the volume control tank and thence to the Gaseous effluent treatment system).

• Iodines, mainly iodine-131 and iodine-133 formed by fission. These also pass into the primary coolant and are purged into the headspace in the RCV [CVCS] tank and thence pass to the gaseous radwaste TEG [GWPS] system. Most are retained in the liquid phase, rather than being lost to the gaseous phase in the TEG [GWPS] system. In most cases, their activity in the Gaseous-effluent Treatment System (TEG [GWPS]) is very low and any discharged are further abated using carbon delay beds in the off gas stream. Iodines are also retained in the iodine traps installed in the building ventilation circuits (these iodine traps are brought into service as required).

• Aerosols, formed mainly by activation (cobalt-58 and cobalt-60) and fission (caesium-134 and caesium-137) that are then brought into fine aerosol form. Those in building areas are removed by continuous filtration in the ventilation plants. The radioactive discharge into the environment as aerosols represents a mass of less than one microgram per year (largely cobalt -60).





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The devices for treating gaseous radioactive effluent (filters, iodine traps, recombination, retarding beds) help to limit radioactive discharge into the environment.

Further information on the design and operation of the gaseous discharge and stack for the EPR are given in Volume 2.

5.2. NATURE OF GASEOUS RADIOACTIVE EFFLUENT

Gaseous radioactive effluent falls into one of three categories, as shown in the following diagram:

TEG CVI

DWN DWN, DWL, EBA or DWQ DWN

Secondary gaseous effluent

Gaseous effluent from ventilation

Primary gaseous effluent

Discharged to the stack

Figure D7.1-h: Nature of gaseous radioactive effluent

These three sources of gaseous radioactive effluents are described in the following paragraphs.

5.2.1. Gaseous effluent from the primary circuit

This comes from degassing in either the primary-effluent degassers in the Primary Effluent Treatment System (TEP [CSTS]), or from the ullages and head spaces in facilities containing primary coolant or primary effluent, such as the RCV ([CVCS] tank) TEP [CSTS] and some RPE [NVDS] tanks and the reactor circuit pressuriser tank. The ullages within these vessels collect gas released from the primary coolant such as hydrogen and accompanying radioactive gases and aerosols.

Nitrogen purging is used to maintain low levels of hydrogen and oxygen and to continuously purge the headspaces of the tanks. This also ensures build up of potentially explosive hydrogen and oxygen cannot occur in these tanks and minimises dissolved oxygen in the liquids in the tanks.

Primary gaseous effluent purged from these tanks is directed to the Gaseous-effluent Treatment System (TEG [GWPS]).





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5.2.2. Gaseous effluent from ventilation

All radiation controlled areas of the Nuclear Auxiliary Building, the Fuel Building, the Safeguard Buildings, the Reactor Building, the Operational Production Centre, the Access Building and the Effluent-treatment Building are served by dedicated HVAC systems. These ensure pressure differentials and air changes are maintained so that air always moves from potentially less contaminated areas to more contaminated areas, in accordance with standard best practice. The ventilation systems use abatement systems to remove potential low levels of iodine isotopes, aerosols etc. from the extracted air.

It is collected in the ventilation circuits in the various buildings on the nuclear island (DWN, DWK, DWL [CSBVS], EBA [CSVS] (high and low flow), DWB, DWW and DWQ), where, if necessary, it is filtered using iodine traps and then discharged via the stacks.

5.2.3. Gaseous effluent from the secondary circuit

Small leaks may occur between the primary and secondary circuit through which tritium leaks and appears in the secondary circuit and condensed secondary water. With low pressure in the condenser wet well during operation, some tritiated water can therefore appear in the main condenser off gas. This is collected in the condenser vacuum system (CVI), and then sent to the ventilation system for the Nuclear Auxiliary Building (DWN), where it is passed through a HEPA filter before being discharged into the stack.

5.3. TREATMENT OF GASEOUS RADIOACTIVE EFFLUENT

A diagram showing an overview of the arrangements for processing and storing gaseous effluent is shown in Figure D7.1-b. Gaseous effluent is segregated at source and treated in different systems, depending on its nature:

• Primary gaseous effluent is processed in the Gaseous-effluent Treatment System (TEG [GWPS]).

• Effluent from ventilation is processed in the ventilation circuits DWN, DWK, DWL [CSBVS], EBA [CSVS] (high and low flow), DWB, DWW and DWQ.

These treatment systems are described in the following paragraphs.

5.3.1. Treatment of gaseous effluent from the primary circuit liquid tanks (TEG [GWPS] system)

Treatment of gaseous effluents from the various tanks and systems serving the primary circuit in the UK EPR is carried out in the Gaseous Radioactive waste treatment system (TEG [GWPS]). This is different to that used on most French PWRs but uses best current methods developed for the German Konvoi design. Key features of this system are as follows:

• The system compensates for the variations in free volume of the purged tanks and vessels and contains gases in these by keeping them below atmospheric pressure, using a continuous nitrogen purge. This also accentuates out gassing of the liquids within the tanks (primary coolant that can be returned to the reactor).





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• A key feature that differs from PWRs to date is the recovery of purge gas (nitrogen) that is compressed and then returned to the system for re-use. Thus, a large portion of gas is retained within the TEG [GWPS] system for return to the various ullages and headspaces in the tanks from which it originated, maximising recirculation and minimising discharges. This retains the shorter-lived radioactive gases (mainly inert gases) to allow decay.

• Hydrogen and oxygen levels lost to the circulating gas from the liquids in the tanks to the purge gas are controlled using a catalytic recombiner. This can deal with initial feed hydrogen up to 4% and oxygen of 1% and reduces the concentrations of these in gas that is recirculated in the system to less that 0.3% and 0.1% respectively. This minimises oxygen in liquids in the various tanks to allow these to be reused in the primary circuit and maintains hydrogen in the tanks below an explosive limit of 4% (eliminating a potential internal hazard).

• The recombination unit may help to ensure that tritium and iodines in the purge gas in the TEG [GWPS] are returned to and retained in the liquid phase, although to date this effect has not been quantified. The dominant isotopes remaining in the purge gas in the TEG [GWPS] are the shorter- lived noble gases (that also have lower environmental impacts).

• A portion of the purge gas in the system is bled off and fed to dryers to remove water vapour and then to a line of three activated carbon delay beds. These retain residual noble gases that have not already decayed within the recirculating part of the system. They thus provide a further period for the decay of these gases prior to discharge, viz xenon is kept for 40 days and krypton for 40 hours. Note these beds are not specifically used for the iodines that are retained mainly in the liquid phases in the recombiner (see above).

• The three beds also operate at a slightly enhanced pressure to maximise their capacity. They finally feed through to a filter to remove any small carry over of particulates from the bed.

• During normal operation (~99% of the TEG [GWPS] operating time) the TEG [GWPS] system bleeds only ~0.2 Nm3/hr to the down-line delay beds and thus to discharge. The 1% time operating at higher discharge rates occurs only during reactor start up and shutdown when there is relatively larger movement of water between interconnected systems and when there is increased nitrogen purging of vessels. At this time the operating pressure of the delay beds increases from 1.5 bar to 9 bars (as in the rest of the TEG [GWPS] system) thus maximising their capacity. The desiccant bed also switches in at this time to dry the gas to ensure maximum efficiency of the delay beds.

After treatment in the TEG [GWPS], the gaseous effluents are directed to the Nuclear Auxiliary Building (BAN) where they are finally treated using one of a series of HEPA filters. Discharge via this route is automatic and controlled via pressure in the TEG [GWPS] delay beds.

The final treated gaseous effluents are then monitored and discharged via a stack shared with the HVAC system serving the BAN building. The stack height and discharge characteristics are designed to ensure maximum rapid dispersion of the discharged gaseous effluents.

The following diagram summarizes the processes for discharging gaseous effluent from the primary circuit:





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Figure D7.1-i: Processes for discharging gaseous effluent from the primary circuit

Recombined gaseous effluent

Radioactive decay…

Retarding beds (TEG)

HEPA filtration

Discharge

5.3.2. Treatment of gaseous effluent from ventilation

The following diagram summarizes the treatment of gaseous effluent from ventilation:

from the Access Station Building

from the POE

Discharge to the

chimney

from the BTE

from the BR (apart from Unit shutdown)

from the BK or the BAS (during accidents)

from the BK (apart from accidents)

from the BR (during Unit shutdown)

from the BAS (apart from accidents)

from the BAN

HEPA filtration and iodine trap (DWL)

HEPA

filtration. Iodine trap if

necessary (DWN)

HEPA filtration and iodine trap (EBA low flow)

HEPA filtration. Iodine trap if necessary (DWQ)

HEPA filtration (DWB)

HEPA filtration (DWW)

EBA high

flow

DWK

Gaseous effluent from

ventilation

Figure D7.1-j: Treatment of gaseous effluent from ventilation





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5.3.2.1. Ventilation of the Nuclear Auxiliary Building (DWN)

The gaseous ventilation effluent processed by the DWN ventilation system comes from contamination controlled zones in the Nuclear Auxiliary Building (BAN), the Safeguard Buildings (BAS) and the Fuel Building (BK) [apart from incidents]; and from purging the Reactor Building when the Unit is closed down and the reactor head removed for refuelling outage (EBA [CSVS] high flow). This circuit has an extraction plant connected to the stack with pre-filters and HEPA filters. If required, the discharge can also be directed through carbon bed filters to allow removal of iodine isotopes.

The extraction plant treatment trains comprise:

• 6 filtration trains with a unit flow rate of 20,000 m3/h, 3 for output from DWN ventilation, 2 for BK ventilation and one for BAS ventilation,

• 1 x 25,000 m3/h filtration train for the high-flow EBA [CSVS].

• 4 exhaust fans.

• 4 iodine traps, each with its own reheater1 If iodine is detected in the premises’ exhaust ducting, the airflow is automatically sent through these iodine traps.

• 4 booster fans to make up the additional pressure loss.

If required, these systems can also act for further clean up and treatment of primary gaseous effluents from the Gaseous-effluent Treatment System (TEG [GWPS]). These would then be monitored and discharged via the stack.

5.3.2.2. Fuel-Building Ventilation DWK

The DWN system manages the supply, the extraction, the treatment/monitoring and the discharge of ventilation air the Fuel building.

5.3.2.3. Ventilation of the controlled area in the Safeguard Buildings DWL [CSBVS]

In normal operations, the DWN manages the supply, extraction, treatment and discharge of air from the safeguard Building.

In the event of a fault involving small loss of coolant accident or fuel handling fault, the DWL [CSBVS] has its own dedicated gaseous radwaste treatment systems consisting of pre-filters, HEPA filters and, if required, iodine adsorption beds as well as its own sampling and monitoring systems for accident/incident management and monitoring.

5.3.2.4. Reactor building ventilation EBA [CSVS]

The Reactor Building ventilation system serves that main reactor building and operates in two modes:

1 Reheater: device used to raise or maintain air temperature





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• Low-flow EBA [CSVS]: This system conditions, extracts and filters the air used to purge the primary containment. It operates whether the Unit is shut down or operational, so that personnel can access the Reactor Building. It has two filtration trains with prefilters, Very High Efficiency (HEPA) filters and iodine traps.

• High-flow EBA [CSVS]. This system conditions and discharges to the chimney the air that ventilates the containment when the Unit is closed down and especially when the reactor head is removed and the refuelling cavity flooded during refuelling. The air flowing through the system during this time also passes through an iodine trap in the DWN system.

5.3.2.5. Ventilation of the controlled area of the Operational Production Centre (POE) DWB

The controlled area of the POE comprises hot laboratories and hot changing rooms. The system has two filtration trains with prefilters and Very High Efficiency (HEPA) filters.

5.3.2.6. Ventilation of the Effluent treatment Building (DWQ)

This system conditions, extracts and filters the BTE’s ventilation air.

It has an exhaust ductwork connected to the chimney with pre-filters, very high efficiency (HEPA) filters and an iodine trap that is bypassed in normal operation.

5.3.2.7. Ventilation of the controlled area of the Access Building (DWW)

The system has two filtration trains with pre-filters and Very High Efficiency (HEPA) filters.

5.3.3. Treatment of gaseous effluent from the secondary circuit

The following diagram summarizes the treatment of gaseous effluent from the secondary circuit:

(CVI)

HEPA filter (DWN) Discharge to the chimney

Secondary gaseous effluent

Figure D7.1-k: Treatment of gaseous effluent from the secondary circuit

Gaseous effluent from the secondary circuit is collected by the condenser vacuum system (CVI), and then sent to the ventilation system for the Nuclear Auxiliary Building (DWN), described in the previous section. It is discharged to the chimney after passing through a HEPA filter.





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5.4. GASEOUS RADIOACTIVE DISCHARGE

Gaseous radioactive effluent produced by the process is described in section 4.1 above. It is discharged from the BAN chimney. Discharged gaseous radionuclides can be divided into five families:

• Tritium,

• Carbon 14

• Noble gases,

• Iodines,

• Other fission or activation products.

For each of these groups, the next parts of the current document show for the UK EPR:

• The expected discharges for normal operation. These are “realistic discharges” with no significant margin for normal operational contingencies/events.

• The maximum estimated discharges that include margins for a range of contingencies (but excluding faults and design basis accidents).

The detailed methods and source terms used to derive these discharges are described in more detail elsewhere (in section D7.2). However, the overall results and discharges through the various discharge routes obtained are summarised below

5.4.1. Expected gas discharge from the EPR excluding contingency

As described above, the EPR’s expected performance for gaseous radioactive discharge is estimated from existing Units, but takes account of improvements and changes in the source terms and the abatement plant. Expected discharges are as follows:

Category Annual expected EPR

performance excluding contingency

Tritium 500 GBq Carbon 14 350 GBq

Iodine 0.05 GBq Noble gases 800 GBq

Other fission or activation products emitting beta or

gamma radiation 0.004 GBq

Table D7.1-h: Expected annual performance (excluding contingency) for gaseous radioactive discharge

The activity relating to iodines, noble gases and other fission or activation products is distributed between the various radionuclides using the averaged discharges from all current French and German 1300 MWe Units, over the period 2002-2004. The 1300 MWe category has been chosen as the reference, since information about it is readily available, and its design is as close as is available to the EPR.





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Category of radionuclide Expected EPR performance

I 131 0.0228 GBq I 133 0.0272 GBq

Total iodines 0.05 GBq Kr 85 111.2 GBq

Xe 133 504.8 GBq Xe 135 158.4 GBq Ar 41 23.2 GBq

Xe 131m 2.4 GBq Total noble gases 800 GBq

Co 58 0.000102 GBq Co 60 0.0001204 GBq Cs 134 0.0000936 GBq Cs 137 0.000084 GBq

Total PF / PA 0.0004 GBq Table D7.1-i: Split of activity between iodines, noble gases and fission and activation

products (expected performance)

5.4.2. Maximum gaseous discharge from the EPR

As for the liquid discharge described above, the estimated maximum discharge of radioactive gas from the EPR Unit includes normal operating contingency, and is intended to cover the different situations likely to be encountered in the Unit during normal operation.

Category Maximum EPR annual gaseous radioactive

discharge Tritium 3000 GBq

Carbon 14 900 GBq Iodine 0.4 GBq

Noble gases 22500 GBq Other fission or activation products emitting beta or

gamma radiation 0.34 GBq

Table D7.1-j: Maximum annual gaseous radioactive discharge

The overall activity relating to iodines, noble gases and other fission or activation products is divided between the various radionuclides using the averaged discharges from all 1300MWe Units in France over the period 2002-2004 chosen as the reference, since information about it is readily available, and the design is as close as is available to the EPR.

Category of radionuclide Maximum EPR annual activity

I 131 182.4 MBq I 133 217.6 MBq

Total iodines 400 MBq Kr 85 3.1275 TBq

Xe 133 14.1975 TBq Xe 135 4.455 TBq Ar 41 0.6525 TBq

Xe 131m 0.0675 TBq Total noble gases 22.5 TBq

Co 58 86.7 MBq





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Category of radionuclide Maximum EPR annual activity

Co 60 102.4 MBq Cs 134 79.56 MBq Cs 137 71.4 MBq

Total PF / PA 340 MBq Table D7.1-k: Distribution of fission and activation products in radionuclides

discharged in gaseous form (maximum values

6. SOLID RADIOACTIVE WASTE

6.1. DIFFERENT TYPES OF SOLID RADIOACTIVE WASTE

The Community Directive EURATOM 92/3 (issued by the European Council on 3 February 1992) regarding the supervision and control of shipments of radioactive waste between Member States and into and out of the Community, gives the following definition of radioactive waste: “Any material containing radionuclides or contaminated with radionuclides, and for which no further use is foreseen”.

In the UK, radioactive waste is classified into one of three main categories depending on the activity and types of radionuclides it contains:

Standard practice at all UK sites is to segregate radioactive waste at source to minimise the volumes of higher level wastes (for which no current disposal route exists and which present the largest costs and hazards in management and handling). Where ever possible, solid wastes are also stored and conditioned in accordance with HSE principles that ensure containment, protection of workers, allow inspection and produce waste forms that are compliant and acceptable for current planned or actual disposal routes.

All these various regulatory requirements are taken account in the handling and treatment of solid radioactive waste in the UK EPR and the treatment systems take due consideration of the UK disposal routes, current or planned. The treatments are described below.

6.2. TREATMENT OF SOLID RADIOACTIVE WASTE IN THE UK EPR

Radioactive waste from the EPR Unit is treated in the Solid Effluent Treatment Plant (TES [SWTS]). This facility is situated between the EPR Effluent-Treatment Building, BTE and the Unit TES [SWTS] (in the EPR Unit).

Waste is segregated at source in each area it arises in, both in terms of its activity and its chemical and physical characteristics. Activity is based on hand held monitors and using in line monitoring systems. Initial waste streaming can be based on fingerprints. The solid waste arisings will be similar in many respects to those already handled at current UK plant and PWRs, with similar finger print characteristics.





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The TES [SWTS] collects the waste and transfers it to the treatment areas. The waste consists of active ion exchange resins from the RCV [CVCS], PTR [FPPS/ FPCS], TEP [CSTS] demineralisers, APG [SGBS] (SG blowdown) resins of lower activity and also RCV [CVCS], PTR [FPPS/ FPCS] and TEP [CSTS] filters and other general lower level waste (maintenance waste etc.). Where required, all transfers and handling is by remote means.

The Unit TES [SWTS] selectively collects waste in the Nuclear Auxiliary Building and ships it to the Effluent-Treatment Building.

The site BTE system collects and sorts solid waste output from the EPR Unit, provides buffer storage for the containers, manages any radioactive decay of highly-radioactive effluent and conditions waste partially or completely so it may be taken off-site.

The BTE adjoins the BAN, and an underground conveyor system between the two buildings has been designed to transfer non-immobilized spent fuel casings without leaving the area.

The conditioning carried out means the waste can be shipped to other planned UK facilities for final storage and disposal.

The only HLW (heat generating) will be in the form of spent fuel that is addressed separately (see later).

It is envisaged that all waste streams from the UK EPR will be compliant with current NIREX waste stream identifiers. No new or novel solid waste streams are expected.

6.2.1. Solid radioactive waste excluding fuel

Solid waste from the nuclear island and the effluent-treatment building that results from normal operation is sent to the TES [SWTS] system, then conditioned for sending off the installation site to a final storage location, or to a treatment plant for additional processing (e.g. incineration, fusion etc.).

The power station produces three types of radioactive waste:

• Waste known as “process” waste, associated with generating power. This results from treating fluids, in order:

o either to limit the deposited contamination and reduce its activity, so that personnel are not exposed to radiation; or

o to reduce the activity of discharged effluent, whether liquid or gaseous.

The process waste is that which results from treating gaseous effluent and comprises mainly filters and iodine traps. For liquids, the process waste consists of filters, concentrates and ion-exchange resins.

• So-called “technological waste” from maintenance work (mending faults, repairs, replacement of radioactive materials, etc.). It comprises mainly compactable materials, such as vinyl, gloves, adhesive tape, papers, trunking for exhaust fans, etc.

• Sundry waste, generally from:

o So called sundry incidents (e.g. contaminated oils),

o One-off operations (e.g. poison rods).





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Notional estimates of volumes are shown in Table D7.1-l below.

TYPE OF WASTE ANNUAL VOLUME OF RAW WASTE

(m3/Unit) Ion-exchange resins from the

nuclear island 3

Resins with very low activity (APG [SGBS])*

2.5 / 7.5 *

Sludge (sumps and tanks) 1 Water filters from effluent

processing systems (>2mSv/h on contact)

5

Process waste

Evaporator concentrates 3 Technological waste

and process waste

< 2 mSv/h on contact

Waste stored in 200-litre metal

barrels:

Pre-compacted technological waste (bulk density 0.5) and non-

compactable waste: maintenance (apart from metals), rubble,

decontamination operations, insulation

Non-compactable process waste: air and water filters

50 4

Technological waste < 2 mSv/h on contact

This waste is stored in concrete containers

1

Oils 2 Special technological waste < 2 mSv/h on contact Metal waste from maintenance 6

TOTAL 77.5 / 82.5 * *regenerable/non-regenerable

Table D7.1-l: Estimated volumes of solid waste produced during operation of the EPR Unit

6.2.1.1. Types of radioactive waste

In the UK, there is no legal definition of the different types of radioactive waste. However (except for fuel), the EPR will only produce radioactive waste within the current UK categories, as follows (these take into account recent information in the UK Policy on LLW published in March 2007):

• Intermediate level radioactive waste (ILW) is “waste with radioactivity levels exceeding the upper boundaries for LLW but which do not require heating to be taken into account in the design of storage or disposal facilities”,

• and LLW is “radioactive waste having a radioactive content not exceeding 4 GBq/te of alpha or 12 GBq/te of beta / gamma activity. This waste which, under existing authorisations, can generally be accepted at the UK national LLW disposal facility, located near to the village of Drigg”.

In practise, some LLW falling within that general definition cannot be disposed of at the Drigg facility, due to radionuclide content and/ or physical/ chemical properties, etc. These wastes have to be considered separately and may have to be managed along with ILW.





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The lower activity limit for LLW, below which waste is not required to be subject to specific regulatory control, is either:

• the levels specified in Schedule 1 of the radioactive Substances Act 1993 (RSA 1993) below which certain natural radionuclides in the uranium and thorium decay chain are outside the scope of the Act or

• the levels laid down in the current suite of Exemption Orders issued under RSA 1993, below which additional controls on certain artificial or man-made radionuclides to those specified in the Exemption Order are not required. In particular, this specifies a level for exemption from regulatory control of 0.4 MBq/te for wastes that are substantially insoluble in water.

Within the UK, Very Low Level Radioactive Waste (VLLW), sub-category of LLW is now defined as:

• In the case of low volume (‘dustbin loads’) – Low Volume VLLW: “Radioactive waste which can be safety disposed of to an unspecified destination with municipal, commercial or industrial waste (“dustbin” disposal”), each 0.3m3 of waste containing less than 400 kilobecquerels (kBq) of total activity or single items containing less than 40 kBq of total activity.

• For wastes containing carbon-14 or hydrogen-3 (tritium): In each 0.1m3, the activity limit is 4,000 kBq for carbon-14 and hydrogen-3 (tritium) taken together; and for any single item, the activity limit is 400 kBq for carbon-14 and hydrogen-3 (tritium) taken together.

Controls on disposal of this material after removal from the premises where the wastes arose, are not necessary (the quantity of low volume VLLW that may be disposed of is currently the subject of research).”

Or in the case of bulk disposals – High Volume VLLW:

• “Radioactive waste within maximum concentrations of four megabecquerels per tonne (MBq/te) of total activity which can be disposed of to specified landfill sites. For waste containing hydrogen-3 (tritium), the concentration limit for tritium is 40 MBq/te. Controls on disposal of this material, after removal from the premises where the wastes arouse, will be necessary in a manner specified by the environmental regulators”.

The principal difference between the two definitions is the need for controls on the total volumes of VLLW in the second (high volume) category being deposited at any one particular landfill site. The definitions supersede that for VLLW in paragraph 53(4) of Cm2919

A summary of the LLW categories expected from the EPR is given in Table D7.1-m below





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Waste Category

Definition Disposal Route

LLW

Max 12,000 Bq/g beta/ gamma activity OR 4,000 Bq/g alpha activity

Nirex facility or the Low Level Waste Repository near Drigg

Max 40 Bq/g for waste containing C-14 or H-3 only

VLLW

Max 4 Bq/g beta/ gamma activity. Some alpha activity may be permitted in VLLW, as specified by the environment agency. LLW has been converted to activity per unit mass using an approximate waste density of 1 te/m3

See text above

SoLA* Max 0.4 Bq/g total man-made activity Table D7.1-m: Different types of UK Low level waste categories

6.2.2. Fuel derived wastes

In the UK, spent fuel is not yet classified as waste. The section here gives an overview of the approach used in the EPR design to minimise resources and waste arising in the EPR fuel cycle. Note that for current purposes, the wastes from fuel are described in terms of French waste classifications (TFA/FA, MA and HA); however, the distribution of the types and volumes of waste arising from EPR fuel under the UK classes of LLW, ILW and HLW are expected to be broadly similar (for example, most fuel cladding and structural components enclosing the fuel would be ILW and after any reprocessing most fission products would pass to a HLW stream).

Reducing the production of fuel waste (particularly so-called “long-life” waste) for a given energy output, is key to optimising the nuclear fuel cycle from the environmental standpoint. This applies whatever the ultimate choice for managing this type of waste.

This objective is integrated into the design and performance options chosen when planning the EPR.

Once it has been producing energy in the reactor for a period of 5 or 6 years, a fuel assembly is spent and must be discharged. It then comprises:

• Structural material enclosing the fuel (cladding, grids, nozzles, etc), which cannot be recycled. They comprise “medium-activity long-life waste”

• Content, the fuel itself, which comprises :

o 96% recyclable material (uranium and plutonium)

o 4% of “high-activity long-life" waste (caesium, americium, etc.).

As regards its core and its use of fuel, the EPR is an evolutionary reactor whose design has drawn on the experience of existing reactors. It uses the same types of fuel, but the yield is better due to its design features and enhancements in fuel performance.





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6.2.2.1. Waste with Medium Activity (MA)

This contains radioactive elements, generally actinides, which emit alpha radiation with an activity of over 3,700 Bq/g and have a half-life of over 30 years. They derive mainly from structures that have contained nuclear fuel.

Such waste must be stored at a temporary intermediate site, until a definitive solution emerges.

6.2.2.2. Waste with High Activity (HA)

This contains radioactive elements that emit alpha, beta and gamma radiation with a half-life over 30 years. They comprise the solutions of fission and activation products that result from irradiated fuel reprocessing.

In vitrified form, HA waste is stored at a temporary intermediate site, where it is housed appropriately.

The proportions of radioactive waste in each category, by volume and activity show that about 95% of the radioactivity is contained in less than 1% of the waste (see Table D7.1-n below).

Categories of radioactive waste Volume Activity

TFA and FA (i.e. lower activity) 97% 1%

MA 2% 4% HA < 1% 95%

Table D7.1-n: Proportion by volume and activity of fuel waste

6.3. TYPES OF CONVENTIONAL WASTE

Conventional waste is dealt with in Volume 3, Part B.

section d7.1 – introductionepr-reactor.co.uk/ssmod/liblocal/docs/v3/volume 3... · fundamental...

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