RPII-98/2

RADIOACTIVITY MONITORING

of the

IRISH MARINE ENVIRONMENT

1996 and 1997

S. LongD. PollardE. HaydenV. SmithM. FeganT.P. Ryan

A. DowdallJ.D. Cunningham

June 1998

i

CONTENTS

Summary

1. Introduction..................................................................................................................... 1

2. Sources of Radioactivity in the Irish Marine Environment........................................... 2

3. Methods of Sampling and Analysis................................................................................. 5

Sampling ........................................................................................................................... 5Analysis............................................................................................................................. 6

4. Radioactivity Concentrations ......................................................................................... 8

Seawater ............................................................................................................................ 8Sediment............................................................................................................................ 9Seaweed............................................................................................................................. 9Fish and Shellfish ............................................................................................................ 13

5. Assessment of Radiation Exposure ............................................................................... 15

The Ingestion Pathway..................................................................................................... 15 Committed Effective Dose........................................................................................... 15 Collective Effective Dose ............................................................................................ 17

External Exposure............................................................................................................ 17Risk Estimates ................................................................................................................. 17

6. Conclusions.................................................................................................................... 18

7. Acknowledgments ......................................................................................................... 18

8. References...................................................................................................................... 19

9. Glossary of Terms ......................................................................................................... 21

10. Radiation Quantities and Units................................................................................... 22

Tables

ii

LIST OF FIGURES

Figure 1 Marine Discharges of Caesium-137 from Sellafield, 1952 – 1997

Figure 2 Marine Discharges of Technetium-99 from Sellafield, 1988 - 1997

Figure 3 Coastal Sampling Locations

Figure 4 Sampling Stations in the Western Irish Sea

Figure 5 Sampling Stations in Carlingford Lough

Figure 6 Caesium-137 in Seawater from N1, Irish Sea, 1985 - 1997

Figure 7 Caesium-137 in Fucus vesiculosus, 1996

Figure 8 Technetium-99 in Fucus vesiculosus from Balbriggan andGreenore, 1988 – 1997

Figure 9 Technetium-99 in Fucus vesiculosus, 1996

Figure 10 Plutonium-239,240 in Fucus vesiculosus, 1996

Figure 11 Radiocaesium in Fish and Prawns Landed at North-East Ports,1982 - 1997

Figure 12 Doses to Heavy Seafood Consumers, due to Radiocaesium, 1982 – 1997

iii

LIST OF TABLES

Table 1 Discharges of Radionuclides from Sellafield, 1996 and 1997

Table 2 Concentrations of the Main Naturally Occurring Radionuclides in Seawater

Table 3 Sampling Locations in the Western Irish Sea, 1996 and 1997

Table 4 Sampling Programme, 1996 and 1997

Table 5 Analytical Techniques

Table 6 Radioactivity in Seawater, 1996

Table 7 Radioactivity in Seawater, 1997

Table 8 Radioactivity in Irish Coastline Sediments, 1996 and 1997

Table 9 Radioactivity in Off-shore Sediments, 1996 and 1997

Table 10 Radioactivity in Fucus vesiculosus, 1996

Table 11 Radioactivity in Fucus vesiculosus, 1997

Table 12 Plutonium in Fucus vesiculosus, 1996

Table 13 Radioactivity in Seawater from Carlingford Lough, October 1997

Table 14 Radioactivity in Seaweed and Sediment from Carlingford Lough,

October 1997

Table 15 Radioactivity in Whiting, 1996 and 1997

Table 16 Radioactivity in Cod, 1996 and 1997

Table 17 Radioactivity in Plaice, 1996 and 1997

Table 18 Radioactivity in Ray, 1996 and 1997

Table 19 Radioactivity in Herring, 1996 and 1997

Table 20 Radioactivity in Mackerel, 1996 and 1997

Table 21 Radioactivity in Farmed Salmon, 1997

Table 22 Radioactivity in Prawns, 1996 and 1997

Table 23 Radioactivity in Mussels, 1996 and 1997

Table 24 Radioactivity in Oysters, 1996 and 1997

Table 25 Radioactivity in Lobster, 1997

Table 26 Radioactivity in Shellfish from Carlingford Lough, 1997

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Table 27 Weighted Mean Activity Concentrations of Artificial Radionuclides in Fish,Crustaceans and Molluscs Landed at North-East Ports, 1996 and 1997

Table 28 Committed Effective Doses, from Artificial Radionuclides, due to theConsumption of Fish, Crustaceans and Molluscs Landed at North-East Ports,1996 and 1997

Table 29 Landing Statistics for Fish, Crustaceans and Molluscs at North-East Irish SeaPorts, 1996 and 1997

Table 30 Collective Effective Doses, from Artificial Radionuclides, due to theConsumption of Fish, Crustaceans and Molluscs Landed at Irish Sea Ports,1996 and 1997

v

SUMMARY

This report presents the results of the marine radioactivity monitoring programme carried out by theRadiological Protection Institute of Ireland (RPII) during 1996 and 1997. The primary objective of theprogramme is to assess the exposure to the Irish population resulting from radioactive contamination of theIrish marine environment and to estimate the risks to health from this exposure. Discharges from the BritishNuclear Fuels (BNFL) reprocessing plant at Sellafield continue to be the principal source of this contamination.Approximately 300 samples of fish, shellfish, seaweed, seawater and sediment were collected each year. Boththe Marine Institute and the Department of the Marine and Natural Resources assisted the Institute with thissampling. The samples were analysed for a range of contaminating radionuclides at the Institute’sradioanalytical laboratory.

The results show that the radionuclide of greatest dosimetric significance continues to be caesium-137. Theactivity concentration of this radionuclide continued the decrease observed since the mid 1980s. However,results reported during the mid 1990s have shown that this decline has become less pronounced due to trends indischarges from Sellafield and remobilisation of radioactivity from an area of mud and silt accumulation in theIrish Sea. The activity concentrations of caesium-137 in the Irish Sea show a clear decrease with increasingdistance from Sellafield, with the highest activity concentrations observed on the north-east coast.

Since 1994 the commissioning and operation of new facilities at Sellafield have resulted in an increase in thedischarges of technetium-99 to the Irish Sea. This has been reflected in an increase in the activity concentrationof this radionuclide at all east coast sampling sites during the reporting period. However, the low radiotoxicityof technetium-99 means that it is of lesser radiological significance than radiocaesium.

During 1997, the Institute collaborated with the Northern Ireland Environment and Heritage Service of theDepartment of the Environment for Northern Ireland in a follow-up of the 1990 survey of radioactivity levels inCarlingford Lough. The aim of this study was to examine the effects of the operation of the new plant atSellafield on the Lough. Results have shown that the activity concentration of technetium-99 measured insamples from Carlingford Lough did not differ significantly from those measured at other coastal sites on thenorth-east coast. A decrease in the activity concentrations of caesium-137 was observed during the period 1990to 1997, in line with that observed at other locations on the north-east coast.

The main pathway contributing to the exposure of the Irish public is the consumption of seafood. Thecommitted effective dose to heavy consumers of seafood due to artificial radionuclides in 1996 was 1.6 _Sv andin 1997 was 1.4 _Sv. Of this, caesium-137 is the dominant radionuclide, accounting for approximately 65% ofthe total dose. The dose to the Irish population due to this radionuclide has declined steadily since themonitoring programme commenced. For example, in 1982 the dose to heavy consumers was estimated to beapproximately 70 _Sv, this had fallen to 0.88 _Sv in 1997.

These doses may be put into context by comparing them with those attributable to the presence of the naturallyoccurring radionuclide polonium-210 in seafood. This has been estimated to be 148 µSv for heavy seafoodconsumers [Pollard et al., 1996]. The estimated doses may also be compared with the annual average dose ofapproximately 3000 µSv from all sources of radiation received by members of the Irish public. The dosereceived in 1997 by a heavy seafood consumer corresponds to a risk of developing a fatal cancer ofapproximately one in 13 million.

It is clear that the activities at Sellafield result in contamination of the Irish marine environment and exposureto the Irish population. However, the doses received through the consumption of seafood, walking on beachesor any other marine based activity, are very small and do not constitute a significant health risk. That thiscontamination of the Irish marine environment should occur, is however, clearly objectionable.

1

1. INTRODUCTION

This report presents the results of the marine radioactivity monitoring programme carried out by theRadiological Protection Institute of Ireland (RPII) during 1996 and 1997. The primary objective ofthe programme is to assess the exposure to the Irish population resulting from radioactivecontamination of the Irish marine environment and to estimate the risks to health. Secondaryobjectives include the determination of the distribution of contaminating radionuclides and theidentification of trends. To achieve these objectives the radioactive contents of fish, shellfish,seawater, seaweed and sediment are routinely monitored. Both the Marine Institute and theDepartment of the Marine and Natural Resources assist the Institute in implementing this programme.

In recent decades Irish coastal waters have been influenced by a number of anthropogenic sources.These include discharges from nuclear installations, fall-out from the Chernobyl accident in 1986,from atmospheric weapons testing during the 1950s and 1960s and discharges to sewage from somehospitals of radionuclides used for medical purposes. The most significant of these is the discharge oflow-level radioactive waste from the Sellafield nuclear fuel reprocessing plant on the Cumbrian coastin the north-west of England.

In addition to its routine monitoring activities, the Institute is actively involved in marineradioecology research aimed at providing a better understanding of the long term fate of radionuclidesin the marine environment. During 1996, the Institute began work on the Arctic MarineRadioecology project (ARMARA). The main objective of this collaborative project is to assess thepotential consequences of contamination of Arctic waters due to the disposal of radioactive wastes.Also in 1996, a survey of the geographical distribution of plutonium in seaweed was carried out andin 1997 the Institute introduced the technology to measure carbon-14 in environmental samples with aview to analysing this radionuclide on a routine basis in the future.

During 1997, the Institute collaborated with the Northern Ireland Environment and Heritage Servicein a follow-up of the 1990 survey of radioactivity levels in Carlingford Lough. The primary aim ofthe study was to determine whether radioactivity concentrations in the Lough were enhanced abovethose levels found elsewhere along the north-east coast and to examine the effects of thecommissioning and operation of the new reprocessing facilities at Sellafield on the Lough.

2

2. SOURCES OF RADIOACTIVITY IN THE IRISH MARINE ENVIRONMENT

The most significant source of radioactive contamination of the Irish Sea is the discharge of low levelliquid waste from the British Nuclear Fuels (BNFL) plant situated at Sellafield in Cumbria. Activitiesat Sellafield include spent fuel storage and reprocessing, the vitrification and storage of high levelradioactive wastes, decommissioning of the obsolete plant and the generation of nuclear power atCalder Hall. The primary source of radioactive waste at Sellafield is the reprocessing of spent nuclearfuel. Low-level liquid waste resulting from the reprocessing operation is treated to reduce itsradioactivity concentration and is then discharged to the Irish Sea. These discharges are authorisedand regulated by the UK Environment Agency, which stipulates that the best practical means be usedto limit the activity of the waste discharged and that discharges do not exceed prescribed limits. TheSellafield marine discharge data for 1996 and 1997 and the discharge limits are presented in Table 1[MAFF and SEPA, 1997; BNFL, 1998].

The discharges from Sellafield began in the early 1950s and were relatively low until the early to mid-1970s, when considerably larger discharges were observed due to problems associated with fuelstorage [Manson, 1994]. Discharges then decreased during the late 1970s and early 1980s. Thecommissioning of the Site Ion Exchange Effluent (SIXEP) and Salt Evaporator waste treatment plantsresulted in a substantial reduction in discharges from the mid-1980s onward. Since 1986, dischargesof most radionuclides from the site have remained relatively constant. The discharges of theradionuclide caesium-137 between 1952 and 1997 are illustrated in Figure 1.

Annual marine discharges of technetium-99 from the Sellafield site have increased significantly since1994.This is clearly shown in Figure 2 which shows annual discharges of this radionuclide for theperiod 1988 to 1997. The average annual discharge for the period 1995 to 1997 is approximatelythirty times that for the period 1990 to 1993. The increased discharges of technetium-99 are duemainly to the processing of a backlog of liquid waste through the Enhanced Actinide Removal Plant(EARP). This liquid waste had been accumulated in storage tanks on site since the early 1980s andcontains a range of long-lived radionuclides including technetium-99, americium and plutonium.EARP, which is designed to reduce the concentrations of actinides in effluent discharged to the IrishSea, is ineffective at removing technetium. Hence the processing of this waste backlog has resulted ina large increase in the quantities of technetium discharged.

Fall-out from nuclear weapons testing, most of which was carried out during the 1950s and 1960s, hasalso resulted in contamination of the marine environment. The longer lived radionuclides, such astritium, carbon-14, strontium-90, caesium-137 and plutonium-239,240, resulting from these testscontinued to contribute to the inventory of artificial radioactivity in the Irish marine environment.

The dumping of low-level solid radioactive waste in the marine environment has been carried out in aregion of the north-east Atlantic. This dumping was regulated and monitored by the Nuclear EnergyAgency (NEA) of the Organisation for Economic Co-operation and Development (OECD). Avoluntary moratorium on dumping solid waste at sea was agreed in 1983 followed by a total ban in1993 [OECD, 1996]. Assessments have shown that these disposals have had negligible impact on themarine environment [OECD, 1985].

The UK Government revealed in 1997 that dumping of radioactive wastes had taken place on alimited scale between 1957 and 1976 at five sites in the Irish Sea. The materials dumped includedsludges and packaged solid wastes. The Minister for the Marine and Natural Resources established aTask Force to examine the impact of this dumping. As part of this study, the Institute, in conjunctionwith the Physics Department of University College Dublin commenced an assessment of the potentialdoses to members of the Irish population from this dumping. Initial results indicate that it wasunlikely to have caused a health hazard. A similar conclusion was reached in studies undertaken bythe UK National Radiological Protection Board. [Titley et. al., 1997].

3

Figure 1 Marine Discharges of Caesium-137 from Sellafield, 1952 – 1997

Radionuclides such as iodine-131 are used for medical purposes and subsequently discharged fromhospitals to sewage, resulting in traces of these radionuclides in some Irish coastal waters. As theseradionuclides are short-lived, their contribution to the inventory of artificial radionuclides in themarine environment is small.

The primary source of radioactivity in the marine environment is of natural origin. The activityconcentrations of the naturally occurring radionuclides most commonly found in seawater aresummarised in Table 2 [Walker and Rose, 1990]. Of these polonium-210, because of the degree towhich it is concentrated by certain species of fish and shellfish and due to its relatively highradiotoxicity, is known to make the most significant contribution to radiation exposure through theconsumption of marine foodstuffs [Pollard et. al., 1998].

Potassium-40, although present in relatively large activity concentrations in the marine environment,is controlled by homeostatic processes in the human body and so its activity concentration in the bodyis normally independent of the amount consumed. Therefore, whilst the activity concentrations of thisradionuclide in seafood are considerably higher than many other natural radionuclides, its presencedoes not result in an increased radiological hazard.

4

Figure 2 Marine Discharges of Technetium-99 from Sellafield, 1988 – 1997

0

20

40

60

80

100

120

140

160

180

200

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997

Year

TBq/

year

5

3. METHODS OF SAMPLING AND ANALYSIS

Sampling

During 1996 and 1997 fish and shellfish were routinely collected from commercial landings at majorfishing ports. Seawater, sediment and seaweed were also collected from a number of coastal sites andseawater and sediment samples were taken annually at a number of off-shore sites in the western IrishSea. The Marine Institute’s research vessels the Lough Beltra and the Celtic Voyager were used foroff-shore sample collection in 1996 and 1997, respectively. Routine sampling sites are shown inFigure 3 and off-shore locations in Figure 4 with their coordinates listed in Table 3. Sampling detailsare given in Table 4. The sampling frequency for each site reflects the resolution judged to benecessary to assess the population dose and to identify important trends. Carlingford Lough samplingsites are shown in Figure 5.

The fish species routinely monitored were whiting (Merlangius merlangus), cod (Gadus morhua),plaice (Pleuronectus platessa), herring (Clupea harengus), mackerel (Scomber scombrus), and ray(Raja sp.). These constitute the major proportion of fish landings and are the more common speciesconsumed by members of the Irish public. The shellfish species routinely monitored were prawns(Nephrops), mussels (Mytilus edulis) and oysters (Crassostrea gigas).

Coastal sampling along the south and west coasts was carried out by the Department of the Marineand Natural Resources’ Fisheries Officers in conjunction with Institute staff. Sampling at CarlingfordLough was jointly carried out by Institute staff and by staff from the Northern Ireland Environmentand Heritage Service. Institute staff carried out all other sampling.

Figure 3 Coastal Sampling Locations

Galway

Greenore

Balbriggan

Bull Island

Carlingford

Clogherhead

Howth

Killybegs

Dunmore East

Cahore

CastletownbereBantry

6

Figure 4 Sampling Stations in the Western Irish Sea

Analysis

Initial preparation included cleaning fish and shellfish samples and separation of the edible portion foranalysis. Seaweed samples were washed to remove all sediment and other extraneous material. Fish,shellfish, seaweed and sediment samples were then dried to constant weight and thoroughly mixed.Following this all samples were individually analysed for caesium-137 and other gamma-emittingradionuclides. Selected individual and bulked samples were analysed for potassium-40, technetium-99, iodine-131, plutonium-238, plutonium-239,240 and americium-241. Analytical and measurementtechniques are summarised in Table 5. The activity concentrations of americium-241 in fish andcrustaceans were calculated using the activity concentration in molluscs and published concentrationfactors [IAEA, 1985].

All results are quoted as activity concentrations in Bq/kg or mBq/l and are decay corrected to the dateof sampling. Bulked samples are decay corrected to the middle of the bulking period. Approximatedetection limits under typical analytical conditions are 0.1 Bq/kg for technetium-99, 1.0 Bq/kg foriodine-131, 0.3 Bq/kg for caesium-134 and caesium-137, 1.0 mBq/kg for plutonium-238 andplutonium-239,240 and 2.0 mBq/kg for americium-241. Under typical counting conditions, two-sigma uncertainties on gamma spectrometry measurements were ± 15% or better, while those fortechnetium-99 measurements were ± 10% or less.

During 1997, the Institute’s radioanalytical laboratory was awarded accreditation by the NationalAccreditation Board (NAB). It implements a comprehensive quality assurance system and allmeasurements are made by reference to certified radioactive sources traceable to internationalstandards. All analytical techniques conform to current best international practice and are normallyvalidated both through participation in intercomparison exercises and by analysis of certifiedreference materials.

7

Figure 5 Sampling Stations in Carlingford Lough

Narrow Water Castle

Golf Course

Rostrevor

Dundalk

Carlingford

Greenore

Ballyagon

Carrigaroan

SoldiersPoint

Killkeel

C4

C3

C2

C1

8

4. RADIOACTIVITY CONCENTRATIONS

Seawater

All seawater samples were analysed for caesium-137 and a selected number for technetium-99. Theresults are presented in Tables 6, 7 and 13.

In 1997 the activity concentrations of caesium-137 in seawater from the Irish Sea coast-line rangedfrom 57 mBq/l at Greenore, the most northern Irish Sea sampling point, to 9 mBq/l at Cahore, themost southern sampling point. The mean activity concentration of caesium-137 measured in seawaterfrom Carlingford Lough was 39 mBq/l. The activity of seawater at the mouth of the Lough was lowerthan inside the Lough. In off-shore samples from the western Irish Sea activity concentrations rangedfrom 36 mBq/l at station N6, off Dundalk Bay, to 14 mBq/l at station S2, south east of Dublin andthose from the south and west coasts from <2 to 3 mBq/l. These activity concentrations were similarto those measured in 1996.

A decrease in the activity concentration of caesium-137 in the Irish Sea has been observed since themid 1980s [McGarry et al., 1994; O’Grady et al., 1991; O'Grady and Currivan, 1990; Cunningham etal., 1988]. The results reported during the mid-1990s show that this decline is less pronounced, withactivity concentrations stabilising [Pollard et al., 1996]. This trend is illustrated in Figure 6, whichshows the activity concentration of caesium-137 in seawater from the off-shore site N1, east ofDublin, between 1985 and 1997. It is attributable to the reduction in discharges of caesium-137 fromSellafield over this period. In addition, areas of mud and silt accumulation in the Irish Sea havebecome secondary sources of radiocaesium. This is due to the higher adsorption of radioactivity bythe fine mud and sediment particles, relative to coarser sediments in other parts of the Irish Sea,followed by remobilisation of the sediment-bound radionuclides into the water column [Hunt andKershaw, 1990]. It has caused a slower decline in the activity concentration of caesium-137 than hadbeen expected due to the decreases in discharges of this radionuclide. The decrease in activityconcentration of caesium-137 measured in samples from Carlingford Lough between 1990 and 1997is in line with that observed at other east coast sites during the period [O’Grady et al., 1991].

The activity concentrations of caesium-137 in the Irish Sea show a clear decrease with increasingdistance from Sellafield. The caesium-137 activity concentrations along the south and west coastsremained unchanged from those measured in previous years.

The mean concentrations of technetium-99 measured in seawater samples from the western Irish Seawere 28 and 40 mBq/l during 1996 and 1997 respectively. The mean concentration of technetium-99measured in seawater from Carlingford Lough during 1997 was 47 mBq/l. Average annualconcentrations at Balbriggan were 19 and 45 mBq/l for 1996 and 1997 respectively. By comparison,the 1995 average values for Balbriggan and the western Irish Sea were 20 and 25 mBq/l respectively.This increase over the period 1995 to 1997 indicates that activity concentrations in the western IrishSea may not yet have reached equilibrium. The activity concentration of technetium-99 measured insamples from the south and west coasts were below the detection limits.

9

Figure 6 Caesium-137 in Seawater from N1, Irish Sea, 1985 – 1997

Sediment

All sediment samples were analysed for caesium-137 and other gamma emitting radionuclides. Theresults are presented in Tables 8, 9 and 14.

In 1997, the mean activity concentration of caesium-137 in east coast sediments ranged from 23.0Bq/kg (dry) at Carlingford Harbour to 0.7 Bq/kg (dry) at Cahore. In general, the activityconcentration measured in sediments from Carlingford Lough has decreased over the period 1990 to1997 [McGarry et al., 1994]. The activity concentrations of caesium-137 in off-shore samples fromthe western Irish Sea ranged from 0.5 Bq/kg (dry) at station S3, south east of Dublin, to 93.4 Bq/kg(dry) at station N5 between Dundalk Bay and the Isle of Man. The activity concentrations insediment from the south and west coasts ranged from <0.3 to 3.9 Bq/kg (dry). These concentrationsare similar to those measured in 1996 and to those measured between 1993 and 1995 [Pollard et al.,1996]. All other artificial gamma emitting radionuclides were below the detection limit of themeasurement system.

The coastal distribution of caesium-137 in sediments was similar to that observed in seawater with adecrease in activity concentration with increasing distance from Sellafield. The relatively highactivity concentrations of caesium-137 measured in sediments from locations between Dundalk Bayand the Isle of Man (N3 – N6 inclusive) may be attributed to their being from an area of mud and siltaccumulation. The activity concentrations measured at these four sites during 1997 were 42.7, 46.9,93.4 and 46.7 Bq/kg respectively.

Seaweed

All seaweed samples were analysed for caesium-137 and other gamma emitting radionuclides and aselected number for iodine-131 and technetium-99. The results are presented in Tables 10, 11 and 14.The results of the 1996 survey of the geographical distribution of plutonium in seaweed are given inTable 12. All results are presented on a dry weight basis and may be converted to wet weight activityconcentration using the mean dry:wet weight ratio of 0.18.

In 1997, the mean caesium-137 activity concentration in seaweed (Fucus vesiculosus) from the IrishSea coastline ranged from 9.8 Bq/kg (dry) at Carlingford Harbour to 1.3 Bq/kg (dry) at Cahore. Theactivity concentrations in seaweed from the south and west coasts were below 0.4 Bq/kg (dry).

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85 87 89 91 93 95 97

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mB

q/l

10

The activity concentrations of caesium-137 measured during 1996 and 1997 exhibit the samedownward trend evident in other marine compartments. Again, this downward trend was lesspronounced than during the late 1980s and early 1990s. The decrease in caesium-137 activityconcentration in samples from Carlingford Lough between 1990 and 1997 is comparable with thatobserved at other sites during the same period. Caesium-137 activity concentrations were observed todecrease with increasing distance from Sellafield. This is illustrated in Figure 7, which shows thegeographical distribution of caesium-137 in Fucus vesiculosus during 1996.

Figure 7 Caesium-137 in Fucus vesiculosus, (Bq/kg, dry weight), 1996

Iodine-131 is discharged to sewage systems as a result of its use in medicine. Mean activityconcentrations for this radionuclide of 57.9 and 76.6 Bq/kg (dry) were measured in samples from BullIsland during 1996 and 1997 respectively. Results ranged from <4 to 277.5 Bq/kg (dry). Variationsof this nature would be expected due to the intermittent use of the radionuclide and the dilution of theradioactivity following discharge. These results are broadly similar to those reported previously[Pollard et al., 1996; McGarry et al., 1994]. All other artificial gamma emitting radionuclides werebelow the detection limits of the technique.

During 1997 the mean activity concentration of technetium-99 measured in seaweed from the IrishSea coastline ranged from 8457 Bq/kg (dry) at Ballyagon, in Carlingford Lough, to 869 Bq/kg (dry) atCahore. Activity concentrations measured in samples collected from south and west coasts weresignificantly lower. An increase in technetium-99 concentrations in seaweeds was observed at all eastcoast sampling stations during the reporting period.

A series of seaweed samples taken from Balbriggan, covering the period 1988 to 1993 were analysedto establish a pre-EARP technetium-99 baseline. The average of these measurements was 336 Bq/kg

Galway

Greenore

Balbriggan

Bull Island

Killybegs

Dunmore East

Cahore

Castletownbere

6.0

4.6

4.6

0.8

0.6

0.6

0.6

0.6

11

(dry). By comparison, annual average activity concentrations at Balbriggan were 2955 and 4976Bq/kg (dry) for 1996 and 1997 respectively. At Rosslare, on the south-east coast, an activityconcentration of 142 Bq/kg (dry) was recorded during 1994 [Pollard et al., 1996]. This may becompared with the activity concentration of 869 Bq/kg (dry) measured at Cahore during 1997. Themaximum value observed corresponds to a twenty-five fold increase over the baseline activityconcentration.

Technetium-99 activity concentrations in seaweed from Balbriggan and Greenore are shown in Figure8 for the period June 1988 to November 1997. These data show the increase between 1994 and 1997and indicate that activity concentrations in seaweeds may not yet have reached equilibrium. Figure 9illustrates the decreasing activity concentration of technetium-99 with increasing distance fromSellafield.

No significant increase was observed in technetium-99 activity concentrations in seaweed from thesouth and west coasts during the reporting period. In general, the differences observed over theperiod at individual sampling stations along these coastlines were within the expected sample tosample variability. At Dunmore East, for example, the mean activity concentration was 24.6 Bq/kg(dry) during the current period as compared to 46 Bq/kg (dry) during the previous period. Similarly, atKillybegs the mean observations for the current and previous reporting periods were 9.1 and 8.5Bq/kg (dry), respectively [Pollard et al., 1996].

Figure 8 Technetium-99 in Fucus vesiculosus from Balbriggan and Greenore, 1988-1997

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Aug-87 Dec-88 May-90 Sep-91 Jan-93 Jun-94 Oct-95 Mar-97 Jul-98Date

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ry w

eigh

t)

Balbriggan

Greenore

12

Figure 9 Technetium-99 in Fucus vesiculosus (Bq/kg, dry weight), 1996

Plutonium activity concentrations were measured in Fucus vesiculosus sampled from 8 locationsaround the Irish coast in 1996. The results are presented in Figure 10 and Table 12. The activityconcentrations of plutonium-238 and plutonium-239,240 decreased down the east coast from 376 and2052 mBq/kg (dry) respectively, at Greenore, to 54 and 164 mBq/kg (dry) respectively, at Cahore.The mean activity concentrations of plutonium-238 and plutonium-239,240 in Fucus vesiculosus fromthe west and south coasts are lower again at 9 mBq/kg (dry) and 54 mBq/kg (dry), respectively. Therelatively higher east coast activity concentrations can be attributed to Sellafield discharges.

The mean activity concentration of the naturally occurring radionuclide potassium-40 did not differsignificantly between sampling locations, and ranged from 626 Bq/kg (dry) at Killybegs to 1390Bq/kg (dry) at Balbriggan in 1997. These are similar to those measured during previous reportingperiods [Pollard et al., 1996; McGarry et al., 1994; O’Grady et al., 1991].

4950

2955

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41

6.9

9.1

Galway

Greenore

Balbriggan

Killybegs

Dunmore East

Castletownbere

13

Figure 10 Plutonium-239,240 in Fucus vesiculosus, (mBq/kg, dry weight) 1996

Fish and Shellfish

All fish and shellfish samples were analysed for caesium-137 and other gamma emitting radionuclidesand a selected number of individual and bulked samples for technetium-99, plutonium-238,plutonium-239,240 and americium-241. The mean and range of all fish results are presented inTables 15 to 21 and those for shellfish in Tables 22 to 26.

During 1997, the mean caesium-137 activity concentrations measured in demersal fish (cod, plaice,ray and whiting) and pelagic fish (herring and mackerel) landed at Irish Sea ports were 1.0 and 0.6Bq/kg (wet) respectively. The mean caesium-137 activity concentrations measured in shellfish fromIrish Sea locations ranged from 0.3 Bq/kg (wet) in oysters from Carlingford to 1.3 Bq/kg (wet) inprawns from Howth. These were similar to those measured during 1996.

In general, the activity concentrations measured in pelagic species were lower than those measured indemersal species. This is because demersal species landed at east coast ports were likely to have beencaught in the Irish Sea, whereas pelagic species were likely to have originated in the Atlantic Oceanor the Celtic Sea [Marine Institute, 1998]. The activity concentrations measured in shellfish tend tobe somewhat lower than those measured in fish due to differences in concentration factors [IAEA,1985].

For fish and shellfish, the general trend in activity concentration during 1996 and 1997 was a gradualdownward one, although not so marked as in recent years. This is illustrated in Figure 11, whichshows the caesium-137 activity concentration in fish and prawns landed at north-east ports from 1982to 1997. The activity concentration of caesium-137 measured in shellfish collected from CarlingfordLough has decreased since the 1990 survey in line with the decrease observed at other east coast sites.As in all other marine compartments, the measured activity concentration of this radionuclide

Galway

Greenore

Balbriggan

Bull Island

Killybegs

Dunmore East

Cahore

Castletownbere

2052

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1919

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46

14

decreases with increasing distance from Sellafield. For example, during 1997, the mean caesium-137activity in whiting from north-east ports was 0.9 Bq/kg (wet), while that from Celtic Sea and AtlanticOcean ports was 0.4 Bq/kg (wet). All other artificial gamma emitting radionuclides were below thedetection limits of the technique.

The mean activity concentrations of technetium-99 in fish, crustaceans and molluscs from north-eastports during 1997 were 0.15, 87.8 and 25.3 Bq/kg (wet) respectively. In general, activityconcentrations were observed to be higher in crustaceans than in molluscs and higher in molluscs thanin fish. This is due to the higher concentration factor for this radionuclide in shellfish than in fish.For lobster, the species with the highest concentration factor for technetium-99, the mean activityconcentration measured in north-east coast landings was 209 Bq/kg (wet). The highest individualobservation for lobster was 465 Bq/kg (wet) for a sample taken from Dundalk Bay in October 1997.

During 1996 and 1997 the activity concentrations of plutonium-238 in fish ranged from <1.0 x 10-4 to6.3 x 10-4 Bq/kg (wet), of plutonium-239,240 from 2.2 x 10-4 to 3.7 x 10-3 Bq/kg (wet) and ofamericium-241 from <2.2 x 10-2 to 1.4 x 10-1 Bq/kg (wet). Activity concentrations measured inprawns, mussels and oysters ranged from 2.8 x 10-4 to 3.6 x 10-2 Bq/kg (wet) for plutonium-238, 5.3 x10-3 to 2.0 x 10-1 Bq/kg (wet) for plutonium-239,240 and <1.5 x 10-2 to 1.3 x 10-1 Bq/kg (wet) foramericium-241. In general, actinide activity concentrations in shellfish are greater than fish due totheir higher concentration factors for these radionuclides [IAEA, 1985]. The activity concentrationsof actinides in fish and shellfish were similar to those reported previously [Pollard et al., 1996].

Figure 11 Radiocaesium in Fish and Prawns Landed at North-East Ports, 1982 – 1997

0

10

20

30

40

50

60

82 84 86 88 90 92 94 96

Year

Bq/k

g, w

et

15

5. ASSESSMENT OF RADIATION EXPOSURE.

The Ingestion Pathway

Committed Effective Dose

The committed effective dose due to the consumption of seafood was estimated for typical and heavyconsumers as follows:

dose = mean activity concentration x annual consumption rate x dose conversion factor

The weighted mean activity concentrations in fish, crustaceans and molluscs from north-east ports arepresented in Table 27. Activity concentrations in prawns and mussels were considered to berepresentative of those in crustaceans and molluscs, respectively. The consumption rates used wereconsidered to be representative of the quantities eaten daily by typical and heavy consumers ofseafood and are 40 g of fish and 5 g of shellfish for a typical consumer and 200 g of fish and 20 g ofshellfish for a heavy consumer. Dose conversion factors used were those recommended by ICRP 72[ICRP, 1996].

The committed effective doses, due to technetium-99, caesium-137, plutonium-238, plutonium-239,240 and americium-241, for typical and heavy consumers of seafood landed at north-east portsare given in Table 28. The total doses for 1996 and 1997 respectively were estimated to be 0.34 and0.32 µSv to a typical consumer and 1.56 and 1.43 µSv to a heavy consumer. These compare withdoses to a heavy consumer during 1993, 1994 and 1995 of 3.3, 2.5 and 2.0 µSv respectively.

These doses may be compared with those attributable to the presence in seafood of the naturallyoccurring radionuclide, polonium-210. The latter were estimated to be 32 and 148 µSv for typicaland heavy consumers, respectively [Pollard et al., 1996]. The doses may also be compared with theannual dose limit for members of the public from practices involving controllable sources of radiationwhich is 1000 µSv [ICRP, 1991]. Thus, during this reporting period, typical and heavy consumerswould have received about 0.05% and 0.2% of this limit respectively.

Another comparison can be made with the annual average dose of approximately 3000 µSv from allsources of radiation received by members of the Irish public. Of this, approximately 90% is due tonaturally occurring radiation and the remainder is mainly due to medical uses of radiation. It can beseen, therefore, that the doses arising from the consumption of fish and shellfish, even by heavyconsumers, are a very small fraction of those received from other sources.

Caesium-137 continues to be the dominant radionuclide, accounting for approximately 65% of thetotal dose due to artificial radionuclides in the marine environment. Although there are significantlyhigher activity concentrations of technetium-99 than of caesium-137 in shellfish, technetium-99accounts for only approximately 15% of the dose. This is because the quantity of shellfish consumedis small relative to the quantity of fish, which have a substantially lower activity concentration oftechnetium-99 than do shellfish. In addition, the dose received per becquerel of technetium-99ingested is approximately 20 times less than that received per becquerel of caesium-137.

Of the dose attributable to caesium-137, approximately 90% is due to the consumption of fish,reflecting the assumed ingestion pattern. This is in contrast to the dose due to technetium-99, whereapproximately 75% of the dose is attributable to crustaceans alone, reflecting the significantly higheractivity concentrations of this radionuclide measured in crustaceans than in molluscs or fish (Table27).

The estimated committed effective dose to heavy consumers due to radiocaesium alone is shown inFigure 12 for the period 1982 to 1997. A downward trend is evident during the mid to late 1980s but

16

in recent years the decrease in dose has been less pronounced, reflecting the pattern of caesium-137activity concentrations in seafood.

Technetium-99 activity concentrations in seaweed from the Irish Sea coastline are substantially higherthan in fish and shellfish. However, commercial harvesting of seaweed as a foodstuff occurs only onthe western and southern coasts of Ireland [Irish Seaweed Industry Organisation, 1998] where nosignificant increase in technetium-99 activity concentrations has been observed. Thus, no ingestiondose results from the presence of technetium-99 in seaweeds from the Irish Sea coastline.

Figure 12 Doses to Heavy Seafood Consumers, due to Radiocaesium, 1982 – 1997

0

20

40

60

80

82 84 86 88 90 92 94 96

Year

uSv/

y

17

Collective Effective Dose

The collective effective dose commitment was calculated for the consumption of fish, crustaceans andmolluscs landed at north-east Irish Sea ports. The quantities of fish, crustaceans and molluscs landed(Table 29) were combined with the mean activity concentration for each radionuclide measured(Table 27). The fraction of the landing weight consumed for fish, crustaceans and molluscs weretaken to be 0.5, 0.35 and 0.15 respectively [Pentreath et al., 1989]. It was assumed that 20% oflandings were consumed in Ireland and the remainder exported.

The collective doses to the Irish population, due to artificial radionuclides, for the years 1996 and1997 were 0.011 and 0.025 manSv respectively (Table 30). This increase in collective dose isattributable to the increased annual landing tonnage at north-east Irish Sea ports (Table 29). Forexample, the 1997 landings of both crustaceans and molluscs at these ports were almost three timesthose in 1996. The collective doses to the Irish population, due to caesium-137 alone, for the years1996 and 1997 were 0.0052 and 0.0074 manSv respectively. The corresponding doses for 1993, 1994and 1995 were 0.017, 0.010 and 0.013 manSv respectively [Pollard et al., 1996]. The observedannual variation in the dose due to caesium-137 is a function of both the reduced activityconcentrations of caesium-137 in seafood and differences in the annual landing tonnage at ports.These doses may be compared to the collective dose to the Irish population from all sources ofradiation of approximately 10,000 manSv per annum.

External Exposure

External exposure from beach occupancy was estimated from activity concentrations in intertidalsediments using the sandy beach model described by Hunt [1984]. The effective dose was calculatedfor an individual spending one hour per day in the intertidal zone and is based on the caesium-137activity concentration in sediment. The activity concentration used in this calculation was the meanfor the two sandy beach sampling locations in the north east, Balbriggan and Greenore, averaged overthe reporting period. External exposure due to technetium-99 activity concentrations in seaweed fromthe Irish Sea coastline is not considered to be of radiological significance.

For 1996 and 1997 the annual external dose was estimated to be 0.3 µSv. In the absence of habitsurvey data it is assumed that the actual number of people who spend 365 hours per year in theintertidal zone along the north-east coast is small compared with the number of typical fishconsumers. Therefore, while the estimates presented here for external dose and ingestion dosecommitment are numerically similar, it is assumed that the number of people exposed via the externalpathway is considerably smaller and so the ingestion pathway is still considered to be the dominantone affecting the Irish population. Other external exposure pathways such as swimming in the sea orboating are considered to be insignificant.

Risk Estimates

Evaluation of the risks associated with radiation exposure is based on the assumption that there is alinear relationship between radiation dose and the risk of a fatal cancer. The probability of a fatalcancer occurring in an exposed population is estimated to be 5 x 10-2 per sievert, i.e. a chance of 1 in20 of developing a fatal cancer after exposure to a radiation dose of 1 Sv [ICRP, 1991]. The radiationinduced risk for 1996 and 1997 are, therefore, about one in 60 million to a typical Irish seafoodconsumer and about one in 13 million to a heavy consumer. These compare with a risk in any year ofdeath from cancer of 1 in 479 and from road accidents of 1 in 9232 [Central Statistics Office, 1996].

18

6. CONCLUSIONS

The consumption of fish and shellfish from the Irish Sea is the dominant pathway through whichradioactive contamination of the marine environment results in radiation exposure of the Irishpopulation. In 1996 and 1997 the radiation doses to a heavy consumer of seafood from the Irish Seawere 1.6 µSv and 1.4 µSv, respectively, showing a continuing slight fall from the values of 3.3 µSv,2.5 µSv and 2.0 µSv in the three previous years.

The increased discharges of technetium-99 from Sellafield since 1994 have resulted in correspondingincreases in the contribution of this radionuclide to the doses to seafood consumers during 1996 and1997. However, because of the lower radiotoxicity of technetium-99 it contributes onlyapproximately 15% of the total dose due to radioactive contamination of Irish Sea fish and shellfish,still significantly less than the 65% contribution made by caesium-137 to this dose.

The balance of the dose to the seafood consumer can be attributed to plutonium and americium. Aparticularly objectionable characteristic of these radionuclides is the fact that, because of theirbehaviour in the marine environment and their long physical half-lives, they will persist in the IrishSea for a very long time.

The above doses to a heavy consumer of seafood from the Irish Sea can be compared with doses inthe region of 70 µSv in the early 1980s [McAulay and Doyle, 1985; Cunningham and O’Grady,1986]. They can also be compared with the dose of about 150 µSv received by the same consumerdue to the presence of the naturally-occurring radionuclide polonium-210 in seafood [Pollard et al,1996], and with the average annual dose to a person in Ireland from all sources of radioactivity ofabout 3000 µSv.

Although radiation doses to Irish people resulting from Sellafield discharges are now very low and donot pose a significant health risk to the public, any contamination of the marine environment, due toan installation from which Ireland derives no benefit, remains highly objectionable from an Irishviewpoint. However, it is emphasised that the levels of radioactive contamination which prevail atpresent do not warrant any modification of the habits of people in Ireland, either in respect ofconsumption of seafood or any other use of the amenities of the marine environment.

7. ACKNOWLEDGMENTS

The authors gratefully acknowledge the assistance of the Department of the Marine and NaturalResources and of the Marine Institute. In particular, the assistance of the Fisheries Officers and thecaptain and crew of the R.V. Celtic Voyager is acknowledged.

The work of other Institute laboratory staff not directly involved in the programme but who providedanalytical support is also acknowledged.

19

8. REFERENCES

Baker, C.W., 1975. The determination of radiocaesium in sea and fresh waters. TechnicalReport No. 16. Lowestoft: Fisheries Radiological Laboratory, Ministry of Agriculture, Fisheries andFood.

British Nuclear Fuels Limited (BNFL), 1998. Personal communication.

Central Statistics Office (CSO), 1996. Vital statistics fourth quarter and yearly summary 1995.Dublin: Stationery Office.

Cunningham, J.D. and O'Grady, J., 1986. Radioactivity monitoring of the Irish marineenvironment during 1982-84. Dublin: Nuclear Energy Board.

Cunningham, J.D., O'Grady, J., Rush, T., 1988. Radioactivity monitoring of the Irish marineenvironment, 1985-1986. Dublin: Nuclear Energy Board.

Department of the Marine and Natural Resources, 1998. Personal communication.

Harvey, B.R., Ibbett, K.D, Williams, J.K. and Lovett, M.B, 1991. The determination oftechnetium-99 in environmental materials. Aquatic Environment Protection: Analytical MethodsNumber 8. Directorate of Fisheries Research, Lowestoft, 1991.

Hunt, G.J., 1984. Simple models for prediction of external pathways. Radiation ProtectionDosimetry, 8, (4), 215-224. Nuclear Technology Publishing.

Hunt, G.J. and Kershaw, P.J., 1990. Remobilisation of artificial radionuclides from the sediment ofthe Irish Sea. J. Radiol. Prot., 10(2), 147-151.

International Atomic Energy Agency (IAEA), 1985. Sediment Kds and concentration factors forradionuclides in the marine environment. Technical Report Series No. 247. Vienna: IAEA.

International Commission on Radiological Protection (ICRP), 1991. 1990 recommendations of theInternational Commission on Radiological Protection. Annals of the ICRP, 21(1-3), PublicationNo. 60.

International Commission on Radiological Protection (ICRP), 1996. Age-dependent doses tomembers of the public from intakes of radionuclides: Part 5, compilation of ingestion andinhalation coefficients. Annals of the ICRP, 26, (1), Publication No. 72.

Irish Seaweed Industry Organisation, 1998. Personal communication.

Manson, P.J., 1994. Radiological history of a magnox fuel handling facility. In: Proceedings of the17th IRPA regional congress held in Portsmouth, June 6-10, 1994. 407-410. United Kingdom:Nuclear Technology Publishing.

Marine Institute, 1998. Personal communication.

McAulay, I.R. and Doyle, C., 1985. Radiocaesium levels in Irish Sea fish and the resulting dose tothe population of the Irish republic. Health Physics, 48(3), 333-337.

McGarry, A., Lyons, S., McEnri, C., Ryan, T., O'Colmain, M. and Cunningham, J.D., 1994.Radioactivity monitoring of the Irish marine environment, 1991-1992. Dublin: RadiologicalProtection Institute of Ireland.

20

Ministry of Agriculture, Fisheries and Food (MAFF) and the Scottish Environmental ProtectionAgency (SEPA), 1997. Radioactivity in food and the environment, 1996. United Kingdom: MAFFand SEPA.

O'Grady, J. and Currivan, L., 1990. Radioactivity monitoring of the Irish marine environment,1987. Dublin: Nuclear Energy Board.

O'Grady, J., Currivan, L., McEnri, C., O'Colmain, M., Colgan, P.A. and Cunningham, J.D., 1991.Radioactivity monitoring of the Irish marine environment, 1988-1990. Dublin: Nuclear EnergyBoard.

Organisation for Economic Co-operation and Development (OECD), 1985. Review of the continuedsuitability of the dumping site for radioactive waste in the Northeast Atlantic. Nuclear EnergyAgency (NEA) of the OECD. Paris: NEA.

Organisation for Economic Co-operation and Development (OECD), 1996. Co-ordinated researchand environmental surveillance programme related to sea disposal of radioactive waste(CRESP). Final Report 1981 – 1995. Paris: OECD.

Pentreath, R.J., Camplin, W.C. and Allington, D.J., 1989. Individual and collective dose rates fromnaturally occurring radionuclides in seafood. In: Proc. Fourth Int. Symp. of the Society ofRadiological Protection, June 1989, Malvern, U.K. 297 – 300. United Kingdom: Institute ofPhysics.

Pollard, D., Long, S., Hayden, E., Smith, V., Ryan, T.P., Dowdall, A., McGarry, A. and Cunningham,J.D., 1996. Radioactivity monitoring of the Irish marine environment, 1993-1995. Dublin:Radiological Protection Institute of Ireland.

Pollard, D., Ryan, T.P. and Dowdall, A., 1998. The dose to Irish seafood consumers from Po-210.Radiation Protection Dosimetry, 75 (1-4), 139-142.

Titley, J.G., Harvey, M.P., Mobbs, S.F., Bexon, A., Penfold, J.S.S., and Cooper, J.R., 1997.Assessment of the radiological implications of dumping in Beaufort’s Dyke and other coastalwaters from the 1950s. NRPB-M859. United Kingdom: National Radiological Protection Board(NRPB).

Walker, M.I. and Rose, K.S.B., 1990. The radioactivity of the sea. Nuclear Energy, 29(4) 267-278.

21

9. GLOSSARY OF TERMS

Absorbed Dose

Quantity of energy imparted by the ionising radiation to unit mass of matter such as tissue. It ismeasured in grays (Gy). One Gy produces different biological effects on tissue depending on the typeof radiation i.e. alpha, beta or gamma.

Activity

Quantity of a radionuclide. It describes the rate at which spontaneous emission occurs. The unit ofactivity is the becquerel (Bq). One Bq is equivalent to one disintegration per second.

Collective Effective Dose

Total dose over a population group exposed to a given source. It is represented by the product of theaverage effective dose equivalent to the individuals in the group by the number of persons comprisingthe group. It is measured in man-sieverts (manSv).

Committed Effective Dose

Total dose gradually delivered to an individual over a given period of time by the decay of aradionuclide following its intake into the body. The integration time is usually taken as 50 years foradults and 70 years for children.

Effective Dose

Weighted sum of the equivalent doses to the various organs and tissues. The weighting factor foreach organ or tissue takes account of the fractional contribution of the risk of death or serious geneticdefect from irradiation of that organ or tissue to the total risk from uniform irradiation of the wholebody. The unit of effective dose is the sievert (Sv).

Equivalent Dose

The quantity obtained by multiplying the absorbed dose by a factor representing the differenteffectiveness of the various types of radiation in causing harm to tissues. It is measured in sieverts(Sv). One Sv produces the same biological effect irrespective of the type of the radiation.

Half-life

The time taken for the activity of a radionuclide to lose half its value by decay.

Radionuclide

An unstable nuclide that emits ionising radiation. The emissions may be either alpha, beta or gammaradiation.

Radiotoxicity

A measure of the dose per becquerel ingested resulting from the intake of a particular radionuclide.

22

10. RADIATION QUANTITIES AND UNITS

Quantity Name and Symbol

Activity Becquerel (Bq)

Absorbed dose Gray (Gy)

Effective Dose

Equivalent DoseSievert (Sv)

Collective dose Man sievert (manSv)

In addition multiples and sub-multiples of the above units are frequently used. The most commonones are given below.

Activity: Dose:

1 millibecquerel (1 mBq) = 1 x 10-3 Bq 1 microsievert (1 µSv) = 1 x 10-6 Sv

1 kilobecquerel (1 kBq) = 1 x 103 Bq 1 millisievert (1 mSv) = 1 x 10-3 Sv

1 megabecquerel (1 MBq) = 1 x 106 Bq

1 terabecquerel (1 TBq) = 1 x 1012 Bq

RADIONUCLIDE SYMBOLS AND HALF-LIVES

Radionuclide Symbol Half-life

Tritium H-3 12.3 years

Carbon-14 C-14 5.73 x 103 years

Potassium-40 K-40 1.28 x 109 years

Strontium-90 Sr-90 29.1 years

Technetium-99m Tc-99m 6.01 hours

Technetium-99 Tc-99 2.13 x 105 years

Iodine-131 I-131 8.04 days

Caesium-134 Cs-134 2.06 years

Caesium-137 Cs-137 30.2 years

Polonium-210 Po-210 138 days

Plutonium-238 Pu-238 87.7 years

Plutonium-239 Pu-239 2.40 x 104 years

Plutonium-240 Pu-240 6.50 x 103 years

Americium-241 Am-241 433 years

23

TABLE 1DISCHARGES OF RADIONUCLIDES FROM SELLAFIELD(1), 1996 AND 1997

Discharge

TBq

Radionuclide Category Limit

TBq

1996 1997

Total Alpha 1.0 0.28 0.2

Total Beta 400 143 138

Tritium 18,000 3,009 2,560

Carbon-14 20.8 10.6 4.4

Cobalt-60 13 0.43 1.5

Strontium-90 48 16.0 37.4

Zirconium-95 + Niobium-95 9 1.15 0.36

Technetium-99 200 155 84

Ruthenium-106 63 9.01 9.8

Iodine-129 1.3 0.41 0.5

Caesium-134 6.6 0.27 0.3

Caesium-137 75 10.3 7.9

Cerium-144 8 0.78 0.49

Americium-241 0.3 0.074 0.05

Plutonium (alpha) 0.7 0.21 0.15

Plutonium-241 27 4.4 3.3

Uranium (kg) 2040 1158 759

Notes (1) from sea pipeline

TABLE 2CONCENTRATIONS OF THE MAIN NATURALLY OCCURRING

RADIONUCLIDES IN SEAWATER

Radionuclide Activity Concentration

mBq/l

Potassium-40 12.0 x 103

Rubidium-87 110.0

Uranium-234 47.0

Uranium-238 41.0

Lead-210 5.0

Polonium-210 3.7

Carbon-14 4.3

Radium-226 3.6

Tritium 0.6

Bismuth-214 0.7

Radon-222 0.7

TABLE 3

24

SAMPLING LOCATIONS IN THE WESTERN IRISH SEA, 1996 AND 1997

Sampling Location Grid Reference

N1 53:25N 6:01W

N2 53:36N 5:56W

N3 53:44N 5:25W

N4 53:52N 5:14W

N5 53:53N 5:33W

N6 53:52N 5:53W

N7(1) 53:52N 4:53W

S1 53:20N 6:00W

S2 53:20N 5:22W

S3 53:04N 5:31W

S4 53:00N 5:55W

S5 53:10N 6:00W

Notes (1) 1996 only

TABLE 4SAMPLING PROGRAMME, 1996 AND 1997

Sampling Location Sample Types

Carlingford Shellfish

Greenore Seawater, Sediment, Seaweed

Clogherhead Fish, Shellfish

Balbriggan Seawater, Sediment, Seaweed

Howth Fish, Shellfish

Bull Island Seawater, Sediment, Seaweed

Cahore Seawater, Sediment, Seaweed

Dunmore East Fish, Shellfish, Seawater, Sediment, Seaweed

Bantry Shellfish

Castletownbere Fish, Shellfish, Seawater, Sediment, Seaweed

Galway Fish, Shellfish, Seawater, Sediment, Seaweed

Killybegs Fish, Shellfish, Seawater, Sediment, Seaweed

Western Irish Sea Seawater, Sediment

25

TABLE 5ANALYTICAL TECHNIQUES

Sample types Radionuclidesmeasured

Analytical techniques

Fish, shellfish,seaweed andsediment

K-40, I-131, Cs-137

High resolution gamma spectrometry using high puritygermanium detectors

Seawater Cs-137 Radiochemical techniques in accordance with the methoddescribed by Baker [1975], followed by high resolutiongamma spectrometry

Fish, shellfish,seaweed andseawater

Tc-99 Radiochemical separation techniques in accordance withthe method described by Harvey et al. [1991], followed bybeta spectrometry using a gas flow proportional counter

Fish andshellfish

Pu-238, Pu-239,240 Am-241

Radiochemical separation techniques, followed by alphaspectrometry using silicon surface barrier detectors

26

TABLE 6RADIOACTIVITY IN SEAWATER, 1996

Activity Concentration mBq/lSamplingLocation

Month

Cs-137 Tc-99Greenore Mar 26 nm

Jun 33 nmAug 58 nmDec 38 23

Balbriggan Jan 61 7Feb 31 7Mar 48 11Apr 21 10May 28 14Jun 21 14Jul 28 28

Aug 26 35Sep 40 32Oct 27 27Nov 17 15Dec 27 26

Bull Island Mar 11 nmMay 14 nmAug 20 nmNov 16 nm

Cahore May 7 nmSept 9 nm

Dunmore East Nov 4 nd

Castletownbere Sep 3 nmNov 3 nd

Galway Sept 4 nmNov 3 nd

Killybegs Mar 7 nmNov 3 nd

Irish Sea N1 Aug 23 31Irish Sea N2 Aug 21 30Irish Sea N3 Aug 22 27Irish Sea N4 Aug 16 nmIrish Sea N5 Aug 22 24Irish Sea N6 Aug 28 36Irish Sea N7 Aug 18 20Irish Sea S1 Aug 22 nmIrish Sea S2 Aug 12 nmIrish Sea S3 Aug 16 nmIrish Sea S4 Aug 14 nmIrish Sea S5 Aug 20 nm

Notes nm = not measured nd = not detected

27

TABLE 7RADIOACTIVITY IN SEAWATER, 1997

Activity Concentration mBq/lSamplingLocation

Month

Cs-137 Tc-99

Greenore Jan 57 nm

Apr 30 nm

Aug 37 nm

Oct 43 nm

Balbriggan Jan 27 nm

Feb 21 18

Mar 22 nm

Apr 28 nm

May 34 40

Jun 39 nm

Jul 33 nm

Aug 36 65

Sep 29 nm

Oct 28 nm

Nov 33 56

Dec 20 nm

Bull Island Feb 15 nm

May 27 nm

Sep 18 nm

Dec 10 nm

Cahore May 9 nm

Sep 9 nm

Dunmore East Oct nd nm

Castletownbere Oct 3 nm

Galway Oct nd nm

Killybegs Oct nd nm

Irish Sea N1 Sep 20 27

Irish Sea N2 Sep 29 nm

Irish Sea N3 Sep 27 44

Irish Sea N4 Sep 15 37

Irish Sea N5 Sep 34 nm

Irish Sea N6 Sep 36 53

Irish Sea S1 Sep 22 nm

Irish Sea S2 Sep 14 nm

Irish Sea S3 Sep 17 nm

Irish Sea S4 Sep 16 nm

Irish Sea S5 Sep 20 nm

Notes nm = not measured

nd = not detected

28

TABLE 8RADIOACTIVITY IN IRISH COASTLINE SEDIMENTS, 1996 AND 1997

SamplingLocation

Year Number ofSamples

Mean (Range) Cs-137,

Bq/kg, dry weight

Greenore 1996 4 10.7 (9.3 - 11.8)

1997 4 10.2 (9.4 - 11.4)

Balbriggan 1996 4 12.1 (11.0 - 12.7)

1997 4 10.0 (9.5 - 11.2)

Bull Island 1996 4 3.8 (3.2 - 4.3)

1997 4 3.4 (2.7 - 4.1)

Cahore 1996 2 0.7 (0.5; 0.8)

1997 2 0.8 (0.7; 0.8)

Dunmore East 1996 1 1.2

1997 2 2.3 (0.6; 3.9)

Castletownbere 1996 2 0.8 (nd; 1.2)

1997 1 nd

Galway 1996 3 0.3 (nd - 0.5)

1997 2 0.6 (0.4; 0.9)

Killybegs 1996 2 0.6 (0.4; 0.7)

1997 1 nd

Notes nd = not detected

29

TABLE 9RADIOACTIVITY IN OFF-SHORE SEDIMENTS, 1996 AND 1997

SamplingLocation

Year Activity Concentration Cs-137,

Bq/kg, dry weight

Irish Sea N1 1996 7.5

1997 6.2

Irish Sea N2 1996 13.0

1997 16.6

Irish Sea N3 1996 50.3

1997 42.7

Irish Sea N4 1996 73.0

1997 46.9

Irish Sea N5 1996 118

1997 93.4

Irish Sea N6 1996 49.7

1997 46.7

Irish Sea N7 1996 19.9

1997 nm

Irish Sea S1 1996 2.3

1997 1.8

Irish Sea S2 1996 0.8

1997 0.8

Irish Sea S3 1996 0.5

1997 0.5

Irish Sea S4 1996 nm

1997 2.7

Irish Sea S5 1996 6.9

1997 7.3

30

TABLE 10RADIOACTIVITY IN FUCUS VESICULOSUS, 1996

Activity Concentration Bq/kg, dry weightSamplingLocation

Month

Cs-137 I-131 (1) K-40 Tc-99

Greenore Mar 5.1 nm 1232 4588

June 5.8 nm 558 4835

Aug 7.8 nm 898 4143

Dec 5.1 nm 1066 6232

Balbriggan Jan 3.2 nm 575 3536

Feb 3.7 nm 1086 2395

Mar 5.2 nm 1184 3954

Apr 4.5 nm 1119 2184

May 4.3 nm 1220 2036

June 3.8 nm 834 2696

July 5.7 nm 1051 2300

Aug 5.1 nm 949 2278

Sept 4.0 nm 716 4153

Oct 7.5 nm 1222 2976

Nov 4.3 nm 931 2131

Dec 3.8 nm 1109 4820

Bull Island Mar 4.7 23.1 810 nm

May nm nd nm nm

Jun 4.0 42.5 956 nm

Sept 6.2 160 1345 nm

Nov 3.4 58.9 1404 nm

Cahore May 1.1 nm 1166 nm

Sept 0.5 nm 618 nm

Dunmore East Nov 0.6 nm 919 41

Castletownbere Sept nd nm 1017 nm

Nov 0.4 nm 1000 26

Galway Sep 0.9 nm 907 nm

Nov 0.6 nm 1174 6.9

Nov 0.3 nm 1073 nm

Killybegs Mar 0.5 nm 1152 nm

Nov 0.6 nm 1092 9.1

Notes (1) analysis performed on wet sample, but results quoted on a dry weight basis forease of comparison

nm = not measured

nd = not detected

mean dry:wet weight ratio = 0.18

31

TABLE 11RADIOACTIVITY IN FUCUS VESICULOSUS, 1997

Activity Concentration Bq/kg, dry weightSamplingLocation

Month

Cs-137 I-131 (1) K-40 Tc-99

Greenore Jan 4.5 nm 1184 6818

Apr 5.5 nm 1108 5146

Aug 4.7 nm 627 nm

Oct 6.1 nm 741 nm

Balbriggan Jan 4.1 nm 1142 3472

Feb 3.0 nm 862 3344

Mar 4.1 nm 1139 3817

Apr 5.8 nm 1337 5475

May 9.2 nm 1117 4636

June 6.8 nm 1019 nm

July 6.2 nm 1390 nm

Aug 6.3 nm 1172 6104

Sept 6.2 nm 1025 nm

Oct 5.0 nm 1015 nm

Nov 5.4 nm 1144 7985

Dec 4.0 nm 1198 nm

Bull Island Mar 3.3 nd 1203 nm

May 4.4 14.1 1112 3337

Aug 5.9 10.7 1063 nm

Nov 4.0 277.5 1103 nm

Cahore May 1.3 nm 917 869

Sept 1.5 nm 970 nm

Dunmore East May nd nm 986 8.2

Oct nd nm 815 nm

Castletownbere Oct 0.4 nm 953 nm

Galway May nd nm 1038 6.2

Oct nd nm 857 nm

Killybegs Oct nd nm 626 nm

Notes (1) analysis performed on wet sample, but results quoted on a dry weight basis forease of comparison

nm = not measured

nd = not detected

mean dry:wet weight ratio = 0.18

32

TABLE 12PLUTONIUM IN FUCUS VESICULOSUS, 1996

Activity Concentration

mBq/kg, dry weight

SamplingLocation

Pu-238 Pu-239,240

Greenore 376 2052

Balbriggan 404 2106

Bull Island 318 1919

Cahore 54 164

Dunmore East 8.4 63

Castletownbere 9 63

Galway 7.3 45

Killybegs 11.3 46

Notes mean dry:wet weight ratio = 0.18

TABLE 13RADIOACTIVITY IN SEAWATER FROM CARLINGFORD LOUGH,

OCTOBER 1997

Activity ConcentrationmBq/l

Location

Cs-137 Tc-99

Lough C1 31 nm

Lough C2 41 45

Lough C3 38 nm

Lough C4 39 46

Greenore 43 nm

Carlingford Harbour 44 51

33

TABLE 14RADIOACTIVITY IN SEAWEED AND SEDIMENTFROM CARLINGFORD LOUGH, OCTOBER 1997

Activity Concentration Bq/kg, dry weightSpecies Location

Cs-137 K-40 Tc-99 Pu-238 Pu-239,240 Am-241

Seaweed Ballyagon 7.3 1193 8457 0.28 1.52 nd

Greenore 6.1 741 nm nm nm nm

Carlingford GolfCourse

8.6 1066 nm nm nm nm

Carlingford Harbour 9.8 1224 6825 nm nm nm

Sediment Lough C2 5.3 nm nm nm nm nm

Lough C4 27.8 nm nm nm nm nm

Ballyagon 11.7 nm nm 0.28 1.89 1.5

Greenore 11.4 nm nm nm nm nm

Carlingford GolfCourse

10.8 nm nm nm nm nm

Carlingford Harbour 23.0 nm nm nm nm nm

Notes mean dry:wet weight ratio for Fucus vesiculosus = 0.18

34

TABLE 15RADIOACTIVITY IN WHITING, 1996 AND 1997

Mean (Range) Activity Concentration Bq/kg, wet weightSampling

Location

Year Number

of

SamplesCs-137 Tc-99 Pu-238 Pu-239,240 Am-241

Clogherhead 1996 4 1.0

(1.0 - 1.1)

0.6

(0.6; 0.5)

2.0 x 10-4 (1) 4.0 x 10-4 (1) nd (1)

1997 4 0.9

(0.3 - 1.6)

0.2

(nd; 0.4)

nd (1) nd (1) nd (1)

Howth 1996 12 1.4

(0.2 - 4.7)

0.2

1997 12 0.9

(0.2 - 4.1)

0.4

(nd; 0.8)

Dunmore East 1996 2 1.1

(0.5; 1.7)

nm nm nm nm

1997 2 0.6

(0.5; 0.8)

nm nm nm nm

Castletownbere 1996 2 0.7

(nd; 0.6)

nm nm nm nm

1997 2 0.4

(nd; 0.3)

nm nm nm nm

Galway 1997 2 0.2

(0.2; 0.2)

nm nm nm nm

Killybegs 1996 2 0.9

(0.4; 1.3)

nm nm nm nm

1997 1 nd nm nm nm nm

Notes (1) composite sample for Howth and Clogherhead

nm = not measured

nd = not detected

35

TABLE 16RADIOACTIVITY IN COD, 1996 AND 1997

Mean (Range) Activity Concentration Bq/kg, wet weightSampling

Location

Year Number

of

SamplesCs-137 Tc-99 Pu-238 Pu-239,240 Am-241

Clogherhead 1996 4 1.4

(0.6 - 2.1)

nd 6.0 x 10-4 (1) 4.0 x 10-3 (1) nd (1)

1997 4 2.2

(0.05 - 4.2)

nd (-) nd (1) nd (1) nd (1)

Howth 1996 12 1.7

(0.7 - 3.8)

nd

1997 12 1.2

(0.3 - 2.4)

nd

Dunmore East 1996 2 0.4

(0.3; 0.5)

nm nm nm nm

1997 2 0.3

(03; 0.4)

nm nm nm nm

Castletownbere 1996 2 0.4

(nd; 0.5)

nm nm nm nm

1997 2 0.9

(0.3; 1.5)

nm nm nm nm

Galway 1996 2 0.6

(0.3; 0.9)

nm nm nm nm

1997 2 1.6

(0.5; 2.6)

nm nm nm nm

Killybegs 1996 2 0.7

(0.7; 0.7)

nm nm nm nm

1997 1 nd nm nm nm nm

Notes (1) composite sample for Howth and Clogherhead

nm = not measured

nd = not detected

36

TABLE 17RADIOACTIVITY IN PLAICE, 1996 AND 1997

Sampling

Location

Year Number

of

Samples

Mean (Range) Activity Concentration

Bq/kg, wet weight

Cs-137 Tc-99 Pu-238 Pu-239,240 Am-241

Clogherhead 1996 4 1.1

(0.6 - 1.4)

1.8

(-)

2.0 x 10-4 (1) nd (1) nd (1)

1997 4 0.8

(nd - 1.7)

1.3

(0.3; 2.3)

nd (1) nd (1) nd (1)

Howth 1996 12 1.1

(0.4 - 4.0)

0.4

(nd; 0.6)

1997 11 0.5

(0.2 - 1.0)

nd

(-)

Dunmore East 1996 2 nd (nd) nm nm nm nm

1997 2 0.2

(nd; 0.2)

nm nm nm nm

Castletownbere 1996 1 0.2 nm nm nm nm

1997 2 0.2

(nd; 0.3)

nm nm nm nm

Galway 1996 2 0.1

(0.1; 0.1)

nm 1.0 x 10-4 (2) 2.0 x 10-4 (2) 1.2 x 10-1 (2)

1997 2 0.2

(0.1; 0.2)

nm nm nm nm

Killybegs 1996 2 0.2

(0.2; 0.3)

nm

1997 1 nd nm nm nm nm

Notes (1) composite sample for Howth and Clogherhead

(2) composite sample for Galway and Killybegs

nm = not measured

nd = not detected

37

TABLE 18RADIOACTIVITY IN RAY, 1996 AND 1997

Mean (Range) ActivityConcentration

Bq/kg, wet weight

SamplingLocation

Year Numberof

Samples

Cs-137 Tc-99

Clogherhead 1996 3 0.6 (0.3 - 1.0) 0.11

1997 4 0.8 (0.2 - 1.6) nd

Howth 1996 12 1.1 (0.4 - 1.9) 0.1 (nd; 0.12)

1997 11 1.0 (0.4 - 2.0) nd

Dunmore East 1996 1 0.3 nm

1997 2 0.3 (0.2; 0.4) nm

Castletownbere 1996 1 0.4 nm

Galway 1996 2 0.5 (0.3; 0.7) nm

1997 1 0.2 nm

Killybegs 1996 1 nd nm

1997 1 nd nm

Notes nm = not measured

nd = not detected

TABLE 19RADIOACTIVITY IN HERRING, 1996 AND 1997

Mean (Range) ActivityConcentration

Bq/kg, wet weight

SamplingLocation

Year Numberof

Samples

Cs-137 Tc-99

Clogherhead 1996 3 0.4 (0.3 - 0.7) nd

1997 3 0.5 (nd - 1.0) nm

Howth 1996 7 0.4 (0.2 - 0.8) nd

1997 2 1.1 (0.3; 1.9) nd

Dunmore East 1996 1 0.4 nm

1997 1 0.4 nm

Castletownbere 1996 1 0.6 nm

Galway 1997 1 nd nm

Killybegs 1996 2 0.6 (0.4; 0.8) nm

1997 1 nd nm

Notes nm = not measured

nd = not detected

TABLE 20

38

RADIOACTIVITY IN MACKEREL, 1996 AND 1997

SamplingLocation

Year Numberof

Samples

Mean (Range) ActivityConcentration

Bq/kg, wet weight

Cs-137 Tc-99

Clogherhead 1996 2 0.3 (nd; 0.3) nm

1997 4 0.7 (nd - 1.9) nd

Howth 1996 10 0.3 (nd - 0.5) nd

1997 10 0.2 (nd - 0.4) nd

Dunmore East 1996 1 0.3 nm

1997 1 0.3 nm

Castletownbere 1996 1 nd nm

1997 1 0.2 nm

Galway 1996 2 0.3 (-) nm

1997 2 0.3 (-) nm

Killybegs 1996 2 0.3 (nd; 0.4) nm

1997 1 0.4 nm

Notes nm = not measured

nd = not detected

TABLE 21RADIOACTIVITY IN FARMED SALMON, 1997

Sampling

Location

Number ofSamples

Cs-137 Mean (Range)Activity Concentration Bq/kg,

wet weight

Castletownbere 1 nd

Galway 2 0.3 (0.3; 0.4)

Killybegs 1 nd

Notes nd = not detected

39

TABLE 22RADIOACTIVITY IN PRAWNS, 1996 AND 1997

Sampling

Location

Year Month Activity Concentration Bq/kg, wet weight

Cs-137 Tc-99 Pu-238 Pu-239,240 Am-241

Clogherhead 1996 Mar 1.1 nm nm nm nm

Jun 1.1 55 nm nm nm

Aug 1.2 69 nm nm nd

Dec 1.2 77 nm nm nm

1997 Jan 1.2 114 nm nm nm

Apr 1.3 125 nm nm nm

Aug 1.1 nm nm nm nm

Oct nd 24 nm nm nm

Dec nd nm nm nm nm

Howth 1996 Feb 1.4 nm nm nm nm

Mar 1.4 64 1.2 x 10-3 7.0 x 10-3 15 x 10-3

Jun 1.0 42 nd 7.3 x 10-3 nd

Aug 0.9 43 1.7 x 10-3 8.9 x 10-3 nd

Oct 1.3 118 1.3 x 10-3 11.5 x 10-3 nd

1997 Jan 1.3 93 2.1 x 10-3 5.9 x 10-3 nd

Apr 1.0 97 2.0 x 10-3 11.2 x 10-3 3.5 x 10-2

Jul 1.2 75 2.9 x 10-3 13.3 x 10-3 nd

Oct 0.9 nm nm nm nm

Nov 0.8 87 2.0 x 10-3 11.3 x 10-3 nd

Dunmore East 1996 Apr nd nm nm nm nm

Nov nd nm nm nm nm

Castletownbere 1996 Sep nd nm nm nm nm

1997 Jul nd nd nm nm nm

Notes nm = not measured

nd = not detected

40

TABLE 23RADIOACTIVITY IN MUSSELS, 1996 AND 1997

Activity Concentration Bq/kg, wet weightSampling

Location

Year Month

C-14 Cs-137 Tc-99 Pu-238 Pu-239,240 Am-241

Carlingford 1996 Mar nm 0.7 nm 2.1 x 10-2 0.12 6.9 x 10-2

Jun nm 0.8 15 3.3 x 10-2 0.19 1.6 x 10-1

Aug nm 0.7 nm 2.7 x 10-2 0.15 8.3 x 10-2

Dec nm 0.8 21 2.3 x 10-2 0.13 9.7 x 10-2

1997 Jan 22.5 0.7 21 2.8 x 10-2 0.17 1.3 x 10-1

Apr 18.9 0.5 23 3.0 x 10-2 0.13 7.4 x 10-2

Aug 25.8 0.7 24 3.3 x 10-2 0.18 1.1 x 10-1

Oct 21.8 0.8 33 3.6 x 10-2 0.20 1.2 x 10-1

Bantry 1996 Sep nm nd nm nm nm nm

Nov nm 0.2 nm nm nm nm

1997 Jul 21.6 nd nm nm nm nm

Oct 21.7 nd 0.15 nm nm nm

Galway 1996 Sep nm 0.1 nm nm nm nm

Nov nm nd nm nm nm nm

1997 May 13.3 nd nm 2.8 x 10-4 (1) 5.0 x 10-3 (1) nd (1)

Oct 16.9 nd nd

Killybegs 1996 Nov nm 0.1 nm nm nm nm

1997 Oct 20.5 nd 0.4 nm nm nm

Notes (1) composite sample for May and October

nm = not measured

nd = not detected

41

TABLE 24RADIOACTIVITY IN OYSTERS, 1996 AND 1997

Activity Concentration Bq/kg, wet weightSampling

Location

Year Month

Cs-137 Tc-99 Pu-238 Pu-239,240 Am-241

Carlingford 1996 Mar 0.3 nm

Aug 0.2 8.5

Dec 0.2 5.0

2.0 x 10-2 (1) 7.3 x 10-2 (1) 1.9 x 10-2 (1)

1997 Jan 0.3 2.7

Apr nd 7.7

Aug nd 11.3

Oct nd 7.9

1.9 x 10-2 (1) 9.8 x 10-2 (1) nd (1)

Notes (1) annual composite sample

nm = not measured

nd = not detected

TABLE 25RADIOACTIVITY IN LOBSTER, 1996 AND 1997

SamplingLocation

Numberof

Samples

Date Tc-99 Mean (Range)

Activity Concentration

Bq/kg, wet weight

Carlingford 3 Jun 1997 279(1) (180 – 352)

2 Oct 1997 88(1) (73 – 102)

Dundalk Bay 2 Oct 1997 280(1) (95; 465)

Clogherhead 1 Jan 1997 83(2)

Howth 1 Dec 1996 13 (2), (3)

1 Jan 1997 56 (2)

3 Jun 1997 267(1) (248 – 280)

Saltees 3 Jun 1997 1.5(1) (0.8 – 2.9)

Notes (1) tail meat only

(2) tail and claw meat combined

(3) source of sample uncertain

42

TABLE 26RADIOACTIVITY IN SHELLFISH FROM CARLINGFORD LOUGH,

OCTOBER 1997

Species Location Activity Concentration

Bq/kg, wet weight

Cs-137 Tc-99

Lobster Carlingford Lough nm 88

Mussels Carlingford Harbour 0.8 33

Oysters Greenore 0.3 6.0

Winkles Carlingford Harbour nm 27

Notes nm = not measured

TABLE 27WEIGHTED MEAN ACTIVITY CONCENTRATIONS OF ARTIFICIAL

RADIONUCLIDES IN FISH, CRUSTACEANS AND MOLLUSCSLANDED AT NORTH-EAST PORTS IN 1996 AND 1997

Activity Concentration Bq/kg, wet weightSpecies Year

Tc-99 Cs-137 Pu-238 Pu-239,240 Am-241

Fish 1996 0.32 1.0 3.3 x 10-4 1.6 x 10-3 2.6 x 10-4 (1)

1997 0.15 0.84 1.0 x 10-4 3.2 x 10-4 2.7 x 10-4 (1)

Crustaceans 1996 67 1.2 1.8 x 10-3 8.7 x 10-3 2.6 x 10-3 (1)

1997 88 1.0 2.3 x 10-3 1.0 x 10-2 2.7 x 10-3 (1)

Molluscs 1996 18 0.80 2.6 x 10-2 1.5 x 10-1 1.0 x 10-1

1997 25 0.66 3.2 x 10-2 1.7 x 10-1 1.1 x 10-1

Notes (1) based on IAEA concentration factors [IAEA, 1985]

43

TABLE 28COMMITTED EFFECTIVE DOSES, FROM ARTIFICIAL RADIONUCLIDES, DUETO THE CONSUMPTION OF FISH, CRUSTACEANS AND MOLLUSCS LANDED

AT NORTH-EAST PORTS, 1996 AND 1997

Radionuclide 1996 1997

Heavyconsumer

Typicalconsumer

Heavyconsumer

Typicalconsumer

µSv

Tc-99 0.21 0.053 0.27 0.068

Cs-137 1.06 0.22 0.88 0.18

Pu-238 0.029 0.0069 0.030 0.0075

Pu-239,240 0.18 0.042 0.17 0.042

Am-241 0.079 0.019 0.084 0.021

Total 1.56 0.34 1.43 0.32

TABLE 29LANDING STATISTICS FOR FISH, CRUSTACEANS AND MOLLUSCS AT

NORTH-EAST IRISH SEA PORTS 1996 AND 1997 (1)

Year Demersal

tonnes

Pelagic

tonnes

Crustaceans

tonnes

Molluscs

tonnes

1996 2652 90 1263 605

1997 3769 4.2 3110.4 1540.6

Notes (1) Dept. of the Marine and Natural Resources, 1998

TABLE 30COLLECTIVE EFFECTIVE DOSES, FROM ARTIFICIAL RADIONUCLIDES, DUETO THE CONSUMPTION OF FISH, CRUSTACEANS AND MOLLUSCS LANDED

AT IRISH SEA PORTS, 1996 AND 1997

Radionuclide 1996 1997

manSv

Tc-99 0.00406 0.013

Cs-137 0.00516 0.00735

Pu-238 0.000166 0.000464

Pu-239,240 0.000985 0.00254

Am-241 0.000432 0.00115

Total 0.0108 0.0245