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Technical Area: Radiological Protection
Issue Number: 12 Issue: Atmospheric dispersion of activity and terrestrial
foodchains
Sub-Issue Number: 12.2.3 Sub-Issue: Heavy particle dispersion
Description of safety issue:
The off-site dose estimates used in support of safety cases in both BNFL Magnox Generation and British Energy
take account of the effects of gravitational settling on the dispersion of heavy particles. This is undertaken using
relatively new capabilities of the NECTAR2-ATMOS computer model.
This model has not been fully
Expected outcome:
A review of the options available for the validation of the heavy particle dispersion predictions of NECTAR2-ATMOS.
Suitable validation studies to determine the suitability of the NECTAR2-ATMOS model and the limits of its applicability.
Date Raised: 17/09/1998 Date Closed: Priority: High
Status: A contract was placed to provide a review of the validation options available. That
work was completed in July 2000. A second contract has been placed to produce
an intercomparison of the results the NECTAR2-ATMOS computer model with
existing data. That work is due to be completed by the end of 2001.
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: RS/GNSR/5071
Contractor: Westlakes
Final Report Title: P.Kruse, Validation Options for Heavy Particle Dispersion Model, 2000
· V.Auld, Validation of the NECTAR2 Heavy Particle Dispersion Model with
Experimental Data, 2001
Final Report Number: 000230/01 Report Date: 03/12/2001
Reason For Closing Issue:
The modelling of the dispersion of particulate activity discharged from Nuclear Power Stations requires
modifications to the standard atmospheric dispersion model used for neutrally buoyant particles. This project
undertook some validation of the heavy particle dispersion model using by the UK nuclear utilities in their safety
cases. The report concluded that the model successfully reproduced the important features of the data
available.
Comments:
Technical Area: Radiological Protection
Issue Number: 12 Issue: Radiological protection
Sub-Issue Number: 12.8 Sub-Issue: ICRP lung model
Description of safety issue:
The calculation of inhalation doses following airborne releases of activity relies on the implementation by
computer programmes of ICRP models. In general the models use look up tables of committed dose per unit
intake. ICRP have produced a new lung model in its publication 66. This model takes account of the presence
of larger particles and chemical form and can in some circumstances reduce the estimated dose. Some work has
already been done by NRPB in the LUDEP program. Further research work has been commissioned to enable
this new model to be implemented as part of radiological consequence calculations across a range of nuclides
and particle sizes and to include children.
The objective is to calculate and document particle size dependant inhalation dose conversion factors using the new
ICRP lung model for a range of fission products and actinide radionuclides contained in irradiated fuel particles for adult
workers and adult members of the public and to extend to other age groups.
Expected outcome:
The contractor must propose a reasonable number of points to allow interpolation between sizes from 0.1 to 100
micron physical diameter UO2 and U3O8. The most recent ICRP biokinetic model should be used. The
following list of radionuclides is to be addressed.
Kr-88 Kr-89 Sr-89 Sr-90 Zr-95 Nb-95 Mo-99 Ru-103 Ru-106 Te-132 I-131 I-132 I-133 I-134 Xe-133
Xe-135 Xe-138 Cs-134 Cs-137 Ba-140 Ce-141 Ce-144 U-137 Np-239 Pu-238 Pu-239 Pu-240
Pu-241 AM-241 Cm-242 Cm-244
Date Raised: 01/04/1995 Date Closed: Priority: High
Status: Closed.
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: RP/GNSR/5009
Contractor: NRPB
Final Report Title: Dose Coefficients for Workers and Members of the Public for a
Range of Aerosols using the New ICRP Model for the Respiratory Tract
Final Report Number: NRPB-M729, 1996 Report Date:
Reason For Closing Issue:
A report tabulating the required dose per unit intake values has been produced. The issue is now closed.
Comments:
Technical Area: Radiological Protection
Issue Number: 12 Issue: Radiological protection
Sub-Issue Number: 12.9 Sub-Issue: Common methodology for meteorological input to
UKADMS
Description of safety issue:
A comparison between UKADMS and the Gaussian plume R91 atmospheric dispersion models has been carried
out under an IMC project (RP/GNSR/02, NE Contract BL/G/30529/E). The newer UKADMS model uses
parameters such as boundary layer depth and Monin-Obukhov scaling length for estimating dispersion
coefficients rather than the semi-empirical Pasquill-Gifford atmospheric stability classes used by the older R91
method. There is no common consensus on how to estimate these parameters and different measures of stability
such as bulk or gradient Richardson number, sensible heat flux and variance in wind angle can give widely
differing estimates.
Sophisticated and expensive instrumentation is required to measure the heat flux (and hence Monin-Obukhov length)
and boundary layer thickness directly. Most nuclear sites are instrumented with much simpler equipment. At the same
time, it may be possible to revisit the R91 atmospheric dispersion model and derive new parameter sets as a cost
effective alternative to implementing the UKADMS model in a large number of existing computer programs which use
the R91 methodology.
The nuclear industry will benefit from a common approach if the new atmospheric dispersion models are to form part of
future safety cases or discharge authorisation applications. Some work has been carried out at Sellafield and it is the
aim of this project to continue and extend this work to achieve robust and accepted analysis methodologies.
It should be noted that the Meteorological Office completed a survey of installed equipment during 1993/94 and the
information gathered at that time is available.
Expected outcome:
To review methods of deriving the input parameters required by the UKADMS atmospheric dispersion model
from simple measurements and recommend the best currently available method.
To revisit the R91 gaussian plume model and derive new sets of parameters to simulate the aspects of the ADMS
model's predictions relative to assessments of the radiological consequences of atmospheric releases.
The likely outputs will be;
1. A report on methods of deriving the input parameters required by the UKADMS atmospheric dispersion model from
the types of simple measurements available at Nuclear Sites.
2. A report on the derivation of new sets of parameters for the R91 atmospheric dispersion model to simulate the
aspects of the ADMS model's predictions relative to assessments of the radiological consequences of atmospheric
releases.
Date Raised: 01/04/1995 Date Closed: Priority: medium
Status: Closed
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number:
Contractor:
Final Report Title:
Final Report Number: Report Date:
Reason For Closing Issue:
A new version of UKADMS has been produced.
Comments:
Technical Area: Radiological Protection
Issue Number: 12 Issue: Radiological protection
Sub-Issue Number: 12.10.1 Sub-Issue: Marine background of C-14: to investigate further
locations
Description of safety issue:
C-14 is an important component of the total activity released from reactor sites and its behaviour in the marine
environment is poorly understood. When considering the results of measurements from the marine environment,
it is difficult to assess the level of natural background which should be subtracted in order to estimate the levels
of man made C-14 taken up into the food chain. Measurements of the terrestrial background have been made
but marine measurements have been mainly confined to the deep ocean and the values are probably not
applicable to coastal waters.
The objective is to obtain a better understanding of the marine background of C-14. This would ultimately help in the
assessment of doses to critical groups and population as a result of discharges from nuclear power plant.
Expected outcome:
To continue the investigation of the levels of C-14 in sea water around the UK coast by increased number of
sampling locations.
Date Raised: 01/04/1996 Date Closed: Priority: Medium
Status: Closed.
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: RP/GNSR/5036
Contractor: SURRC
Final Report Title: Geochemistry and Budgetary Considerations of C-14 in the Irish Sea
Final Report Number: RSTG/P(01)03 Report Date: 10/08/2001
Reason For Closing Issue:
Comments:
Technical Area: Radiological Protection
Issue Number: 12 Issue: Radiological protection
Sub-Issue Number: 12.12 Sub-Issue: Support of the SURRC flying gamma detection
system
Description of safety issue:
Information concerning the gamma dose rate around nuclear installations is very useful as it provides a snap shot
in time regarding the radiological status of the area. This can be used as reference material for other studies.
There is an element of key capability as there are limited resources to undertake such work. In the event of an
emergency situation there is a need for this capability. Hence there is a technical need to provide periodic
updates of this information particularly if new plant have been constructed eg Sizewell. Also unless some work is
identified there is the danger of the capability disappearing.
Expected outcome:
There is a requirement to ensure that this facility remains available to the U.K. Industry. Funding can be made
on an ad-hoc basis by commissioning a base line survey of a different site each year. This would also allow
baseline data to be collected over a period of several years and emergency response plans formulated for each
station. This work will provide support of the flying gamma detector programme as a "key resource".
Date Raised: 01/04/1996 Date Closed: Priority: Medium
Status: Closed.
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number:
Contractor:
Final Report Title:
Final Report Number: Report Date:
Reason For Closing Issue:
A base line survey of the Sizewell Area was completed and the results reported. This addresses and closes this
issue.
Comments:
Technical Area: Radiological Protection
Issue Number: 12 Issue: Radiological protection
Sub-Issue Number: 12.13 Sub-Issue: Comparison of consequence assessments based on
R91 and ADMS
Description of safety issue:
Some early IMC work has been done to gain a greater understanding of the ADMS system in relation to existing
R91 methodologies. The results of these projects ( issue 12.9 refers) confirm that the two methodologies give
very different predictions for the dispersion of a release in a given set of weather conditions, with neither one
giving consistently larger or smaller results than the other. The weight of evidence suggests that ADMS is an
improvement over R91 and the use of Pasquill categories is not the best description of atmospheric stability.
Given the likelihood in the future of a move towards ADMS it is important for the nuclear industry to know what
effect this could have on consequence calculations performed as part of safety cases. There is the potential for
changes to the frequency consequence bandings for fault conditions and on the methodologies used for these
types of assessments throughout the industry. It is therefore necessary to gain an understanding of whether such
a change in atmospheric modelling approach will have an impact on either the safety case conclusions or
require changes to the plant
Expected outcome:
For a number of power stations it is intended to use actual meteorological data in a form suitable for use in both
codes ie a common data set. Other calculational parameters will be set in accordance with the industry
methodology. Air concentration at ground level and ground deposition are to be calculated at a range of
distances and for a range of release heights. This approach should further the understanding of the implications
of any change in dispersion codes and also give information on the likely uncertainties between the two
approaches.
Date Raised: 01/04/1996 Date Closed: Priority: High
Status: Closed
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: RP/GNSR/5010
Contractor: Cambridge Environmental Research Consultants
Final Report Title: Comparison of Dispersion Calculations using ADMS and R-91 Dispersion Models
based in the Industry Working Group Methodology
Final Report Number: Report Date: 01/10/1997
Reason For Closing Issue:
Work has been completed to the satisfaction of the Radiological Protection Working
Group to the original contract specification.
Comments:
Technical Area: Radiological Protection
Issue Number: 12 Issue: Radiological protection
Sub-Issue Number: 12.14 Sub-Issue: Ecological effects of hypothetical radiation
accidents
Description of safety issue:
The effects of major nuclear accidents on humans and agriculture are a routine output from consequence
assessment codes. Ecological effects have not been addressed as systematically. Understanding of the harm in
this area has developed significantly in recent years, IAEA and NCRF have published reports and results from
some of the Chernobyl studies are emerging.
There is a need to bring together information on the levels of radioactivity to be expected from major accidents coupled
with the most recent studies on radiation effects on plants and animals. This would address a current gap in
knowledge.
Expected outcome:
The objective of the work would be to assemble predictions of concentrations and dose rates as a function of
space and time for commonly studied UK major accidents and combine them with dose response relationships
for plants and animals. Initially this would be aimed at producing sufficient information to make some
judgements regarding importance.
Date Raised: 01/04/1996 Date Closed: Priority: Medium
Status: Closed.
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: RP/GNSR/5026
Contractor: Institute of Terrestrial Ecology (Natural Environment Research Council)
Final Report Title: Ecological Effects of a Hypothetical Radiation Accident
Final Report Number: Report Date: 01/07/1997
Reason For Closing Issue:
A report by ITE and Mouchel investigated the potential ecological damage that might result from a major
nuclear accident in the UK. The report concluded that ecological damage may be apparent close to the scene
of an accident but that the damage would be limited in extent and that the system would recover with time.
Comments:
Technical Area: Radiological Protection
Issue Number: 12 Issue: Radiological protection
Sub-Issue Number: 12.17 Sub-Issue: Atmospheric dispersion modelling for article 37
work
Description of safety issue:
Article 37 of EURATOM requires Member States to perform assessments of the impact of radioactive releases on
other Member States. Releases to the atmosphere arising from within the UK will be transported over water
before crossing the boundaries of Member States.
Expected outcome:
This issues will examine the effect of the presence of large bodies of water on the dispersion of atmospheric
discharges.
Date Raised: 01/05/1998 Date Closed: Priority: Medium
Status: Closed.
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: RP/GNSR/5034
Contractor: NRPB
Final Report Title: Atmospheric Dispersion Model for use in Article 37 Submissions
Final Report Number: NRPB-M960 Report Date:
Reason For Closing Issue:
The NRPB were contracted to review the methods and data used to estimate the dilution of airborne activity for
use in Article 37 submissions (potential dose to EU neighbour states from discharges).
Their final report (J A Jones, R Busby, C Toumette, Atmospheric Dispersion Model for Use in Article 37 Submissions,
NRPB-M960) discusses the limitations of the current models (NRPB-R123 & NRPB-R124) and the possible
improvements that could be made.
The report suggests a simple to use model which should give a realistic prediction of the concentrations at the receptor
points.
This method could be used for future Article 37 atmospheric dispersion calculations.
Comments:
Technical Area: Radiological Protection
Issue Number: 12 Issue: Radiological protection
Sub-Issue Number: 12.18 Sub-Issue: Impact of the new ICRP recommendations on PSA
calculations
Description of safety issue:
Until recently, the basic recommendations of the International Commission on Radiological Protection (ICRP)
were those published in 1977, subsequently reprinted and updated in 1987 as ICRP-26. In April 1991, new basic
recommendations were published (ICRP-60), recommending the use of a new basic quantity 'effective dose'
(similar in calculation to the previous 'effective dose equivalent', but with revised weighting factors) and revised
risk coefficients for fatal cancers. During the same period other organisations (including ICRP) recommended
revised dosimetric parameters, eg. new gut uptake factors for particular nuclides, and more recently an ICRP task
group has published their recommendations for a new lung model (ICRP-66). In the light of these changes,
NRPB have recently updated their recommended risk coefficients, as appropriate for a UK population, and their
dosimetric models.
It is now deemed necessary to investigate the effects that these changes have on probabilistic safety assessments.
This would be a jointly funded project with the CONDOR User's Group, producing results of general interest to the
Nuclear community.
Expected outcome:
To update CONDOR to implement the newer recommendations.
To compare the results of probabilistic safety assessments using the old and new advice and analyse the impacts of
the new recommendations.
Date Raised: 01/04/1996 Date Closed: Priority: High
Status: Closed.
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number:
Contractor:
Final Report Title: Impact on PSA for UK Nuclear Plant of the Recent Changes in ICRP/NRPB
Recommendations
Final Report Number: Report Date:
Reason For Closing Issue:
A report for the IMC-RSTG by J Boardman, J McClymont & A Jones.
ICRP Publication 60 introduced new dose quantities for radiological protection purposes. These recommendations,
and revision of the recommended metabolic models, has led to a new set of dose per unit intake parameters being
proposed by the IAEA, the EU and the ICRP for future dose estimates.
The models and parameters used to estimate the risk of early health effects and late health effects as a function of
dose and dose rate have also been reviewed and updated since CONDOR was written.
It was agreed that a sufficient number of changes had accumulated to justify a major revision of CONDOR. The
intention of the revision was to ensure that CONDOR continued to use up to date models and parameters and thus
remained fit for purpose as the first choice PSA code within the nuclear industry in the UK.
An IMC-RP project was approved to provide funding support for the updating of CONDOR and a series of
intercomparisons of the old and new to seek a better understanding of the impacts of the changes on PSA cases
supporting the operation of nuclear power reactors in the UK.
A number of source terms were chosen for the comparison. These included 3 PWR and an AGR source term with
different isotopic mixtures and different magnitudes.
The results show that the effects of the changes are most noticeable in the inhalation doses (increased by up to a
factor of 2), early deaths (reduced in all cases and up to a factor of two orders of magnitude for the smaller source
terms) and fatal cancers, which show a slight increase.
With the exception of early fatalities all the results presented show the CONDOR2 results to be within the 90%
confidence bounds of CONDOR as determined in the earlier uncertainty analyses.
This report:
Provides evidence that the PSA calculations performed using CONDOR to support the operation of the nuclear power
reactors in the UK remain robust against updated dose factors and risk models.
Provides an understanding of the changes in PSA results resulting from these revisions.
Has allowed CONDOR2 to be developed and carefully checked.
Comments:
Previously 12.6.1 (1998/99)
Technical Area: Radiological Protection
Issue Number: 12 Issue: Radiological protection
Sub-Issue Number: 12.19 Sub-Issue: Atmospheric dispersion modelling for article 37
work
Description of safety issue:
There is a continuing need to develop computer codes and models for the rapid assessment of dose to
individuals in the population following emergency situations. This work is of use to emergency planners and
those involved in decision making in emergencies. Some of this work is more appropriate for the licensees to
fund but there is also research work which is supported by Government departments.
Expected outcome:
To continually review developments to ensure that the industry gains full advantage of any new or improved
methods for providing cost effective emergency response capability.
Date Raised: 01/04/1994 Date Closed: Priority: Medium
Status: Closed.
Licensees:
Nominated Research N/A
Officers:
Contract Number:
Contractor:
Final Report Title:
Final Report Number: Report Date:
Reason For Closing Issue:
See sub-issues 12.19.1 and 12.19.2.
Comments:
Previously 12.3 (1998/99)
Technical Area: Radiological Protection
Issue Number: 12 Issue: Radiological protection
Sub-Issue Number: 12.19.1 Sub-Issue: Development of emergency methods - appraisal of
off-site monitoring tools for operator training
Description of safety issue:
Techniques are now available which enable instrumentation to respond in a manner which mimics radioactivity
in a plume. Such instruments have the potential to be a useful training tool. During training exercises the
off-site monitoring teams will see their instruments respond to the modelled plume and can therefore react in a
more realistic manner. This would greatly enhance the quality of training these teams receive. The use of this
system would also reduce the confusion between real measured data (background readings) and exercise data
(injected by the umpires), provided the system can be programmed to give realistic cloud doses.
Expected outcome:
To review such system and assess its effectiveness.
To assess the suitability of the plume generation algorithm.
To consider how many instruments would be required for the different types of exercise.
To consider suitability for use in the field of the instruments - expected battery life, ease of use, comparability with real
instruments etc.
To consider the work load involved in setting up an exercise and programming all of the required instruments.
To estimate the setup (including initial programme development) and maintenance costs of the system and make a
judgement on its worth.
This work would be of generic use throughout the industry.
Date Raised: 01/04/1996 Date Closed: Priority: High
Status: Closed
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: RP/GNSR/5043
Contractor: NRPB
Final Report Title: Appraisal of the Off-site Monitoring Training Tools "Plumes"
Final Report Number: NRPB -M800 Report Date:
Reason For Closing Issue:
Work has been completed to the satisfaction of the Radiological Protection Working
Group to the original contract specification.
Comments:
Previously 12.3.1 (1998/99)
Technical Area: Radiological Protection
Issue Number: 12 Issue: Radiological protection
Sub-Issue Number: 12.19.2 Sub-Issue: Review of emergency gamma spectrometry
Description of safety issue:
In the event of a nuclear emergency leading to the release of radioactivity to the environment, protection of the
public is a high priority. The countermeasures of shelter, evacuation and application of stable iodine (PITs) can
all reduce the risk to the general public if applied correctly.
The decision to apply countermeasures is taken by comparing the dose that may be averted by the countermeasure
with NRPB's Emergency Reference Levels (ERLs). Timely imposition of countermeasures requires dose assessments
to be made with great rapidity. Current practice is to measure gamma dose rates in air at fixed points along the site
perimeters. A number of off-site survey vehicles measure beta/gamma dose rates in air and airborne concentrations
downwind of the release point. Gamma spectroscopy of samples is currently performed after a sample has been
recovered from off-site and taken to a district survey laboratory. In the mean time, the dose estimates upon which
countermeasure decisions are made are based on isotopic compositions calculated in safety cases or considered to be
conservative. Gamma spectroscopy will also be used in the post accident phase to aid long term recovery
planning.
Over the last few years portable high resolution gamma spectroscopy systems with powerful gamma spectroscopy
analysis capability have been developed. The question is, could these be introduced in emergency plans to good
effect? A cost benefit analysis is therefore required.
Expected outcome:
A review of the use of gamma spectroscopy in current emergency plans.
A review of options for in-situ and mobile laboratory gamma spectroscopy and potential benefits.
An assessment of the training requirements.
An assessment of the maintenance requirements and reliability of gamma spectroscopy kit.
An assessment of the set up costs of gamma spectroscopy.
A summary of costs and benefits.
Date Raised: 01/04/1997 Date Closed: Priority: High
Status: Closed.
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: RP/GNSR/5033
Contractor: AEA Technology
Final Report Title: Review of In-Site Gamma Spectroscopy
Final Report Number: Report Date:
Reason For Closing Issue:
AEAT were contracted to review the provision of gamma spectroscopy in emergency situations. The report
reviewed current provisions in the UK and abroad and looked at recent developments in high resolution gamma
spectroscopy systems.
The report concluded that putting high resolution gamma spectrometry into the current off-site survey vans would be
difficult and expensive and probably not cost effective. Mobile laboratories that could be deployed in the event of a
nuclear accident may help in the timescale of days after the event.
Comments:
Previously 12.3.2 (1998/99)
Technical Area: Radiological Protection
Issue Number: 12 Issue: Radiological protection
Sub-Issue Number: 12.20 Sub-Issue: Radiation dosimetry
Description of safety issue:
The recommendations contained in ICRP60 reduce the current annual dose limits for workers. In addition the
quality factor for neutrons will be increased by 1.5. These recommendations will ultimately be cast in UK
legislation. The changes are likely to place added emphasis on the accuracy and background sensitivity of
neutron detection systems.
Much of the neutron dosimetry in the UK will soon be based on etching of CR39 plastic, which is currently in routine
use. The background sensitivity of this material is determined by areas of elevated pit density arising from the material
itself rather than from neutron tracks. These high background regions occasionally give rise to spurious high readings
of neutron dose. The reduction in dose allowances will bring with it a need for lower background plastics.
There is evidence that the quality of the etch plastic could be improved by fundamental studies of the polymerisation
process. Research could provide an opportunity to obtain information on the characteristics of such material and its
suitability for personal dosimeter applications.
Expected outcome:
Undertake a fundamental study of the relation between polymerisation conditions and the performance of the
resulting plastic as a neutron dosimeter. Several aspects are worthy of further study:
- Influence of monomer purity.
- Effect of additives on cross-linking and hence radiation sensitivity.
- Relation between polymer structure and track recording performance.
- Effect of material ageing on performance.
Undertake fundamental studies to evaluate methods for the characterisation and dosimetry of radioactive hot particles.
As the work is basic research, laboratories to develop the plastics and facilities to run test exposures, using a
neutron flux, are required.
Date Raised: 01/04/1994 Date Closed: Priority: Medium
Status: Closed.
Licensees:
Nominated Research N/A
Officers:
Contract Number:
Contractor:
Final Report Title:
Final Report Number: Report Date:
Reason For Closing Issue:
The CR39 dosimeter is in routine use within the industry. Nuclear Electric have undertaken their own evaluation
of this work and investigated the research proposal. They have concluded that there is little to be gained by
pursuing the issue further. The issue is therefore closed.
Comments:
Previously issue 12.1.
Technical Area: Radiological Protection
Issue Number: 12 Issue: Radiological protection
Sub-Issue Number: 12.21 Sub-Issue: CONDOR uncertainty analysis
Description of safety issue:
Nuclear Electric and AEA Consultancy Services (SRD) have undertaken an uncertainty analysis of the CONDOR
computer code, in collaboration with NRPB. Analysis of uncertainties arising from the atmospheric dispersion,
countermeasures, food, dose and health effects modules has been completed. The uncertainty analysis of the
whole code has been largely completed during the 1994/95 FY but this is a major project and further work has
been indicated in discussions during the course of the current work and an allowance needs to be made for a
carry-over into the 1995/96 FY. It is intended to complete the CONDOR uncertainty analysis exercise by
including a consideration of sensitivity to uncertainties in the source term. The work in general terms is as
follows:
1. To complete reporting the multi-parameter uncertainty analysis of the CONDOR program by production of an open
publication. This is to be carried out jointly with Nuclear Electric staff at BTC.
2. To extend the CONDOR uncertainty analysis to include studies of sensitivity to the source term. This is to be carried
out jointly with Nuclear Electric staff at BTC.
Expected outcome:
The programme of work is essentially to identify the principal uncertainties in the CONDOR code and produce a
publicly available report. This work is largely complete with the report to be produced in 1995/96.
Date Raised: 01/04/1995 Date Closed: Priority: Medium
Status: Closed.
Licensees:
Nominated Research J S Griffiths
Officers:
Contract Number: RP/GNSR/01
Contractor: AEAT Consultancy Services
Final Report Title: Uncertainty and Sensitivity Analysis of the CONDOR Probabilistic Consequence
Assessment Program
Final Report Number: AEAT/16423548/R/001 Report Date: 01/04/1996
Reason For Closing Issue:
Work has been completed to the satisfaction of the Radiological Protection Working
Group to the original contract specification.
Comments:
Two reports have been issued by the contractor, AEAT Consultancy Services - AEAT/16423549/R/01 and
AEAT/16423549/R/02.
Previously issue 12.4.
Technical Area: Radiological Protection
Issue Number: 12 Issue: Radiological protection
Sub-Issue Number: 12.22 Sub-Issue: Review of regional agricultural practices
Description of safety issue:
Calculation of ingestion doses following airborne releases from nuclear utilities rely on models implemented
within computer programs for the assessment of radiological consequences. These models make assumptions
regarding how the radioactive material gets into the body. In order that these models reflect as near as possible
actual practice there is a need to build in appropriate databases of information.
The dose to man following deposition of activity on agricultural land depends on a number of factors including:
The nature of the deposition - isotopes, chemical form and physical form.
The mode of dispersion.
The use of the land eg. which food crops and grazing animals.
Traditionally under these headings conservative assumptions have been made. In recent years some research has
been undertaken to refine this data to provide a best estimate model of land usage and to implement any parameter
improvements into the existing database. This model should reflect actual practice for areas around nuclear facilities
and take account of seasonal variations. The objective being to prepare a database of parameters suitable for
inclusion in consequence models. In some cases this may need extension to enable appropriate interface with the
assessment model.
Expected outcome:
There is an existing project for 1995/96. This work is likely to need extension so that the databases can be
reviewed and to establish methods for interface with existing consequence modelling methodologies.
Date Raised: 01/04/1995 Date Closed: Priority: Medium
Status: Closed.
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: BL/G/31295N
Contractor:
Final Report Title: Agricultural Practices around Selected Nuclear Power Plants, 1995 & 1996
Final Report Number: BL/G/31295N Report Date:
Reason For Closing Issue:
A number of projects have been successfully completed on reviewing agricultural practices around UK nuclear
sites. A database of agricultural practices now exists. The contract work has been completed. The model
validation has been completed and a copy of the database has been made available.
Comments:
Previously issue 12.5.
Technical Area: Radiological Protection
Issue Number: 12 Issue: Radiological protection
Sub-Issue Number: 12.23 Sub-Issue: Consequence assessment code updates
Description of safety issue:
CONDOR was designed as a state-of-the-art probabilistic consequence analysis (PCA) program to analyse the
consequences to society as a whole following an accidental release of radioactive material to the atmosphere.
The CONDOR code was originally developed by AEA, Nuclear Electric and NRPB, and has since been adopted
by the participating organisations and by other areas of the nuclear industry. In 1993, a Users Group was formed
to support the maintenance and development of the program, in order to keep pace with changes in UK and
International recommendations. The code has also been the subject of comparison with other probabilistic
codes in use worldwide ( eg COSYMA and MACCS).
Since the issue of CONDOR version 1.0 in 1990, major updates to the recommendations of the International
Commission on Radiological Protection have been made (eg Publications 56, 60, 66 and other related documents).
The estimated costs associated with the overall updates to CONDOR are outside the scope for funding of the Users
Group. The research issue is therefore to update and maintain a UK based code. to update the code to take account of
recommendations of ICRP as they affect the CONDOR PCA Program.
Expected outcome:
The programme of work requires knowledge of and access to the code plus facilities to undertake the necessary
additions to ensure that the code is maintained in a benchmarked form.
Date Raised: 01/04/1995 Date Closed: Priority: High
Status: Closed
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number:
Contractor:
Final Report Title:
Final Report Number: Report Date:
Reason For Closing Issue:
Comments:
Technical Area: Radiological Protection
Issue Number: 12 Issue: Radiological protection
Sub-Issue Number: 12.24 Sub-Issue: Freshwater pathways evaluation
Description of safety issue:
The role of the freshwater pathway has traditionally been ignored as unimportant in the field or radiological risk
assessment and, as such, has not been considered by the current generation of probabilistic consequence codes
such as CONDOR and COSYMA etc. However, following the consequences of the Chernobyl accident, there is
some evidence that the pathway may have greater importance to the economic and health effect consequences
of accidental releases of radionuclides than previously considered. Over the past few years the CEC has
supported significant research in to the modelling of the transfer of radionuclides through freshwater
environments and the OTTER freshwater modelling code was developed by AEA as part of this programme.
The initial work would be to investigate the use of freshwater modelling codes such as OTTER, in conjunction
with a probabilistic consequence assessment program. This would form part of an investigation into the
importance of the freshwater pathway relative to the more traditionally considered pathways such as ingestion of
terrestrial foods, inhalation, groundshine, etc. The work is to consider the doses to both the society as a whole
and the critical group. Economic consequences may also be investigated.
Expected outcome:
For selected hypothetical releases, release sites and freshwater environments, use a probabilistic consequence
assessment code to estimate economic costs and doses from traditional pathways. The predicted deposited
concentrations of radionuclides in the freshwater environment and this information would be used as inputs to
codes such as OTTER. The results would enable the doses from the freshwater pathway to be estimated and
compared to the more traditional pathways. Work could also be performed to estimate the economic
consequences of any drinking water and freshwater fish bans.
The principal objective of the work is to try and establish whether this pathway is important and to have any judgements
backed by scientific information.
Date Raised: 01/04/1995 Date Closed: Priority: Medium
Status: Closed
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: RP/GNSR/5030
Contractor: Westlakes
Final Report Title: Scoping Study on the relative importance of Freshwater Dose Pathways following a
major Nuclear accident
Final Report Number: Report Date: 01/05/1997
Reason For Closing Issue:
The issue has been satisfactorily addressed by the work described.
Comments:
Contract ref BL/G/44219/C.
Previously issue 12.7.
Technical Area: Radiological Protection
Issue Number: 12.1 Issue: Emergency response capability
Sub-Issue Number: 12.1.1 Sub-Issue: Review of airborne gamma spectroscopy (AGS)
Description of safety issue:
Airborne gamma spectroscopy (AGS) has been developed as a technique to survey the ground contamination of
a large area in a relatively short timescale. This has potential value in the post-accident monitoring phase.
At this stage of development a review of the technique, considering how it complements other post-accident
environmental monitoring and the costs and benefits of its implementation is considered timely.
There is also a need to support and develop the AGS capability within the UK while its worth is being evaluated.
Expected outcome:
A review of the capabilities of AGS and consideration of the potential value of the data AGS can provide. The
review to include discussion about which organisations may benefit from the use of AGS.
The DETR are co-ordinating a three year project to investigate the spatial and temporal aspects of airborne gamma
spectroscopy. The IMC-RSTG has agreed that this project merits support and let a contract in 1998/99 to DETR
to part fund the first year of the project.
Date Raised: 01/04/1999 Date Closed: Priority: High
Status: Closed.
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: RP/GNSR/5046
Contractor: SURRC
Final Report Title: Investigation of Spatial and Temporal Aspects of Airborne Gamma Spectrometry:
Preliminary Report on Phase II Survey Conducted March 2000
Final Report Number: RW 8/6/80 Report Date: 01/04/2000
Reason For Closing Issue:
A general industry wide agreement is needed on the value of AGS and how, if at all, it is to be supported. The
IMC view is that this work should not be supported by licensees as it is a national issue with a greater potential
risk from incidents external to the UK.
Comments:
See also RP/GNSR/5059 - NRPB.
Technical Area: Radiological Protection
Issue Number: 12.1 Issue: Emergency response capability
Sub-Issue Number: 12.1.2 Sub-Issue: Review of emergency monitoring
Description of safety issue:
In the event of a nuclear emergency leading to the release of radioactivity to the environment, protection of the
public is a high priority. The countermeasures of shelter evacuation and the application of stable iodine (PITs)
can all reduce the risk to the general public if applied correctly.
The decision to apply countermeasures is taken by comparing the dose that may be averted by the countermeasure
with NRPB's Emergency Reference Levels (ERLs). Timely imposition of countermeasures requires dose assessments
to be made with great rapidity. These dose assessments are based on an understanding of the off-site radiological
conditions gained from off-site monitoring and attempts to understand the causes of the emergency on-site.
There are a number of off-site monitoring options available and the ease with which these measurements can be taken
and reported is changing with developments in the fields of instrumentation, computers and communications.
There is a perceived need to review current off-site monitoring strategies to ensure that the techniques used are
optimised for their purpose.
Expected outcome:
A critical review of the current off-site monitoring strategies used by the member companies of IMC to include
consideration of practices in Europe and America.
Date Raised: 17/09/1998 Date Closed: Priority: Medium
Status: A report covering UK practices was completed in 2000. Consideration is being
given to the need for further work addressing practices in other countries.
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: RP/GNSR/5062
Contractor: BNFL Magnox Electric
Final Report Title: Review of Off-site Monitoring During Nuclear Emergencies
Final Report Number: M/TE/GEN/REP/0003/00 Report Date: 01/03/2000
Reason For Closing Issue:
A review of off-site monitoring procedures at different UK nuclear establishments was undertaken. This shows
that similar procedures are in place at all British nuclear establishments. It was concluded that the priorities for
the off-site survey should be to confirm that a release has occurred, to determine the areas affected and to
estimate the likely doserates within the affected area.
Comments:
Technical Area: Radiological Protection
Issue Number: 12.1 Issue: Emergency response capability
Sub-Issue Number: 12.1.2 Sub-Issue: Review of emergency monitoring
Description of safety issue:
In the event of a nuclear emergency leading to the release of radioactivity to the environment, protection of the
public is a high priority. The countermeasures of shelter evacuation and the application of stable iodine (PITs)
can all reduce the risk to the general public if applied correctly.
The decision to apply countermeasures is taken by comparing the dose that may be averted by the countermeasure
with NRPB's Emergency Reference Levels (ERLs). Timely imposition of countermeasures requires dose assessments
to be made with great rapidity. These dose assessments are based on an understanding of the off-site radiological
conditions gained from off-site monitoring and attempts to understand the causes of the emergency on-site.
There are a number of off-site monitoring options available and the ease with which these measurements can be taken
and reported is changing with developments in the fields of instrumentation, computers and communications.
There is a perceived need to review current off-site monitoring strategies to ensure that the techniques used are
optimised for their purpose.
Expected outcome:
A critical review of the current off-site monitoring strategies used by the member companies of IMC to include
consideration of practices in Europe and America.
Date Raised: 17/09/1998 Date Closed: Priority: Medium
Status: A report covering UK practices was completed in 2000. Consideration is being
given to the need for further work addressing practices in other countries.
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number:
Contractor:
Final Report Title:
Final Report Number: Report Date:
Reason For Closing Issue:
Comments:
Technical Area: Radiological Protection
Issue Number: 12.1 Issue: Emergency response capability
Sub-Issue Number: 12.1.3 Sub-Issue: Source terms for emergency planning
Description of safety issue:
Nuclear Site Licence Condition 11 requires the licensee to implement adequate emergency arrangements. This
must include the provision of detailed plans for the implementation of pre-planned countermeasures to protect
members of the public from the effects of radiation following a nuclear accident.
The current emergency arrangements have generally been developed assuming highly unlikely large releases from a
design basis or reference accident approach. Therefore only a small number of highly unlikely potential accident
scenarios are considered, and little account is taken of the smaller, but more likely, release scenarios. Consequently it
is difficult to demonstrate that the pre-planned countermeasures are ALARP in terms of dose aversion to the public.
There is a need for the provision of source terms which dominate the off-site risk to the public, and thus would
allow more realistic initial emergency dose assessments because initial predictions of off-site doses could be
based on a source term expected to best match the true reactor situation. These could then be used to evaluate
the emergency arrangements and optimise pre-planned countermeasures.
Expected outcome:
There is a requirement to provide a representative set of source terms appropriate to emergency planning for
dominant risk faults for at least each reactor type.
Date Raised: 13/04/1999 Date Closed: Priority: Medium
Status: Closed
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: RS/GNSR/5052
Contractor:
Final Report Title:
Final Report Number: RSTG/P(00)10 Report Date:
Reason For Closing Issue:
The project to provide a representative set of Magnox source terms for emergency planning (RS/GNSR/5052)
has been completed (report RSTG/P(00)10). There is no requirement for further work. This issue is closed.
Comments:
Technical Area: Radiological Protection
Issue Number: 12.1 Issue: Emergency response capability
Sub-Issue Number: 12.1.4 Sub-Issue: Mobile communications
Description of safety issue:
In the response to a nuclear emergency communications is a key component. Poor communications will
inevitably lead to a badly coordinated response.
Current emergency plans involve a number of centres and mobile facilities undertaking a wide range of tasks and
generating significant quantities of information which would be of value at other locations provided it could be
transmitted successfully.
New mobile communications technologies are being developed and introduced. There is a perceived danger that these
new technologies will be introduced in an uncoordinated, piecemeal manner leading to ever more complex and
cumbersome systems.
Expected outcome:
There is a perceived requirement to consider what may be available in terms of emergency communications
systems in 5 to 10 years time to give guidance to those responsible for maintaining and developing current
systems.
Date Raised: 07/07/1999 Date Closed: Priority: Medium
Status: Closed.
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: RS/GNSR/5063
Contractor: SCOMAGG
Final Report Title: Review of Mobile Communication Technologies
Final Report Number: RSTG/P(00)12 Report Date: 13/10/2000
Reason For Closing Issue:
The final report has been issued by the contractor and accepted by the Topic Group. The implications of the
report will be considered by those responsible for emergency planning arrangements.
Comments:
A contract was placed to provide a review of mobile communications technologies. The report was issued in
October 2000. The implications of this report will be considered by those responsible for Emergency Planning
arrangements. The Issue is now considered to be closed.
Technical Area: Radiological Protection
Issue Number: 12.2 Issue: Atmospheric dispersion of activity and terrestrial
foodchains
Sub-Issue Number: 12.2.1 Sub-Issue: Dispersion/speciation of H-3, C-14 and S-35 near
nuclear sites
Description of safety issue:
The chemical form of radionuclides has an important effect on their mobility and subsequent dose to man. The
speciation around nuclear sites is not well known and it is proposed to carry out a study to determine deviations
from simple dispersion models caused by chemical speciation and other effects. The distribution across
chemical species will effect the uptake to the foodchain.
This is a three year study to be co-funded by the Food Safety (Radiation) unit of the Ministry of Agriculture, Fisheries
and Food to study the deviations from dispersion models caused by chemical speciation with a view to examination of
impact on food chain models.
Expected outcome:
To develop analytical techniques to measure the chemical speciation of H-3, C-14 and S-35 at environmental
concentrations near nuclear sites.
To make measurements of chemical speciation in a number of environmental media at a number of nuclear sites.
Date Raised: 01/04/1995 Date Closed: Priority: Medium
Status: A contract was placed to develop appropriate equipment and carry out
environmental measurements near nuclear sites. In an extension to that contract
further measurements were carried out subsequently with samples from the
contaminated ventilation air systems at an AGR and at a Magnox station with
reactor gas sampled from an AGR. The implications of the results are being
considered by the appropriate working group.
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: RP/GNSR/5044
Contractor: RCD
Final Report Title: See comments below.
Final Report Number: Report Date:
Reason For Closing Issue:
The chemical form of gaseous activity discharged from nuclear power stations is excepted to have an impact on
the uptake by crops. This project developed and installed samplers that would allow the concentrations of
different chemical forms of H-3, C-14 and S-35 to be measured over an extended period of time.
Comments:
Three reports have been produced
Speciation of H-3, C-14 and S-35 in the Environment
Sampling for gaseous species of s-35 from air samples taken from the contaminated air vent system at Oldbury Power
Station.
Speciation of C-14, S-35 and H-3 in the vent gas of Hinkley Point B AGR.
Technical Area: Radiological Protection
Issue Number: 12.2 Issue: Atmospheric dispersion of activity and terrestrial
foodchains
Sub-Issue Number: 12.2.2 Sub-Issue: Uptake by fruit of particulate activity, C-14 and S-35
Description of safety issue:
Presently there is a paucity of information concerning the uptake of C-14 and S-35 by fruit. This represents a gap
in knowledge and has implications for assessment of doses by ingestions as a result of routine releases. It is also
of relevance to accident scenarios. MAFF are committed to research in this area and are initiating a specific
project. Co-funding by the IMC represents an effective way of achieving research results in a cost effective
manner.
Expected outcome:
The work programme requires crops to be exposed at defined periods in their growth cycle under controlled
conditions. In this way aspects such as the rate of loss of radioactivity following exposure and concentration at
harvest can be established. It is anticipated that both field and wind tunnel experiments will be necessary. This
will allow for the rate of incorporation to be assessed more accurately and provide an input to modelling of this
exposure route.
Date Raised: 01/04/1996 Date Closed: Priority: Medium
Status: Closed.
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: RP/GNSR/5027
Contractor: Imperial College London
Final Report Title: Deposition of Carbon 14, Sulphur 35 and Tritium to fruit crops.
Final Report Number: Report Date:
Reason For Closing Issue:
This was a four year project co-funded by MAFF (now FSA) to produce a comprehensive database of
radionuclide fluxes in support of foodchain modelling.
A number of reports were generated during the course of the project. The final report, issued in November 2000
summarises the background to the project and describes how the database was constructed and populated.
The database, delivered on CD-ROM, contains nearly 20,000 records on the transfer of radionuclides in terrestrial
systems. It contains information required for the development of time-dependent models and for parameters that are
consistent with current models. The issue of this CD-ROM satisfies the requirements of the project.
Comments:
There was a gap in knowledge about the uptake of S-35 by fruit. The project has provided data on the uptake of
S -35, C -14 and H -3 to fruit which helps to fill these gaps.
Technical Area: Radiological Protection
Issue Number: 12.2 Issue: Atmospheric dispersion of activity and terrestrial
foodchains
Sub-Issue Number: 12.2.4 Sub-Issue: Dispersion of carbon dioxide from reactor circuit
breach
Description of safety issue:
The coolant in AGR and Magnox reactors is carbon dioxide gas at high pressure. In the event of a breach
occurring in one of the reactor penetrations, coolant would be discharged from the breach, depressurising the
reactor. In most cases, the gas discharge would be "choked" at the breach, so that close to the breach the gas
would be hot and have a velocity close to that of sound. The subsequent dispersion of the carbon dioxide in the
atmosphere will depend on the temperature of the gas (it may or may not be buoyant with respect to the
surrounding air), the location of the breach and the direction in which the gas is first discharged. It is necessary
to be able to predict this dispersion in order to predict the local carbon dioxide concentrations and gas-borne
activity concentrations, in order to assess the risk to operators at the site should a breach occur.
Expected outcome:
Some work has already been carried out for AGR reactors. The requirement is to provide a methodology for
predicting the dispersion of carbon dioxide from a Magnox reactor breach, suitable for a range of breach sizes,
gas temperature and breach locations. The use of the methodology should be demonstrated by use in a number
of diverse situations.
Date Raised: 13/04/1999 Date Closed: Priority: Low
Status: Closed
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number:
Contractor:
Final Report Title:
Final Report Number: Report Date:
Reason For Closing Issue:
This NRI item was concerned with predicting the dispersion of CO2 and entrained activity from a breach in the
coolant circuit of an operating gas cooled reactor. Under these conditions the gas would be hot and have a
velocity close to that of sound.
Further consultation with engineers within the Magnox Plant Modelling Group and British Energy has led to the
conclusion that these engineers are satisfied that current methods for predicting the dispersion remain fit for purpose
(RSTG/M(00)6).
Therefore, no further work is required and the issue can be closed.
Comments:
Technical Area: Radiological Protection
Issue Number: 12.2 Issue: Atmospheric dispersion of activity and terrestrial
foodchains
Sub-Issue Number: 12.2.5 Sub-Issue: Chemical form of iodine
Description of safety issue:
Radioactive forms of iodine are often a major contributor to the assessed off-site doses in the safety cases written
in support of gas cooled reactors. These dose assessments are sensitive to assumptions about the chemical and
physical form of the released iodine. What is required is a review of the understanding of the chemical and
physical forms of iodine likely to be released to atmosphere in gas-cooled reactor faults, the changes in chemical
and physical form in the atmosphere, and the effects of these forms on dose uptake.
Expected outcome:
The current understanding of the atmospheric chemistry of those forms of iodine expected to be released to the
environment during reactor operation and fault will be reviewed. This will result in predictions of the likely
chemical and physical form of iodine downwind of a nuclear accident.
Current understanding of the deposition velocity to ground, the deposition velocity to skin and the retention times on
skin, the dose per unit inhalation and the likely behaviour in food chains of the surviving atmospheric forms (both
particulate and vapour) should be reviewed.
Date Raised: 07/07/1999 Date Closed: Priority: Medium
Status: A contract has been placed for the first part of this work, concerning the likely
chemical and physical forms of iodine downwind of a nuclear accident. The final
report was due to have been received early in 2001, but has been delayed. After
that report has been received, the need for further work(on deposition, inhalation
uptake and transport through the foodchain) will be reviewed by the licensees.
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: RS/GNSR/5065
Contractor: NNC
Final Report Title: Investigation into the chemical forms of iodine in the atmosphere post accident
Final Report Number: C6384/TR/001 Report Date: 01/09/2001
Reason For Closing Issue:
The chemical form of Iodine in the atmosphere can make a significant difference to its estimated dose implications.
The objective of this project was to consider how the chemical form of iodine species might change in the atmosphere
after release. The report consists of a literature review and a number of calculations.
It was concluded that methyl iodide is essentially stable in the time scales of interest while several other forms
convert to the oxide. The report is a valuable contribution to our knowledge of the potential environmental and
off-site dose implications of releases of iodine.
Comments:
Technical Area: Radiological Protection
Issue Number: 12.3 Issue: Atmospheric dispersion of activity and aquatic
foodchains
Sub-Issue Number: 12.3.1 Sub-Issue: Marine background of C-14
Description of safety issue:
C-14 is an important component of the total activity released from reactor sites and its behaviour in the marine
environment is inadequately understood. When considering the results of measurements from the marine
environment, it is difficult to assess the level of natural background which should be subtracted in order to
estimate the levels of man made C-14 taken up into the food chain. Measurements of the terrestrial background
have been made but marine measurements have been mainly confined to the deep ocean and the values are
probably not applicable to coastal waters.
The objective is to obtain a better understanding of the marine background of C-14. This would ultimately help in the
assessment of doses to critical groups and population as a result of discharges from nuclear power plant.
Expected outcome:
To define a sampling scheme of sites (about 20) around the British coast, with consideration given to their siting
relative to sources of anthropogenic C-14 and the dilution effects of ocean currents. The sampling programme
should include the use of an indicator nuclide such as Cs-137 of Tc-99 as a means of identifying potential C-14
inputs from anthropogenic sources. The spatial distribution of sample sites should allow for a determination of
variation of C-14 concentrations with distance in the Irish Sea from the Sellafield site in particular.
To collect samples and make measurements of C-14 which will concentrate on seawater (inorganic carbon) and fish
samples. Species taken at each site may vary but should total no more than six and should include fish and,
where possible, crustacean.
Analysis by NAMAS accredited laboratories and methods would be preferred. A proven track record of laboratory
intercomparison for C-14 determination in environmental samples would be preferred.
Date Raised: 01/04/1995 Date Closed: Priority: Medium
Status: Two projects have been completed. The first project provided the background
measurements which were required. In the second project, completed recently, a
more detailed investigation was carried out into the behaviour of carbon-14 in the
Irish Sea. It is not expected that further research will be needed.
Previously 12.10 (1998/99)
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number:
Contractor: Scottish Universities Research Reactor Centre(SURRC)
Final Report Title:
Final Report Number: Report Date:
Reason For Closing Issue:
The chemical and physical form of C-14 in the seas can be expected to have an impact on the dose
implications of liquid discharges of this isotope. This project collected a significant body of data for analysis
and model development.
Comments:
Technical Area: Radiological Protection
Issue Number: 12.4 Issue: Exposure of the environment and public to
radiation
Sub-Issue Number: 12.4.1 Sub-Issue: Clearance levels for materials and sites
Description of safety issue:
The disposal and/or reuse of potentially contaminated materials from nuclear sites is a matter that is emerging
from nuclear decommissioning. This issue has been raised to examine levels that may be acceptable for the
clearance and reuse of nuclear sites and the materials thereon.
Expected outcome:
To investigate acceptable levels for the clearance of nuclear sites and contaminated materials.
Date Raised: 18/05/1998 Date Closed: Priority: Medium
Status: Closed
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number:
Contractor:
Final Report Title:
Final Report Number: Report Date:
Reason For Closing Issue:
The specification of acceptable levels for the clearance of nuclear sites and contaminated materials is a matter
for the appropriate regulator and is not an appropriate subject for a research project. It has therefore been
decided that this Sub-issue should be closed. The issue will be addressed under Section 13.4.3.4. Previously
12.16 (1998/99)
Comments:
Technical Area: Radiological Protection
Issue Number: 12.4 Issue: Exposure of the environment and public to
radiation
Sub-Issue Number: 12.4.2 Sub-Issue: S-35 dose per unit intake factors
Description of safety issue:
The nuclear utilities are obliged to calculate the potential dose consequences of their discharges of activity for
the purposes of discharge authorisation negotiations and safety case preparation. A component of the off-site
dose resulting from the operation of gas cooled reactors is caused by the inhalation of S-35. This is believed to
be predominantly in the chemical forms COS and H2S although there are some suggestions that CS2 is also
produced. Dose per unit intake values for these chemical forms of S-35 are not available in standard
publications. This information is sought.
Expected outcome:
Tabulation of the dose per unit inhalation factors for COS, H2S and CS2 for a range of age groups.
Date Raised: 07/07/1999 Date Closed: Priority: Medium
Status: Closed.
Licensees:
Nominated Research L M Bevington
Officers:
Contract Number: RP/GNSR/5054/5060
Contractor: NRPB
Final Report Title: Dose Coefficients for Vapours of Sulphur 35
Final Report Number: NRPB-M1177 Report Date:
Reason For Closing Issue:
This was a small project which completes work on dose per unit intake factors for S-35.
Comments:
Technical Area: Radiological Protection
Issue Number: 12.5 Issue: Radiation dosimetry
Sub-Issue Number: 12.5.1 Sub-Issue: Hot particle dosimetry
Description of safety issue:
The radiological hazard posed by small radioactive sources in close contact with skin or the internal surfaces of
the lung, is commonly known as the "hot particle" effect. Hot particles are of particular concern because of the
potential for high localised exposure of the skin. There is a difficulty in calculating or measuring the magnitude
of spatially non-uniform exposure from hot particles and in evaluating the likely biological response to such
exposure.
Expected outcome:
A three year contract was placed with a University to develop and validate measurement and calculational
techniques for hot particle dosimetry. The final report on that work was issued in August 2000. There is a
requirement for further work to develop this research into improved methods of detection, characterisation and
dose assessment of hot particles which are suitable for use by Health Physics staff in Power Stations.
Date Raised: 01/04/1997 Date Closed: 01/08/2005 Priority: High
Status: A contract was placed with Birmingham University to develop practical methods
of detection, characterisation and dose assessment of hot particles for use by
health physics staff in power stations. All three reports, dealing with the detection
of hot particles have been issued.
Licensees:
Nominated Research Mr I Wilson
Officers:
Contract Number: IMC/RS/5069
Contractor: Birmingham University
Final Report Title: Detection, Characterisation and Dose Assessment of Large Hot Particles (LHPs)
Final Report Number: RSTG/P(03)2 Report Date: 01/07/2003
Reason For Closing Issue:
The project has provided a methodology for the detection, characterisation and assessment of the doses from
hot particles. No further work is required.
Comments:
Technical Area: Radiological Protection
Issue Number: 12.7 Issue: Radiological protection
Sub-Issue Number: 12.7.1 Sub-Issue: Overview of international developments in
radiological protection
Description of safety issue:
Developments in the methodology and data used for the prediction of the radiological effects of releases of
radioactivity are being undertaken worldwide. The results of these analyses could impact on the approach
adopted within the UK by the utilities and Regulators. There is therefore a need to be informed of all such work
which is proceeding; to assess the associated results; and to comment on the implications and the applicability
of these with respect to the information currently in use by the utilities.
Expected outcome:
A report reviewing international developments, that is in both the UK and overseas, in radiological protection
methodology and data will be issued every six months during the period of the Contract. The first report should
define all on-going issues in this area; what the output from the work will be; when it is expected to be
completed; and where the results will be reported.
Subsequent reports should identify any new work; highlight the progress with on-going tasks in so far as can be
ascertained; review the results of completed work and comment on the implications of these results for existing utility
methods and data.
Date Raised: 01/04/2000 Date Closed: 01/08/2005 Priority: Medium
Status: The contract placed in financial year 2000/01 identified and reviewed
international developments, that is both in the UK and overseas, in radiological
methodology and data.
Future reports will identify new work, highlight progress in on-going tasks, review
completed work and comment on the implications of all issues of potential relevance to
the assessment of the off-site consequences of radioactive releases. The two reports
have been issued.
Licensees:
Nominated Research Mr I Wilson
Officers:
Contract Number: 53/14948.30
Contractor: BNFL Magnox
Final Report Title: Review of Radiological Protection 2003-2004
Final Report Number: M/RS/GEN/REP/0003/04 Report Date:
Reason For Closing Issue:
BNFL proposes to that it should be closed. BNFL considers that maintaining an awareness of international
developments in radiological protection does not require the production of an annual report of this kind.
Comments:
