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Variations in the concentration of radon in parts of the Ogof Ffynnon Ddu system, Penwyllt, South Wales and estimates of doses to recreational cavers.

Abstract：

:A new winter and summer investigation of radon concentrations in parts of the Ogof Ffynnon Ddu system at Penwyllt, South Wales, has been carried out using 100 environmental National Radiological Protection Board track etch detectors. Fifty detectors were installed in the system in December 1998 and again in August 1999 for a period of a month. The data obtained confirm that the system has moderately high radon concentrations with a system mean of 2318 Bq m(-3) in winter and 2844 Bq m(-3) in summer. Traverse means have a summer high of 3094 Bq m(-3) for OFDI to Cwm Dwr and a winter low of 1946 Bq m(-3). The extremely high concentrations approaching 20,000 Bq m(-3), reported previously from the system (Hyland, 1995), have not been reproduced. The data show that the airflow directions at the entrances are not what might have been predicted. Air appears to be largely continuously emerging from the lowest entrance but, at the higher entrances, conversely to the predictions, in winter air enters and in summer appears to be coming out or is variable. Internally, there are sites that in winter have very low radon concentrations that can only be explained by the ingress of fresh air. These are not matched in the summer experiment, again indicating that ingress of fresh air to some parts of the system is very variable. The data illustrate the complexity of airflow within a multi-entrance system but behind these variations several mean concentrations can be obtained from which an approximation of the dose likely to be received can be calculated. Using the maximum mean concentration obtained, 3094 Bq m(-3), and using the latest dose conversion, a 10 h underground trip in the Ogof Ffynnon Ddu system yields a calculated dose of 0.12 mSv. Given that the recommended limit for a member of the public is 1 mSv, this dose would be reached after about 80 h of caving in the system.

journal_name

J Environ Radioact

journal_title

Journal of environmental radioactivity

authors

Friend CR,Gooding TD

doi

10.1016/s0265-931x(01)00029-7

subject

Has Abstract

pub_date

2002-01-01 00:00:00

pages

45-57

issue

eissn

0265-931X

issn

1879-1700

pii

S0265-931X(01)00029-7

journal_volume

pub_type

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Variations in the concentration of radon in parts of the Ogof Ffynnon Ddu system, Penwyllt, South Wales and estimates of doses to recreational cavers.