The petrology and paragenesis of fracture mineralization in the Sellafield area, west Cumbria

Milodowski, Antoni E.; Gillespie, Martin R.; Naden, Jonathan; Fortey, N. J.; Shepherd, T. J.; Pearce, Jonathan; Metcalfe, Richard

doi:10.1144/pygs.52.2.215

Cited by 54 publications

(33 citation statements)

References 52 publications

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“…It must therefore be present in trace quantities, and so most likely has a relatively fast dissolution rate to produce the observed increase in sulphate. This is consistent with either anhydrite or pyrite dissolution, both of which have relatively fast dissolution kinetics and commonly occur as fracture-filling phases within the BVG in the Sellafield area and elsewhere in west Cumbria (Milodowski et al, 1998;.…”

Section: Reactions Of Young Cement Porewater (Ynfp) With Bvg Changes supporting

confidence: 76%

A long-term experimental study of the reactivity of basement rock with highly alkaline cement waters: Reactions over the first 15 months

et al. 2016

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A series of long-term laboratory experiments was started in 1995 to investigate longer-term dissolution/precipitation reactions that may occur in the alkaline disturbed zone surrounding a cementitious repository for radioactive waste. They consist of samples of UK basement rock reacting with either Na-K-Ca-OH water ('young' cement porewater) or Ca-OH water ('evolved' cement porewater) at 70°C. This paper summarises results of reactions occurring over the first 15 months. Experiments of both fluid types showed many similar features, though primary mineral dissolution and secondary mineral precipitation were more extensive in the experiments involving Na-K-Ca (younger) cement porefluids compared to more evolved (Ca-rich) cement porefluids. Dissolution of dolomite, and to a lesser extent silicates (most probably K-feldspar, but possibly also mica) occurred relatively rapidly at 70 °C. Dolomite dissolution may have been a key factor in reducing pH values, and may be a key mineral in controlling the extent of alkaline disturbed zones. Dissolution was followed by precipitation of brucite close to dolomite grains, at least two generations of CSH phases

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Section: Reactions Of Young Cement Porewater (Ynfp) With Bvg Changes supporting

confidence: 76%

A long-term experimental study of the reactivity of basement rock with highly alkaline cement waters: Reactions over the first 15 months

et al. 2016

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“…The age of the quarry is not known, but it seems likely that it was probably worked during the last 100-200 a to produce local stone for the construction of field boundary walls. However, the presence of euhedral secondary calcite crystals lining the surfaces of fractures within the carbonated larnite nodules might indicate that the calcite crystals grew within water-saturated pores (Milodowski et al, 1998) -i.e. when the rock was below the groundwater table.…”

Section: Low-temperature Alterationmentioning

confidence: 99%

Carbonation of borehole seals: Comparing evidence from short-term laboratory experiments and long-term natural analogues

Rochelle

Milodowski

2013

Applied Geochemistry

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It is crucial that the engineered seals of boreholes in the vicinity of a deep storage facility remain effective for considerable timescales if the long-term geological containment of stored CO 2 is to be effective. These timescales extend beyond those achievable by laboratory experiments or industrial experience. Study of the carbonation of natural Ca silicate hydrate (CSH) phases provides a useful insight into the alteration processes and evolution of cement phases over long-timescales more comparable with those considered in performance assessments. Samples from two such natural analogues in Northern Ireland have been compared with samples from laboratory experiments on the carbonation of Portland cement. Samples showed similar carbonation reaction processes even though the natural and experimental samples underwent carbonation under very different conditions and timescales. These included conversion of the CSH phases to CaCO 3 and SiO 2 , and the formation of a well-defined reaction front. In laboratory experiments the reaction front is associated with localised Ca migration, localised matrix porosity increase, and localised shrinkage of the cement matrix with concomitant cracking. Behind the reaction front is a zone of CaCO 3 precipitation that partly seals porosity. A broader and more porous/permeable reaction zone was created in the laboratory experiments compared to the natural samples, and it is possible that short-term experiments might not fully replicate slower, longer-term processes. That the natural samples had only undergone limited carbonation, even though they had been exposed to atmospheric CO 2 or dissolved HCO 3 -in groundwater for several thousands of years, may indicate that the limited amounts of carbonate mineral formation may have protected the CSH phases from further reaction. IntroductionAcceptable performance of the geological storage of CO 2 will need to be demonstrated in order to satisfy operational, regulatory and public acceptance criteria, and a key element of this will be the effectiveness of the seals preventing CO 2 migration. At a generic level, the occurrence of natural CO 2 accumulations demonstrates the containment potential of caprock materials that have not been penetrated by human activity over time periods measurable in 10

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“…24,25 The volcanic rock was the mineralogically most complex of the geomaterials. 26 It consisted of approximately 50 wt% quartz, with chlorite, mica (probably muscovite; Fig. 1C), plagioclase, and calcite (apparently with some Mg content because the main peak is displaced from 3.03 to 3.024Å; Fig.…”

Section: Characterisation Of Geomaterialsmentioning

confidence: 99%

A conceptual model to predict uranium removal from aqueous solutions in water–rock systems associated with low- and intermediate-level radioactive waste disposal

et al. 2017

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a Global stores of radioactive waste are housed in surface stores where actinides are susceptible to environmental release. It is imperative that waste disposal facilities are built to safely contain this waste.However, to do this we must ensure that the engineered and natural barriers are sufficient to prevent the buried materials from migrating through to the surface. Solutions migrating from repositories (ILW and LLW) will have a wide range of chemical compositions and conceptual models constraining the key mineral-water interactions with realistic lithologies are urgently needed. To this end, we conducted experiments to study U removal from solution via mineral-surface interactions with quartz, sandstone, and volcanic rock over a pH range of 2-12, with varying concentrations of U (10 ppb, 0.1 ppm, 1 ppm, and 10 ppm) and with and without bicarbonate added (2 mM) with 0.1 M NaCl electrolyte. We observed that the U concentration in solution had little effect on the extent of U removal from solution as a function of pH or bicarbonate concentration with quartz and sandstone but was important for volcanic rocks, where removal of U, due to adsorption, decreased with increasing U concentration between pH 4 and 8. When bicarbonate was added to solution then the quartz, sandstone, and volcanic rock geomaterials acted similarly in their abilities to immobilize uranium, with an adsorption envelope from pH 4-8 followed by an increase in U removal, likely via precipitation, at high pH.

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The petrology and paragenesis of fracture mineralization in the Sellafield area, west Cumbria

Cited by 54 publications

References 52 publications

A long-term experimental study of the reactivity of basement rock with highly alkaline cement waters: Reactions over the first 15 months

A long-term experimental study of the reactivity of basement rock with highly alkaline cement waters: Reactions over the first 15 months

Carbonation of borehole seals: Comparing evidence from short-term laboratory experiments and long-term natural analogues

A conceptual model to predict uranium removal from aqueous solutions in water–rock systems associated with low- and intermediate-level radioactive waste disposal

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