Madam,

Your article regarding the disposal of nuclear waste (‘Locations for radioactive waste burial considered’) draws the attention of the public to an issue that has exercised the minds of governmental authorities for at least the last 40 years.

Earlier in this planning phase various European governments were tasked to examine different rock types and their suitability.

The UK opted to look at the suitability of granite – hence they concentrated on sites at least 700 miles from London in northern Scotland.

Foremost in the thinking is whether to bury the waste and forget it, or entomb it and monitor the situation.

Turning to the Welsh option, it must be stated there are few sites on land that can be identified as suitable for the disposal of nuclear waste for the long term, whether it is monitored or not. There are two reasons for this.

Firstly, the country is criss-crossed with faults, many of which are still active today.

The second reason is that Wales remains a dynamic region as it is still recovering from the imposition of major ice caps. These ice caps melted away some 14,000 years ago, yet the land is still recovering in the form of isostatic adjustment.

Major faults such as the Bala and Ystwyth continue to release minor tremors, whilst the coastal faults such as the Mochras Fault are historically active.

Regarding the marine prospects, south of Harlech in the offshore there is a very thick sequence of Lower Lias (Lower Jurassic) calcareous mudstones that might be a consideration.

Such a prospect would need to be well west of the coastal fault and might offer a solution, although monitoring such a respository would be expensive and preclude any subsequent fracking interest.

Also mentioned are the Permo-Triassic basins in the Southern Irish Sea, notably the one lying west of Llyn Peninsula.

These basins do contain the thick beds of salt which can be competent seals but such deposits are subject to flow.

In the St George’s Basin, north west of Strumble Head, the salt has migrated up the local fault reaching near to the seabed. They thus are a risk, given the long-term nature of nuclear waste storage.

The nuclear industry is in a quandary as the waste is accumulating at an unsustainable rate. Pens such as those at Sellafield are not the solution, but certainly the rocks of Wales and the immediate offshore do not provide a long-term solution either.

Remote locations such as St Kilda might be attractive, as might the Eocene Clay beneath London, but politics might dominate such options.

Clearly creative thinking is required.

Yours etc, Max Dobson, retired geologist, Waunfawr, Aberystwyth.

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