Nearly twenty years after Chernobyl the victims have been largely forgotten. It is to redress this injustice that Mario Petrucci has produced his long poem. As he explains in a foreword, the inspiration comes from a book, Voices from Chernobyl, which describes the scale of the devastation, and the experiences of those affected. Petrucci gives voice to the many nameless victims: the soldiers and miners ordered to participate in the clean-up; the evacuated local population; and those dying of the hideous effects of radiation sickness. Many of the poems are narrated by the victims themselves, some are in the form of dialogue, or question and answer, giving the voices immediacy and vitality.

Petrucci's motive is political in the widest sense - he has a message, `Forget nothing. You must not / forget'. To that end he exploits the most appalling of images: `One man, they say, bought a pillbox hat - / you know, black market. Had to watch his wife's head / grow the black brim.' His judicious use of anecdote and description (a kitten's dried apricot head, the moulting of black skin) ensure that these victims stay with us, haunt our dreams, shock and shock again.

Petrucci's poem is also political in a narrower sense. Chernobyl was, after all, a man-made disaster. Heavy Water throbs with the anger of a people left in ignorance and exposed to death by a régime which was profoundly indifferent to them. In `Directive 1 A' the firemen and soldiers are `still warm from their beds' like the victims of the night arrests during the 1937 purges. In other pieces he explores the curious way in which the superstitious local population of subsistence farmers and peasants are forced to become conversant with the technology of atomic power: `Out there they took my crucifix / and hung a Geiger round my neck. / Had to switch it off to make myself / heard. Put a spoonful of goose shit / in vodka. That's what they said...'

Different poets have approached disasters of such magnitude in different ways. The poems of Paul Celan address the horrors of the Holocaust through more oblique images. Wilfred Owen's poems give the nightmares of war a formal and lyrical beauty. In either case the poetry acts as a shutter, allowing glimpses of the horror, but preventing a toxic over-exposure. Petrucci's poem pulses with a raw anger - everything is exploited in the need to make us remember - and at times he risks overexposing the material and blinding us with its force. In a couple of the pieces child victims (presumably taken from the book Voices of Chernobyl) are given voice: `My parents kissed and I was born', `Breathing' and `Olya'. The stories of these dying children and their bravery are extraordinary and harrowing, but they rather overshadow the poetry and might even strike the reader as slightly sentimental.

Poetry must be able to accommodate these cataclysmic events - it would be an empty genre if it couldn't. Still, the almost physical nausea which some of the pieces induce is a direct response to the facts themselves, and not perhaps a response to the `poetry' of Petrucci's endeavour.

In contrast the pieces about radiation, alpha, beta and gamma rays, and the curious litany of elements and their half-lives which opens the poem are compelling. Petrucci the scientist has precision and gravity. In these pieces the abstract beauty of the atomic process is a soothing counterpart to the human disaster.