Planning the Unplannable – an evening considering the project to implement the Chernobyl Shelter

On 30th January 2025 we enjoyed a truly engaging and insightful evening with Dr Miles Shepherd, explaining how the Chernobyl reactor shelter construction project was implemented, from the point of view of one of the project engineers “there on the ground”. By way of introduction, the evening was a joint event between the Association for Project Management (APM) and the Nuclear Institute (NI) and was well attended by members of both organisations, around 50 in attendance. Miles is very well known to APM members, having been a past chairman and vice president of APM, and with a glittering CV that spans the decades. He first became involved with the nuclear industry through employment with AEA Technology plc, the erstwhile privatised arm of UKAEA, in the late 1990s (following an earlier military career). I’ve had the privilege of collaborating with Miles in the early days at AEAT and seeing him deservedly awarded the President’s medal (one of only three ever awarded) at an APM Fellows Forum a year or so ago.

Miles presented us with a talk which delved into some of the history of the Chernobyl incident, from particularly a “people” perspective. Not the science of what actually happened, or why (there are plenty of online documents on that theme) but more the human impact, the use of terminology, and social aspects. For instance, the “liquidators” were not asset management people, they were the emergency service and military people drafted in to throw highly radioactive rubble down from the roof of the reactor into the gaping hole which had appeared in the building following the explosion. Many of them subsequently died.

Miles described how the first concern was to stabilise the building, and minimise the risk of further contamination release. The reactor pressure vessel lid (very heavy) was in a precarious location, almost on its edge, and if that fell there would be significant disturbance and release of radioactive dust. The initial efforts to construct something (in a hurry) were made in a context of building something on largely sandy ground, so the constructed shield walls were not reliably assured of withstanding any severe weather or mild seismic disturbance.

The further remediation programme – to build the “sarcophagus” – was international. The sources of funding – were international and varied. A pie chart indicating the various sources of funding was illuminating, as there were many more donors than might have been expected. To some extent, this tied in with the internationally widespread (geographical) spread of contamination across Europe, and the resulting restrictions on eating foodstuffs from certain locations in other countries.

Miles also described the geography of the location – on the Dneiper river very close to the border with Belarus. In view of the urgent need to remedy the situation, a facility for international workers was constructed a safe distance away. This consisted of not only sleeping accommodation but also all the aspects of civilian life you would expect for a modern day town of many thousand inhabitants. However, access to the reactor site was difficult by road, as the border with Belarus was tortuous and featured a significant peninsula of Belarus territory jutting into Ukraine, between the reactor site and the workforce facility. Road transport was slow and tedious, involving checkpoints. Rail was far swifter, although the route crossed Belarus there were no stations along the way, and took less than 30 minutes.

Social and cultural matters were peculiar to the project. For most people, English was the technical language, although all documentation had to be produced also in Russian and Ukrainian. The project plan extended to 17 volumes (obviously, one third of this, per language). It took a wheelbarrow to move the documentation around.

The mobile structure. The concept of the mobile structure, in two halves and moved on rails to enclose the stricken reactor was a novel solution necessitated by the needs to do as much pre-assembly as possible away from the reactor site, so that on-site work (in a radiation environment) was minimised. Also, the nature of the soil and geology (sandy soil, as already noted) meant that heavy civil engineering had to be carefully managed and simply pouring heavy concrete was not the way to go. The “sarcophagus” is not of itself a robust radiation shield (obviously it has some shielding effect) but its great advantage is to prevent further spread of loose contamination and dust. Unlike the earlier radiation shield structure, the sarcophagus was equipped with engineered ports to enable insertion of measuring and observation devices, where they were actually needed, to maintain a continued safety monitoring regime. There was once some idea of controlled ventilation, but the end product featured only some natural ventilation where small gaps between the end-walls and the reactor structure were unavoidable.

The good thing about radioactivity is that it has a half-life. In the immediate aftermath of the reactor incident it was discovered that much of the core had melted and had descended through the structure, and the molten material had flowed somewhat to one side (not directly downwards) resulting in a solidified flow structure known as “the elephant’s foot”. Photographs and radiation measurements of the elephant’s foot with time interval of a couple of decades had indicated that the radiation field had decreased somewhat more rapidly than had been expected (but of course still very high by human safety standards).

Health and safety. A clash of cultures. The very concept of “a safe way of working” was originally problematic for some elements of the local workforce, except for the power station staff. The logic of “don’t do this – because I tell you not to” seemed to be the only approach that worked in a command-culture such as had been the case in the Soviet era, and the culture had scarcely been touched by the few years between the collapse of the Soviet Union and the emergence of the Commonwealth of Independent States (CIS) which arose in its place, with new distinct nations and their own identities. The nation of Ukraine had hardly been in existence for more than a few years before the reactor incident occurred.

Don’t pick the mushrooms! The reactor site is of course in an exclusion zone, and all but a few people have left the area. Meanwhile, the local flora and fauna have enjoyed a re-wilding experience with no humans about. Nonetheless, they can act as mechanisms for collecting and concentrating radioactivity, for instance the leaf litter on the woodland floor contains significant radioactivity absorbed from airborne sources, and the dust / volatile releases which have been transiently fixed by rainfall and absorption into the ground. Much more recently the area has been occupied by Russian military forces as part of the ongoing Ukraine conflict, but nobody told the soldiers not to pick the mushrooms. Apparently there have been fatalities from eating caesium-enriched fungi.

Following the presentation Miles opened the floor to questions, and there were many. So much so that we overshot our intended finishing time, by some margin. Nevertheless, the presence of a relatively young audience with lots of questions added to the value of the evening, many enthusiastic and enquiring minds were keenly interested in all that Miles had to say. Miles was sincerely thanked by all present as the evening drew to a close.

Steve Walters
Deputy Lead APM Thames Valley Regional Network
Chair, Nuclear Institute Central England Branch.