Radiation Threat Still Permeates Chernobyl’s Entombment

http://enr.construction.com/infrastructure/environment/2008/1119-ChernobylRadiation.asp

11/19/2008
By Peter Reina in Chernobyl

Thousands of workers daily take the train from their homes at Slavutich, across 55 kilometers of unpopulated woodland and marsh in northern Ukraine to their workplace. No ordinary commuters, they are workers at the Chernobyl powerplant, scene of the world’s worst-ever nuclear disaster. Nearly 4,000 people work at Chernobyl, safeguarding the destroyed reactor building No. 4 and tending to the three surviving shut-down units. Among the construction teams is Alexander Nikolayevich Plotnikov, project manager at contractor Utem Engineering, Bucha.

Background radiation levels determine type of protective gear and how long workers are allowed to toil in a particular area.

Utem helped build the plant until its completion a couple of years before the accident. Among local contractors on the current $1.4-billion Shelter Implementation Plan (SIP) to securely isolate the destroyed reactor, Utem claims the lion’s share. “Nobody in the world ever did a job like this at a facility like this,” says Plotnikov.

It’s not just the ubiquitous threat of radioactivity that makes Chernobyl a unique workplace. Because of its frantic construction in lethal conditions, the “sarcophagus” enclosing reactor 4 lacks normal engineering certainties. And when SIP was being established in the mid-1990s, Ukraine, emerging from Communism, was institutionally unprepared.

“It was thought to be a 10-year effort,” recalls Laurin Dodd, managing director of SIP’s project management unit (PMU). More than 10 years into the job, less than 60% of the $743 million committed has been disbursed and much more is needed.

Firefighting

Within three weeks of the April 1986 accident, Soviet engineers began de­signing a sarcophagus for a 15-year life to staunch leaking radioactivity. In November 1986, they completed the job with 400,000 tonnes of concrete and 7,000 tonnes of steel work.

The reactor building’s destroyed north wall was re­placed with a stepped concrete structure and the west wall was reinforced with 50-meter-tall buttresses.

To support the new roof, crews used cranes to lift two, 36-m-long beams onto internal walls. Steelwork was fixed without bolting or welding to reduce workers’ exposure. Surveying and checking construction was impossible.

Of some 200,000 people working on Chernobyl after the accident, 90,000 were used on the shelter's construction, according to operator SSE ChNPP. Of those, around 50 have since died from radiation, claims a study by U.N. agencies, which forecasted 4,000 deaths. The figure was challenged by a 2006 study for the environmental group Greenpeace, predicting nearly 100,000 deaths.

Since the accident, only about 40% of the shelter’s rooms have been surveyed. Nevertheless, scientists estimate that 95% of irradiated fuel remains in lava-like mounds, dust, core fragments and crystallized minerals. In Chernobyl’s 30-km exclusion zone, “there are open sources of ionizing radiation scattered all around,” says Eric Schmieman, PMU safety assurance manager.

In the absence of people, boars, horses and eagles are among creatures said to be thriving in the zone. Some 1,500 eld­erly former residents also have returned.

People at Chernobyl can be exposed to ionizing radiation, as well as airborne and solid contamination, warns Vladimir Borysovich Malyshev, ChNPP’s senior health and safety inspector. Daily working times for construction crews can range from seconds to hours. Ukraine’s legal exposure limit at nuclear plants is an average of 2,000 millirem per year over five years, not exceeding 5,000 millirem in one year. As a precaution, ChNPP operates at 70% of that limit, says Malyshev.

Inside PMU’s offices, radioactivity is below background levels of U.S. cities, says Schmieman. Yet floors are constantly mopped to pick up traces of contamination brought in on footwear. Highways and walkways in and around the plant have been cleaned and are relatively safe. “But I can’t tell you the level of contamination in the grass around here,” says Schmieman, advising visitors to sidestep vegetation and rainwater puddles.

Radiation levels rise closer to the reactor building, around which contaminated soil is covered with deep earth and, in places, concrete. Next to the building, radiation at around 20 millirem per hour would limit an individual’s annual working time to under 10 days.

Radiation on the reactor building’s recently repaired roof reaches 8,000 millirem per hour, rising to “tens of thousand” near the core, says Schmie­man. He’s been in there a few times, briefly, in full protective gear and with a safety team.

Chernobyl’s working days are punctuated by radiation checks. Crews pass through portal radiation scanners time after time, and get total body counts for cesium-17 in and out of shifts. At all times, they wear protective clothing ranging from impervious full body suits with respirators to cotton overalls and coats, depending on the risk.

Lapel dosimeters that record monthly exposures are mandatory. In riskier areas, units showing radiation accumulation in real time also are worn. On the new shelter project, expat workers will have a third dosimeter, for recording in home countries.

The productivity impairment of all the safety precautions is recognized in contract prices, says Schmieman. Labor costs also are inflated to overcome Chernobyl’s notoriety.

As an inducement, site crews work 15 days on and 15 off. They are eligible for longer vacations than other workers, and earlier retirement, says Malyshev. They also can earn bonuses of up to 25%.

“Any employee who plans to work at the shelter needs to take a biomedical examination,” says Utem’s Plotnikov. “It takes three day. About 40% fail.”

Successful applicants then must undergo 40 hours of health and safety induction by ChNPP. Sometimes workers “do not understand the difference between any construction site and this construction site,” says Plotnikov.

Training is not always successful. PMU staff have found workers not wearing dosimeters or tampering with them to extend allowable working times. “It happened too frequently,” says Dodd.

As purse holder of SIP’s multinational fund, the European Bank For Reconstruction and Development cares about health and safety at Chernobyl, says Director of Nuclear Safety Vince Novak. So far, there have not been any serious accidents after more than six million hours of work, he says.

The U.S. government and European Union began formulating SIP in 1995. Two years later, SIP’s elements were defined. A year after that, the PMU contract went to Dodd’s consortium of Bechtel National Inc., San Francisco, Battelle Memorial Institute, Columbus, Ohio, and Paris-based Electricité de France.

SIP’s 22 tasks aim to reinforce the un­stable sarcophagus for another 15 years, create a new shelter and introduce monitoring and other safety systems. Stabilization work is substantially complete, though some risk of localized internal collapses remains. The most visible stabilization project has been Utem’s erection of two 50-m-tall steelwork towers against the west wall. They substantially reduced the risk of sarcophagus collapse by taking 80% of the roof beams’ end loads.

Working in and around the reactor building is all about preparation, says Plotnikov. “The personnel were so well trained that we spent as little time as possible,” he adds. “If an engineer was trained to make a measurement using a tape, that’s all he did.”

After a long association with Chernobyl, Utem knew the plant well. But like other Ukrainian organizations, Utem was new to western methods. Now a joint stock company, Utem was created after the Russian Revolution to implement Lenin’s Soviet electrification plan.

SIP’s emergence represented a new world to many Ukrainians. “There was no experience at all in terms of contracting, the rules of FIDIC or procurement,” says Andrey Ivanovich Savin, ChNPP’s senior PMU representative and SIP’s chief engineer.

Savin suspects bidding rules have contributed to delays of some projects. They include a $70-million solid radioactive waste disposal system at three locations. Long-term storage is complete [see sidebar p. 84]) but the retrieval and storage units, due for completion in 2003, are delayed to next year, he says.

Work on Chernobyl’s liquid radwaste-disposal system halted two years ago when the contract was terminated. Redesign has begun “and will take up to two years” says Savin. The plant will solidify liquids kept temporality at the site for storage at the new solids facility.

Savin suspects different procurement rules might have avoided snags with the dry-storage facility for over 20,000 spent fuel rods. Last year, ChNPP recruited Holtec International, Marlton, N.J. to re­design the partially built plant after the original French team agreed to terminate its contract, signed in 1999. Fuel from the three surviving reactors, now stored in pools, will be placed in leak-tight containers just outside the plant.

Aspects of EBRD’s procurement still worry Savin. In the two-envelope bidding, technical proposals “do not provide details of how the contractor is going to do the work,” he says. The contract then goes to the lowest qualifying bidder “who may not have the best technical proposal,” he says.

Savin’s concerns “reflect a misunderstanding of the procedure,” believes the bank’s Novak. “You allow to the second [bidding] stage only those who fully meet all the requirements,” he says. Of the three troubled projects, “their circumstances are very different,” he adds.

Another snag in Ukraine’s recent emergence from the U.S.S.R. was old standards still governing safety equipment. “We had to use Soviet-era respirators,” says Schmieman. Now, they have western ones, but “it took five years fighting customs officials,” he adds.

PMU got “ a bit smarter” when introducing safety harnesses for high-level work instead of standard Soviet-style belts, says Schmieman. “Rather than getting them to change the standards, we wrote them into the contracts,” he adds.

SIP work so far has been a preamble to construction of the new shelter, to confine the reactor building for 100 years and provide tools for its re­moval. A turnkey shelter contract was awarded last September to Novarka, a joint venture of Paris-based Vinci S.A. and Bouygues S.A. The 150-m-long steelwork vault will span 257 m, rising 105 m over the sarcophagus.

Novarka will minimize work near the sarcophagus by setting up sites for offices, concrete casting and steelwork in locations a few kilometers away, says health and safety man­ager Dav­id Driscoll. Novarka must first deal with radioactivity at those sites.

Vault steelwork will be prefabricated into small modules abroad and shipped to Odessa, transported to site and bolted together at Chernobyl. “We want to avoid the necessity of excessive amounts of welding,” says Driscoll.

Using cable jacks on steelwork towers, Novarka will assemble the arch well away from the sarcophagus in a series of ribs. It will fit out the vault with decommissioning equipment and push it along large concrete runway girders over the building.

Novarka is now de­signing the shelter in Paris and Kiev, while setting up of­fices and homes at Slavutich. Thirty-five months of construction could begin next year. The total workforce will peak at about 1,300, including some 400 Novarka people, around 80 of them expatriates.

The shelter contract was worth the equivalent of around $500 million in dollars and euros when signed. The final figure will not be known until the contractor procures its 18,000 tonnes of steel­work and fixes other costs.

Dodd’s team is now revising SIP’s current $1.4-billion budget. With few change orders, the rise from the original $760 million reflects mainly inflation and currency fluctuations. By late next year, cost estimates should be sufficiently robust for donors to be recruited, says Novak. New grants raised will cover the new shelter and remnants of SIP. But the subsequent cleanup remains unfunded.

“I think the international community needs to really encourage Ukraine to provide the budgets to do the work that is required after we complete this new safe confinement,” says Dodd. “They ought to be planning that work today”.

Removing remains of the stricken reactor and its enclosure will take decades and cost at least $1 billion, estimates Savin. “The willingness of donor countries will depend on how successfully the new safe confinement is built,” he says.