Dear Minister Chiarelli,

I am writing this email as a former OPG research scientist to document a number of concerns I have over the Provincial Government’s decision to refurbish all four Units at Darlington NGS starting in October 2016. My concerns are based on the false claims that have been made about the rationale and alleged benefits of the Darlington refurbishment project as discussed below:

  1. In April 2014 OPG President and CEO Tom Mitchell said:

The Darlington station has served Ontario well. Refurbishment would provide 30 additional years of clean, low-cost, reliable power for the province.”

Unfortunately there is a problem with this claim, and that is that no Darlington Unit will ever achieve 30 years of service prior to its refurbishment, especially given the fact that Darlington Units 1 and 2 barely ran for two years after their first connection to the grid in 1990 because of serious problems with their heat transport pumps. Thus, based on OPG’s own reported refurbishment timeline, the useful working lives of Darlington NGS Units will be as follows:

Unit 1: 28 years

Unit 2: 23 years

Unit 3: 26 years

Unit 4: 29 years

These shortfalls in the working lives of these Units may appear to be of little consequence but they translate into lifetime financial losses of up to $500 million per Unit and lead to the unfortunate conclusion that Darlington – old or rebuilt – will not recover its exorbitant construction/refurbishment and OM & A costs. Thus I fail to see how OPG CEO, Tom Mitchell could claim: “The Darlington station has served Ontario well.”

  1. Darlington Units 1 – 4 are all being refurbished well before their cost recovery target dates because their pressure tubes and feeder pipes will, in the next few years, fail to meet fitness for service limits imposed by CSA Standards N 285.4 – 14 and N285.8 – 10, as described in Darlington’s License Condition Handbook.

The poor performance of these components may be traced back to OPG’s penchant to cut corners in order to save money – in the present case this involved the choice of the alloys used to manufacture the pressure tubes, (Zr-2.5%Nb), and feeder pipes, (carbon steel), in Darlington Units 1 – 4.

Thus, for example, up until 1993 the Zr-2.5%Nb alloy specification for trace impurities allowed a finished pressure tube to contain up to 25 ppm of hydrogen. However, if deuterium is picked up at the typical rate of 1 ppm/year, hydride precipitates would be present after only 26 years of operation in a tube with high initial hydrogen concentration. This fact was well known in the early 1990s but OPG permitted high initial hydrogen pressure tubes to be installed in Darlington regardless of this problem.

Similarly, the fracture toughness of Zr-2.5%Nb is known to be degraded by the presence of the trace elements chlorine, phosphorus and carbon and these impurities may be eliminated in the pressure tube manufacturing process by repeated melting of ingots prepared by the Kroll process – quadruple melting producing a very pure product. Nevertheless, quadruple melting was not used in the manufacture of any of Darlington’s initial pressure tubes.

Darlington’s feeder pipes were manufactured using cheap grade B carbon steel which is known to be susceptible to flow accelerated corrosion, (FAC). Flow accelerated corrosion causes high rates of wall loss at outlet feeder pipes in the regions close to the Grayloc end fittings and stress analyses have to be performed to demonstrate feeder fitness for service with reduced wall thickness as per ASME Section III . Based on inspection data since 2007 it was identified that thinning near the Grayloc weld was randomly distributed throughout Darlington’s outlet feeders, with more than 230 feeders in all Units requiring replacement/repair before 2020. The replacement of a single feeder pipe costs approximately $250,000 – an expense that OPG could have avoided had it used a better alloy for Darlington’s feeder pipes.

  1. We also need to consider Darlington’s steam generators and why they are not being replaced as part of the refurbishment project. This is apparently because OPG believes Darlington’s steam generators are “in good condition”. However, in OPG’s DNGS Application for Licence Renewal, issued December 2013, we discover that OPG’s plan for Darlington’s steam generators only “goes out to ten years”, which gets us to 2030. This is certainly consistent with the CANDU industry’s longstanding position on steam generator life management, as stated back in the 1990s, (See AECL Report 11912, issued in 1998):

AECL and the CANDU utilities have defined programs that will enable existing or new steam generators to operate effectively for 40 years

The designers and operators of CANDU reactors have always accepted that steam generators cannot be expected to perform adequately beyond 40 years. However, the problem is that in order to pay for themselves, Darlington’s refurbished Units have to operate with a capacity factor of at least 80% for 30 years or to 2050, at which point their steam generators will have operated for 60 years – an unreasonable expectation. In fact, no steam generator worldwide has operated beyond 50 years!

Worse yet, Darlington steam generators have had a far from perfect track record over the past 25 years. For example, signs of tube fretting in the U-bend of some steam generators were observed as early as 1995 in Unit 4 and in 1998 in Unit 2.  Other problems with Darlington’s steam generators have emerged since then including OD pitting, volumetric flaws, divider plate leakage and hydrodynamic degradation in the preheaters. This is perhaps why OPG’s “forward looking plan” for steam generator life cycle management at Darlington extends to only 2030. However, most remarkable of all, in its 2011 EIS for DNGS Refurbishment , OPG stated: “The project will include the construction and operation of facilities for interim storage of any steam generators that may have to be replaced as part of normal maintenance“. Since when are steam generator replacements part of normal maintenance?  

But I believe there is another issue with Darlington’s steam generators and that is the fact that replacing these steam generators is fraught with very serious problems, both technical and economic, that could prevent the continued operation of Darlington beyond 2030. First and foremost, Darlington’s steam generators are giants compared to the steam generators that were successfully replaced in Bruce Units 1 & 2 in 2008. Thus, Bruce steam generators are about 40 feet tall and weigh less than 100 tons; by comparison, Darlington’s steam generators are 73 feet tall and weigh 380 tons. Because of their sheer size, it is very questionable that Darlington’s steam generators could ever be replaced and the decision to proceed with the refurbishment of Darlington could prove to be a disastrous mistake if it is discovered that steam generator replacement is in fact needed in the next 10 to 15 years.

  1. To date, four CANDU Units have been refurbished here in Ontario: Pickering Unit 1 (2005), Pickering Unit 4 (2003), Bruce Unit 1 (2012) and Bruce Unit 2 (2012). Unfortunately, however, the capacity factors for these Units, post-refurbishment, have averaged less than 70 % which is well short of the greater than 85 %  performance historically achieved by new CANDU Units. This reveals the uncomfortable truth: a refurbished CANDU reactor is no substitute for a new one. To make matters worse, Pickering Units 1 & 4 are to be permanently shut down by 2020 after less than 20 years of operation. And no one is telling us why!
  1. There is also a rarely asked question concerning the type of performance a fully refurbished Darlington station can offer: Will refurbished Units provide the necessary flexibility that is required to meet Ontario’s electrical energy requirements over the next 30 years? Regrettably, the answer to this question appears to be a resounding “no”, and here’s why: Over the past few decades nearly all of Ontario’s electricity supply was provided by three sources – coal, hydro-electricity and nuclear – and so-called load following during periods of peak demand was handled very effectively by coal powered stations. However, with the phase out of coal-fired generation in Ontario over the past few years, the need for load following by other power sources has become of paramount importance. Furthermore, the recent occurrence of significant periods of surplus base load generation has only served to heighten this electricity supply problem.

When Darlington was being planned in the mid 1970’s the need for daily load cycling at certain times of the year was anticipated. Consequently the Darlington station was designed to follow a daily load cycle between 100% and 60% full power without using a turbine condenser steam bypass system. The intent was to design a reactor with sufficient operational margins to load cycle so that steam bypass would not be required. Nevertheless, Darlington’s current operating license does not allow it to operate as a daily load cycling plant. Thus, Darlington’s four Units are not categorized as “flexible nuclear” by the IESO since they take no part in the reduction of surplus base load generation.

But as pointed out by the Ontario Society of Professional Engineers in a letter to Energy Minister Brad Duguid, dated March 8th, 2011, each Unit at Darlington could load cycle its electrical output if it had a robust steam bypass system installed as part of its refurbishment. Essentially this would be a closed steam/condensate loop configured as a separate system for each Unit. The size of the steam bypass system could be matched to the amount of load cycling or load maneuvering that would be required.

However, I would argue that steam bypass as a method of load cycling and/or maneuvering makes very little economic sense because it requires the Unit to run at 100 % full fission power accompanied by a partial diversion of steam directly to the condenser in order to reduce the electrical power output to the desired level. Thus steam bypass at a refurbished Darlington station would be a load following technique whereby some of the useful energy generated by the nuclear fuel is simply dumped directly into Lake Ontario as waste heat – hardly an effective use of the nuclear fuel.

Furthermore, steam bypass is clearly a bad approach to “flexible nuclear” because electrical power from a CANDU reactor only becomes competitive when the Unit is operated above about 6000 effective full power hours per year. Thus, anything short of base load operations will turn the Unit from a money maker into a money loser. Worse yet, frequent load following cycling leads to thermal stresses, fatigue and mechanical wear on the effected equipment. As a consequence, “flexible” CANDU reactors are likely to age much more rapidly than those operating at base load.

  1. And finally, the quantities and nature of Darlington’s refurbishment waste and the cost of disposing of it need to be considered because of the very substantial amounts and high levels of radioactivity involved. Thus, each Darlington Unit refurbishment will create the following metallic wastes:

Pressure tubes = 480 × 61 kg = 29.3 tonnes

End Fittings = 960 × 163 kg = 156.5 tonnes

Calandria Tubes = 480 × 23 kg = 11.0 tonnes

Feeder Pipes = 960 × 108 kg = 103.7 tonnes

  Total Single Unit Waste = 300.5 tonnes

Hence, the refurbishment of all four Darlington Units will generate 1202 tonnes of radioactive waste metal – an amount equivalent in mass to about 100 school buses! The total activity of this waste will be about 40,000 TBq, all of which will have to be stored on site or shipped to OPG’s Western Waste Management Facility (WWMF) in Kincardine for permanent disposal. In addition, 24,960 irradiated fuel bundles will have to be removed (prematurely!) from the four Darlington Units and stored on-site in spent fuel bays. But I have to ask: is the minimum $240 million cost of dealing with this waste included in OPG’s price tag for the Darlington refurbishment? I suspect not!

Discussion and Conclusions

Even though we have not been told precisely why this project has been given the go ahead by the CNSC, refurbishing Darlington is clearly nothing more than putting a dying industry on life support at the taxpayer’s expense. And the inconvenient truth is that, after less tan 25 years of operation, Darlington NGS is a mess. Its feeder pipes are falling apart and its pressure tubes are ready to crack. In short, and like its predecessor at Pickering before it, Darlington is another failed CANDU station desperately in need of a fix.

The obvious solution to this problem should be to shut Darlington down completely and permanently and commission one or more new sources of electrical power. Unfortunately for Canada’s ailing nuclear industry, however, the new CANDUs offered by AECL proved to be far too expensive for our Provincial Government to accept. AECL’s $26 billion bid was based on the construction of two 1,200-megawatt Advanced CANDU Reactors, working out to $10,800 per kilowatt of power capacity. By comparison, in 2007 the Ontario Power Authority had assumed for planning purposes a price of $2,900 per kilowatt, which works out to about $7 billion for a Darlington expansion.

But, as the history of the dirty and dangerous “open-heart surgery” on 480 sections of radioactive pipe work has shown, refurbishment of old CANDUs is not a simple or safe alternative to their closure and replacement with new build. Thus, during CANDU refurbishment operations at the Bruce site in 2009, over 500 workers were exposed to plutonium-contaminated airborne dust for over three weeks due to the incompetence or negligence of Bruce Power Radiation Safety personnel who failed to provide workers with respirators, failed to verify analytical data showing the presence of alpha-emitters and neglected to properly test the air for such contamination, actions – or should I say inactions – that were subsequently covered-up by our nuclear industry-friendly regulator, the CNSC.

And as I have already discussed in this email, refurbished reactors are not performing as promised by OPG and Bruce Power but in some cases are already being slated for closure after only 20 years of post-refurbishment operation – well short of their supposed 30-year “lifetime” warranty.

But what is also troubling is the fact that Darlington’s CANDU Units are 1960’s technology and no amount of “refurbishment” razzle-dazzle can hide the fact that such technology was obsolete over 20 years ago. Indeed, and most importantly, Darlington’s reactors are only base load Units that cannot provide the much needed load following capability offered by newer reactor designs. Thus Ontario is buying four (rebuilt) steam engines when “high-tech” Maglev trains are available!

So, Minister Chiarelli, may I urge you to reconsider your government’s ill-conceived plan to refurbish all four Darlington Units, for I fear you are not considering the important issues I have raised in this email but have instead bought the CANDU industry’s hype “hook line and sinker”!

Minister Chiarelli, in a recent interview you said:

Ontario’s nuclear industry creates jobs and growth across many sectors. The nuclear industry generates $2.5 billion in direct and secondary economic activity in Ontario annually. An additional 9,000 jobs are expected to be created as a result of the proposed refurbishment, bringing the total number of people employed in Ontario’s nuclear energy sector to approximately 25,000.

 I’m sorry to say that such statements do not impress me because they suggest your primary focus in choosing to refurbish Darlington is job creation, not energy security. But the real story here is that there are about 300,000 fewer people working today in Ontario’s manufacturing sector than 10 years ago – a 15.8 % decline. And over the same time period the annual electricity demand in Ontario has decreased from 157 TWh in 2005 to 137 TWh in 2015 – or a 12.7 % decline. And let’s remember that in 2014 (for example) there were 588 nuclear reductions due to surplus base load generation, representing a total of 1215.7 GWh or about ½ of Pickering’s entire Unit 1 production for 2014! So, I have to ask: Does Ontario really need 3400 MW of base load power?

And while we are on the subject of electricity supply and demand consider the following: The Ontario Chamber of Commerce released a report in July 2015 called Empowering Ontario: Constraining Costs and Staying Competitive in the Electricity Market, on the issue of electricity pricing in Ontario. The report argued that the price of electricity directly affects business decisions to move to or stay in Ontario. And the report included a chart which showed our electricity rates were higher than many of the jurisdictions Ontario competes with and more than double the rates in the American mid-west, Manitoba, Texas, Quebec and British Columbia.

The same conclusions were also reached by AMPCO, (The Association of Major Power Consumers of Ontario), in a 2014 study which showed that Ontario’s industrial electricity rates are the highest in Canada and significantly higher than the equivalent electricity rates in New York State, New England, Pennsylvania, New Jersey and Maryland.

So in conclusion Minister Chiarelli, I am quite mystified that you would consider the refurbishment of Darlington to be some sort of solution to Ontario’s economic woes, when in fact the premature failures of Pickering and Darlington are a major cause of Ontario’s economic problems and have cost the Province dearly. 

Spending billions of dollars trying to patch-up Darlington’s four dilapidated reactors will simply continue the bleeding; indeed, the only long-term financial beneficiaries of this blatant make-work project will be small in number and dominated by the top brass at SNC-Lavelin, GE Hitachi, Cameco, Black & McDonald, Aecon Group and BWXT Canada.

Minister Chiarelli, please stop this nuclear madness now!


Dr. F. R. Greening

OPG Senior Scientist, (retired), Hamilton, ON