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August 28, 2005

From: Dr. FR. Greening



To: Mr. Jan Carr
Chief Executive Officer
Ontario Power Authority
175 Blues Street East
North Tower, Suite 606
Toronto, Ontario
M4W 3R8

Dear Mr. Carr,

It is my understanding that the Ontario Ministry of Energy has issued a directive to the Ontario Power Authority to develop an integrated plan to ensure a reliable long-term electricity supply for Ontario. To this end, I believe the OPA will be seeking input on supply options from the general public during the period September to December of this year.

Based on recent statements from Energy Minister Dwight Duncan, new nuclear generation capacity is being considered as a major component of Ontario's future electricity supply, and various "improved" CANDU reactor designs are already being actively promoted by

AECL.

I am writing as a former OPG research scientist, with 23 years experience in nuclear operations, to suggest that any further investment in generating capacity based on the CANDU design would be a serious mistake. I have put together a summary of my reasons for rejecting CANDU technology in an attachment to this letter and would ask that this material be considered by the OPA.

Sincerely,


Dr. F. R. Greening


c.c Mr. Dwight Duncan

Minister
Ministry of Energy
Hearst Block 4th. Floor
900 Bay St.
Toronto ON M7A 2E1



From: Dr. FR. Greening



To: Mr. Jan Carr
Chief Executive Officer
Ontario Power Authority
175 Blues Street East
North Tower, Suite 606
Toronto, Ontario
M4W 3R8

September l2, 2005


Dear Mr. Carr,


In my August 28th. submission to the OPA I addressed the question of new electrical generating capacity for Ontario and argued that the CANDU reactor should not be considered as a viable option for this Province because of design features that have led to unacceptable performance in so many Units at Pickering "A" and Bruce "A"

Atomic Energy of Canada, (AECL), the designer of first generation CANDUs, has in the works a number of new reactors, described as "advanced" or "next generation" CANDUs. AECL is promoting "advanced" CANDU reactors as the best possible solution to Ontario's over-worsening electrical energy deficit. Certainly these new reactors, such as the highly publicized ACR-700, look wonderful on paper however, they are still at the design stage, existing only on paper or in the minds of AECL engineers, and remain experimental and unproven in conception.

The truth is that Ontario in the year 2005 cannot afford the luxury of once again dabbling in unproven nuclear reactor technology in the way it did back in the early 1970s, especially since "first-of-a-kind" reactors are known to involve higher then average OM&A costs. What is more, as I intend to show, the "advanced" CANDU reactor being offered by AECL still has most of the design flaws that plagued Ontario's original fleet of power reactors. Worse yet, the history of CANDU reactor performance strongly suggests that intent design flaws lie hidden in AECL's new designs

So, let us consider the design of an advanced CANDU reactor such as the ACR-700 In some detail. First it should be stated that even AECL admit that the ACR-700 is based on the well-known CANDU-6 design as exemplified by the Unit at Point Lepreau. Significantly, most of the "improvements" in the CANDU-6 design - changes that no doubt prompted AECL to use the catchy name "advanced reactor"- involve the troublesome systems and components that are notable for being so complex and unreliable in first generation CANDUs. The offending systems and components which were described in detail my August 25th. submission, are the D20 coolant and moderator, the zirconium alloy pressure tube and find channel assemblies, the annulus gas and the steel feeder pipes carrying coolant to and from the reactor core. These

systems and components, which are completely absent from other reactor designs are considered in detail below.

D20 Coolant and Moderator

A CANDU-6 reactor requires about 450 tonnes of heavy water (D20), valued at about $250 million. The use of such large amounts of very costly D20 is a problem in itself, but it is made far worse by the neutron activation of deuterium resulting in the production of radioactive tritium in a CANDU core. The need to minimize D20 loss and tritium emissions leads to elaborate and expensive liquid collection and water vapor recovery systems in all CANDU plants.

The ACR-700 design manages only a partial solution to this problem by substituting light water for the heavy water coolant, but leaving the moderator D20 unchanged. This reduces the total inventory of D20 by more than 50%, saving over $100 million. However, this ACR-700 design "improvement" does nothing to reduce the production of tritium in the moderator, which is by far the largest source of tritium in a CANDU reactor. A moderator vapor recovery enclosure is still required in the ACR-700 design together with the associated high capacity dryers.

But this is not the end of the story.... Replacing a portion of a CANDU's inventory of D20 with H20 comes with a significant cost to the neutron economy of the reactor. This problem is overcome though the use of enriched uranium fuel The fact that an ACR-700 reactor needs enriched, rather than natural, uranium oxide fuel has a three-fold negative impact on its operation, particularly in Canada.

(i) Enriched fuel is about twice the cost of natural uranium fuel

(ii) Because no U enrichment facilities exist in Canada, enriched fuel will have to be manufactured and shipped from outside this country. Thus the ACR-700 loses the "homegrown" appeal of its predecessor.

(iii) Production of 1 tonne of advanced CANDU fuel will produce 2 tonnes of highly undesirable depleted uranium waste.

Pressure Tubes

The ACR-700 design requires 292 pressure tubes compared to the 380 used in a CANDU-6. Pressure tube problems have plagued CANDU reactors since the early days of Pickering NGS in the mid 1970s. These problems have been largely caused by hydrogen isotope (H or D) embrittlement and irradiation-induced deformation. The CANDU Owners Group, (COG), have collectively spent over $100 million on pressure tube research and development in the past 20 years but achieved only marginal improvements in pressure tube performance.

Because of this situation, AECL are faced with an almost endless list of options to produce the best possible pressure tube for the ACR-700. These options include changes in the manufacturing process such as the extrusion, heat and surface pre-treatment of the pressure tube as well as strict control of alloy impurities such as H, C, P and Cl. These impurities need to be kept to a minimum concentration because they are suspected of playing a role in zirconium fracture toughness, hydrogen pickup and neutron-induced deformation. Unfortunately these impurities also appear to exhibit synergistic effects in the presence of other impurities such as Fe. It is therefore difficult to predict the in-reactor behaviour of pressure tubes, especially their deuterium pickup, which is often observed to be highly variable even for ostensibly similar tubes.

AECL argue that pressure tubes exhibiting high deuterium pickup are not a major concern because they are identified through regular inspection campaigns and are replaced before they compromise reactor safety. However, time, cost and radiation dose constraints associated with the inspection procedures, mean that only a limited selection of pressure tubes are ever subjected to hydrogen or deuterium sampling, and the measured concentrations are generally very approximate due to problems with sample contamination and hydrogen isotope migration.

And on a final note, AECL acknowledges that the ACR-700 will require a full pressure tube replacement about halfway through its predicted lifespan. Thus pressure tubes remain problematic and potentially life limiting even for "advanced" CANDU reactors.

Feeder Pipes

Recognizing that carbon steel feeder pipes in first generation CANDU reactors have been prone to serious wall thinning from flow accelerated corrosion, AECL specifies stainless steel feeders for its "advanced" CANDUs. There appears to be sound experimental evidence that stainless steel feeder pipes will perform better than carbon steel feeders; nevertheless feeder pipes in an ARC-700 reactor will still be subject to regular inspection under CSA N285.4, (or equivalent), the Canadian standard the nuclear pressure boundary materials. The accessibility of centre-core feeders to inspection is already a problem for the CANDU-6 reactor where the lattice pitch is about 29 cm. The compact design of the ACR-700 core means that the feeder pipes are about 6 cm closer together than in a CANDU-6, making the ACR-700 center-core feeders even more inaccessible to inspection. The compact core of the ACR-700 also means that the reactor face radiation field will be higher than the equivalent CANDU-6 field, placing even more constraints on feeder pipe inspections of an ACR-700.

The Annulus Gas System

An annulus gas system (AGS) is a standard feature of all CANDU reactors, including the ACR-700, and is used to provide early warning of D20 leakage from the heat transport system. The capability of detecting incipient D20 leaks in an AGS is mandated by the CNSC in support of the "leak-before-break" strategy of dealing with pressure tube failures during reactor operation.

N2 was initially used to fill the AGS but was replaced with CO2 in the 1990s to limit troublesome C-14 production from the large cross section N-14(n,p)C-14 nuclear reaction. Nevertheless, CO2 has proved to be less than ideal as an annulus gas because of chemical interactions with other species that are invariably present in the AGS. Deuterium gas permeates into the AGS through the stainless steel end fittings and reacts with CO2 to form CO and D20. This the water vapor pressure in the AGS increases over time and gradually reduces the sensitivity of the dewpoint meters used for heat transport water leak detection. In addition, CO2 under radiolysis undergoes complex reactions with the D2, N2 and CO invariably present in an AGS to frm polymeric deposits that restrict gas flows and further compromise D20 leak detection.

O2 additions to the AGS have been implemented at currently operating CANDUS to oxidize D2, N2 and CO to non-deposit-forming species, but the associated production of ozone and nitrogen oxides raises the probability of enhanced corrosion of AGS components such as radiation shielding sleeves and bearing journals. Thus the AGS continues to be one of the more problematic systems in a CANDU reactor; problems that will, no doubt, be inherited by the ACR-700.

Discussion

In the material presented above I have considered AECL's "next generation" or "advanced" CANDU reactor design and shown it to be little more than a list &partial solutions to some well known problems with first generation CANDU reactors. It would obviously have been preferable for AECL to completely eliminate the source of each of these problems and produce a simplified, yet truly advanced, reactor design. However, because a D20 moderator, a zirconium pressure tube and a CO2 gas annulus are essential to the CANDU reactor design, it is all but impossible to remove these systems without compromising the functionality of the reactor. It is therefore inevitable that AECL's "advanced" CANDU looks a lot like a 1st. generation CANDU in a new suit. In short, the ACR-700 is a CANDU-6 with some new plumbing and high performance fuel.

This being said, the few design changes that are incorporated in the ACR-700 design Should offer at least some improvement in reactor performance compared to Canada's first generation CANDUs. It might then be argued that the ACR-700 Is still worth building, especially in light of Ontario's burgeoning electrical energy crisis. However, before proceeding with the construction of even one ACR-700 Unit In Ontario, our energy planners need to be convinced of AECL's ability to deliver a working power reactor, incorporating new design elements, on time and within budget. Unfortunately AECL's recent performance in this regard has been less than reassuring. as the on-going saga of the Maple X reactor illustrates.

In 1996 AECL signed an agreement with MDS Nordion to build two Maple X Isotope production reactors at Chalk River for $140 million. The reactors were slated for completion by May2000 (Maple 1), and November2001 (Maple 2). The first Maple did indeed go critical on schedule but over the ensuing 3 years the newly commissioned reactor experienced serious problems with shut-Off rods and a positive, rather than the predicted negative, reactor power coefficient. By January 2002, the CNSC was so concerned with the performance of Maple 1 that it temporarily withdrew the reactor's low-power commissioning license. At the time of writing, the Maple project is more than $160 million over budget, five years behind schedule and AECL are facing a multi-million dollar lawsuit from MDS Nordion that may take years to be resolved.

I believe AECL's predicament with regard to the Maple X reactor stems from the fact that, in spite of a 50-year legacy of building nuclear reactors, this once great engineering company has lost most of its expertise in reactor design. Many of the CANDU reactors operating in Ontario today were designed in the 1960's, other, newer, reactors commissioned in Ontario in the 1980's or early 1990's, we essentially old AECL designs modified by OPG's Design and Development Division. Hence, AECL engineers have done very little reactor design since the 1980s, and what has been done was mainly the design of add-on systems or re-design modifications of existing systems for aging CANDUs. Thus it is hardly surprising that AECL are struggling with the design of a new 10MW isotope production reactor, never mind a 700 MW power reactor. And AECL can no longer turn to OPO for help in designing new reactors because OPG also lost its expertise in this area when it disbanded its own Nuclear Design and Development Division back in theI990's.


Sincerely,


Dr. P.R. Greening


c.c Mr. Dwight Duncan
Minister
Ministry of Energy
Hearst Block 4th. Floor
900 Bay St.
Toronto ON M7A 2E1

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