By Steven Goetz, Kincardine News – Thursday, March 27, 20144:05:20 EDT PM
A conceptual computer model of Ontario Power Generation's Deep
Ontario Power Generation (OPG) must resubmit the safety case for its proposal to bury nuclear waste at the Bruce nuclear site after a retired OPG chemist and research scientist discovered the radioactivity level of the waste material was grossly underestimated.

Recent correspondence between Dr. Frank Greening and the [Nuclear Waste
Management Organization] has raised questions regarding the accuracy of OPGs [inventory of nuclear waste], the independent federal panel reviewing the proposal wrote in a letter on Mar. 21. The concentrations of some radioisotopes appear to have been significantly underestimated or not estimated at all.

The joint review panel (JRP) — which will recommend to the federal environment minister whether the project should be approved — ordered OPG to submit a new safety assessment and a plan to improve the accuracy of its inventory of waste slated to be buried.

If approved, the project — known as the deep geologic repository (DGR) for low- and intermediate-level nuclear waste — will see waste from Ontarios nuclear fleet buried in vaults carved out of limestone 680 metres beneath the ground, about 1.2 kilometres from the shores of Lake Huron on OPG-owned land near the village of Tiverton, Ont.

While not including the spent reactor fuel, some of the waste material will stay dangerously radioactive for over 100,000 years.

Greening first raised the alarm over OPGs faulty estimates in a letter to the NWMO in January.

The NWMO acknowledged in writing on Feb. 20 that OPGs estimates were low, noting the radioactivity of pressure-tube waste is significantly underestimated by a factor of 2,300.

After re-running computer models with the new data, the NWMO wrote that it had concluded the revised estimates do not change the safety case.

(The NWMO is providing technical support to OPG on the project and is currently looking for a site to locate a similar facility for spent fuel from Canadas nuclear reactor fleet.)

OPG is asked to include plans for an independent expert evaluation of its methods and verification procedures in its response, and the panel has asked the Canadian Nuclear Safety Commission (CNSC) to conduct its own review in light of Greenings findings.

With a PhD in chemistry, Greening worked for Ontario Hydro, and then OPG, for more than 30 years. He was a specialist studying the pressure tubes that surround the uranium fuel inside nuclear reactors, which are some of the most radioactive material to be buried if the DGR receives regulatory approval.

In a telephone interview, Greening told the Kincardine News he decided to look at OPGs estimates for the radioactivity of pressure tubes and discovered they were very low given the data that is readily available.

I reached the conclusion their numbers were suspect so I wrote to tell them they were getting it wrong, Greening said.

Despite having real-world measurements from nuclear facilities in Canada, OPG decided to use theoretical models to present the potential radioactivity of the material, Greening said.

I asked them why they relied on calculations instead of data from real measurements and they have basically ignored the question, he said. It is not as if this data is not available to them.

In its letter to Greening, the NWMO acknowledged his complaint that OPG did not include the radiation from garter springs – round coils that wrap around the pressure tubes — in their calculations. Although small in size, the springs are in the running for most radioactive material to come out of the reactors after spent fuel.

The panel also requested OPG and the CNSC report on a radiation leak at a nuclear waste site in New Mexico, which OPG cited in regulatory filings as an example of a successful facility.

In February, monitors began detecting radiation in underground vaults below the waste isolation pilot plant (WIPP) outside Carlsbad.

Thirteen aboveground workers later tested positive for radiological contamination and the facility was closed to personnel. An independent agency detected airborne radiation — within government safety standards but higher than previously recorded — about a kilometre from the facility.

The panel told OPG and the CNSC to report on the relevance of the WIPP leak to worker and public health and safety at the proposed DGR and how such an incident was accounted for in OPGs models for accidents, malfunctions, and malevolent acts.

The WIPP is operated by the U.S. Department of Energy and is used to store radioactive materials from the U.S. nuclear weapons program in vaults carved into salt deposits. It is one of only a few underground nuclear storage facilities anywhere in the world and was visited by members of the federal panel so they could better understand OPGs proposed facility in Kincardine.

In its filings, OPG cited the WIPP — and facilities in Sweden and Finland — for a proven track record internationally in the safe management of low and intermediate nuclear waste.

The panel has promised to hold additional days of public hearings after OPG makes new submissions, promising to delay any final recommendation. Hearings had originally ended in the fall.

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