ML20058A610
| ML20058A610 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 11/17/1993 |
| From: | Grimes B Office of Nuclear Reactor Regulation |
| To: | PORTLAND GENERAL ELECTRIC CO. |
| Shared Package | |
| ML20058A584 | List: |
| References | |
| NUDOCS 9312010147 | |
| Download: ML20058A610 (7) | |
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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the Matter of
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PORTLAND GENERAL ELECTRIC COMPANY,
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(Trojan Nuclear Plant)
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EXEMPTION I.
The Portland General Electric Company, et al., (PGE or the licensee), is the holder of Facility Operating License No. NPF-1, which authorizes possession and maintenance of the Trojan Nuclear Plant (Trojan or plant). The license provides, among other things, that the plant is subject to all rules, regulations, and Orders of the Commission now or hereafter in effect.
The facility is a permanently shutdown pressurized water reactor, currently in the process of being decommissioned, and is located at the PGE site in Columbia County, Oregon, on the west bank of the Columbia River.
II.
The licensee, by letter dated February 2,1993, informed the NRC that Trojan had permanently ceased power operations, all fuel had been removed from the reactor to the fuel pool, and that PGE had begun to develop detailed plans to decommission the facility. The NRC, in License Amendment 190, dated May 5, 1993, modified License No. NPF-1 to a Possession Only License (POL). The license is conditioned so that PGE is not authorized to operate the reactor or place fuel in the Trojan reactor vessel, thus formalizing the commitment of the licensee to permanently cease power operations.
9312010147 931117 POR ADOCK 05000344 g
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, By letter dated July 8,1993, the licensee requested an exemption from the requirements of 10 CFR 50.54(w) which requires licensees to obtain and s
maintain a minimum of $1.06 billion of decontamination insurance coverage for radiological accidents at the reactor site. The level of coverage required by
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the regulation was based on an evaluation of potential accidents that could occur at an operating facility. The July 8,1993 letter requested a full exemption to 10 CFR 50.54(w) but commits the licensee to maintain a minimum coverage of $5 million to stabilize and decontaminate the reactor and the reactor station site.
III.
i The PGE bases for the exemption request are that the reactor has been defueled, the fuel placed in the spent fuel pool, and that the reactor cannot be returned to operation.
In addition, PGE stated that the types of accidents defined in the regulation,10 CFR 50.54(w)(2)(1), can no longer occur at the plant.
The licensee also stated that the potential risk to the public was therefore significant1., reduced and that the range of credible accidents and accident consequences for Trojan was greatly diminished. The licensee analysis shows that the worst case design basis accident for this. plant, in its permanently shutdown defueled state, is a fire in the radioactive waste annex building. The licensee calculated that a postulated fire in the Trojan radioactive waste annex would result in estimated cleanup costs of
$4.9 million. To provide a conservative estimate, the licensee estimated the cost to recover from the fire and added a 25 percent cushion to arrive at the i
value of $4.9 million. The licensee also considered a second design basis accident scenario, a fuel handling accident. The licensee estimated site
p decontamination cost for the fuel handing accident at $0.5 million. This estimate also includes a 25 percent cushion.
In both accident scenarios, the licensee estimated site boundary radiation doses to the public would be less than the U.S. Environmental Protection Agency (EPA) Protective Action Guidelines (PAG).
The NRC staff evaluated the hypothetical fire in the radwaste storage building located onsite.
The staff concluded that, if such a highly unlikely event were to occur, the immediate impact would be the burning of dry activated waste.
Because of the extremely low activity commonly associated with dry activated waste the staff concludes that the doses to the public resulting from a fire will not approach the EPA PAGs.
Unsolidified resins could contribute to the offsite dose and site contamination; however,.the staff concludes that a release from stored resins at the Trojan site would require a fire of significant magnitude and intensity to melt the resins.
The staff concludes that a fire of such magnitude could not occur in or in the vicinity of the radwaste storage building and that such event is not credible.
This conclusion is based on the location of the radwaste storage _ building in relation to adjacent buildings, its construction, and the lack of a significant quantity of combustible material inside or in the general area of the building.
The NRC staff also evaluated the consequences of a fuel handling accident.
In a hypothetical fuel handling accident, contamination would be restricted to the immediate vicinity of the fuel building since there is no credible energy source available to widely disperse the irradiated fuel onsite during the fuel handling accident. The staff has data on two comparable
- events. The first event, the dropping of a fuel bundle that resulted in some i
ruptured fuel rods, incurred costs in excess of $2 million; however, we determined that most of the costs consisted of the capital cost of the fuel assembly replacement and three days of lost power generation due to the accident. Neither of these costs is pertinent to Trojan in its permanently shut down status. The remaining costs of about $45,000 were for recovery from the accident and are applicable to evaluate the postulated decontamination costs associated with a fuel handling accident at Trojan.
The second comparable accident, the dropping and rupturing of fuel rods during bundle reconstitution, occurred at a plant for which its licensee prepared an internal investigation report.
The report contained detailed cost data and showed a recovery cost of $50,000. Therefore, with respect to a fuel handing accident at the Trojan plant, the historical data supports the licensee assertion that $5 million represents a conservative upper bound for recovery costs from a design basis fuel handling accident.
The NRC staff also independently calculated the offsite doses resulting from a fuel handling accident at Trojan. The staff analysis shows that the doses at the exclusion area boundary for the whole body, the thyroid, and the skin would be a small fraction of the EPA PAGs.
The NRC staff also requested that the licensee examine a hypothetical accident sequence involving the complete or partial loss of water from the Trojan spent fuel pool as a result of a major seismic event near the plant.
This beyond design basis postulated accident sequence, described in NUREG-1353, could result in a zirconium fuel cladding fire in some of the recently irradiated spent reactor fuel stored in the pool that could then
E propagate through the spent fuel pool and result in a significant radioactive release, and associated site contamination.
The licensee responded to the staff request for additional information and the staff conducted a review of the licensee submittal. The staff determined that the Trojan spent fuel pool will maintain, with an adequate margin, its structural integrity even for an earthquake with a resulting ground acceleration value of 0.5. The 0.5g value 9
was found to be appropriate for the geographic location of Trojan and could be used to evaluate plant vulnerabilities significantly beyond the design basis.
Therefore, the staff concluded that there is an extremely low likelihood of a complete or partial loss of water from the Trojan spent fuel pool.
Furthermore, the staff has also determined that in view of the low likelihood of the postulated event and the time elapsed since shut down of the facility (one year), and the configuration of the fuel in the spent fuel pool, there would be sufficient time after a postulated loss of water and before the initiation of a cladding fire for the licensee to implement actions to cool the spent fuel and avert a cladding fire.
The licensee has implemented procedures that provide this additional level of protection using a variety of cooling water sources.
Thus, the staff concludes that the likelihood of a beyond design basis cladding fire in the spent fuel pool resulting in significant onsite contamination is extremely remote and insurance coverage to recover from this accident scenario is unnecessary.
Based on a thorough evaluation of potential accidents at the Trojan site, the staff concludes that a significant reduction in onsite liability coverage te str.bilize and decontaminate the site is warranted.
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! l The Commission will not consider granting an exemption unless special circumstances are present.
In its letter of July 8, 1993, PGE addressed these special circumstances as follows:
" Application of the regulation in the particular circumstances would not serve the underlying purpose of the rule..."
Licensee response:
PGE concludes that maintaining the $1.06 billion 1evel of decontamination insurance stipulated in 10 CFR 50.54(w) is not required to achieve the underlying purpose of the rule.
Since no accidents as defined in 10 CFR 50.54(w)(2)(i), can occur with the plant in the permanently defueled condition, it is no longer necessary to maintain coverage to ameliorate the consequences of an accident.
" Compliance would result in undue hardship or other costs that are significantly in excess of those contemplated when the regulation was adopted,..."
Licensee response:
PGE currently maintains $1.06 billion of decontamination insurance coverage at an annual premium of $2,017,585.
Although valid for an operating power reactor, the cost of maintaining insurance coverage at the $1.06 billion required by the regulatico is not justifiable for a permanently defueled power plant such as Trojan. The proposed exemption would allow PGE to establish insurance coverage commensurate with the need for onsite decontamination rather than the-level of coverage needed for decontamination efforts associated with operating power reactor accidents. Operating power reactor accidents as stated in the regulation constitute the underlying basis for the regulation.
PGE has determined that the level of coverage commensurate with onsite decontamination would be $5 million resulting in an annual premium of $250,000, a savings of $1,767,585 annually based on the current annual premium for $1.06 billion of coverage.
IV.
The staff, based on its independent evaluation, finds the PGE analysis acceptable and concludes that there are special circumstances present that satisfy the requirements of 10 CFR 50.12(a)(2)(ii) and (iii).
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V.
Based on Sections III and IV above, the Commission has determined that pursuant to 10 CFR 50.12(a)(1), this exemption is authorized by law, will not present an undue risk to the public health and safety and is consistent with the common defense and security.
The staff also concludes that issuance of this exemption will have no significant effect on the safety of the public or the plant.
Further, the licensee has shown special circumstances as described in the safety evaluation r
supporting this exemption.
Pursuant to 10 CFR 51.32, the Commission has determined that the issuarce of this exemption will have no significant impact on the environment (58 FR 60705, dated November 17, 1993).
Accordingly, the Commission hereby grants an exemption to 10 CFR 50.54(w) to PGE for the Trojan Nuclear Plant. However, the licensee shall either maintain a minimum limit of $5 million of property damage insurance or be able to demonstrate self-insurance of this amount. The PGE letter of July 8, 1993, contained a commitment to maintain this amount of protection.
This exemption is effective immediately.
FOR THE NUCLEAR REGULATORY CO ISSION s
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,. -M Brian K. Grimes, Director Division of Operating Reactor Support Office of Nuclear Reactor Regulation Dated at Rockville, Maryland this 17th day of November 1993.
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