Applications, hearings, determinations, etc.: Connecticut Yankee Atomic Power Co.,

[Federal Register: September 4, 1998 (Volume 63, Number 172)]

[Notices]

[Page 47331-47333]

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

[DOCID:fr04se98-129]

NUCLEAR REGULATORY COMMISSION

[Docket No. 50-213]

Connecticut Yankee Atomic Power Company and Haddam Neck Plant; Exemption

I

Connecticut Yankee Atomic Power Company (CYAPCO or the licensee) is the holder of Facility Operating License No. DPR-61, which authorizes the licensee to possess the Haddam Neck Plant (HNP). The license states, among other things, that the facility is subject to all the rules, regulations, and orders of the U.S. Nuclear Regulatory Commission (the Commission or NRC) now or hereafter in effect. The facility consists of a pressurized-water reactor located at the licensee's site in Middlesex County, Connecticut. The facility is permanently shut down and defueled and the licensee is no longer authorized to operate or place fuel in the reactor.

II

Section 50.54(q) requires power reactor licensees to follow and maintain in effect emergency plans that meet the standards of Section 50.47(b) and the requirements of Appendix E to 10 CFR Part 50.

Pursuant to 10 CFR 50.12(a), NRC may grant exemptions from the requirements of the regulations, which are (1) authorized by law, will not present an undue risk to public health and safety, and are consistent with the common defense and security, and (2) present special circumstances. Special circumstances exist when application of the regulation in the particular circumstance would not serve the underlying purpose of the rule or is not necessary to achieve the underlying purpose of the rule (10 CFR 50.12(a)(2)(ii)). The underlying purpose of Section 50.54(q) is to ensure that licensees follow and maintain in effect emergency plans which provide reasonable assurance that adequate protective measures can and will be taken in the event of an emergency at a nuclear reactor.

III

By letter dated May 30, 1997, CYAPCO requested an exemption from the provision of 10 CFR 50.54(q) that requires emergency plans to meet all of the standards of 10 CFR 50.47(b) and all of the requirements of Appendix E of Part 50. The request for exemption was based on the substantially reduced the risk to public health and safety resulting from the permanently shutdown and defueled condition of the Haddam Neck Plant (HNP). In addition, the licensee submitted a proposed Defueled Emergency Plan (DEP) for NRC approval. The DEP proposed to discontinue offsite emergency planning activities and to reduce the scope of onsite emergency planning, which met only a portion of the standards and requirements. Thus, an exemption is required from the provision of 10 CFR 50.54(q) that requires emergency plans to meet all of the standards of 10 CFR 50.47(b) and all of the requirements of Appendix E of Part 50. By letter dated September 19, 1997, the licensee submitted the Emergency Action Levels that it proposed to use with the DEP. By letter dated September 26, 1997, the licensee submitted the results of an assessment of the ability of the HNP spent fuel to heat up in the absence of water in the spent fuel pool (SFP). By letter dated October 21, 1997, the licensee submitted additional information on certain aspects of the DEP and identified the specific standards and requirements of 10 CFR 50.47(b) and Appendix E of Part 50 which the proposed DEP would no longer meet. By letters dated December 18, 1997, January 22, March 25, June 19, and July 31, 1998, the licensee sent additional information on the proposed DEP. Tables 1 and 2 of Attachment 2 of the licensee's March 25, 1998 letter revised and consolidated the list of standards and requirements of 10 CFR 50.47(b) and Appendix E to Part 50 that would remain in effect.

The licensee stated that special circumstances exist at HNP because of the plant's permanently shutdown and defueled condition. With the plant in this condition, most of the design-basis accidents postulated for operating reactors are no longer possible.

However, CYAPCO postulated two design-basis accidents that are relevant to the permanently shutdown condition: (1) a release from combustible radioactive ion exchange resin, and (2) fuel handling accidents. With the exception of Kr-85, the noble gas and iodine nuclides that contribute to the dose consequences of releases from operating reactors have decayed to a negligible amount. CYAPCO calculated doses due to resin handling and fuel handling accidents and concluded that doses at the residence nearest to HNP would not exceed the Environmental Protection Agency (EPA) Protective Action Guides (PAGs) for activation of the offsite emergency response organization.

In addition, the licensee has evaluated the potential consequences of a beyond-

[[Page 47332]]

design-basis event that would completely remove the spent fuel pool water inventory. The analysis demonstrated that, even with no cooling by water, the decay heat load has decreased to the point that air cooling would maintain fuel cladding temperatures low enough to ensure the integrity of the cladding material.

In the permanently shutdown and defueled condition, the source term of nuclides that are readily dispersible in air and the energy available to propel radioactive materials off site are significantly reduced in comparison to an operating plant. The staff has evaluated the potential for a permanently shutdown plant with spent fuel stored in the spent fuel pool to generate a release of radioactive material that would result in offsite dose consequences. The two source terms of primary concern are low-level radioactive waste generated by decommissioning activities and the spent fuel.

The first source term, from low-level radioactive waste at the site, is much lower than the one from the spent fuel. However, the potential dose consequences of a release from a low-level waste container have been evaluated. An event that would provide a motive force for the release and transport of airborne activity offsite is a fire in low-level radioactive waste. The bounding accident for low- level radioactive wastes present on site is a fire in ion exchange resins used to process wastes from a reactor coolant system chemical decontamination. While they are in use, the resins are immersed in water. Upon depletion, used ion exchange resins are placed in containers called liners for dewatering prior to shipment to a disposal site. The licensee calculated that a fire in a resin liner, loaded with wastes having the maximum activity allowed by procedure, would result in an offsite dose which does not exceed the EPA PAGs. The staff reviewed the calculational methods and assumptions used by the licensee to determine the consequences of a resin fire and found them to be acceptable. The staff concludes that the consequences of a resin liner fire at HNP would not exceed the EPA PAGs.

The second source term considered is spent fuel. However, wet storage of spent fuel possesses inherently large safety margins due to the simplicity and robustness of the SFP design. The design basis includes the ability to withstand an earthquake and retain the ability to hold sufficient water to adequately cool and shield the spent fuel. Thus, the loss of all the water from the Haddam Neck SFP is a beyond- design-basis event, with a very low probability of occurring.

However, there are two potential consequences from a beyond-design- basis event that postulates the complete removal of water from the SFP. In the absence of water cooling, during the period that decay heat generation is relatively high the fuel could heat up to such a degree that a release could occur. In the absence of water shielding, the radiation from the fuel could cause radiation exposure to individuals offsite from the scatter of gamma rays streaming up from the pool.

In order for a release that would result in offsite dose consequences to occur, a motive force must exist to cause radioactive material to move into an unrestricted area. At a permanently shutdown and defueled plant, decay heat in the spent fuel could provide this force. However, decay heat decreases over time, and at some point it can no longer overcome the ability of the fuel cladding to retain fission products. When decay heat can no longer cause the fuel to heat to the point where fission products could be released, a significant release off the site is no longer possible by this means.

The licensee analyzed the heatup characteristics of the spent fuel in the absence of SFP water, when cooling depends on the natural circulation of air through the spent fuel racks. By letter dated September 26, 1997, the licensee presented the results of an analysis showing that as of October 1, 1997, decay heat could not heat the spent fuel cladding above 538 deg. C, in the event all water was drained from the SFP. The licensee's heat up analysis was based on a particular configuration of the spent fuel in the SFP. By letter dated December 18, 1997, the licensee stated, that as of October 23, 1997, the spent fuel had been moved into a configuration consistent with the analysis. The staff evaluated the licensee's analysis by performing heat up calculations using computer codes validated to be accurate to within 15 deg.C of actual peak fuel cladding temperatures. The licensee's value for peak fuel cladding temperature was found to be acceptable. On the basis of a previous staff determination that fuel cladding will remain intact if its temperature remains below 565 deg.C, the staff concluded that it is no longer possible for a complete loss of water from the Haddam Neck SFP to result in a release offsite that exceeds the early phase EPA PAGs.

Although a significant release of radioactive material from the spent fuel is no longer possible, in the absence of water cooling, a potential exists for radiation exposure to an offsite individual in the event that shielding of the fuel is lost. Water and the concrete pool structure serve as radiation shielding on the sides of the pool. However, water alone provides most of the shielding above the spent fuel. A loss of shielding above the fuel could increase the radiation levels offsite because of the gamma rays streaming up out of the pool being scattered back to a receptor at the site boundary. The licensee calculated the offsite radiological impact of a postulated complete loss of SFP water and determined that the dose rate at the residence nearest to HNP would be 0.016 rem per hour. At that rate, it would take 2.6 days for the event to exceed the EPA early phase PAG of 1 rem. The PAGs were developed to respond to a mobile airborne plume that could transport and deposit radioactive material over a large area. In contrast, the radiation field formed by scatter from a drained SFP would be stationary, rather than moving, and would not cause transport or deposition of radioactive materials. The 2.6 days available for action allows sufficient time to develop and implement mitigative actions and provides confidence that additional offsite measures could be taken without planning, if efforts to reestablish shielding over the fuel are delayed.

The staff has evaluated the radiological consequences, onsite emergency organization, facilities, equipment, procedures, and support resources of the licensee's proposed DEP. The staff reviewed the licensee's proposed DEP against the planning standards in 10 CFR 50.47(b) and (d), the requirements of Appendix E to 10 CFR Part 50, the acceptance criteria in NUREG-0654/FEMA-REP-1, Revision 1, and the guidance contained in NUMARC/NESP-007, Revision 2. The staff review took into consideration the permanently shutdown and defueled status of the facility, the configuration of the stored fuel, and the length of time since power operation.

IV

The NRC staff has completed its review of the licensee's request for an exemption from the requirement of 10 CFR 50.54(q) that emergency plans must meet all of the standards of 50.47(b) and all of the requirements of Appendix E of 10 CFR Part 50. Standards and requirements that remain in effect are listed in Tables 1 and 2 of Attachment 2 to the licensee's letter dated March 25, 1998 (Docket No. 50-213, Accession No. 9804020370). On the basis of this

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review, the NRC staff finds that the radiological consequences of accidents possible at HNP are substantially lower than those at an operating plant. The analyses submitted by the licensee are consistent with the commitment made in their Post Shutdown Decommissioning Activities Report, which stated that any radiation exposure to an offsite individual will be bounded by the EPA PAGs. The upper bound of offsite dose consequences limits the highest attainable emergency class to the alert level. In addition, due to the reduced consequences of radiological events still possible at the site, the scope of the onsite emergency preparedness organization may be reduced. Thus, the underlying purpose of the regulations will not be adversely affected by eliminating offsite emergency planning activities or reducing the scope of onsite emergency planning.

For these reasons, the Commission has determined that, pursuant to 10 CFR 50.12, elimination of the offsite emergency planning activities and implementation of the DEP will not present an undue risk to public health and safety and is consistent with the common defense and security. Further, special circumstances are present as stated in 10 CFR 50.12(a)(2)(ii).

Pursuant to 10 CFR 51.32, the Commission has determined that granting this exemption will have no significant impact on the environment (63 FR 43967, dated August 17, 1998).

This exemption is effective upon issuance.

Dated at Rockville, Maryland this 28th day of August 1998.

For the Nuclear Regulatory Commission. Samuel J. Collins, Director, Office of Nuclear Reactor Regulation.

[FR Doc. 98-23878Filed9-3-98; 8:45 am]

BILLING CODE 7590-01-P

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