2010-23114. University of Wisconsin; University of Wisconsin Nuclear Reactor Environmental Assessment and Finding of No Significant Impact

The U.S. Nuclear Regulatory Commission (NRC or the Commission) is considering issuance of a renewed Facility Operating License No. R-74, to be held by the University of Wisconsin (the licensee), which would authorize continued operation of the University of Wisconsin Nuclear Reactor (UWNR), located in Madison, Dane County, Wisconsin. Therefore, as required by Title 10 of the Code of Federal Regulations (10 CFR) Section 51.21, the NRC is issuing this Environmental Assessment and Finding of No Significant Impact.

Environmental Assessment

Identification of the Proposed Action

The proposed action would renew Facility Operating License No. R-74 for a period of 20 years from the date of issuance of the renewed license. The proposed action is in accordance with the licensee's application dated May 9, 2000, as supplemented by letter dated October 17, 2008. In accordance with 10 CFR 2.109, the existing license remains in effect until the NRC takes final action on the renewal application.

Need for the Proposed Action

The proposed action is needed to allow the continued operation of the UWNR to routinely provide teaching, research, and services to numerous institutions for a period of 20 years.

Environmental Impacts of the Proposed Action

The NRC has completed its safety evaluation of the proposed action to issue a renewed Facility Operating License No. R-74 to allow continued operation of the UWNR for a period of 20 years and concludes there is reasonable assurance that the UWNR will continue to operate safely for the additional period of time. The details of the NRC staff's safety evaluation will be provided with the renewed license that will be issued as part of the letter to the licensee approving its license renewal application. This document contains the environmental assessment of the proposed action.

The UWNR is located in the Mechanical Engineering Building on the main campus of the University of Wisconsin. The UWNR is housed in the Reactor Laboratory, a 13 meter (43 feet) by 22 meter (70 feet) room of conventional construction within the Mechanical Engineering Building. Throughout most of the Reactor Laboratory, the ceiling height is approximately 11 meters (36 feet) with a portion of the ceiling above the console area a height of only 7 meters (22 feet). The floor of the room is concrete. There is no basement or crawl space below the Reactor Laboratory floor. The walls are concrete and brick. The ceiling is a 2.25 centimeter (11/2 inch) steel deck with 5 centimeters (2 inches) of rigid insulation and a 4-ply, built-up surface roof. The Mechanical Engineering Building also contains classrooms, laboratories, shops, and staff offices for the Departments of Mechanical Engineering, Industrial Engineering, and Engineering Physics. The Mechanical Engineering Building is near the southwestern border of the University of Wisconsin campus. The nearest property not owned by the University of Wisconsin is 130 meters (425 feet) from the reactor site. The reactor site is 700 meters (2,300 feet) south of the shore of Lake Mendota. The nearest permanent residence is approximately 150 meters (485 feet) west of the reactor site and the nearest dormitory is approximately 400 meters (1,300 feet) away. There are no nearby industrial, transportation, or military facilities that pose a threat to the UWNR.

The UWNR is a heterogeneous pool-type nuclear reactor currently fueled with low-enriched uranium TRIGA (Training, Research, Isotope Production, General Atomics) fuel which is cooled by natural convection. The aluminum-lined concrete pool is 2.5 meters (8 feet) wide, 3.7 meters (12 feet) long, and 8.5 meters (27.5 feet) deep. Light water acts as the coolant and the moderator as well as being a biological shield. The reinforced concrete pool walls also serve as a biological shield. The core is reflected on two sides by graphite and on two sides by water. The water-reflected areas are being utilized as irradiation facility locations. The reactor is shielded by concrete and water. The core is normally covered by 6 meters (20 feet) of water. Maximum steady-state power level is 1,000 kilowatts. Reactivity is controlled by three shim safety blades, a regulating blade, and a transient control rod. All control elements move vertically. The top and bottom reflector region is partially graphite and partially water. A detailed description of the reactor can be found in the licensee's Safety Analysis Report.

On June 11, 2009, the NRC issued an order for UWNR to convert from high-enriched uranium fuel to low-enriched uranium fuel (Agencywide Documents Access and Management System (ADAMS) Accession No. ML091390802). The conversion to low-enriched uranium fuel was completed and normal operations resumed on January 22, 2010. As part of the analysis for the conversion, the staff determined that the changes involved no significant hazards consideration, no significant increase in the amount of effluents, no significant change in the type of effluents that may be released off site, and no significant increase in individual or cumulative occupational radiation exposure.

The licensee has not requested any further changes to the facility design or operating conditions as part of the application for license renewal. No significant changes have been made in the types or quantities of effluents that may be released offsite.

The licensee has systems in place for controlling the release of radiological effluents and implements a radiation protection program to monitor personnel exposures and releases of radioactive effluents. The design of the experimental facilities, the reactor pool, and the reactor shield includes protective measures and devices which limit radiation exposures and limit releases of radioactive material to the environment. The systems and radiation protection program are appropriate for the types and quantities of effluents expected to be generated by continued operation of the reactor. Accordingly, there would be no increase in routine occupational or public radiation exposure as a result of license renewal. The proposed action will not significantly increase the probability or consequences of accidents. Therefore, license renewal would not change the environmental impact of facility operation. The NRC staff evaluated information contained in the licensee's application and data reported to the NRC by the licensee for the last five years of operation to determine the projected radiological impact of the facility on the environment during the period of the renewed license. The NRC staff finds that releases of radioactive material and personnel exposures were all well within applicable regulatory limits. Based on this evaluation, the NRC staff concluded that continued operation of the reactor would not have a significant environmental impact.

I. Radiological Impact

Environmental Effects of Reactor Operations

The radiation protection program at the reactor facility is similar to the campus radiation safety program but the reactor program has some specific aspects that apply only to the reactor facility. These protective measures and devices are discussed more thoroughly in the UWNR Safety Analysis Report.

The ventilation system is designed to prevent the spread of airborne particulate radioactive material into occupied areas outside the Reactor Laboratory. It removes particulates with high efficiency filtration and assures that all releases of both gaseous and particulate activity are monitored and discharged at an elevated release point. Calculations and measurements have been performed by the licensee to determine production and release rates of the various activities that might be discharged due to normal operation. Argon-41 is the only activity released in significant quantities during normal operations. The maximum release rate for Argon-41 activity is 13.3 microCuries per second (μCi/sec). Using the ventilation system rated flow-rate of 9,600 standard cubic feet per minute, this activity is diluted to 2.94E-6 microCuries per milliliter (μCi/ml) at the stack outlet. The resulting maximum concentration downwind is calculated to be 1.25E-9 μCi/ml. The maximum release rate of Argon-41 would occur with the reactor operating continuously at 1,000 kilowatts and all four beam ports and the thermal column open. Such operation is not reasonable, but it does establish an upper limit to the activity that might be discharged. Using the Environmental Protection Agency's (EPA) COMPLY program, it was calculated that the maximally exposed receptor, in the above-mentioned worst case, would receive a dose of 0.6 millirem/year if all activity generated was discharged continuously. Total gaseous radioactive releases reported to the NRC in the licensee's annual reports were less than the air effluent concentration limits set by 10 CFR Part 20, Appendix B.

The only activity produced in liquid form in amounts sufficient to present a personnel exposure hazard is Nitrogen-16, which is produced in the reactor coolant as it passes through the reactor core when operating at power levels above 100 kilowatts. Nitrogen-16 is controlled by use of the diffuser system, which reduces the dose rate at the pool surface to 2 to 3 millirem/hour during full power operation. If the diffuser system fails during full power operation, the dose rate at the pool surface is less than 100 millirem/hour. Small quantities of liquid radioactive waste are generated by regeneration of the demineralizer and from liquids irradiated as part of sample irradiation. The radiation level from such liquids is extremely low and does not produce radiation exposure hazards. Liquid wastes can be transferred to the campus University Safety Department, Radiation Safety Office, but most are placed into the holdup tank. The Reactor Laboratory occasionally discharges liquid waste from the holdup tank to the sewer system. Before discharging liquid waste into the sanitary sewer, the discharges are filtered so that no particulate activity above 0.5 micron size is discharged. Sampling, analysis, and release of the holdup tank contents are governed by a written procedure that assures releases are within 10 CFR Part 20 Appendix B Table 3 limits, and that the pH of the aqueous liquid is within local limits for discharge to the sewer. Annual liquid releases have ranged from 0 to 10,000 gallons, with 3,000 gallons being typical. The licensee maintains a pool leak surveillance program. The pool water leak surveillance program continues to monitor the pool water evaporation rate, the pool water make-up volume, and pool water radioactivity. The pool leak surveillance program indicated that approximately 2,449 gallons of water have been released to the environment in 2008-2009 and 736 gallons in 2007-2008. The annual reports for 2006-2007 and 2005-2006 indicate there was no water released to the environment associated with pool surveillance; however, the 2004-2005 annual report indicates that water had been released. The radionuclide of concern associated with pool water leakage would be hydrogen-3 (tritium). Annual reports indicate that the maximum concentrations and maximum quantity released from the facility would have no significant impact.

Annual reports reviewed from the last five years indicate that when solid waste is generated from use of the UWNR, it is transferred to the University of Wisconsin broad scope license for ultimate disposal in accordance with regulations set forth under that license. In the years that solid waste was generated, less than 400 milliCuries of solid waste was transferred for disposal.

Dosimeters are used for monitoring operating personnel and individuals that frequently conduct experiments. Electronic dosimeters are used for visitors and for tour groups. Doses received by visitors and tour groups are so low that they are often unmeasurable. The maximum dose rate permitted during any tour is 0.5 millirem/hour. The maximum dose rate permitted for non-radiation workers is 2.0 millirem/hour. Visitors who are radiation workers but not part of the campus dosimetry program, such as visiting researchers, are allowed access to higher dose rates; however, rarely does the dose rate exceed 2.0 millirem/hour. No student dosimeter has ever received a measurable radiation exposure from reactor operation. Occupational exposures received by operations and maintenance personnel have historically been very low, seldom exceeding 0.5 rem total effective dose equivalent in a year and usually below 100 millirem/year. The occupational exposure limit for total effective dose equivalent from 10 CFR 20.1201(a)(1)(i) is 5 rem per year. No changes that would lead to an increase in occupational dose are expected as a result of the proposed action.

The licensee has in place an environmental monitoring program that uses area monitors placed in most volume occupied areas around the reactor laboratory. The area monitors are changed out quarterly. The exposure reading would indicate the maximum exposure an individual would receive if continuously present in that area. Presently, there are 26 monitoring points. Effluents are also monitored at the point of release. According to the licensee's annual reports, the dose a person would receive if continuously present in any of the monitored areas would be less than limits set forth in 10 CFR Part 20 for dose to the general public.

The licensee conducts an environmental monitoring program to record and track the radiological impact of UWNR operation on the surrounding unrestricted area. The program consists of quarterly exposure measurements at four locations on the site boundary and at two control locations away from any direct influence from the reactor. Review of the last five annual reports submitted by the licensee indicates that radiation exposure at the monitoring locations were not significantly higher than those measured at the control locations. Based on the NRC staff's review of the past five years of data, the NRC staff concludes that operation of the UWNR does not have any significant radiological impact on the surrounding environment. No changes in reactor operation that would affect off-site radiation levels are expected as a result of the license renewal.

Environmental Effects of Accidents

Accident analyses are discussed in Chapter 13 of the UWNR Safety Analysis Report and updated in the low-enriched uranium conversion report dated August 25, 2008 (ADAMS Accession No. ML090760776). The maximum hypothetical accident for UWNR is postulated as damage to a fuel element resulting in failure of the fuel cladding. The likelihood of a major fuel element cladding failure is considered small. The elements must meet rigid quality control standards; pool water quality is carefully controlled; and care is taken in handling fuel. Though the likelihood is small, such a cladding failure is possible. In the event of such an accident, the amount of volatiles released to the room would be 11.28 Curies. If this activity is distributed uniformly in the laboratory volume, the resulting concentration would be 5.18E-3 Ci/m³. The maximum dose to a worker in confinement for 5 minutes would be 1.35 rem total effective dose equivalent, 35.8 rem committed dose equivalent to the thyroid gland, and 278 millirem effective dose equivalent. The proposed action will not result in any changes that will increase the probability or consequences of accidents.

II. Non-Radiological Impacts

The UWNR is cooled by a system that contains three loops: The closed loop primary system; the closed loop intermediate coolant system; and the closed loop campus chilled water system. Heat from the primary coolant system is transferred to the intermediate coolant system through the primary heat exchanger. Heat from the intermediate cooling system is then transferred to the campus chilled water system through the intermediate heat exchanger. The system is designed to maintain a pressure gradient towards the pool in order to prevent the inadvertent loss of pool water. A 5 centimeter (2 inch) diameter line whose rupture could have caused loss of pool water has been permanently plugged inside the concrete shield and is presently sealed off outside the shield. A pool drain line and valve have been eliminated. There are no valves in the system that, if opened, can drain the pool. The proposed action would not make any changes that would increase the non-radiological consequences of accidents.

National Environmental Policy Act (NEPA) Considerations

The NRC has responsibilities that are derived from NEPA and from other environmental laws, which include the Endangered Species Act (ESA), Coastal Zone Management Act (CZMA), National Historic Preservation Act (NHPA), Fish and Wildlife Coordination Act (FWCA), and the Executive Order on Environmental Justice. The following presents a brief discussion of impacts associated with these laws and other requirements.

I. Endangered Species Act

No effects on the aquatic or terrestrial habitat in the vicinity of the facility, or to threatened, endangered, or protected species under the Endangered Species Act, would be expected.

II. Coastal Zone Management Act

The site occupied by the UWNR is not located within any managed coastal zones, nor do the UWNR effluents impact any managed coastal zones.

III. National Historic Preservation Act

The NHPA requires Federal agencies to consider the effects of their undertakings on historic properties. There are a few historic sites located on the UW campus within 0.5 miles of the site but the closest to the site of the UWNR is the old U. S. Forest Products Laboratory. The location of the old U. S. Products Laboratory is approximately 31 meters (100 feet) from the Mechanical Engineering Building where the UWNR is located. Continued operation of the UWNR will not affect this historic designation. It is unlikely that there would be any potential impacts of license renewal that would have an adverse effect on historic and archaeological resources at UWNR.

IV. Fish and Wildlife Coordination Act

The licensee is not planning any water resource development projects, including any of the modifications relating to impounding a body of water, damming, diverting a stream or river, deepening a channel, irrigation, or altering a body of water for navigation or drainage.

V. Executive Order 12898—Environmental Justice

The environmental justice impact analysis evaluates the potential for disproportionately high and adverse human health and environmental effects on minority and low-income populations that could result from the relicensing and the continued operation of the UWNR. Such effects may include human health, biological, cultural, economic, or social impacts. Minority and low-income populations are subsets of the general public residing around the UWNR, and all are exposed to the same health and environmental effects generated from activities at the UWNR.

Minority Populations in the Vicinity of the UWNR—According to 2000 census data, 9 percent of the population (approximately 1,014,000 individuals) residing within a 50-mile radius of UWNR identified themselves as minority individuals. The largest minority groups were Black or African American and Hispanic or Latino (32,000 persons or 3.2 percent), followed by Asian (21,000 or 2.0 percent). According to the U.S. Census Bureau, about 12.7 percent of the Dane County population identified themselves as minorities, with persons of Black or African American origin comprising the largest minority group (6.1 percent). According to the census data 3-year average estimates for 2006-2008, the minority population of Dane County, as a percent of the total population, had increased to 15.5 percent.

Low-income Populations in the Vicinity of the UWNR—According to 2000 Census data, approximately 10,500 families and 75,000 individuals (approximately 4.1 and 7.4 percent, respectively) residing within a 50-mile radius of the UWNR were identified as living below the Federal poverty threshold in 1999. The 1999 Federal poverty threshold was $17,029 for a family of four.

According to Census data in the 2006-2008 American Community Survey 3-Year Estimates, the median household income for Wisconsin was $52,249, while 7.0 percent of families and 10.7 percent of the state population were determined to be living below the Federal poverty threshold. Dane County had a higher median household income average ($61,818) and a lower percent of families (4.6 percent) and similar percentage of individuals (10.9 percent) living below the poverty level, respectively.

Impact Analysis—Potential impacts to minority and low-income populations would mostly consist of radiological effects; however, radiation doses from continued operations associated with this license renewal are expected to continue at current levels, and would be well below regulatory limits.

Based on this information and the analysis of human health and environmental impacts presented in this environmental assessment, the proposed relicensing would not have disproportionately high and adverse human health and environmental effects on minority and low-income populations residing in the vicinity of UWNR.

Environmental Impacts of the Alternatives to the Proposed Action

As an alternative to license renewal, the NRC considered denying the proposed action. If the NRC denied the request for license renewal, reactor operations would cease and decommissioning would be required. The NRC notes that, even with a renewed license, the UWNR will eventually be decommissioned, at which time the environmental effects of decommissioning would occur. Decommissioning would be conducted in accordance with an NRC-approved decommissioning plan, which would require a separate environmental review under 10 CFR 51.21. Cessation of facility operations would reduce or eliminate radioactive effluents and emissions. However, as previously discussed in this environmental assessment, radioactive effluents and emissions from reactor operations constitute a small fraction of the applicable regulatory limits. Therefore, the environmental impacts of license renewal and the denial of the request for license renewal would be similar. In addition, denying the request for license renewal would eliminate the benefits of teaching, research, and services provided by the UWNR.

Agencies and Persons Consulted

In accordance with the agency's stated policy, on July 1, 2010, the staff consulted with the State Liaison Officer regarding the environmental impact of the proposed action. In an electronic mail message dated July 2, 2010, the State Liaison Officer indicated that the State had no comments with respect to the environmental assessment and for the Finding of No Significant Impact.

In a communication dated July 9, 2010, the Wisconsin State Historic Preservation Office agreed that no historic properties would be affected as a result of continued operation of the UWNR.

Finding of No Significant Impact

On the basis of the environmental assessment, the NRC concludes that the proposed action will not have a significant effect on the quality of the human environment. Accordingly, the NRC has determined not to prepare an environmental impact statement for the proposed action.

For further details with respect to the proposed action, see the licensee's letter dated May 9, 2000 (ADAMS Accession No. ML093570404), as supplemented by letter dated October 17, 2008 (ADAMS Accession No. ML100740573). Documents may be examined, and/or copied for a fee, at the NRC's Public Document Room (PDR), located at One White Flint North, 11555 Rockville Pike (first floor), Rockville, Maryland. Publicly available records will be accessible electronically from the ADAMS Public Electronic Reading Room on the NRC Web site http://www.nrc.gov/​reading-rm/​adams.html. Persons who do not have access to ADAMS or who encounter problems in accessing the documents located in ADAMS should contact the NRC PDR Reference staff at 1-800-397-4209, or 301-415-4737, or send an e-mail to [e-mail].

Dated at Rockville, Maryland, this 10th day of September 2010.

For the Nuclear Regulatory Commission.

Linh Tran,

Senior Project Manager, Research and Test Reactors Licensing Branch, Division of Policy and Rulemaking, Office of Nuclear Reactor Regulation.