Northern States Power Company; Monticello Nuclear Generating Plant; Environmental Assessment and Final Finding of No Significant Impact

NUCLEAR REGULATORY COMMISSION

[Docket No. 50-263]

Northern States Power Company; Monticello Nuclear Generating

Plant; Environmental Assessment and Final Finding of No Significant

Impact

The U.S. Nuclear Regulatory Commission (the Commission) is

considering issuance of an amendment to Facility Operating License No.

DPR-22, issued to Northern States Power Company (NSP), for operation of

the Monticello Nuclear Generating Plant (MNGP) located in Wright

County, Minnesota.

Environmental Assessment

Identification of the Proposed Action

By letter dated July 26, 1996, as revised December 4, 1997, NSP

requested an amendment to License No. DPR-22 for MNGP that would

increase the maximum power level from 1670 megawatts-thermal (MWt) to

1775 MWt. This change is approximately 6.3 percent above the current

maximum license power level and is considered an extended power rerate.

The Need for the Proposed Action

NSP has projected the need for additional generation resources

through a comparison of needs to available resources. NSP has projected

a shortfall of generating capacity in the future. The proposed action

would provide increased reactor power, thus adding an additional 26 MW

of reliable electrical energy generating capacity without major

hardware modifications to the plant. Hardware changes are not needed

because of improvements in technology, performance, and design. These

improvements have resulted in a significant increase in the difference

between the calculated safety analysis results and licensing limits

established by the original license.

Environmental Impacts of the Proposed Action

The issuance of the operating license for MNGP stated that any

activity authorized by the license is encompassed by the overall action

evaluated in the Final Environmental Statement (FES), which was issued

in November 1972. The license for MNGP allowed a maximum reactor power

level of 1670 MWt. NSP submitted an environmental evaluation supporting

the proposed power rerate action and provided a summary of its

conclusions concerning both the radiological and nonradiological

environmental impacts of the proposed action. The evaluations performed

by the licensee concluded that the environmental impacts of power

rerate are well bounded or encompassed by previously evaluated

environmental impacts and criteria established by the staff in the FES.

A summary of the nonradiological and radiological effects on the

environment that may result from the proposed amendment is provided

below.

Nonradiological Impacts

Land Use. Power rerate does not modify land use at the site. No new

facilities, access roads, parking facilities, laydown areas, or onsite

transmission and distribution equipment, including power line right of

way, are needed to support the rerate or operation after rerate. No

change to above or below ground storage tanks would occur as a result

of power rerate and the rerate does not affect land with historical or

archeological sites.

Based on the operating history at the MNGP, the effects of drift,

icing, and fog have been negligible. The frequency of fog and drift

were provided by the licensee at the time of original licensing and the

impacts of that frequency of drift and fog are bounded by the

evaluation contained in the FES. The FES assumed cooling tower

operation of 7 months, with the total fogging time estimated at 45

hours per year. If the cooling tower fogging rate is assumed to

increase proportional to the proposed power increase, the amount of

fogging due to power rerate could increase by approximately 6.3 percent

above the normal summer operating period of 4 months. Additionally, the

licensee determined that power rerate may involve an extra week of

cooling tower operation. Taking into account the additional fogging

rate and the additional cooling tower operation, the conditions at

power rerate are still bounded by the FES.

The increase in power level would cause a current and magnetic

field increase on the onsite transmission line between the main

generator and the plant substation. The line is located entirely within

the fenced, licensee-controlled boundary of the plant, and it is not

expected that members of the public or wildlife would be affected.

Exposure from magnetic fields from the offsite transmission system is

not expected to increase significantly.

Water Use. Power rerate does not involve a significant increase in

water use at MNGP. Both ground and surface water appropriation limits

are established by the Minnesota Department of Natural Resources.

Operating history shows that over the last 5 years MNGP has used less

than 13 million gallons of ground water per year. The annual limit

established in the permit for groundwater use is 15 million gallons.

Power rerate is not expected to change the groundwater usage and,

therefore, operation within the allowable limit would continue. Under

the surface water appropriation limit, MNGP may withdraw a maximum of

645 cubic feet per second (cfs) from the Mississippi River. There are

special restrictions when the river flow is particularly high or low;

however, power rerate is not expected to change the surface water

requirements of the plant and, therefore, current appropriation limits

would be maintained. Power rerate would result in an increase in the

evaporation rate of the cooling towers resulting in an increase in

evaporative losses from the river. Assuming the evaporation rate of the

cooling towers increases linearly in proportion to the power increase,

the evaporation rate would increase to 4400 acre-ft/yr [acre-foot per

year]. The value assumed in the FES was 5000 acre-ft/yr evaporative

losses; therefore, the FES is still bounding.

Discharges to the water are governed by the National Pollutant

Discharge Elimination System (NPDES) permit, issued by the State of

Minnesota. Temperature and effluent limits at certain points are

established in the permits. As a result of power rerate, a slight

increase in circulating water discharge temperature is projected to

occur. This is due to an increase in heat rejected by the condenser due

to the increased power levels and increased steam flow. A conservative

estimate by the licensee predicts a maximum 1.7 deg.F [degrees

Fahrenheit] increase in the temperature of the water entering the

discharge canal. This increase would

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not result in exceeding the limits delineated in the FES or the limits

established by the State in the permit. Additionally, temperature

monitoring is continuous and this maximum temperature increase would

occur only at certain times of the year with certain river flows. In

the past, when MNGP has approached the limit designated in the NPDES

permit, NSP has reduced power at the plant to maintain compliance; this

will continue in the future. The slight increase in temperature does

not require any changes to permit requirements and would not result in

any significant impacts to the environment that are different from

those previously identified or change the previous Clean Water Act

Section 316(a) demonstration concerning thermal plume in the

Mississippi River.

Power rerate would not introduce any new contaminants or pollutants

and would not significantly increase the amount of potential

contaminants previously allowed by the State. NSP will continue to

adhere to effluent limitation and monitoring requirements as part of

compliance with the NPDES permit. As a result of the additional week of

cooling tower operation, a slight increase in normal bromine and sodium

hypochlorite injection may be required; however, the effluent

concentrations would continue to be well below the NPDES permit limits.

Continuous flowrate monitoring at designated points will continue.

Over the years of operation, a number of modifications to the

intake structure have been implemented to reduce cold shock,

impingement, and entrainment of organisms and fish. Because the

discharge canal inlet temperature is expected to increase 1.7 deg.F at

power rerate, the overall discharge canal temperature is not

significantly increased; therefore, the temperature decrease during

cold shock is not significantly changed.

Additionally, impingement and entrainment mortality of drift

organisms is not increased above what was previously evaluated by the

staff.

Other Impacts

No significant increases or changes to the noise generated by MNGP

are expected as a result of power rerate; therefore, the FES remains

bounding. A small number of endangered and threatened species exist

within the licensee-controlled area at MNGP. Using information from the

Minnesota Department of Natural Resources, the licensee performed a

biological assessment of the impact of power rerate on these species.

The assessment did not identify any impacts. Power rerate would not

result in any significant changes to land use or water use, or result

in any significant changes to the quantity or quality of effluents;

therefore, no effects on the endangered or threatened species or on

their habitat are expected as a result of power rerate.

The proposed power rerate would not change the method of generating

electricity nor the method of handling any influent from the

environment or nonradiological effluents to the environment. Therefore,

no changes or different types of nonradiological environmental impacts

are expected.

Radiological Impacts

MNGP has a number of radioactive waste systems designed to collect,

process, and dispose of solid, liquid, and gaseous radioactive waste.

No changes to these systems are required for power rerate conditions.

The licensee considered the effect of the higher power level on solid

radioactive wastes, liquid radioactive wastes, gaseous radioactive

wastes, and radiation levels.

As a result of power rerate, a slight increase in solid waste from

the reactor water cleanup (RWCU) system demineralizers and condensate

demineralizers would occur. This is due to more frequent filter

backwashes. Additional RWCU filter backwashes would result in less than

1 cubic meter of additional resin waste per year; condensate

demineralizer filter backwashes are estimated to result in an

additional 4 cubic meters of resin waste per year. Therefore, the

projected increase in spent resin volume is less than 6 cubic meters

per year, which would bring the total generation rate to approximately

55 cubic meters per year.

In addition to the solid process waste, there are solid reactor

system wastes generated from the plant. These include irradiated fuel

assemblies and control blades. Due to extended burnup and the higher

enrichments, the number of irradiated fuel assemblies is not expected

to significantly increase the volume of waste; however, the activity of

the waste generated from spent control blades and incore ion changers

may increase slightly. This is due to the higher flux conditions

expected under power rerate. Improvements in technology and longer fuel

cycles are expected to offset this slight increase. The increase in

waste would be insufficient to impact the amount of waste generated at

the site. Further, the licensee believes ongoing efforts at MNGP to

reduce radioactive wastes will balance the slight increase in waste

that would be generated as a result of power rerate.

The FES and Technical Specifications allow MNGP to discharge a

limited amount of liquid radioactive waste. The FES concluded that,

based on the allowed amounts, no adverse environmental impact would

result from release of the allowable radioactive waste. However, since

1972, an administrative limit of zero radioactive liquid release has

been imposed by NSP. MNGP expects to keep the zero release

administrative limit and remain well within the bounds of the FES.

A slight increase in input to the liquid radioactive waste system

is expected due to the increase in backwash frequency of the RWCU and

condensate demineralizer system. However, the liquid radioactive waste

input will be recycled instead of discharged and will not result in a

significant increase in volume of liquid radioactive waste. Other

sources of liquid radioactive waste such as valve packings, pump seal

flows, drain waste, etc., are not expected to change or increase as a

result of power rerate. Based on the above, it does not appear that

power rerate will cause an increase in liquid radioactive waste above

the presently allowed limits and will not affect compliance with the

limits of 10 CFR Part 20 or Appendix I of 10 CFR Part 50.

Gaseous radioactive waste effluents consist of two pathways:

reactor building ventilation system and offgas system pathway.

Operational experience at MNGP shows a 4-year average release of 688

Ci/yr [curies per year] noble gas and 0.22 Ci/yr iodine and particulate

release. The FES assumed release rates of 110,376 Ci/yr for noble gases

and 0.75 Ci/yr for iodine and particulate releases. Assuming power

rerate increases the offgas release rate linearly in proportion to the

core thermal power increase, the increase in offgas stack release would

be well below that assumed in the FES. Assuming the radioactivity of

the reactor coolant system increases in a linear fashion proportional

to the power increase, the reactor building release rate is well below

that assumed in the FES. Based on the above, power rerate has an

insignificant effect on the present production and activity of gaseous

effluents released through the reactor building ventilation system and

the offgas system pathways and the dose from effluent releases is well

within the bounds of Appendix I to 10 CFR Part 50 and 10 CFR Part 20.

The changes in core flux profile would result in increased consequences

of a fuel defect for a bundle in a non-leak location; however, this

continues to be bounded by the consequences for the peak bundle and

those limits are not changed.

[[Page 46491]]

Power rerate does not introduce any new or different radiological

release pathways and does not increase the probability of an operator

error or equipment malfunction that would result in a radiological

release. Thus, there will be no significant increase in the types or

amounts of radiological effluents.

Tables S-3 and S-4 of 10 CFR 51.51 and 10 CFR 51.52, respectively,

outline the environmental effects of uranium fuel cycle activities and

fuel and radioactive waste transportation. The environmental evaluation

supporting Table S-3 assumed a reference reactor with a specific

capacity factor that results in an adjusted daily electricity

production during a reference year. An average burnup and enrichment

are also assumed. MNGP will not exceed the assumption of the reference

reactor year, but will exceed the average burnup and fuel enrichment

criteria as a result of power rerate. The environmental impacts of the

higher burnup and enrichment values were documented in NUREG/CR-5009,

``Assessment of the Use of Extended Burnup Fuels in Light Water Power

Reactors,'' and discussed in the Environmental Assessment and Finding

of No Significant Impact, which was published in the Federal Register

on February 29, 1988 (53 FR 6040). The staff concluded that no

significant adverse effects will be generated by increasing the burnup

levels as long as the maximum rod average burnup level of any fuel rod

is no greater than 60 Gwd/MtU [gigawatt-days per metric ton of

uranium]. The staff also stated that the environmental impacts

summarized in Tables S-3 and S-4 for a burnup level of 33 Gwd/MtU are

conservative and bound the corresponding impacts for burnup levels up

to 60 Gwd/MtU and uranium-235 enrichments up to 5 weight percent. These

conclusions are applicable to MNGP since the burnup levels and

enrichment amounts bound the values that will occur during Monticello

rerate. Based on the above, there are no adverse radiological or

nonradiological impacts associated with the use of extended fuel burnup

and/or increased enrichment and, therefore, power rerate will not

significantly affect the quality of the human environment.

Alternatives to the Proposed Action

As an alternative to the proposed action, the staff considered

denial of the proposed action (no-action alternative). Denial of the

proposed action would result in no change in current environmental

impacts of plant operation but would restrict operation to the

currently licensed power level. The environmental impact of the

proposed action and the alternative action are similar.

Alternative Use of Resources

This action does not involve the use of any resources not

previously considered in the Final Environmental Statement for the

MNGP.

Agencies and Persons Consulted

In accordance with its stated policy, on August 10, 1998, the NRC

staff consulted with the Minnesota State official, Mr. Timothy

Donakowski, of the Minnesota Department of Public Health, regarding the

environmental impact of the proposed action. The State official had no

comments.

Final Finding of No Significant Impact

The staff has reviewed the proposed power rerate for the MNGP

relative to the requirements set forth in 10 CFR Part 51. On January

27, 1998, the staff published a draft Environmental Assessment in the

Federal Register (63 FR 3929), for public comment. No comments were

received.

Based upon the environmental assessment, the Commission concludes

that the proposed action will not have a significant effect on the

quality of the human environment. Accordingly, the Commission 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 submittals dated July 26, 1996, and December 4, 1997, which

are available for public inspection at the Commission's Public Document

Room, The Gelman Building, 2120 L Street, NW., Washington, DC, and at

the local public document room located at the Minneapolis Public

Library, Technology and Science Department, 300 Nicollet Mall,

Minneapolis, Minnesota 55401.

Dated at Rockville, Maryland, this 27th day of August 1998.

For the Nuclear Regulatory Commission.

Cynthia A. Carpenter,

Director, Project Directorate III-1, Division of Reactor Projects--III/

IV, Office of Nuclear Reactor Regulation.

[FR Doc. 98-23460 Filed 8-31-98; 8:45 am]

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