[Federal Register Volume 62, Number 176 (Thursday, September 11, 1997)]
[Notices]
[Pages 47835-47838]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-24219]
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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-390]
Tennessee Valley Authority Watts Bar Nuclear Plant, UNIT 1;
Environmental Assessment and Finding of No Significant Impact
The U.S. Nuclear Regulatory Commission (the Commission or NRC) is
considering issuance of an amendment to Facility Operating License No.
NPF-90, issued to Tennessee Valley Authority (TVA), for operation of
the Watts Bar Nuclear Plant, Unit 1 (WBN), located in Rhea County,
Tennessee.
Environmental Assessment
Identification of the Proposed Action
TVA has requested a change to the current WBN Technical
Specifications (TSs) to provide for insertion of four lead test
assemblies (LTAs) containing 32 tritium producing burnable absorber
rods (TPBARs) into the WBN reactor during Fuel Cycle 2. After a single
cycle of operation the TPBARs will be removed from the reactor and
stored in the spent fuel pool. Then the TPBARs will be placed in
shipping casks and transported off-site under Department of Energy
(DOE) control.
The Need for the Proposed Action
As discussed in the NRC staff report, NUREG-1607, ``Safety
Evaluation Report related to the Department of Energy's proposal for
the irradiation of lead test assemblies containing tritium-producing
burnable absorber rods in commercial light-water reactors,'' May 1997,
DOE is responsible for establishing the capability to produce
[[Page 47836]]
tritium, an essential material used in U.S. nuclear weapons, by the end
of 2005, in accordance with a Presidential decision directive. Tritium
is an isotope of hydrogen that decays at a rate of approximately 5
percent per year (a 12.3-year half-life). The United States has not
produced tritium for use in nuclear weapons since 1988, when DOE closed
its production facility at Savannah River. Resumption of tritium
production for weapons will be essential for maintaining the U.S.
nuclear weapons stockpile and the U.S. nuclear deterrent. DOE has
selected a dual-path strategy to meet its schedule, one of which
proposes to produce tritium in commercial light water reactors (CLWRs),
either through acquisition of reactor(s) under Government ownership or
by contracting for target irradiation services at a plant under private
ownership.
DOE has developed a design for burnable poison rods using lithium,
rather than the boron which is currently used in reactor fuel
assemblies. As a result of irradiation by neutrons in the rector core,
some of the lithium in the target rods would be converted to tritium.
The irradiated burnable poison rods can then be removed from the fuel
assemblies and shipped to another location for tritium extraction. The
first phase of the tritium program involving CLWRs is a lead test
assembly (LTA) demonstration. LTA irradiation would serve as a
confirmatory test of the design for TPBARs that DOE has developed over
the past 10 years. For this purpose, DOE has selected TVA as a host
utility to perform LTA irradiation. Accordingly, TVA proposes to insert
four LTAs into the WBN reactor during Fuel Cycle 2 to provide
irradiation services to support DOE investigations into the feasibility
of using commercial light water reactors to maintain the nation's
inventory of tritium. The proposed action is in accordance with TVA's
application for amendment dated April 30, 1997, as supplemented by
letters dated June 18, July 21 (3 letters), and August 7 and 21, 1997.
Alternatives to the Proposed Action
As stated in the NRC staff report, NUREG-1607, the second phase of
DOE's tritium production program that would involve CLWRs and require
NRC review would be DOE's submittal of a topical report for production
irradiation in mid-1998. The staff plans to initiate review of that
report concurrently with the irradiation of the LTAs and anticipates
that it will document its review in a safety evaluation report to be
issued in early 1999. DOE has stated that, because the primary purpose
of the LTA demonstration is to build confidence among prospective
licensees, completion of the LTA demonstration is not an essential
precursor to submittal of the topical report. The NRC staff could
initiate review of the production topical report independent of the LTA
demonstration. However, the staff may need information from the LTA
demonstration before it can complete its review of the production
topical report.
No Action Taken
The principal alternative would be to take no action to approve the
LTA program in the WBN during Fuel Cycle 2. That alternative would
avoid any environmental impacts which may be associated with this
action, but as indicated herein, there are no significant environmental
impacts associated with this action. Denial of this proposed action
would have the result that further CLWR tritium production activities,
including any NRC staff review of subsequent proposals for production
of tritium in a CLWR, would then be made without the benefit of the
results of the LTA program. This could result in additional
uncertainties affecting DOE's choice of alternatives in the tritium
production program, as well as the NRC staff's review, and is not
considered a desirable option.
Environmental Impacts of the Proposed Action
Radiological Impact
The WBN has waste treatment systems designed to collect and process
waste that may contain radioactive material. The radioactive waste
treatment systems were evaluated in the WBN Final Environmental
Statement (FES) and its supplement. Results are reported in Tables 5.2
and 5.3 of NUREG-0498, Supplement 1, April 1995. The proposed amendment
will not involve any change in the radioactive waste treatment systems
or flowrates described in the FES and its supplement.
Tritium produces less dose per unit of radioactivity taken into the
human body than many other nuclides because tritium (a) decays by the
emission of a low-energy beta radiation, (b) passes through the human
body in a short period of time, and (c) does not concentrate in a
single organ. Furthermore, tritium in liquid effluents from Watts Bar
is diluted to a relative low concentration before it reaches even the
most highly exposed member of the public; i.e. the release of the
entire 214 Ci (7.93 TBq) in a year's cooling water would produce an
average concentration of only about 0.24 pCi/gm (8.9 Bq/kg) in the
receiving water. Consequently, the maximum annual dose to a member of
the public would be less than 0.02 mrem (0.2 micro-Sievert). This dose
is less than 1 percent of the NRC criterion for liquid effluents and
only about 0.007 percent of the average annual dose resulting from
naturally occurring radionuclides.
The tritium would be further diluted before it reached the
substantial number of people (about 216,000) residing in population
centers downstream of Watts Bar so the resulting individual doses would
be small, averaging about 0.4 micro-rem (4 nano-Sievert). The resulting
population dose would be less than 0.09 person-rem (person-cSv).
A portion of the tritium might be released to the atmosphere. The
amount would depend on plant conditions and the manner in which it is
operated. If the entire 214 Ci (7.93 TBq) were released to the
atmosphere, individuals could be exposed via a variety of pathways.
These pathways include inhalation and skin absorption, as well as the
consumption of meat, vegetables and milk. The total dose by all
pathways to the most highly exposed member of the public is calculated
to be less than 0.05 mrem (0.50 micro-Sievert). This is less than 1
percent of the NRC criterion for airborne effluents and less than 0.02
percent of the average person's annual dose resulting from naturally
occurring radionuclides.
Tritium in the atmosphere also could reach the more highly
populated areas in the vicinity of Watts Bar, but the airborne tritium
would be diluted even more than would water-borne tritium. Thus the
population dose would be smaller from a release to the atmosphere than
from a release to the river.
It is concluded that the releases from Watts Bar, and the resulting
off-site doses, will not be significantly affected by releases of
tritium from the TPBPRs.
The proposed amendment is not expected to significantly affect the
doses to the workers in the fuel storage area. The TPBARs are designed
to have minimal effect on plant operations, including refueling
operations. Since the unirradiated TPBARs are essentially not
radioactive, they will produce no increase in exposure, occupational or
non-occupational. After irradiation, the TPBARs are expected to contain
some 370,000 Ci (13.7 PBq) of tritium (\3\H). This is far more tritium,
but far less radioactivity, than that produced by the reactor core. The
tritium does not pose a particular threat because (1) tritium emits
only a low-energy (Emax= 18.6 keV) beta and (2) the tritium
is bound in the TPBARs. Some of the tritium beta
[[Page 47837]]
energy is converted into x-rays (bremsstrahlung) but 370,000 Ci of
tritium produces less photon energy than is produced by 1 Ci (37 GBq)
of 137 Cs and the 137 Cs radiation is much more
penetrating. The spent fuel removed for refueling contains about a
million curies of 137 Cs and many other nuclides. Thus, the
effect of tritium as a source of external radiation in the reactor
environment is negligible.
The TPBARs are designed to minimize the leakage of tritium and DOE
experience indicates that leakage will be less than 6.7 Ci (0.248 TBq)
per rod annually. If all 32 of the TPBARs were to leak at this rate,
the annual tritium release to the reactor coolant would be less than
214 Ci (7.93 TBq). This quantity is consistent with the nominal amounts
of tritium expected in pressurized water reactor (PWR) coolant systems.
The NRC licensing calculation, the GALE code, predicts about 250 Ci
(9.25 TBq) of tritium in the reactor coolant and tritium releases to
the environment from large PWRs are averaging over 600 Ci (22.2 TBq)
per year per reactor and ranging as high as 4,000 Ci (148 TBq) per year
without exceeding regulatory limits. Thus, the TPBARs might produce an
observable but not dramatic increase in the tritium concentration in
the spent fuel pool. Increasing the tritium in the spent fuel pool
could increase occupational exposure but, since tritium exposure is not
an important contributor to occupational exposure (according to NRC
data summarized in NUREG-0713, ``Occupational Radiation Exposure at
Commercial Nuclear Power Reactors and Other Facilities, 1995'', January
1997), the increase would be expected to be negligible. This is
consistent with the results reported in the DOE report.
The staff concludes that the TPBARs could cause some increase in
occupational radiation exposure. However, this increase would be
negligible and would not constitute a safety, or an ``as low as is
reasonably achievable'' (ALARA) concern.
Based on the above, the staff concludes that there are no
significant radiological environmental impacts associated with the
proposal.
Non-Radiological Impact
The proposal does not affect non-radiological plant effluents and
no changes to the National Pollution Discharge Elimination System
(NPDES) permit are needed. The proposal does 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 and no
effects on endangered or threatened species or on their habitat are
expected. Therefore, no changes or different types of non-radiological
environmental impacts are expected as a result of the amendment.
Accident Considerations
In its application, TVA evaluated the possible consequences of
postulated accidents and described the means for mitigating these
consequences should they occur. This evaluation included the effects of
a TPBAR on postulated accidents, including a TPBAR assembly dropped
during refueling, radiological consequences of release of reactor
coolant (steam generator tube rupture or steamline break), and TPBAR
damage and radiological consequences during a design-basis loss-of-
coolant accident (LOCA). On the basis of its analysis, TVA concluded
that the effect of the TPBAR on accident consequences would be small
and that the calculated consequences are within regulatory requirements
and staff guideline dose values.
As TVA has reported in its application and the staff has previously
evaluated in NUREG-1607, there are increases in the potential
radiological consequences resulting from a design basis LOCA; and the
LOCA is the most limiting accident with regard to TPBAR failure. The
DOE report states that the effect of TPBARs and the additional tritium
on the combustible gas inventory following a LOCA is negligible. In
addition, the maximum stored inventory of tritium in TPBAR LTAs is a
very small fraction of the hydrogen that would be released from a
zirconium-water reaction. Consequently, TPBARs would have no
significant contribution to combustible gas in a LOCA. The tritium
released to the coolant would not be released as a gas and, therefore,
would not produce an increase in hydrogen concentration. The resulting
dose at the exclusion area boundary would be about 0.3 mrem (3
Sv). The potential increase in the offsite radiological
consequence as a result of accidents has been determined to be
negligible. The environmental impacts of any credible accidents are
found not to be significant.
Summary
The Commission has completed its evaluation of the proposed action.
The change will not significantly increase the probability or
consequences of accidents, no changes are being made in the types and
no significant increases are being made in the amounts of any effluents
that may be released offsite, and there is no significant increase in
the allowable individual offsite dose or cumulative occupational
radiation exposure. Accordingly, the Commission concludes that there
are no significant radiological environmental impacts associated with
the proposed action.
With regard to potential nonradiological impacts, the proposed
action involves features located entirely within the restricted area as
defined in 10 CFR Part 20. It does not affect nonradiological plant
effluents and has no other environmental impact. Accordingly, the
Commission concludes that there are no significant nonradiological
environmental impacts associated with the proposed action.
Alternative Use of Resources
This action does not involve the use of any resources not
previously considered in the FES for WBN Units 1 and 2, dated April
1995.
Agencies and Persons Consulted
In accordance with its stated policy, on August 20, 1997 the staff
consulted with the Tennessee State official, Mr. Eddy Nanney, of the
Division of Radiological Health, regarding the environmental impact of
the proposed action. The State official indicated that TVA and NRC
should consider very carefully anything designed and fabricated by DOE
that is to be put into the Watts Bar reactor. As stated herein, the NRC
staff does believe that its review carefully considers the impacts of
inserting the LTAs containing the TPBARs into Watts Bar during Fuel
Cycle 2.
Finding of No Significant Impact
The staff has reviewed the proposed lead test assembly program at
WBN relative to the requirements set forth in 10 CFR Part 51. Based
upon its environmental assessment, the staff has concluded that there
are no significant radiological or non-radiological impacts associated
with the proposed action and that the proposed license amendment will
not have a significant effect on the quality of the human environment.
Therefore, the Commission has determined, pursuant to 10 CFR 51.31, not
to prepare an environmental impact statement for the proposed
amendment.
For further details with respect to the proposed action, see the
licensee's letter dated April 30, 1997, as supplemented by letters
dated June 18, July 21 (3 letters), August 7 and 21, 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 Chattanooga-Hamilton
County Library, 1001 Broad Street, Chattanooga, Tennessee.
[[Page 47838]]
Dated at Rockville, Maryland, this 8th day of September 1997.
For the Nuclear Regulatory Commission.
Frederick J. Hebdon,
Director, Project Directorate II-3, Division of Reactor Projects--I/II.
[FR Doc. 97-24219 Filed 9-10-97; 8:45 am]
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