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Case 1:98-cv-00126-JFM
I) Inn1111811110
Document 783-5
DE90- 004456
Infarm8tIon .. ow
SHUTDOWN REACTORS:
SPENT FUEL ACCEPTANCE SCENARIOS DEVOTED TO PRELIMINARY ANALYSIS
PACIFIC NORTHWEST LABORATORY RICH LAND,
OCT 89
s. DEPARTMENT OF COMMERCE
National Technical Information Service
0025
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~i~I~~~~iu~fillllll
PNL-1143
UC.a12
Spent Fuel Acceptance Scenarios Devoted to Shutdown Reactors:
A Preliminary Analysis
T. W. Wood A. M. Plummer
D. G. Dippold S. M. Short
October 1989
Prepared for the U. S. Department of Energy
under Contr~ct DE-AC06. 16RLO
1830
P~clfic Northwest uboratory Oper~ted for the U. S. Department of Energy by B~ttelle Memorial Institute
. REPRODUCED BY
S. DEPARTMENT OF COMMERCE
NATIONAl TECHNICAL INFORMATION SERVICE SPRINGFIELD. VA. 22161
._u_-.-_u
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DISCLAIMER
This pros ram was prepared as an account of work sponsored by an asency of
Information, apparatuI, product, or prDCe.. disclosed, or '.pr....n" that
liability Dr responsibility for the accuracy, completeness, or useful..... of any Its
Reference
the United States Government. Neither the United States Government nor any agency thereof, nor Battelle Memorial Institute, nor any or their employees, makes any warranty, expre...d or Implied, or assumes IepI
specific commercial product, process, or service by trade name, trademark manufacturer, or otherwise, does not necessarily constitute or Imply Its en-
ute would not Infrlnle privately owned rip".
herein to any
dorsement, recommendation, or favoring by the United States Government of any agency thereof, or Battelle Memorial Institute. The views and opinions
of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
PACIFIC NORTHWEST LABORATORY
operated by
BATIELLE MEMORIAL INSTITUTE
for the
UNITED STATES DEPARTMENT OF ENERGY under Contract DE.AC06-76RLO 1830
Printed In the United SUites of America
Available to DOE and DOE contractors from the
Office of Scientific and Technical 'nformation. P. O. 801162, Oak Ridge, TN 17831;
prices available from (615) 576-&401. frS 626-8401.
Available to the public from the National Technical Information Service. S. Oep.rtmentofCommerce. 5285 Port Royal Rd., Springfield, VA 22161.
NTIS Price Codes, Microfiche AO1
Prinled Copy
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PNl- 7143 UC- 812
SPENT FUEL ACCEPTANCE SCENARIOS DEVOTED TO
SHUTDOWN REACTORS: A PRELIMINARY ANALYSIS
T. A. D. S.
W, M. G. M.
Wood Plummer (a) Dippold(a) Short
October 1989
the u. S.
Prepared for Department of Energy under Contract DE- ACO6- 76RlO 1830
Paci fi c Northwest Laboratory
Richland. Washington
99352
(a) Office of Transportation Systems Planning
Nucl ear Systems
Battelle Memorial Institute
Group
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EXECUTIVE SUMMARY
Spent fuel acceptance schedules and the allocation of federal acceptance capacity among commercial nuclear power reactors have important operational
and cost consequences for reactor operators.
A1
ternat i ve all ocat i on
schemes
were investigated to some extent in DOE' s MRS Systems Study (DOE 1989a). The
current study supplements these analyses for a class of acceptance schemes in
which the acceptance capacity of the federal radioactive waste management (a) is allocated principally to shutdown commercial power reactors, and
system
extends the scope of analysis to include considerations of at.reactor cask
load i ng rates.
The ope rat i ona 1 consequences of these schemes for power reactors, as measured in terms of quant i ty of spent fuel storage requ i rement above storage
pool capacities and number of years of pool operations after last discharge,
are estimated, as are the associated utility costs. This study does not
attempt to examine the inter.uti1ity equity considerations involved in
departures from the current 01dest- fue1-
fi rst (OFF) all ocat ion ru1 e as
specified in the " Standard
Contract for Disposal of Spent Nuclear Fuel and/or
High- level Radioactive Waste " (DOE 1988b). In the sense that the alternative a 11 ocat ions are more economi ca 11 y effi c i ent than OFF, however, they approximate the allocations that could result from free exchange of acceptance
rights among ut
inter.uti1 ity equity.
i1 it ies. Such
a process would result in the preservation of
This study shows that a scenario that grants exclusive spent fuel
acceptance rights to shutdown reactQrs in order ' of shutdown date could substant i a 11 y reduce the average time between 1 ast di scharge and comp 1 et i on
spent fuel removal for currently operating power reactors and those under
construction and expected to be completed. Implementing such a scheme, using
a strict " longest-shutdown- first"
priority rule, would require at.
reactor
cask loading rates in excess of prel iminary estimates of capabil ities.
(a) As presently planned by the DOE, this system would include a transporta-
geologie repositories.
tion element, a monitored retrievable storage faci1 ity,
and one or mo~e
iii
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Because of the relative timing for reactor shutdown and federal acceptance as currently planned, this scenario would not fu1 ly utilize the spent fuel
acceptance capacity planned for the federal system. In addition. the requirements for additional at-reactor storage would be much greater under
such a scheme than under an all ocat i on of acceptance based on spent file 1
A modified shutdown priority scenario is developed that grants first
age.
priority to reactors with imminent storage capacity needs. second priority to
shutdown reactors, and third priority based on spent fuel age an~ individual
at-reactor cask loading constraints as currently estimated. This scenario is
. shown to have lower at-reactor storage impacts in terms of both capa~ity
requirements and average time between last discharge and fuel pickup than an
allocation based on age of spent fuel, and would fully utilize the . p1anned
acceptance capacity of the waste management system.
All of the scenarios studied would have some impact on the character.
istics of the spent fuel accepted. The
qualitative fashion.
effects of fuel characteristics on
transportation cask capacity and fleet requirements are treated here in a
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CONTENTS
EXECUTIVE SUMMARY 1. 0 INTRODUCTION
11 i
1.1
THE DECOMMISSIONING SEQUENCE FOR POWER REACTORS SCENARIO DEVELOPMENT
3. )
THE REFERENCE ACCEPTANCE SCENARIO
BASIC CONSIDERATIONS IN FORMULATING A SHUTDOWN PRIORITY ACCEPTANCE SCENARIO Spent Fuel Availability
2 At- Reactor Cask Loading Rate Constraints
OTHER ASSUMPTIONS
. 3,
Timing .
Repository Capacity and Second- Repository
Pool Capacity and Spent Fuel
All ocat i on of Acceptance
Inventory
Minimum Spent Fuel Age Since Discharge
Among Shutdown
Reactors .
Allocation of Residual Acceptance Capacity
Shipment Dedication and Size
Other Transportation Assumptions
SUMMARY OF CASES ANALYZED
ANALYSIS OF EFFECTS
FIGURES OF MERIT ASSOCIATED WITH AT .REACTOR STORAGE
Additional Storage Capacity.
Duration and Cost of Pool Operations After last
Discharge
RESUL IS OF ANAL YS IS
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The Reference Case
Case 2 - A literal Construction of EDF
De 1 ayed Acceptance
Secondary Priorities
loading Rate Constraints
Sensitivity Cases
OTHER TRANSPORTATION CONSIDERATIONS
Transportation Co~t and Cask Capacity
Modal Mix Variations
SUMMARY OF CONCLUSIONS
0 REFERENCES
APPENDIX A - CUMULATIVE PROJECTED POOL AND DRY STORAGE INVENTORIES IN ORDER OF REACTOR SHUTDOWN
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FIGURES
Schedule of Last Discharge Dates to Reactor Spent Fuel
Pool s . .
Spent Fuel Inventory Accumulation and Planned Acceptance
Distribution of Annual Rail Caskloadings for Case 1
Distribution of Annual Truck Caskloadings for Case 1 .
Distribution of Annual Rail Caskloadings for Case 2
4~ 7
Distribution of Annual Truck Caskloadings for Case 2 .
Distribution of Spent Fuel Age at Time of Shipment; Decommissioning and OFF Priorities Compared
Comparison of Rail Cask Fleet Requirements
Comparison of Truck Cask Fleet Requirements
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TABLES
Derivation of Estimated Maximum Feasible Cask Loading Rates
Description of Cases Analyzed
Reactors Shari ng Pool s
Pool Maintenance Cost and logistics Impacts of Alternative
Acceptance Scenarios
Pickup Schedules and Quantities of Spent Nuclear Fuel Infeasible for Pickup in Case 2
Transportat ion Costs
Age and Burnup Distributions for Case 1
Age and Burnup Distributions for Case 2
Projected Inventory of Spent Fuel at Reactors at Time of
Shutdown .
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INTRODUCTION
In June 1988, the U. S. Department of Energy s (DOE) Office of Civilian
Radioactive Waste Management (OCRWM) initiated a series of studies to provide
a technical basis for a re-eva1uation of OCRWM policy on development of a
monitored retrievable storage (MRS) facil ity. These studies covered several
topics, and are described in a summary report (DOE
1989a). Together, these
studies address the effects of various alternative MRS configurations, stor-
age capacities, and deployment dates on the functioning and cost of both the federal waste management system and spent fuel storage at commercial power
reactors. This analysis is framed comparatively, against a series of
reference cases for a system without an MRS facil ity. These
repository-only
cases include . cases with initial
facility operation in the year 2003 and
sensitivity cases for delayed repository development (as late 1$2013) and
for a repository emplacing intact rather than consolidated spent fuel.
In January 1989, testimony before the MRS Review Commission by the Environmenta1
Defense Fund (EDF) suggested that a val id comparative analysis of
an MRS facility should include a case in which a repository-only system was
formulated around " single,
dedicated shipping campaigns of fuel from each
reactor at the time of its decommissioning.
Previous comments on the
Ini-
tial Version Dry Cask Storage Study (DOE 1988a) suggested a system that
wou1d entail mostly single bulk shipping campaigns from each reactor
repository, preferably immediately after reactor decommissioning.
toa
While the
study on system storage conducted as part of DOE' s MRS Systems Study (Wood
et a1. 1989) included analysis of granting priority to decommissioning reac-
tors as an alternative to priority based on fuel age, the specific scenario
suggested had not been analyzed. The current study was initiated as a supplemental effort to analyze the specific scenario suggested by EOF, and to develop an acceptance scenario incorporating the general principles suggested
and resulting in low costs to uti1 ities.
The acceptance scenarios developed in this report involve allocations of
spent fuel acceptance rights other than the current olde~t- fuel-
fi rst (OFF)
allocation established by the . Standard
1.1
Contract for Disposal of Spent
Nuclear Fuel and/or High- Level Radioactive Waste " (DOE 1988b). Although
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there is a provision in the Contract that provides for shutdown reactor
priority in acceptance allocations, this study does not advocate implementathe sense that the alternative allocations are more economically efficient than OFF,
tion of such a policy as an administrative action by the DOE. In
however, they approximate the allocations that could result from free
exchange of acceptance rights among utilities. Such a process would result in the preservation of inter-utility equity.
of the same figures of merit developed and applied in the evaluation of system storage
(Task G) and transportation (Task F) in the MRS Systems Study, and was con-
The eva uati on of system
effects in thi s study i nc 1 udes many
ducted by staff involved in these efforts, using essentially the same analysis
evaluation included 1) quantity, dura ti~n, and cost of at-reactor storage, 2) logistical feasibi1 ity and cost of spent fuel transportation, and 3) spent fuel characteristics. The study
developed these measures for several repository-only cases based on the general scheme described above, and compares them with the standard repository-
framework. Specific aspects of this
only reference case used in the MRS Systems Study. Although results presented here may be validly compared with MRS scenario results previously
reported, such compari
sons were not undertaken in thi s report.
The cost measures and other results reported herein are measures of
a result of alternative acceptance allocations. Some of these alternative acceptance allocations would result in the receipt of
younger spent fuel in the system than would an OFF allocation. The analysis of impacts of this younger fuel on the other elements of the system was
beyond the scope of this study, although aspects of this problem have been
uti1 ity impacts as
qual itatively
addressed for the transportation element of the system in
Section 4.
1. More detailed analysis of the impacts to the transportation
element, as well as analysis of impacts on the HRS and repository elements,
is ongoing. The results of the study reported herein provide important
information regarding aspects of various acceptance allocations with respect
to the transportation and waste generator elements of the system. However,
it is important to real ize that the reported cost impacts or savings to the
utilities from the allocation schemes developed in this report do not represent potential impacts on the entire waste management system.
1.2
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THE DECOMMISSIONING SEQUENCE FOR POWER REACTORS
Spent fuel removal from a power reactor site is a necessary prerequisite
to site decommissioning. Although some alternative decommissioning sequences
involve storage of spent fuel at reactor sites for prolonged periods. spent
fuel removal is required prior to final closure of a
site. Thus. the sug-
gested removal of spent fuel " immediately after decommissioning " is interpreted in this report as immediately after shutdown (e. g., the last discharge
to a particular spent fuel pool). A
decommissioning "
reactor that has completed its last
discharge is referred to as " shutdown " in this report, and a reactor pool or
dry storage yard that serves only shutdown reactors is referred to as a
pool or yard.
A reference decommissioning sequence giving shipping priority to shut-
down reactors 5 years after last discharge was developed for Task G of the
MRS Systems Study (Wood et a1. 1989). For the current study. shipping priority was given to shutdown reactors immediately after last discharge with the
constraint that the spent fuel had to be cooled a minimum of a specified
number of years before it could be shipped. Schedules with 5- and 10- year
minimum ages were formulated.
Although the specifics of power reactor decommissioning pl ans remain to
be developed in most cases, projected dates of last discharge are available
based on operating license data, and were used as a basis for this study.
Figure 2. 1
pOD 1 s .
illustrates the schedule of last discharge dates for spent fuel
These dates assume a 40- year 1 i
fe after grant i ng of reactor
ope rat i ng
icense except incases where earl ier shutdowns
have already occurred.
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ell
'i)
CJ)
1970
FIGURE 2.
1980
1990
2000 2010
Year
2020
2030
2040
Schedul e of Last Oi scharge
Dates to
Reactor Spent Fuel Pool s
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SCENARIO DEVELOPMENT
THE REFERENCE ACCEPTANCE SCENARIO
The repository-only case used most broadly as a reference point for cal-
culation of MRS benefits 1n the MRS Systems Study (DOE 1989a) is a scenario
in which the repository is developed and deployed on the schedule shown in
the Draft 1988 Mission Plan Amendment (DOE 1988c), but without the MRS
facility described in that document. This case assumes initial acceptance in
the year 2003 at a rate of 400 MTU, ramping up to a design rate of 3000MTU
by the year 2008. The
reference allocation of this acceptance capacity among
reactors is based on the OFF rule as specified in the " Standard
1988b). A1
Contract for
capacity to
Disposal of Spent Nuclear Fuel and/or High- Level Radioactive Waste " (DOE
though thi s ru1 e does allocate
substanti
a 1 acceptance
shutdown reactors, it does not maximize the ability of the federal system to
assure timely decommissioning, since reactors relatively early in their ser-
vice lives (e.g., 10 years after initial criticality) will have fuel as old
as shutdown reactors whose pools are being drawn down in preparation for.
decommi ss ioni ng,
BASIC CONS IOERATIONS IN FORMULATING A SHUTDOWN PRIORITY
ACCEPTANCE SCENARIO
Eva1uation of the proposal to dedicate federal waste management system
acceptance to shutdown reactors requi res the
formu1 at ion of specific cases or
scenario! for quantitative analysis, and calculation of the at-reactor stor-
age and t ransportat i on consequences of these scenari
cons i derat
os. Because of some
ions uni que to shutdown priori ty
scenarios, these consequences are
sensitive to the details of acceptance scenario definition, and a very lit-
eral interpretation of the EDF proposal is much less desirable than one in
which relatively minor adjustments are made for these considerations.
This
section introduces two considerations of this type-- the aggregate quantity
of spent fuel e1 igib1e for shipment from shutdown reactors and the possible
limitation of system acceptance by at-reactor cask loading rate constraints.
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In each case, the consequences of these considerations under a
iteral inter-
pretation of the EOF proposal are developed, and adjustments are made which
circumvent undesirable features of these scenarios.
SDent Fuel Availability
The data on projected last discharge dates illustrated in Figure 2. 1 can
be combined with spent- fuel discharge data to show the quantity of spent fuel
available from shutdown reactors as a function of time.
Figure 3. 1
shows the
result of this calculation, over which is superimposed the planned cumulative
spent fuel acceptance schedule from the Draft Mission Plan Amendment
(reposfu11-o
itory-only system), wh1chca11s for initiation of acceptance in 2003 and
rate acceptance of 3000 MTU per year by 2008. As shown by the figure,
restricting acceptance of spent fuel to only shutdown reactors would not pro-
vide a supply of spent fuel adequate to operate the planned federal system at
full rate. A cumulative shortfall of almost 20, 000 MTU would occur by 2012,
....-.-. Total
Inventory
Invenlory at Shutdown Pools
Inventory ~ Yrs Old at Shutdown Pools
'I 70
- Planned Acceptance
~ 40
Q; 30
iI':
::I
1970
1980
1990
2000
2010
2020
2030
2040
Year
FIGURE 3.
Spent Fuel Inventory Accumulation and Planned Acceptance
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after which the system could operate at design rate. In practice, such a
situation would be an inefficient use of plant and operating staff. Should it
be desi rable to restrict acceptance to shutdown sites, spent fuel avail
abil ity
could be insured by either 1) refonmulation of the aggregate acceptance sche-
dule for either later initiation of acceptance or 2) a different aggregate
acceptance rate. The spent fuel availability problem could also be solved by
reallocation of the acceptance capacity remaining after acceptance of availab 1 e rue
1 from shutdown
reactors,
Of these possibilities, two were analyzed in this study: 1) the delay
(until 2013) of initial acceptance, and 2) the allocation of unused system
acceptance capacity to other reactors. The later first-repository start date
was used as a sensitivity case in the MRS Systems Study (DOE 1989a) and has
been suggested (DOE 1989b) as a reasonable initial date for spent fuel acceptance in a scenario devoted to shutdown reactors (state of Nevada s coments
on DOE' s Dry Cask Storage Study). Three reasons argued against analysis
(during the current study) of a ~ase in which system acceptance rate was
altered. First, a
complete evaluation of this case requires extensive con-
sideration of alternative facility designs, at least at a preconceptual
design level. Second, this sort of evaluation is now planned for inclusion in
a comprehensive study of system processing rate, to be conducted in
fiscal.
year 1990. Lastly, although
the cumulative spent fuel available from shutdown
reactors is less than system acceptance capacity for intenmediate years, the
cumulative availability is almost exactly equal to the
capacity at the planned end of the emplacement period.
planned 70, 000 MTU
At- Reactor
Cask LoadinQ Rate Constraints
The allocation of acceptance to only shutdown reactors tends to concentrate any 9i
yen year
OFF case where
s acceptance in a few reactors rel at ive to the reference smaller Quantities are loaded at many sites. The extent
this concentration will vary with the details of the sh~tdown priority rule considered, but in some cases could exceed preliminary estimates of loading
rate capabilities of some sites. This problem can be circumvented by reallocation of acceptance among other shutdown pools or to pools serving operating
reactors.
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ava i labi lity for loading of transport casks at an operating reactor is a single IO- hour shift per d~y, 365 d~s per year. While this may be a conservative assumption for
The current reference assumpt
i on on spent fuel pool
a pool serving only shutdown reactors, re-eva1 uation of thi s assumption requires a detailed analysis of decommissioning sequence operations.
The
approach taken in the current study was to: 1) demonstrate the extent of this loading rate constraint on system throughput for a shutdown priority
scheme, and 2) show that even the loading rate limits imposed by the single
)O~hour shift assumption can provide for planned system acceptance rates if
acceptance is suitably reallocated among sites.
OTHER ASSUMPTIONS
Other general assumpt ions, adopted from MRS Systems Study Tasks G and F~'
are di scussed in the fo 11 owi ng sections.
ReDosi tory CaDac i tv and Second- ReDositorv Timina
Although the timing of the ~econd repository, and particularly the continuity of acceptance between the first and second repositories, can affect
the time required for spent fuel removal after shutdown, no explicit second-
repository assumptions were made for thi s
study. It was
assumed that all of
the 86, 760 HTU of spent fuel projected to be ge~erated under the 1988 EIA no-
new-orders increasing burnup case could be accepted at a continuous rate of
3000 HTU per year once the first repository was fully operational.
(This
could be accomplished with any set of first- and second-repository capacities
totaling 86, 760 HTU, provided first- and second-repository acceptance were
properly coordinated.
The first-repository operation was assumed to ramp up
to full rate in the pattern 400 MTU/yrt (3 years), 900 MTU/yr,
Pool Caoacitv and Soent Fuel Inventory
1800MTU/yr.
Pool capacity data were taken from the Energy Information Administra-
tions
s RW 859 survey (DOE 1988d). Appendix A summarizes the cumulative
projected pool and dry storage inventories in order of reactor shutdown.
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Minimum Spent Fuel Aae Since Discharae
As noted in Section 2. 0,
spent fuel younger than 5 years is classified as
non-standard. Thus, S years is typically assumed as a minimum age of spent
fuel acceptance in simulations of the federal waste management system.
signi ficant portion of
the current designs for waste management system compo-
nents is based on spent fuel of 10 years age since discharge (DOE
1986a,
1986b). In practice, this difference
between minimum contractually acceptable
age and design basis spent fuel age has not been regarded as problematic,
since under an OFF allocation and spent fuel selection scheme, the
actual
average age of spent fuel at time of recei pt
greater quantity of " young "
is about 20 years.
Under an acceptance scenari 0 devoted to shutdown reactors, however, a
spent fuel is e1 igib1e for shipment than under
OFF, even with similar selection rules, and it is possible for the average age
of spent fuel accepted to be closer to the minimum acceptable age. For this
reason, a case was formulated with a minimum spent fuel age of 10 years rather
than 5 years.
All ocat i on of AcceDtance Amona Shutdown Reactors
Two methods of allocating acceptance among shutdown reactors were ana~
lyzed. The first, which is a standard assumption in the system simulation
model WASTES-II (Ouderkirk 1988) used for the study, is priority based on
order of pool shutdown. This is the " longest
Shutdown First, " or LSF rule.
second method analyzed was allocation of capacity to those ,shutdown sites with
the smallest spent fuel inventory remaining (the " Smallest
Inventory First,
or SIF rule). This rule was an attempt to minimize the system aggregate cost
of pool operations after last discharge. Since these costs are independent of
the quantity of spent fuel onsite (Wood et al. 1989), such a rule will tend to
allocate 1 imited capacity to those sites where it will have the greatest
impact in terms of reduced operational costs.
Allocation of Residual Acceptance Caoacitv
In those cases where the assumed 1 imits on cask loading constrain the
quantity of annual acceptance, residual acceptance capacity would either go
unused or be allocated to other pools. The standard assumption used here is
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that acceptance capacity that would normally have been allocated to a given
pool but is above the logistically feasible allocation would be reallocated
. to the next sites in the
the SIF rule) ~
shutdown reactor queue (e.g.. either the pool with
the next shutdown date under the lSF rule or the next smallest inventory under
If decommissioning pools are not available. the acceptance
capacity is allocated to operating reactors under various alternative priority
schemes. (One
approach. )
case is analyzed under the assumption that this system accep-
tance capacity 1s unused in order to illustrate the problem with this
ShiDment Dedication and Size The cases in which the repository is dedicated to shutdown reactors
assume that when a pool is
serviced. all the el igible
spent fuel (up to sys-
tem capacity) in its inventory 1s transported to the repository in 1
year.
This does not imply that this fuel is shipped in a single shipment. If the
reactor is ra i 1- served. it
is assumed that the spent fuel is loaded onto a
series of dedicated trains each having three casks per train. Thi s assumption
of dedicated trains is the reference assumption for all spent fuel transportation scenarios (Brentlinger et al. 1989). The three-casks- per- train assump-
tion is based on the fact that in an oldest- fuel- first pickup scenario the
average amount of spent fuel transported from reactors per year is about three
cask loads.
Three casks per train may not be the optimum shipment size from a trans-
portation economics point of view. Because of the dedicated train charge per
shipment (a three-cask train is considered one
shipment). per-shipment costs
fall as the shipment size increases. Although larger shipment sizes are
11b.l1 in a shutdown priority scenario than under OFF. it is not clear that
the impl lcations of 1 arger
shipment sizes on the overall waste management sys-
tem or on cask fleet requirements are desirable. Shipment sizes large enough
to deplete a reactor' s inventory of spent fuel in one very large shipment per
year would tend to require larger amounts of lag storage at the repository
than would smaller. more frequent shipments. Such
large shipments could tax
the repository s cask unloading capacity, forcing large numbers of casks to
sit idle while waiting to be unloaded. Since the logistics questions related
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to shipment size are beyond the scope of the present effort, the three-
casks- per-shipment
assumption was used.
Other Transportation Assumotions
The following assumptions for the physical characteristics, logistics
data, and cost data were taken from MRS System Study Task F assumptions:
Cask Physical Characteristics
- Casks are designed for IO- year-old spent fuel having burn 35K MWd/MTU - Rail cask capacity (assemblies): 21 (PWR)/48(BWR) 3(PWR)/7(BWR) - Truck cask capacities (assembl - Rail cask weight(lb): 200, 000(10aded)/168, 000(unloaded) - Truck cask we;ght(lb): 56, 000(loaded)/5I, 500(unloaded)
up of
ies):
Log; st ics
Data
- Rail cask life (yr):
- Truck cask 1 i
- Truck cask availability (days/yr): 310 - Rail cask turnaround time (days): 2 . 5(PWR)/3. 5(BWR) - Truck cask turnaround time (days): 2. 0(PWR)/2. 0(BWR)
Cost Data
- Rail cask availability (days/yr): 280
fe (yr):
- Cask purchase price ($ million): 2.
- Annual maintenance cost ($ mill ion):
0(rail)/0. 8(truck)
. 125(rail )/. O75(truck)
the shutdown
It is further assumed that shutdown reactors can support a continual
cask loading activity throughout the year. That is, because ,
reactors are no longer generating electricity, they can allow their pools to
be used exclusively for loading spent fuel into transportation casks; cask
loading i s assumed
operat ing reactor.
to take place at these reactors 365 days per year on a one
10 hour shift per day basis. This is the current reference assumption for an
The above assumptions establ ish, for the purposes of this study, an upper
1 imit on the annual spent fuel quantity loaded into transportati~n casks at
each pool. For example, it takes 2. 5 days to load a PWR rail cask with 21
assemblies. Thus,
with continual loading, 146 PWR casks (3066 assemblies) can
be loaded over 1 year s time. Table 3. 1 summari zes the upper 1 imi ts
truck, PWR, and BWR casks.
for rail,
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TABLE 3.
Derivation of Estimated Maximum Feasible Cask loading Rates
PWR- Truck
BWR- Truck
Cask Loading Constraints
PWR- Rail
BWR- Rail
Turnaround Time (days)
~asks Loaded/year SF assemblies/cask
SF assembl ies loaded/yr
182
182
146
104
546
251
1214
MTU loaded per year
229
3066 1410
4992 899
Cask loading rates are based upon one 10more shifts per day are assumed, the maximum feasible loading rate would
hr shift/day. If
increase.
At the site of a shutdown reactor, it may be possible and desirable to
exceed the cask loading rates assumed in Table 3.
1. Since definitive data on
the extent to which this would occur is not available, the approach taken in
this study is to use the estimates 1n Table 3. 1, even if lower than might
actually be achieved, and show that any resulting constraints on system
throughput can be mitigated by reallocation among reactors.
SUMMARY OF CASES ANAL VZED
Table 3. 2
sununarizes the nine cases formulated for analysis in this
study in terms of the assumptions discussed above. Cases
2 through 7 do~ument
the development of a shutdown priority scenario that is feasible and has rela-
tively low costs to utilities, beginning with a very literal construction of
the EDF suggestion in Case 2 and making refinements in the allocation rules.
Cases 8 and 9 are sensitivity analyses for the form of allocation among shut-
down reactors and the minimum acceptable fuel age.
Results are discussed in
Section 4.
In each of these cases, the repository s receipt requirements are satis-
fied by applying the allocation and priority rules to the set of reactors to
determine a reactor pickup schedule (sequence in which the reactors are serv-
iced and the amount of spent fuel picked up at each). For example, in Case 8
the order in which the reactors are serviced and the amount of spent fuel
transported are based upon several criteria. First, those reactors that
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TABL
Description of Cases Analyzed
Repository
Case mber
Start
2003
2003 2013 2003
2013
Shutdown
llocatio
OFF
DEeOM
DECOM
Shipping
Rule
Minimum
Coo11ng Time
Pool Priority
(ye rs)
N/A
LSF( a)
lSF
LSF
LSF LSF
DECOM/FCR/OFF
DECOM(RJ (b)
2003
2003
DECOM (RJ/FCR/OFF
FCR/DECOM(RJ/OFF FCR/DECOM(RJ/OFF FCR/DECOM(RJ/OFF
LSF
2003
. 2003
SIdc)
lSF
(a) longest Shutdown First (lSF) - pools at shutdown reactors that have
(b)
(c)
been waiting the longest to be emptied have highest shipping . priority. DECOM(RJ indicates a case in which acceptance rights are based on shutdown status but have been rea 11 ocated among shutdown sites so . that estimated cask 1 oadi ng rates are not exceeded in any year. Smallest Inventory First (SIF) - pools at shutdown reactors that have the smallest inventory of spent fuel have highest shipping
pri or1 ty .
cannot satisfy the full core reserve (FCR) margin within their pools are
granted first shipping rights, reactors that are shut down are granted
shipping rights for any remaining system capacity and, if there is any system
capacity still available, additional shippings rights are granted to reactors
on an OFF basis. Second, for any given year, the shutdown reactors are
ranked according to the size of their spent fuel inventory, smallest inven-
tory first. Third, starting at the top of the ranking, spent fuel that is at
least 5 years old is loaded into casks and shipped to the repository until
the reactor s inventory of eligible fuel is exhausted or until the repository
receipt rate is satisfied, whichever comes
first. Reactor pickup schedules
for the other cases are determi ned in analogous ways, except that the all
cation and priority rules differ.
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