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111))11111111118
DE90- 004456
Inform8dOn .. cu ........
SPENT
FUEL
SHUTDOWN REACTORS:
ACCEPTANCE SCENARIOS DEVOTED TO PRELIMINARY ANALYSIS
PACIFIC NORTHWEST LABORATORY RICHLAND, WA
OCT 89
s. DEPARTMENT OF COMMERCE
National Technlcellnformetion Service
OCR
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~i"II~Mii"~rWIIII
PNL.7143 UC-812
Spent Fuel Acceptance Scenarios Devoted to Shutdown Reactors:
A Preliminary Analysis
T. W. Wood A. M. Plummer
D. G. Dippold S. M. Short
Odober 1989
Prepared for the u. S. Department of Energy
under Contr~ct DE-AC06-76RlO
1830
P~clfic Northwest Labor~tory Oper~ted for the u. s. Dep~rtment of Energy
by B~"elle
Memori~llnstltute
r:. REPRODUCED BY
S. DEPARTMENT OF COMMERCE
NATIONAl TECHNICAL INFORMATION SERVICE
SPRINGAELD. VA. 22161
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DISClAIMER
specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or Imply Its en-
the United States Government. Neither the United States Government nor any agency thereof, nor Battelle Memorial Institute, nor any or their employees, makes any WalrMty, apr.,sed or implied, or alSU..... MY IepI liability or ""on."111ty for the accuracy, completene.., or uleful..... of any Information, apparatus, product, or proceu dlsdoHd, or repr...en" that ... ute would noC Infrlnle privately OWIIed rlpts. Reference herein to any
This prOiram wu prepared as an account of work sponsored by an agency of
dorsement, recommendation, or favoring by the United States Government
of any asencythereof, 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 agencythereot.
PACIFIC NORTHWEST LABORATORY
operated by
BATTEllE MEMORIAL INSTITUTE
for the
UNITED STATES DEPARTMENT OF ENERGY
under Contract DE-AC1J6.76RLO 1830
Printed In the United States of America
Available to DOE and DOE contractors from the '
Office of Scientific and Technical Information, P.O. Box 62, OK Ridge, TN 17831;
prices available from (615) 576-&401. frS 626-3401.
Available to the public from the National Technical Information Service. U.s. De~rtment of Commerce, S28S Port Royal Rd., Springfield, VAll161.
NTIS Price Codes, Microfiche AO1
Printed Copy
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AD'
AO8 AO9
A10 A11 A12
OCR
0027
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PNl-7143 OC- 912
SPENT FUEL ACCEPTANCE SCENARIOS DEVOTED TO
SH~TOOWN REACTORS: A PRELIMINARY ANALYSIS
T. A. D. S.
W. M. G. M.
Wood Plummer (a) Dippold(a) Short
October 1989
Prepared for Department of Energy under Contract DE-ACO6- 76RLO 1830
the u. S.
Pac1 f1 c Northwest Laboratory Richland, Washington 99352
(a) Office of Transportation Systems Planning Nue 1 ear Systems Group
Battelle Memorial Institute
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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. Alternative allocation schemes were investigated to some extent in DOE' s MRS Systems Study (DOE 1969a). The
current study suppl
ements these ana lyses for a cl ass
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 n9 rates.
The operational consequences of these schemes for power reactors, as
measured in terms of quantity of spent fuel storage requirement 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.util ity equity considerations involved in
departures from the current oldest- fuel- first (OFF) allocation rule as
specified in the " Standard
High. level
Contract for Disposal of Spent Nuclear Fuel and/or
Radioaet ive Waste " (DOE 1988b). In the sense that the alternative
allocations are more economically efficient than OFF, however, they approxi-
mate the all ocat ions
inter-utility equity.
that caul
d resul t from free exchange
of acceptance
rights among utilities. Such a process would result in the preservation ~f
This study shows that a scenario that grants exclusive spent
fuel
acceptance rights to shutdown reactors in order ' of
shutdown date could sub-
stantially reduce the average time between last discharge and completion of
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 preliminary estimates of capabilities.
(a) As presently planned by the DOE. this system would include a transporta-
geologic repositories.
tion element, a monitored retrievable storage facil ity, and one or mo~e
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Because of the relative timing for reactor shutdown and federal acceptance as
currently planned, this scenario would not ful
ly util ize 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 allocation of acceptance based on spent
fllel age.
A modified shutdown priority scenario is developed that grants first
priority to reactors with imminent storage capacity needs,
secondpriority to
spentfue1 age an~ indiVidual at-reactor cask loading constraints as currently estimated. This scenario is
shutdown reactors, and third priority based on
. shown to have , lower
at-reactor storage impacts in terms of both capa~ity
requirements and average time between last discharge and
fliel pickup than 'an
planned
allocation based on age of spent f~el, and would fully utilize the ~
acceptance capacity of the waste management system.
All of the scenarios studied would have some impact on the charactereffects of fuel characteristics on transportation cask capacity and fleet requirements are treated here in a
qualitative fashion.
istics of the spent fuel accepted. The
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CONTENTS
EXECUTIVE SUMMARY
11 i
0 INTRODUCTION
THE DECOMMISSIONING SEQUENCE FOR POWER REACTORS
2. J
SCENARIO DEVELOPMENT
3. J
THE REFERENCE ACCEPTANCE SCENARIO
BASIC CONSIDERATIONS IN FORMULATING A SHUTDOWN PRIORITY ACCEPTANCE SCENARIO
Spent Fuel Availability
At-Reactor Cask loading Rate Constraints
OTHER ASSUMPTIONS
'Repository Capacity and Second- Repository
. 3.
. 3.
Timing .
Pool Capacity and Spent Fuel Inventory
Minimum Spent Fuel Age Since Discharge
Allocation of Acceptance Among Shutdown
Reactors
Allocation of Residual Acceptance Capacity
Shipment Dedication and Size
Other Transportation Assumptions
SUMMARY OF CASES ANALYZED
ANALYSIS OF EFFECTS
4. I FIGURES OF MERIT ASSOCIATED WITH AT - REACTOR STORAGE
Additional Storage Capacity.
Duration and Cost of Pool Operations After last
Discharge
RESUl TS OF ANALYSIS
4. )
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The Reference Case
Case 2 - A literal Construction of fOF
Delayed Acceptance
Secondary Priorities loading Rate Constraints
Sensitivity Cases
OTHER TRANSPORTATION CONSIDERATIONS
10.
10'
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
Poo 1 s
Spent Fuel Inventory Accumul
at1on and Pl anned 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
Distribution of Annual Truck .
4~7
Caskloadings for Case 2
12 .
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
.4 .
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TABLES
Derivation of Estimated Maximum Feasible Cask loading Rates
Oeser; pt i on 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 1 on
Costs
11'
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-evaluation of OCRWM pol icy on development of a
monitored retrievable storage (MRS) facility. These studies covered
topics, and are described in a summary report (DOE 1989a).
several 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 connerchl power
reactors. This analysis is framed comparatively, against a series of
reference cases for a system without an MRS facility. These repository-only
cases include ' cases with
initial facility operation 1n the year 2003 and
sens1t1vfty cases for delayed repository development (as late as 2013) and
for a repository emplacing intact rather than consolidated spent fuel. In January 1989, testimony before the MR~ Review Commission by the Envi-
ronmental Defense Fund (EDF) suggested that a valid 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.
tia1 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 reactors 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 EDFt and to
develop an acceptance scenario incorporating the general principles sugge'Sted and resulting in low costs to utilities.
The acceptance scenarios developed in this report involve allocations of
spent fuel acceptance rights other than the currentolde~t- fuel- first (OFf) allocation ~stab1ished by the . Standard Contract for Disposal of Spent
Nuclear Fuel and/or High- level Radioacthe Waste " (DOE 1988b). Although
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there is a provision in the Contract that provides for shutdown r~actor
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.
The evaluation of system effects in this study includes many of the same figures of merit developed and applied in the evaluation of
syste~. storage
(Task G) and transportation (Task F) in the MRS S'ystems Study, and' wascon ducted by staff involved in these efforts~ using essentially the same analysis 1) quantity, dura t~~n, and cost of at-reactor storage, 2) logistical feasibility and cost of
framework. Specific aspects of this evaluation . included
spent fuel transportation, and 3) spent fuel characteristics.
Thestudy
developed these measures for several repository-only cases based on the general scheme described above, and compares them with the standard repository-
on1y 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
as a result of alternative acceptance allocations. Some of these alternative acceptance allocations would result in the receipt of
util ity impacts
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 qu~litativelY addressed for the transportation element of the system in
Section 4.
e1 ,ment ,
1. More detailed analysis of the impacts to the transportation
reported herein provide important
as well as analysis of impacts on the MRS and repository elements,
is ongoing. The results of the study
information regarding aspects of various acceptance allocations with respect
to the transportation and waste generator elements of the system. However, important to realize that the reported cost impacts or savings to the
it1s
utilities from the allocation schemes developed in this report do not represent potential impacts on the entire waste management system.
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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 suggested removal of spent fuel " imediately 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 sequenc~ giving shipping priority to shut-
down reactors 5 years after 1 ast
discharge was developed for Task
Gof the
MRS Systems Study (Wood et ale 1989). For the curr~nt study, shipping prior-
itywas 9i ven
to shutdow~ .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 plans 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
illustrates the schedule of last discharge dates for spent fuel
dates assume a 40- year 1 ife after granting of reactor operating
pools. These
license except in cases where earlier shutdowns have already occurred.
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CII
'i)
1970
FIGURE 2.
1980
1990
2000 2010
Year
2020
2030
2040
Reactor Spent Fuel Pool
Schedule of last Di scharge Dates to
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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 HRS benefits in the MRS Systems study (DOE 1989a) is a s~enario in which the repository is developed and deployed on the schedule shown in
the Draft 1988 Mission Plan Amendment (DOE 1988c), but With~ut the HRS
facility described in that document. This case assumes initial acceptance in
the year 2003 at a rate of 400 MTU, rampi~g up to a design rate of 3000 MTU
by the year 2008. The reference allocation of this acceptance capacity among
reactors is based on the OFF rule as specified in the " Standard Contract for Disposal of Spent Nuclear Fuel and/or High- level Radioactive Waste " (DOE
1988b). Although
this rule does allocate substantial acceptance capacity to
shutdown reactors, it does not maximize the ability of the federal system to
early in their service lives (e.g., 10 years after initial criticality) will have fuel as o1d
assure timely decommissioning, since reactors rel atively
as shutdown reactors whose pools are being drawn down in preparation for;
decommi ss ioning.
BASIC CON~IDERATIONS IN FORMULATING A SHUTDOWN PRIORITY
ACCEPTANCE SCENARIO
Eva1uation of the proposal to dedicate federal waste management system
cases or scenario! for quantitative analysis, and calculation of the at-reactor storacceptance to shutdown reactors requi res
the formulation of speci fie
age and transportation consequences of these scenarios. Because of some:
considerations unique . to
shutdown priority scenarios, these consequences are
sensitive to the details of acceptance scenario definition, and a very lit-
eral interpretation of the EOF 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 el igible 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 t
the consequences of these considerations under a
iteral nter-
pretation of the EDF 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.
shmils the
result of this calculation, over which is superimposed the planned cumulative
spent fuel acceptance schedule from the Draft Mission Plan Amendment
(repos-
itory~only system), which calls for initiation of acceptance in 2003 and
full-:
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 provide a supply of spent fuel adequate to operate the planned federal system at
full rate. A cumulative shortfall of almost 20, 000 HTU would occur by 2012,
....--. Total Inventory
Inventory 81 Shutdown Pools
Inventory
~ Yrs Old at Shutdown Pools
- Planned Acceptance
t- 50
-; 30
::I
1970
1980
1990
2000 2010
Year
2020
2030
2040 .
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 desirable to restrict acceptance to shutdown sites, spent fuel avai1abi1
ity
could be insured by either J) reformulation 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 available fuel 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 comments
on DOE' s Dry Cask Storage Study). Three reasons argued against analysis
(during the current study) of a .case
in which system acceptance rate was
altered. First,
a complete evaluation of this case requires extens'ive conat least at a preconceptua1
sideration of alternative facil ity designs,
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 cumul
reactors is 1
ative
spent fuel avail able
from shutdown
ess than system acceptance capaei ty
for i ntermedi
ate years,
the
cumulative availability is almost exactly equal to the
capacity at the planned end of the emplacement period.
planned 70, 000 HTU
At- Reactor
Cask loadina Rate Constraints
The allocation of acceptance to only sh~tdown reactors tends to concen-
trate any given year s acceptance in a few reactors relative to the reference
OFF case where 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 prel iminary estimates
ofc loading
rate capabilities of some sites. This problem,
can be circumvented by reallo-
cation of acceptance among other shutdown pools or to pools serving operating
reactors.
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The current reference assumption on spent fuel pool availability for loading of transport casks at an operating reactor is a single la-hour shift
per d~y, 365 d~s per year. While this ~ay be a conservative assumption for
a pool serving only shutdown reactors, re-evaluation of this 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 1 imits imposed by the single )O~hour shift assumption can provide for planned system acceptance rates if
acceptance is suitably reallocated among sites.
. 3.
OTHER ASSUMPTIONS
Other general assumptions, adopted fr~m MRS Systems Study Tasks G and F;' are discussed in the following sections.
Reoositorv Caoacitv and Second- ReDositorv Tfminq
Altho~gh the timing of the ~econd r~p~sitory, and particularly the continuity of acceptance between the first and second repositories, can affect
removal after shutdown, no expl icit secondrepository assumptions were made for this study. It was assumed that all of
the 86, 760 HTU of spent fuel projected to be gerterated under the
the time required for spent fuel'
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.
could be accomplished with any set of first- and second-repository
(This
capacities"
total in9 86, 760 HTU, provided first- and second-repository acceptance were
properly coordinated.
to full rate in the pattern
The first-repository operation was assumed to ramp up
400
MTU/yr. (3 years), 900 MTU/yr, 1800MTU/yr.
Pool CaDacity and Soent Fuel Inventorv
Pool capacity data were taken from the Energy Information Administra-
tions
s RW 859 suryey (DOE 1988d). Appendix A summarizes the cumulative
projected pool and dry storage inventories in order of reactor shutdown.
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Minimum Soent Fuel Aae Since Oischarae
As noted in Section 2. 0,
non-standard. Thus, 5 years
spent fuel younger than 5 years is classified as
is typically assumed as a minimum age of spent
fuel acceptance in simulations of the federal waste management system.
significant 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
age and design basis spent fuel
between minimum contractually acceptable
been regarded as problematic,
age' has not
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 scenario devoted to shutdown reactors, however, a spent fuel is eligible for shipment than
under.
OFF, even ,with simil~r 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 . Acceotance Amono
Shutdown Reactors
Two methods of allocating acceptance among shutdown reactor$ were ana~
lyzed. The first, which is a standard assumption in the system simulation
model , WASTES.I1 (Ouderkir/( 1988) used for the study, is priority based orf
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 limited capacity to those sites where it will have the greatest
impact in terms of reduced ope rat i ona 1
costs.
Allocation of Residual Acceotance 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 shutdown reactor queue (e. g.. either the pool with
or the next small est inventory under
the next shutdown date under the lSF rul e
the SIF ru1e).. If decommissioning pools are not available. the
acceptitnce :
capacity is allocated to operating reactors under various , alternative priority
schemes. (One
case 1s analyzed under the assumption that this system accep-
tance capacity is unused in order to illustrate the problem with this
approach. )
Sh1Dment Dedication and
Size
The cases in which the repository is dedicated to shutdown reactors
assume , that when ~ pool is serviced. all the eligible spent fuel (up tosys-
tem capacity) in Us inventory is transported to the repository in 1 year. This does notimpl Y that this fuel is shipped in a single shipment. If the
reactor is rail-served. it is assumed that the spent fuel i~ loaded onto a
series of ded1cated trains each having three casks per train. This assumption
of dedicated trains is the reference assumption for all spent fuel transporta-
tion scenarios (Brentl inger
et ale 1989). The three-casks- per- train assump-
tion is based on the fl ct that in an oldest- fuel- first pickup scenario the
average amount of spent fuel transported from reactors per year is about thre~
cask loads.
Three casks per train may not be the optimum shipment size from
atrans-
portation economics point of view. 8ecause of the dedicated train charge per
shipment (a three-cask train is considered one shipment). per-ship~ent costs
fall as the shipment size increases. Although larger shipment sizes are
1ib.le in a shutdown priority scenario than under OFF, it is not clear that
the implications of larger 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 Tra
ortat i o n A ssu
t i
The following assumptions for the physical characteristics, logistics
data, and cost data were taken from MRS System Study Task F assumptions:
sk PhYsical Characteristic
. Casks are designed for 10- year-ol d spent fuel having burn up of
35K MWd/MTU Rail cask capacity (assemblies): 21(PWR)/48(BWR) Truck cask capacities (assembl ies): 3 (PWR)/7(BWR) Rail cask weight(lb): 200, OOO(10aded)/168, 000(unloaded) Truck cask weight(lb): 56, 000( 10aded)/51 , 500(unl oaded)
Logistics Data
- Rail cask life (yr): 20
- Rail cask availability (days/yr): 280 - Truck cask availability (days/yr): 310 - Rail cask turnaround time (days): 2. 5(PWR)/3. 5(8WR)
st
- Truck cask 1 i
fe (yr):
- Truck cask turnaround time (days): 2. 0(PWR)/2. 0(BWR)
- Cask purchase price ($ million): 2. 0(rail )/O. 8(truck) - Annual maintenance cost ($ million): . 125(rail)/. 075(truck)
It is further assumed that shutdown reactors can support a continual
cask loading activity throughout the year. That is, because .
the shutdown
reactors are no longer generating electricity, they can allow their pools to
be used exclusively for loading spent fuel into transportation casks; cask
loading is assumed 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
operat i n9 reactor.
The above assumptions establish, for the purposes of this study, an upper
imit on the annual spent fuel quantity loaded into transportatio 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 summarizes the upper limits for rail,
truck, PWR, and BWR casks.
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Description of Cases Analyzed
Repository
Case
Shutdown
Start
2003
2003
Shipping
ation Rule
Pool Priority
ule
N/A
Cool ingrime
Minimum
(ve rs)
OFF
DECOM
DECOM
lSF( a)
2013 2003
2013 2003 2003 2003
. 2003
DECOM/FCR/OFF
DECOM(R) (b)
DECOM( R)/FCR/OFF
FCR/DECOM(R)/OFF
FCR/DECOM (R)/OFF
lSF lSF lSF lSF lSF
SIF(c)
lSF
FCR/DECOMfR)/OFF
(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(R) 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 loading 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
priori 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 bas
is. Second, for any gi
ven 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 Reactor pickup schedules receipt rate is satisfied, whichever comes
first.
for the other cases are determined in analogous ways, except that the allocation and priority rules differ.
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