ML20217A415
| ML20217A415 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 11/14/1990 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | |
| Shared Package | |
| ML20217A406 | List: |
| References | |
| NUDOCS 9011210053 | |
| Download: ML20217A415 (10) | |
Text
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METROPOLITAN EDISON COMPANY JERSEY CENTRAL POWER & LIGHT COMPANY l
AND l
PENNSYLVANIA ELECTRIC COMPANY I
e THREE MILE ISLAND NUCLEAR STATION, UNIT 1 Operating License No. DPR-50 Docket No. 50-289 i
Technical Specification Change Request No. 201 i
This Technical Specification Change Request is submitted in support of Licensee's i
request to change Appendix A to Operating License No. DPR-50 for Three Mile Island Nuclear Station, Unit 1.
As a_ part of this request, proposed replacement pages for Appendix A are tiso included.
GPU NUCLEAR CORPORATION
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BY:
Vice Pre'si' dent & Director, TMI-1 Sworn and subscribed M day of 7]Munhm/l/
to before. me this 1990.
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Notary Pytilic Rwan R tsary Pitic wMTdfRffff6
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9011210053 901114 PDR ADOCK 05000289 P
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TECHNICAL SPECIFICATION CHANGE REQUEST (TSCR) NO. 201 L'
GPUN requests that the folicwing changed replacement pages be inserted into the existing Technical Specifications:
Revised pages: viii, 5-6, and 5-7 Added figure: 5-4 i
These pages are attached to this ch wge request.
11.
REASON FOR CHANGE TMI-1 has two spent fuel pools (SFP) which at the present time contain inter-connected spent fuel storage racks with a total capacity of 749 storage cells. The present racks provide adequate capacity for storage of spent fuel while maintaining reserve full core discharge capacity through Cycle 9.
However, beginning with startup of Cycle 10 (anticipated to be in 1993), TM1-1 would lose full core reserve storage capability with the_ existing racks. A fuel assembly discharge schedule is provided in Table 1.1 of the enclosed Licensing Report. Therefore, to preclude this situation and to ensure that sufficient spent fuel storage capacity continues to exist at TMI-1, GPUN will install high density spent fuel storage racks whose design incorporates Boral as a neutron absorber in the cell walls thereby allowing for more dense storage of spent fuel. The new racks will provide an ultimate storage capacity of 1494 fuel assemblies (including three locations for defective fuel containers) in pool A.
The initial installation, however, will consist of a partial rerack to provide 846 locations installed in Pool A (including 3 defective fuel container storage locations). The module layout for the Spent Fuel Pool "A" is provided in Figures 1.1 and 2.3 of the enclosed Licensing Report. The existing racks will remain in Pool B thus continuing to provide 496 installed locations in Pool B.
Technical Specification Section 5.4.1.a is revised to replace the L
description of the nominal center to center distance of the existing Pool "A" racks with the description of. the nominal center to center distance of the new Region I and Region 11 racks. This Section is also revised to clarify that the new racks for the Spent Fuel Pool "A" are designed to maintain a K effective of less than 0.95 based on fuel assemblies with an enrichment of 4.6 weight percent O' ". The new fuel storage vault and Spent Fuel Pool "B" remain sufficient to maintain a K effective of less than 0.95 based on fuel assemblies with an' enrichment of 4.3 weight percent U'85 As presently specified in existing Technical Specification Section 5.3.1.6, reload fual assemblies and rods are not to exceed an enrichment of 4.3 percent of U***.
Technical Specification Section 5.4.2.d is changed to identify the j
revised number of fuel assembly storage locations and the corresponding equivalent full core capacity for the new racks as initially installed in the Spent Fuel Pool "A", and the "*** footnote is revised to identify that an additional 648 storage cell locations can be installed to provide a total of 1494 storage locations or B.44 cores. Footnote "***" is editorially revised to delete the word " reduced" from the description of the center-to-center spacing of the Pool "B" racks since its dimension is no longer the minimum spacing dimension for spent fuel storage racks.
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Reference to the fuel assembly storage capability in the Fuel Transfer Canal in Technical Specification Sections 5.4.1.b, 5.4.2.c, 5.4.2.d and 5.4.2.e is deleted as tnese racks have been removed and discarded. This is an administrative change to the Technical Specifications.
o Technical Specification Section 5.4.2.g and Figure 5-4 are added to provide administrative controls to limit storage of spent fuel assemblies in Region II of the Spent Fuel Pool "A" storage racks based on initial enrichment and cumulative exposure.
Technical Specification page viii is editorially revised to identify the new Figure 5-4,. and to correct an editorial change in Amendment No.150.
Amendment No. 150 deleted Figures 3.5-2K thru 3.5-2L and Figure 3.5-2M remained in Technical Specifications.
III.
SAFETY EVALUATION JUSTIFYING CHANGE The new free-standing high dent.ity spent fuel storage racks will store fuel in two discrete regions of the Spent Fuel Pool "A".
Region I includes two modules having a total of 195 storage es11s.
Each cell in Region I is' designed for storage of fresh or irradiated fuel assemblies with Uranium-235 initial enrichments up to 4.6 weight percent while maintaining the required suberiticality (K.rr f 0.95). Region I has enough locations to store a full core discharge (177 fuel assemblies).
Region II includes nine modules having a total of 1296 storage cells, which are available for storage of spent fuel assemblies. Of the 1296 designed storage cell locations in Region II, only 648 storage cells will be installed at the present time. However, this safety evaluation justifies the complete Pool "A" raracking and the technical specification change request provides for the. future installation of the final 648 storage cell locations.
Region II'is designed to store fuel which has experienced sufficient burnup such that storage in Region I is not required.
The high density spent fuel storage rack cells are fabricated from 0.075" thick Type 304 austenitic stainless steel sheet material..In Region I, strips of Boral neutron absorber material are emplaced between the cell-walls and a stainless steel coverplate, and the cells are separated by a specified water gap.
In Region II, the Boral strips are between the checkerboard boxes and the sheathing without a water gap. The cells are welded together in a specified manner to become a free-standing structure which is seismically qualified without depending on neighboring modules or fuel pool walls for support.
The nominal center-to-center spacings of the cells within Regiet I are 11.1". The nominal pitch in Region II is 9.20",
A minimum of 1M. of all poison panels will be examined by Blackness testing upon initial installation of the racks in the pool. A poison surveillance program will be implemented which allows access to representative poison samples without disrupting the' integrity of the storage system. This program provides the capability to evaluate the TSCR201
i material in a normal use mode, and to forecast changes that might occur within the storage system prior to occurrence of such changes. This is accomplished utilizing test " coupons" removed at periodic intervals and tested, as well as direct testing of installed poison panels in the fuel racks. The periodic testing methods, intervals, and acceptance criteria are described in Section 10.0 of the TMI-1 Licensing Report.
Criticality Analyses The high density spent fuel storage racks for TMI-1 are designed to assure that the effective neutron multiplication factor (k.rc) is equal to or less than 0.95 with the racks fully loaded with fuel of the highest anticipated reactivity. The maximum calculated reactivity includes a margin for unctrtainty in reactivity calculations including mechanical tolerances. All uncertainties are statistically combined, such that the final k.r, will be equal to or less than 0.95 with a 95% probability at a 95% confidence level. The evaluation of criticality safety in the TMI-1 storage racks assumes the infinite multiplication factor to be 0.95, which is more conservative than the limit specified in the regulatory guidelines. Additional conservative assu;nptions included in the criticality analyses are:
- 1) Moderator is unborated water at a temperature that results in the highest reactivity (68'F).
- 2) Neutron absorption in minor structural members is neglected.
The design basis fuel assembly contains 00, at a maximum initial enrichment of 4.6xt% U-235, corresponding to 59.4 grams U-235 per axial centimeter of fuel assembly. Two separate storage regions are provided in the spent fuel storage pool, with independent criteria defining the highest potential _ reactivity in each of the two regions as follows:
o Region I is designed to accommodate new fuel with a maximum enrichment-of 4.6 wt.% U-235 or spent fuel regardless of the discharge burnup.
o Region II is designed to accommodate fuel of various initial enrichments which have accumulated minimum burnups within the acceptable domain depicted in Technical Specification Figure 5-4.
The water in the spent fuel storage pool normally contains soluble boron which would result in large suberiticality margins under actual operating conditions.
However; the NRC guidelines, based upon the accident condition in which all soluble poison-is assumed to have been lost, specify that the limiting k.rr of 0.95 be evaluated in the absence of soluble boren. The double contingency principle of ANSI N-16.1-1975 and of the April 1978 NRC letter allows credit for soluble boron under other abnormal or accident conditions since only a single accident need be considered at one time.
Consequences of abnormal and accident conditions have also been evaluated, where " abnormal" refers to conditions (such as higher water temperatures resulting from full-core discharge) which may reasonably be expected to occur during the lifetime of the plant and
" accident" refers to conditions which are not expected to occur but nevertheless must be protected against.
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l A discussion of the potential for criticality accidents is included in Section 4.0 of the TMI-1 Licensing Report. The methods used in the criticality analysis for TMI-1 reracking conform to the applicable codes, standards and specifications listed in Section 4.0 of the Licensing Report.
The computer programs, data and benchmarking used in the evaluation have been used in previous reracking applications by other licensees and have been reviewed and approved by the NRC staff.
Postulated events that could potentially involve accidental criticality (eccentric fuel positioning, temperature effects on reactivity, a dropped fuel assembly, lateral rack movement, and abnormal location of a
' fuel assembly) were evaluated and it is concluded that the limiting value for criticality (k.cr of 0.95) would not be exceeded. None of the postulated events would result in a criticality accident based on the administrative controls as included in the amended Technical Specifications to limit storage of spent fuel assemblies in Region II of the Spent Fuel Pool "A" storage racks based on initial enrichment and cumulative exposure, and the existing requirement in Technical Specification Section 5.4.1 to maintain a boron concentration of 600 ppmb when fuel is moved in or over the Spent Fuel Pool "A" and fuel is being stored in the pool.
Thermal - Hydraulic Analyses The thermal-hydraulic evaluation of the completely reracked configuration is described in Section 5.0 of the TMI-1 Licensing Report, and considers the maximum fuel cladding temperature and the increase in spent fuel pool water temperature. The methods of analysis are similar to previous licensing efforts on high density spent fuel. racks and have been approved by the NRC Staff. The new storage configuration will result in an increase in the' heat load in the spent fuel pool. The evaluation shows that the existing spent fuel cooling system will maintain the bulk pool water temperature at or below 1600F, The revised pool water temperature value exceeds the previous calculated limit of 150*F.
However, the new limit of 160'F results in a negligible decrease in the time-to-boil evaluation. Thus,.it is confirmed that the peak value of the pool bulk temperature remains considerably lower than the pool bulk boiling temperature (212*F),
evaluation also shows that maximum local water temperatures along th-
- est fuel assembly are below the nucleate
. boiling condition valu.
1 Rack and Fuel Pool Structural Considerations The TMI-1 high density spent fuel storage racks have been analyzed to show structural-adequacy under postulated stress combinations associated with level A,B,C, and D conditions as defined'in the ASME B&PV Code,Section III,. Subsection NF.
Structural adequacy of the rack design is shown for normal and accident loading combinations using methods of analysis similar to those previously used in licensing reports on high density spent fuel racks as described in Section 6.0 of the TMI-1 Licensing Report. The spent fuel storage racks are Seismic Class I and are designed to remain functional during and after a safe Shutdown Earthquake (SSE) under all fuel loading conditions. The analysis shows thst no rack-to-rack or rack-to-wall impacts will occur for either the TSCR201
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-S-initial reracking installation or the final reracking configuration. The analysis shows that significant margins of safety exist against local deformation of the fuel storage cell due to rattling impact of fuel assemblies. The potential for overturning has been analyzed and shown to be not possible. The maximum mechanical loading due to the fuel handling bridge has been shown to be acceptable.
Pool slab analysis has demonstrated adequate structural integrity for all postulated loading conditions and th6rmal gradi:rd.s as described in Section 8.0 of the TMI-1 Licensing Report. The fuel pool is analyzed using a finite element modelling scheme.
Load combinations specified by NRC Standard Review Plan (SRP) Section 3.8.4 have been applied and it has been demonstrated that structural integrity is maintained wher, the pool is assumed to be fully loaded with high density fuel racks and all storage locations are occupied by fuel assemblies. Moment and shear capacities of the critical regions have been evaluated. Gross section integrity under bending and shear is evaluated, as well as local punching and bearing integrity in the vicinity of a fuel rack pedestal. The structural capacity evaluations are performed in accordance with the requirements of the American Concrete Institute (ACI) Codes as described in the TMI-1 FSAR. The applied loads specified in SRP 3.8.4 are more i
severe.than those used in the applicable ACI Codes. Therefore, in this analysis, the higher. load factors of SRP 3.8.4 have been used together with the allowable concrete and reinforcement loads specified in the ACI
~ Codes. This constitutes the most conservative approach to the structural qualifications of the pool structure.
Resulting safety factors'for bending of pool structure regions and for pool slab shear are tabulated in Tables 8.1 and 8.2, respectively, of the attached Licensing Report.
Accident Analysis Accidents involving the spent fuel pool have been reevaluated to ensure that the proposed-spent fuel pool modification does not impact public j
L health and safety. These analyses are described in detail in Section 7.0 l
of the TMI-1 Licensing Report.
- a. Spent Fuel Assembly Drop l
E For this accident condition, the maximum effective neutron 1
l multiplication factor, k.cc, ic less than 0.95.
The radiological l
consequences of a fuel assembly drop remain bounded by the existing TMI-1 FSAR analysis.
Evaluation has shown that a dropped spent fuel j
assembly on the racks will not distort the racks such that they would not perform their safety' functio...
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- b. Spent Fuel Cask Drop The existing TMI-1 Technical Specifications preclude movement of spent fuel shipping casks near the spent fuoi pool when there is any spent fuel in storage in the spent fuel storage pecis in Unit 1.
This ensures that in the unlikely event of a load drop accident, there would be no possibility of this event resulting in any damage to the spent fuel pool structure or racks. Therefore, the proposed reracking does not affect this event.
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- c. Installation Accident With regards to wet rack installation with spent fuel in the pool, the existing TMI-1 Technical Specifications and administrative controls will preclude the' movement of a rack directly over any fuel. The existing racks'and the new' racks are considered heavy loads as defined in WUREG-0612, " Control of Heavy Loads at Nuclear Power Plants".
In lieu of providing a single failure proof crane system, the control of i
heavy load guidelines is satisfied by establishing that the potential for a heavy load drop is extremely small. An evaluation of storage rack movements which will be accomplished with the TMI-1 Fuel Handling Building crane to determine conformance with NUREG-0612, Appendix C, guidelines domonstrates that the alternative to single failure proof 4
crane design is satisfied. The Fuel. Handling Building crane has a rated capacity of,110 tons, which incorporates a design safety factor l
of five. ' The maximum. weight of any existing or replacement storage rack and its associated handling tool is less than 15 tons.
L Therefore, there is ample safety factor margin for movements of the
' storage racks by the Fuel Storage Building crane. This applies to
'non-redundant load-bea' ring components. Redundant special lifting L
devices, which.have a rated capacity sufficient to maintain sufficient.
l safety. factors, will.be utilized in the movements of~the storage racks.
As per NUREG-0612, Appendix B,.the safety margin ensures that-the probability of.-'a load drop is. extremely low.
'In addition,-a neavy load will not ce carried in the' spent fuel-pool.
area until-all fuel.in the pool has decayed for a minimum of 72 t
hours. This provides sufficient time for decay of gaseous e
radionuclides in the fuel (gap activity) such that an assumed L
accidental release ofl gases from. damage to all stored fuel assemblies L
'would'. result in a potential offsite dose less than 10% of'10 CFR 100 p
-l imits.
In addition, there is'no equipment which is essential to the
? safe shutdown of the reactor.or employed to mitigate the consequences L
of an accident that-can be damaged during the expansion modification..
L Specifically, thel new fuel' storage vault and the decontamination pit-will be equipp'ed with structural impact shields adequate to sustain l;
postulated rack drop accidents..Therefore, the consequences of a
. construction accident are not' increased from previously evaluated i
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- events.
- d. Loss of' Spent Fue1~ Pool Cooling _
The consequences.cf loss of spent fuel pool cooling have 'been
' evaluated and'are described in Section.5.0'of the TMI-1 Licensing
- Report.
If a' loss of' spent _ fuel pool cooling occurred, there'is
. sufficient' time (a minimum of 10~ hours to pool boiling) still available to: provide an alternate?means for cooling.
The potential accidents associated with the proposed reracking have been evaluated in accordance with the design bases specified in the TMI-1 Updated FSAR,.the guidance contained in NRC position paper "0T Position.for Review and Acceptance of Spent Fuel Storage and Handling Applications", applicable NRC Regulatory Guides and Standard Review Plans, and the appropriate industry codes and standards' listed in the enclosed TM1-1 Licensing Report.
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Total occupational exposure for the reracking operation is estimated to be between 5 and.10 person-rem, as described in Section 9.0 of the TMI-1 Licensing Report. Prior to the beginning of reracking, detailed operating procedures will be prepared with full consideration of ALARA principles.
i The existing storage racks will be removed, decontaminated, packaged and shipped to a licensed processing / disposal facility.. Shipping containers and procedures will conform to Federal and State DOT regulations and requirements.
IV.
NO SIGNIFICANT HAZARDS CONSIDERATIONS GPUN has determined that this Technical Specification Change Request involves no.significant hazards consideration as defined by NRC in 100FR 50.92.
- 1. Operation of'the: facility in accordance with the proposed amendment I
would not involve a significant increase in the probability of i
occurrence or the consequences of an accident previously evaluated.
'he following _previously analyzed accident scenarios have been
' considered as part of the. analyses required to support the installation of _ high density spent fuel storage rteks:
1 a.
Spent Fuel Assembly. Drop - The criticality acceptance criterion, k re < 0.95, is maintained.and the radiological _ consequences t remaiii bounded by previous analysis. Therefore, the proposed change has noteffect on this accident scenario.
b,
' Spent Fuel Cask Drop - TMI-1 Technical Specifications preclude
' movement of spent fuel _ cask:when fuel is' stored in the spent fuel storage pools. =T_herefore,-the proposed change has no~effect on this accident scenario.
c.; seismic Event - The~new racks are designed and fabricated to remain functional during'and after-a Safe Shutdown Earthqueke under all loading conditions. Analysis has demonstrated that.no rack-to-rack or_ rack-to-wall _ impacts occur..The potential ~ for.
4 overturning has;been' analyzed and; shown.to 'be not possible.
Pool' f
slabianalysis has demonstrated adequate structural integrity for -
p all. postulated loading conditions. - Therefore, the proposed
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change'has no.effect on this accident' scenario.
d.
' Loss of Spent Fuel Pool Cooling - Sufficient time is available to-l provide an alternate means of cooling in the event-of a failure 3
1 in the cooling system. Therefore, the proposed change has no j
effect on this-accident scenario.
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.Accordingly,'the proposed modification does not increase the probability of occurrence or the consequences of an accident
. previously evaluated.
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- 2. Operation of the facility in accordance with the proposed amendment would not create the possibility of a new or different kind of accident from any accident previously evaluated. Administrative controls during rack installation will preclude the movement of a new or' existing racks directly over any fuel. The new fuel storage vault 1
and the decontamination pit will be equipped with structural impact shields adequate to sustain a potential rack drop. The Fuel Sturage Building crane has sufficient safety factor to preclude potential single-failure mechanisms. Therefore, this change has no effect on the possibility of creating a new or different kind of accident from any accident previously evaluated.
- 3. Operation of the facility in accordance with the proposed amendment would;not involve a significant reduction in a margin of safety.
Analysis has demonstrated that the established criticality acceptance g
_ criterion,'k cr < 0.95 including uncertainties, is maintained with L
the racks fully Toaded with fuel of the highest anticipated L
reactivity. Thermal-hydraulic analyses demonstrate that the maximum allowable temperature for bulk boiling is not exceeded for the increase. in pool heat: load, and that the maximum local water- ~
temperature along.the hottest ft:31 assembly is below the nucleate.
boiling condition value. The inaximum calculated bulk' pool water L
temperature of 160*F results. in a negligible decrease in the time-to-boil margin of safety. The rack materials used are_ compatible with the spent fuel pool and the spent fuel assemblies. The structural considerations have maint'ained margins of safety against tilting 'and deflection or movement. Therefore, this change has no.
.effect on the margins of safety related.to nuclear criticality, thermal and structural; integrity, and material compatibility.
The proposed ~ amendment is.considere'd to be in the ame category as example (x) of! amendments that are considered not likely to involve significant hazards consideration.as provided.in.the final;NRC adoption
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of 10 CFR 50.92 published on page 7751 of.the Federal Register. Volume 51, i
No '44, March 8,,1986. :This~ example indicates that an amendment is not-4 likely to involve a 'significant hazards condition as follows:
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' Criterion (1):.
.-The storage expansion method consists.of.either. replacing existing racks ~with-a design which allows closer spacing between stored spent.
fuel assemblies or placing additional racks of the original design on the pool floor if space peuits..
Proposed Amendment:
t The TMI-1 spent-fuel pool rerack involves both replacing existing and adding new racks where space permits. The new racks allow closer spacing of the. stored spent fuel by in orporating a neutron absorber and requiring that only burned fuel be stored in Region II.
Region I is designed for allowing safe storage of kesh or irradiated fuel.
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Criterion'(2)
-l The-storage expansion method does not involve rod consolidation or double tiering.
Proposed Amendment:
The TMI-1 racks are not double tiered and all racks will sit on the spent fuel, pool floor. Additionally, the amendment application does not involve consolidation of spent fuel.
Criterion (3)
The k re of the' pool is maintained less than or equal to 0.95.
proposed Amendment The design of'the new spent fuel racks contains a neutron absorber, Boral, to allow close' storage of spent fuel assemblies while ensuring
- that the k re. remains less than 0.95 under all operating conditions I
with pure water in-the pool.
Criterion (4)
No new technology or unproven technology is utilized i., either the construction-process or the analytical techniques necessary to justify.
- the expansion, proposed Amendment q
The rack. designer, Holtec International, has licensed at :least ten l
.(10) other racks of the same design. The construction processes.and analytical techniques' remain substantially the same'as these other ten (10) rack ins:a11ations. Thus, no new or unproven technology is
-utilized'.in tie construction'or analysis of the high density TMI-1
- spent fuel ranks.
Thus, the submittal meets example'(X)' presented in the supplementary information accompanying publication of the Final Rule and is considered
, as not. involving significant hazards considerations.
- V.
IMPLEMENTATION l
It is. requested that the amendment authorizing this cha'ngeLb'e issued'_to.
? support installation of the new storage racks during Cycle 9 operation which is scheduled-to begin December 1991. The amendment should become effective upon completion of the initial rerack installation.
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