ML20211P198
| ML20211P198 | |
| Person / Time | |
|---|---|
| Issue date: | 07/18/1986 |
| From: | Rouse L NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Goldmann K TRANSNUCLEAR, INC. |
| References | |
| REF-PROJ-M-42 NUDOCS 8607230034 | |
| Download: ML20211P198 (32) | |
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DISTRIBUTION:
Project No 4 42J PDR NMSS r/f FCAF r/f JRoberts
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Project No. M-42 i
Transnuclear, Inc.
ATTN: Dr. Kurt Goldmann Chief Engineer One North Broadway White Plains, NY 10601
Dear Dr. Goldmann:
This is in response to your letter of August 30, 1985, submitting for NRC staff review your TN-24 Dry Storage Cask Topical Report. As you are aware, our staff review has necessarily been delayed because of licensing activities which have precedence over topical report reviews.
I thank you for your patience in this matter.
Our specific comments are enclosed in two enclosures. The first enclosure contains comments concerning matters related to our safety review of the TN-24 cask design for an independent spent fuel storage installation to be located at a power reactor site. The second enclosure concerns comments related to your quality assurance program.
You may, if you wish, proceed to resolve these latter questions independently of the remainder of the review.
If you have any questions concerning our comments, the NRC staff contact is Mr. John P. Roberts (telephone number (301) 427-4205) of my branch.
Sincerely, Orisinal as me Islanec.asas.tby e
Leland C. Rouse, Chief Advanced Fuel and Spent Fuel Licensing Branch Division of Fuel Cycle and Material Safety
Enclosures:
1.
Coments 2.
Request for Additional Information-QA
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- FCA NAME:
s/jl:LCRouse :
BATE. hh h bb bhhfh bb OFFICIAL RECORD COPY 8607230034 860718 PDR PROJ i
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i Transnuclear TN-24 Dry Storage Cask Comments i
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1 Introduc' tion and General Description 1.1 Introduction' 1.1. 2 Principal Design Features of Installation The poor quality of the drawings makes it difficult to understand the principal design features.
It would be helpful if the reviewer could refer to full-sized drawings of the components important.to safety.
1.2 General Description of Installation 1.2.2 Principal Design Criteria (a) Why was Subsection NC, Article NC-3200 of Section III of the ASME Boiler and Pressure Vessel Code, chosen as a design criteria'rather than Subsection NB?
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(b) Nitrogen has been selected as the primary fill gas for the cavity.
Nitrogen in the presence of water vapor and radiation field over long
' periods of time may produce nitric acid and subsequent corrosion.
How do you assure that essentially all water is removed from the cask cavity?
Alternatively, you may wish to discuss the significance of the expected consequences of the presence of water.
1.2.5 Structural Features (a) The reference drawings provided in Appendix 1A (9718-4, 9718-5, 9718-6, 9718-10, and 9718-11) do not provide enough dimensional detail.
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(b) A list of past numbers and materials is provided in Table 1.2-3.
- However, the material for the basket plates is not given.
While reference is made to Dwg. 9718-11 for the material..is there any reason it should not be identified in the table?
(c) The-cavity surfaces and the outer shell have a sprayed metallic coating for corrosion protection. What are the metallic coating (s)? Briefly describe the coating process.
(d) How are the poison rods installed into the fuel ~ assembly and held in place during handling operations, storage conditions and accident. conditions?
Provide a drawing of the poison rod assembly.
(e)
Is the copper on the fuel basket a cladding or coating? How is the copper applied? What process is used? Provide assurance that the copper remains in place on the stainless steel at.high temperatures (2 600 F) and for periods of time up to 20 years.
(f) What thickness of copper is used? The drawing 1A-9 shows one set of values, the criticality analysis (Table 3.3-1) uses another set and the
- thermal analysis a third set (5.1.3.6) in conflict with Figure 5.1-7.
Validate the assumption that'the copper coating or cladding will conduct heat at 222.45 BTU /hr-ft *F over the temperature ranges associated with normal and accident conditions.
1.3 General Systems Description The statement is made that the cask is a passive system requiring only minimal monitoring or maintenance on the part of the license applicant.
Be more spec-ific with regard to what minimal monitoring and maintenance activities will be required during the twenty year design lifetime of the storage cask.
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2 Site Characteristics i
2.1 Geography and Demography of Site Selected It is stated that "the minimum dose rates specified in.10 CFR Part 72 can be met with a cask-to-boundary distance 'well below 328 ft."
How many casks are reflected in this statement? ' From-Table 7.3-3 (TN-24 Dose Rates at Lohg Distances) it would appear that the number of casks is less than.or equal to 21.
2.3 Meterology (a) The sub. ject of tornado wind loads is addressed.
However, tornado missile loading in accord with NUREG-0800 Section 3.5.1.4 should also be addressed.
3 Principal Design Criteria 3.1 Purposes of Installation 3.1.1 Materials to be Stored (a) What are the irradiation conditions associated with the ORIGIN calcula-tions? Demonstrate that the 3.2% enrichment is more conservative than the 3.7% enrichment for definition of the radiological characteristics of the spent fuel.
Demonstrate that the 15 x 15 assembly is conservative for the analysis.
(b) With respect to the comments regarding "various combinations of burnup, specific power, enrichment, and cooling time" that appear in this section and Table 3.1-2 (Thermal, Gamma and Neutron Sources for the Design Basis 17 x 17 PWR Fuel Assembly), it is important that the spectral conditions be the same or the distribution be shifted to lower energies. The gamma and neutron sources are energy dependent and, consequently, affect the shielding analysis.
In addition, the analysis is isotope dependent so that isotope content must also be considered in the safety evaluation.
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(c) Why is no spectral information provided for the gamma and neutron sources?
It should be included or referenced to the information in Section 7.2.1 (Characterization of Sources).
.(d) Why is there no mention of the fission product gas inventory in this section? It.should be included or referenced to the information in
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Section 7.2.2'(Airborne Radioactive Material Sources)..
(e) What are the activation product activities associated with the materials in the. head and. foot pieces,and structural materials? Why are they not addressed here? Spectral and source information should be provided for these regions as well.
A reference to the information in Section 7.2.1 (Characterization of Sources) would be appropriate.
(f) The criticality design for the 17 x 17 assembly depends on the use of poison rods and the results do not directly apply to 14 x 14 and 15 x 15 fuel assemblies.
If 14 x 14 and 15 x 15 assemblies are to be included supporting criticality analyses must be provided showing the number, size, and location of the poison rods.
3.2 Structural and Mechanical Safety Criteria 3.2.1 Tornado and Wind Loadings (a) The statement is made that an ISFSI need not be protected from tornado
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. missiles.
Paragraph 72.72 of 10 CFR 72 is cited as a reference.
This provision is rewritten in an amendment to 10 CFR Part 72 proposed in the j
Federal Register (51 FRN 19106, May 27, 1986).
See Section 72.92(b)(2).
Accordingly, we request an analysis of the effect of the tornado missiles specified in NUREG-0808 Section 3.5.1.4, " Missiles Generated by Natural Phenomena".
(b) Provide a reference and/or equations that support the use of a drag l
coefficient of 1 in the tornado loads analysis.
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(c) It is not clear how the calculated 332 psf due to a tornado wind load is converted to a linear load of 204 lb/in.
3.2.1,2a Stability o'f the Cask in the Vertical Position Support the st.atement that the friction coefficient for the cask in the upright position is 0.25.
Provide a sketch' showing dimensions used for the tip analysis.
Describe how the tipping wind velocity of 409 mph was calculated.
3.2.1.2b Stability of the Cask in the Horizontal Position Reference is made to Figure 3.2-14.
Probably Figure 3.2-lb is meant.
Provide more detail in this sketch especially with regard to the dimensions of the saddle.
Another view of the saddle would be helpful.
3.2.2 Water Level (Floods, Hurricanes, Tsunami and Seiches ) Design (a) The storage cask is designed for an external pressure of 25 psi.
There does not appear to be an analysis of cask response to external pressure.
(b) There does not appear to be an analysis in Section 3.2.1.2 regarding the required drag force to. move the cask. 'In any case, the force required for,
the cask to slide under water is not the same as the force causing it to slide on dry ground.
(c) There is no discussion of dose levels in Section 3.3.2.2 (Analysis of Cask Pressures and Leakage Rates) referred to in 3.2.2.
l 3.2.3 Seismic (Earthquake) Design 3.2.3.1 Seismic-System Analysis In 10 CFR 72.66 reference is made to a standardized acceleration of.25 g's used east of the Rockies in known nonseismic regions.
This acceleration is applied in each of two orthogonal horizontal directions.
(See NUREG-800, Section 3.7.1.)
Thus, the combined horizontal acceleration is J2(.25)2 =.35 g's.
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A tipping analysis based upon the dimensions on page 1A-4 (Base diam = 56.25",
height = 184") and the weight given in Figure 3.2-10 (196,600 lbs.) for a vertical storage position shows the following:
79p = (G)(196,600)(92) + (2/3)(G)(196,600)(28.13)
M where G = the combined hor.izontal acceleration stabilizing = (196,600)(28.13)
M The cask may start to tip if M
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Therefore, the staff assumes that the cash will tip in.all earthquakes with a base acceleration greater than.18 g's in each of two orthogonal horizontal directions.
3.2.5 Dead Weight Loads List actual cask weights, loaded and unloaded.
3.2.6 Handling Loads (a) A design lift load is given in this section as 3 g's, based on ANSI 14.6.
Actually, the requirements of ANSI 14.6, Sections 3.2 and 6.2 are that the lift loads must be less than 1/3 yield and 1/5 ultimate, for a redundant lifting system.
For a nonredundant lifting system the allow-ables are reduced by half.
(b) The figures for this section, Figures 3.2-2 through 3.2-6, and Table 3.2-4 all include references to "g loads" on various cask components.
It is not clear what this means.
For example, does 1.5 g to each trunnion mean that these trunnions are each designed for 1.5 times the total weight of the cask plus contents? Or does it mean that each trunnion is designed for 1.5 times the weight it is expected to carry under normal operating conditions?
It would be more precise to list the load specifically in lbs, rather than in "g's".
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(c) Is there a figure which shows the location of all six trunnions? Is each trunnion attached to the cask body with twelve 1-1/2-inch bolts? Under what conditions will each trunnion.be used?
3.2.7 Internal Pressure Nitrogen is not an inert gas.
3.2.9 Bolt Loads A summary of bolt loads due to various loading conditions is given in Table 3.2-6.
Where are the calculations for these loads?
3.2.10 Thermal Loads Ambient Variation Provide a thermal analysis for various weather conditions that might cause thermal cycling and fatigue of the cask, e.g., heavy cold rain on the cask following several hot days in the sun.
3.2.11 Cask-Drops (a) Two postulated accidents are presented and discussed.
A figure would be helpful in defining dimensions, drop heights, etc.
For example, in the first accident cited, if the support is eight feet off of the ground, and the cask is lifted two feet off the support, then a ten-foot drop is appropriate, not eight feet.
(b) In the second postulated accident, how is the angle selected to maximize the " slap down" effect?
i (c) More detati needs to be given about the dynamic analysis using (A00C).
What does the model look like? How is the cask-target interface handled?
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3.2.11.1 Crushing Strength of Targets A preliminary review of the concrete slab strength calculation reveals the following:
For an end on drop from anx height, the results in this section imply that the cask will see a maximum of 4.3 g's due to a drop onto the 10-inch reinferced concrete slab:
's = Weight,(Area)(Pressure),(28.13)2n340 = 4.3 F
Weight 196,000 and 11 g's due to'an end on drop from any height onto the 24-inch reinforced concrete slab.
This implies that the force due to impact on the slab is uniform regardless of drop beight.
This needs to be justified.
Even for a low velocity (low drop height) impact, the g loads presented appear to be incredibly low.
l 3.2.11.2 Analysis of Cask Impact (a) Please discuss how the code ADOC, developed to analyze impact limiter crushing due to impact, can be used for analysis of cask impact without impact limiters.
(b) The statement is made "it is clear that the target material has a perfectly plastic stress-st' rain curve."'
It is the opinion of the staff that this is not at all clear.
(c) A figure would be helpful in this section.
Does the statement, "The contact area is divided into segments," refer to the cask or the target?
If the target is meant, explain a following statement:
"the orientation of these segments varies to remain normal to the target surface."
(d) This section also discusses the comparison of experimental drop rcsults with results of analysis with ADOC.
Provide more detail regarding this comparison.
What were the dimensions, weight, velocity, material, and orientation of the dropped cask? Show how the cask was modeled for ADOC.
How were the g loads determined? What does the maximum deformation refer to specifically?
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3.2.11.3 Results of Analysis
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(a) What is the missing number in the first sentence on page 3.2-29?
(b) This section refers to 600 psi and 800 psi crushing targets.
However, the table.in Section 3.2.11.1 lists 690 and 830 psi' targets along with lower values. The numbers should be reconciled.
(c) The analysis in this section _ indicates that.the concrete slab will deform uniformly 5 inches underneath the impacting cask during impact with an 800 psi target. Where will this material go? The results from Section 3.2.11.1 are based, in part, on assumptions concerning the soil bearing pressure.
Eearing pressures of soils are used by geotechnical engineers to determine the pressure that soils or rock can support without a bearing-capacity failure.
Design allowable soil pressures are conservative for preventing bearing failures but are not conservative for evaluating forces due to
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deceleration.
These values do not imply that if these pressures are exceeded the soil will fail.
The soil may tilt slightly or nothing may happen.
Failures which do occur are generally slow, time-dependent phenomena.
Furthermore, the concrete slab on top of the soil distributes the 1oad and decreases the likelihood of soil failure.
The slab also serves to contain the soil such that soil upheaval is. preven'ted It is
- very unlikely that the impact force due to a cask without limiter falling onto a concrete slab will remain constant throughout the impact.
(d) How is dynamic load amplification taken into account?
3.2.12 Cask Tipping i
A.
Tipping About Trunnions (a) Figure 3.2-10 does not indicate how this tipping accident would occur.
Under what circumstances would the lower two trunnions, only, be held by the cable? A sketch of the situation should be provided.
Are the lower trunnions resting on a saddle?
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(b) The 800 psi crush strength is used for a reinforced concrete pad just under 24 inches thick.
The analysis in this section is based upon a cask tip whereby the C.G. loses 9.2 ft in height.
It appears incredible that the cask could completely penetrate the 2 ft slab and see only 25 g's.'
3.2.13 Combined Loading Criteria for Containment Vessel 3.2.13.1 Containment Vessel (a) The statement, "the Magnitude of the Primary Service Loads envelops the maximum level A, B, and C Service Loads," does not appear to'be correct.
According to Table 3.2-9, Primary Service Loads indicates a partial fission gas release.
How can this envelope Level B service loads which specify 100% fission gas release?
(b) With respect to the primary service loads presented in Table 3.2-9, why is partial fission gas release used for the internal pressure while 100%
fission gas release is used for the bolt loads?
3.2.13.2 Basket (a) The handling loads listed'in Table 3.2.'4 are insufficien't.
We would prefer a listing of the actual loads in 1bs and their points of application.
(b) Where are the basket thermal and structural analyses?
l (c) The stress intensity limit for manual handling loads should be something less than yield strength, to accommodate a margin of safety against permanent deformation.
ASME rules, particularly subsection NG, for determining stress intensity limits may be used.
Stress intensity limits for thermal loads may be limited to two times yield strangth provided (1) yield stress rather than ultimate tensile strength is the basis for the stress intensity limit and (2) the borated stainless steel from which the basket is made is well characterized especially with regard to its ductility 10
and toughness.
The ability of this material to withstand local plastic strains without cracking must be convincingly demonstrated as should the assumption of a plastic hinge as an appropriate limit load.
3.2.13.3 Trunnions The specified allowables are correct only if the lifting system is redundant.
Again, provide the actual forces implied by the g loads.
3.2.13.4 Outer Shell What is the basis for establishing the maximum internal pressure for the outer shell to be 25 psi (1.7 atm).
3.3~ Safety Protection Systems 3.3.1 General The following statement is made, "A double barrier system for all potential lid leak paths consisting of multiple covers and seals is utilized".
The drawing 9718-3 on page 1A-4 shows a single lid plus a protective cover.
Is it the intent that the protective cover qualify as the.seconcf barrier?
3.3.2 Protection by Multiple Confinement Barriers and Systems 3.3.2.1 Confinement Barriers and Systems (a) What is " unacceptable leakage" and how is its detection indicated? What is the " containment" cover and where is it described? What would be the total leak rate for a lid and containment cover system?
(b) Are the Helicoflex lid seals bore seals or face seals? Is there a figure r
which shows their location?
(c) Are stainless steel seal sealing areas preferred over nickel? What are I
the properties of stainless that improve the surface control of the seal sealing areas?
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(d) This section indicates that the seal is permanently maintained due to the outward force exerted by the helically-wound spring.
Is there.any likeli-hood of creep in the spring so that the outward sealing force would not be maintained? How will the seals be affected by long term exposure to temperatures over 100 C?
(e) What is the difference between a single metallic seal and a double metallic seal? The figure showing the seals,-Figure 3.3-1, is hard to. read. Where are the three double metallic seals? This sketch needs to be improved.
3.3.2.2 Analysis of Cask Pressures and Leakage Rates Provide sufficient information on all seals, valves, etc. used for containment to demonstrate that they are properly manuf'actured and qualified for their intended use.
3.3.3 Protection by Equipment and Instrumentation 3.3.3.2 Instrumentation In Section 5.1.1 (General Description), it is stated that, " seal interspace pressure wil.1 be continuously monitored." 'Why 1,s there no mention.of such continuous monitoring in Chapter 3?
3.3.4 Nuclear Criticality Safety 3.3.4.1 Control Methods for Prevention of Criticality (a) Criticality results for the 17 x 17 assembly cannot be directly applied to the 14 x 14 and 15 x 15 assemblies.
See 3.1.1 comments.
(b) How is it assured that the poison rods have been properly installed into all fuel bundles and provide their safety function? What is K,ff if the l
poison rods are inadvertently left out?
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3.3.5 Radiological Protection 3.3.5.2 Shielding (a) Is the design surface dose rate 60 mr/hr or 60 mrem /hr? Why are the referenced guidelines of 10 CFR Par't 20 and 10 CFR Part 72 not explicitly cited?
(b) With respect to the dose rate in Table 3.3-5 (Occupat.?nal Exposures for Cask Loading, Transport, and Emplacement), what cask surface (s) is considered and what is the effective distance between the individual and the surface in question? Reference to the. distance information in Table 5.1-2 (Anticipated Time and Personnel Requirements for Cask Handling Operations) is certainly appropriate here.
How were the dose rates at effective distances other than contact and 2 m (6.56 ft) determined? How were the times required to perform the various functions determined and are they conservative? A summary of the dose to an individual would also be of interest in Table 3.3-5.
(c) Why doesn't Table 3.3-5 list dose rates for any maintenance-type operations?
3.3.7 Material Handling and Storage 3.3.7.1 Spent Fuel Handling and Storage (a) Please provide a temperature vs time curve for the hottest fuel rod cladding for the twenty year storage lifetime, along with a basis for determining this curve.
(b) It is stated that surface temperatures will be measured for each cask after fuel loading until equilibrium conditions are achieved.
What is the purpose of this measurement, and how will it be used?
(c) Provide the appropriate structural analysis to support the statement:
"The poison rods within each fuel assembly will remain in place..."
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analysis should include both impact and thermal loads.
Also, thermal creep should be considered as a failure mechanism for the poison rods because they are fab'ricated with aluminum tubing and are exposed to temperatures in excess of 600 F.
- 3. 4 Classification of Structures, Components, and Systems (a) Ta'ble 3.4.1 lists components that are important to safety, and those that,
are not important to safety.
In 10 CFR 72, paragraph 72.3(w) "important to safety" is defined.
The criteria include (1) maintaining the condi-tions required to store spent fuel safely, and (2) preventing damage to the fuel during. handling and storage.
Explain why the trunnions, trunnion bolts, and protective cover are not considered important to safety.
(b) The neutron shield should be included among the components important to safety since the neutron shield serves to reduce neutron radiation and provide a fire barrier.
Furthermore, the neutron shield may become damaged under accident conditions yet must provide a reasonable heat path for the decay heat of fuel.
3.5 Decommissioning Considerations (a)
It is unclear how the equation for the neutron flux at the cavity wall was derived.
How was the volumetric source strength determined? How was the effective source radius determined? Why is 71.75 cm used for the cavity radius instead of 72.71 cm?
(b) What are the other trace elements in the low alloy carbon steel? Is Co present?
(c) To justify the statement, "the cask can be considered low level waste (after decontamination)," requires a discussion relative to 10 CFR Part 61 (Class A, B or C).
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4 Installation Design 4.2 Storage Structures 4.2.1 Structural Specifications 4.2.1.1 Containment Vessel (a) Table 4.2-1 (Design Bases for Containment Vessel) shows the internal atmosphere as " nitrogen with trace helium'." Figure ~3.3-1 (Seal and Pressure Monitoring Protection System) shows 90% nitrogen and 10% helium.
Which is correct since 10% helium qualifies as more than a trace?
(b). The Level D. stress allowables listed on Table 4.2-2a should read 2.45, and 0.75 ; 3.65, and S, etc.
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(c) How were the seismic loads listed in Table 4.2-3 determined? How were the attachment loads determined?
4.2.1.2 Basket
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Rema.rks concerning the basket design bases contained in SectIion 3.'.13.2 appif 2
here.
In addition, Table 4.2-10 should 'be revised to reflect more conservative values of allowable stress.
4.2.1.3 Trunnions (a) Does the sentence "The bolt material conforms to ASME material specifica-tion SA-320, Gr. L43" mean that the bolts are actually made of SA-320 Gr.
L43 material?
(b) See the comments on trunnion allowables in Section 3.2.6.
It must be shown that the lifting system is redundant in order to use the allowable stresses listed in Section 4.2.1.3 and 3.2.6.
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v (c) In Table 4.2-11 the allowable stress for Sg loading should be 135,000 psi.
4.5 Shipping Cask Repair and Maintenance (a) What is the frequency.of the calibration of the leak detection instru-mentation?
(b) What is involved in the installation'and seal we'iding of the containment cov'er?
4.6 Cathodic Protection It is stated in this section that the cask, interior and exterior surfaces will be given surface protection by a metallic flame-sprayed coating..However, in Section 4.2.1.1, Taole 4.2.1, the surface protection is indicated to be either Metallic Coating or Painting. Which is.it?
Appendix 4A Structural Analyses of TN-24 Storage Cask 4.A Structural Analysis of the Containment Vessel 4 A. 5.1. 2 Method of Analysis Please discuss the assumptions applied in using Bijlaard's method.
4A.5.1.5 Applied Loads It is not clear how the loads are applied.
Provide a free body diagram of the cask and trunnions, and the applied loads.
4A.5.2 Stress Analysis of Junction of Cask Body Cylindrical Shell with the Bottom Closure Plate 4A.5.2.3 Model, Boundary Conditions and Assumptions (a) It is not clear whether the correction factor discussed in this section accounts for the 45 chamfer at the junction of the cylinder and plate, or 16
the reduction in thickness, or both.
This should be clarified.
Further-more, what is the value of this factor, and how was it determined?
(b) Define the terms used in the formula given in this section. What is the purpose of the formula?.Is there d reference for it?.
4 A'. 5. 2. 4 Analysis (a) Provide references, list assumptions, and define the erms in all formulas used.
(b) In Section B the statement is made that inertia forces which occur during handling result in a statically-applied load to the bottom closure plate.
This appears to be a contradiction in terms.
If these loads will be analyzed statically, an assumption must be made.
(c) The assumption is made that the handling loads are uniformly distributed on the bottom plate.
This needs further clarification. What is the actual loading pattern?
(d) In Section C it is stated that detailed temperature distribution calcula-tions are discussed in Section 3.2.10.
However; th'ere are no details of calculations or, for that matter, any discussion of calculations in that section.
Section 3.2.10 merely refers the reader to Section 5.1.3.6 where thermal calculations are discussed.
4A.5.3 Stress Analysis of the Lid and the Junction of the Lid with the Cask Body Cylindrical Shell 4A.5.4 Stress Analysis of Cask Cylindrical Shell C.
Loads Imposed by the Trunnions The applied loads listed in Table 4A.5-3 do not provide sufficient information.
Please provide free body diagrams illustrating the direction and point of 17
i application of these loads and the boundary constraints.
Where is the analysis for these loads?
L.
Distributed Loads
.How is the bending moment calculated?
4A.5.5 Containment Vessel Stresses Due to Cask Drop Accidents 4A.5.5.2 Method Comments regarding the analysis in Section 3.2.11 apply here as well.
As stated in our review of that section, the calculated g loads are not acceptable unless it can be shown that it is realistic to assume that the force due to impact on the slab is not only uniform regardless of drop height, but is also constant throughout the impact interval.
The discussion in this section regarding dynamic amplification is based on the results of Section 3.2.11, and is not convincing.
4A.5.6 C6ntainment Vessel Stresses Due to Cask Tipping Accidents 4A.5.6.3 Stresses Caused by Tipping Accident A.
Rotation About the Trunnions as a Pivot (a) Describe more completely how this accident would occur.
Show the whole length of the cask in Figure 4A.5-19, not just the section between the trunnions.
Why are the loads shown acting on the casks free surface? Are R and R the only loads on the cask?
L R
(b) How was the peak deceleration of 0.159 g/ inch calculated? What do these units mean?
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B.
Tipping of the Case About the Base How is the angular deceleration of 0.156 g/ inch calculated?
4A.-6 Structural Analysis of the Basket 4A.6.4.4 Material Properties What is Ref. lA?
B.
Inelastic Analysis (a) What is the basis for assuming that the plastic hardening modulus is 0.05 times the elastic modulus?
(b) The material properties of 1.3% borated stainless steel are not the same as 304 stainless steel without boron.
The ASME code does not list the material properties as 1.3% borated stainless steel.
Consequently, the reference to the code is not correct.
Furthermore, the assumption that the elevated temperature properties of 1.3% borat.d stainless steel can be obtained by. extrapolating stainless st, eel properties is not obvious.
10 CFR Part 72 Section 72.72(a) requires quality standards commensurate with importance to safety be used.
The TSAR lists the basket as a component important to safety.
Consequently, the material used for this component should be manufactured, fabricated, and tested in accordance with an authoritative specification.
No such specification has been invoked so that the reviewer is at a loss to find a basis for acceptable stress intensity limits.
In the absence of an authoritative specification for the borated stainless steel the applicant should provide sufficient information to characterize the material with regard to its ability to resist, with an acceptable margin of safety, all the design basis loads.
This would include, at the very least, the basis for stress intensity limits under normal and accident conditions, evidence of sufficient ductility to avoid fracture at localized strain concen-trations, evidence of sufficient notch toughness where the design requires the 19
use of notches and evidence of acceptable fracture toughness under dynamic loading conditions.
The lack of an authoritative specification also raises questions of how the uniformity,of the material is assured. This~is usually indicated by the-acceptance tests spelled out in the specification.
In the' absence of an authoritative' specification it is suggested that a specification in ASTM format, as recommended by ASME code procedures for new materials, be provided in the topical report.
4A.6.5 Loading Calculations The fuel assemblies are assumed to distribute their weight uniformly over the bas.ket compartment wells.
Yet, in the following paragraph care is taken to locate the spacers and end fittings away from the joints.
It would seem that the loads on the plates are expected to be applied discretely rather than uniformly.
How does this affect the stresses in the basket structure especially near the points where the loads are actually applied? Is the assumption of uniform load conservative?
4A.6.6.2 Flange Analysis Justify the use of a plasticity / elasticity modulus ratio of 0.5.
Providing a stress / strain diagram for the borated stainless steel would help.
4A.7 Structural Analysis of the Trunnions See comments in Section 3.2.6 about the Trunnion requirements per ANSI 14.6.
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Operation Systems 5.1 Operation Description 5.1.1. General Description-(a) It is' stated that "the cask is then decontaminated to the levels specified in Sec' tion 3.3.7.1," yet'there are no decontamination levels'specified in
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the referenced section.
(b) When the cask cavity is evacuated and dried what are the maximum tempera-tures of the fuel rods.
How are the fuel rod temperatures and evacuation times controlled?
5.1.2 Flow Sheets (a) With respect to Table 5.1-1 (Sequence of Operations), what are the
" weather shields" and the " neutron shield vent holes" identified in Item 1 of " Cask Loading Pool" and Item 2 of " Decontamination Area"? Comments made in Section 5.1.1 (General Description) with respect to decontamina '
tion levels apply to Item 1 of "Decon,tamination Area" as well.
(b) The " top neutron shield drum" identified in Item 22 of " Decontamination Area" needs to be described somewhere in the TSAR.
(c) With respect to the times and average distances in Table 5.1-2, how were they determined and are they conservative?
5.1.3 Identification of Subjects for Safety Analysis 5.1. 3.1 Criticality Prevention All criticality control features are required to be in place at all times to assure the capability to unload the cask in the reactor pool.
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5.1.3.6 Heat Transfer Design One-Dimensional Model The heat transfer model of the aluminum'for.the neutron shield in Figure 5.1-2 is no't consistent with Drawing 1A-5.
The heat conduction path is shorter and th'e cont.act length longer at the stainless steel interface.
Justify the
' differences or show them to have no affect on the calculation for maximum temperatures.
Three-Dimensional Model (a) The. thermal analysis was performed for the nominal clearance between the plate intersection.
What is the tolerance that governs the clearance?
What are the temperature results when the maximum clearances are used?
(b) What clearances were used between the basket and cask wall for the thermal analysis? What range of clearance is permitted? Can the basket contact the cask wall?
(c) The fuel rod tenperatures were calculated using ORNL-3648.
Describe briefly the modeling assumptions. Was uniform radi'osity assumed? Were shadowing effects considered? Was the computer code benchmarked against tests? If so, briefly describe the test and the correlation with the analytical model.
Temperature Distribution in the Cask Body and Outer Shell Was a computer code written based on the information in Reference 8?
If so, describe the code. What kind of mesh was generated for this analysis?
Fire Analysis (a) What effect does the fire have on the cask closure and valve seals? Are the seals qualified for high temperatures?
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(b) What happens to the aluminum box and the neutron shield at temperatures above 1100 F.
Will the heat transfer path provided by the aluminum box be degraded following the fire?
5.2 Fuel Handling Systems (a)~ Spent fuel storage operations to include placement, storage surveillance, and removal should be summarized.
Reference to and use of information in.
Section 5.1.1-(General Description) and Section 5.1.2 (Flow Sheets) is appropriate her.e.
(b) Any features of the spent fuel storage system which are important to safety that provide for safe operation under both normal and off-normal conditions should also be summarized.
So too, should any limits that are selected to a commitment to action.
5.3 Other Operating Systems The response in the TSAR to the component / equipment spares requirement is incomplete. The need to " describe in detail design features that include installation of spare or alternative equipment to provide continuity of safety i
under normal and' abnormal' conditions" is not" met.
Furthermore, as already indicated, a desc'ription of the " containment cover" should appear somewhere in the TSAR.
Reliability of the pressure monitoring system is also of interest here.
Design provisions to minimize exposure to radiation during repair operations should also be addressed.
5.4 Operation Support Systems Some discussion of the instrumentation associated with the pressure monitoring system is needed here.
Monitoring during normal and off-normal ope-ations and accident conditions and/or redundancy of safety features are to be addressed.
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7 Radiation Protection 7.1 Ensuring that Occupational Radiation _ Exposures are as Low as is
' Reasonably Achievable (ALARA) 7.2 Radiation Sources 7.2.1 Characterization of Sources (a) As indicated in Section 3.1.1 (Materials to be Stored), what are the irradiation conditions associated with the ORIGIN calculations?
(b) With respect to the activation of the structural materials, where is the source term located? Are the head piece and foot piece regions being referenced here or is it only the region along the active fuel length? If it does not include the head piece and foot piece regions, why were they not included and why were they not addressed as separate source regions in the calculations?
If the head piece and foot piece regions are being referenced here, why include the source strength with the fission product gamma distribution in Table 7.2-6 (Primary Gamma fource Distribution)?
Co production in the structural
.(c) With respect to the calculation of,the 60 materials, the irradiation time does not appear consistent with the l
irradiation time required for the specified burnup (35,000 mwd /MTU).
Furthermore, the volume used for the structural material is not specified, nor can the macroscopic cross section be verified.
(d) What is the reference for the flux-to-dose conversion factors? Are they based upon ANSI /ANS-6.1.1?
(e) What are the units for the fission spectrum in Table 7.2-5 (BUGLE Neutron Energy Groups)? Where is the primary neutron source spectrum?
(f) It is requested that "the sources of radiation...be described in the manner l
needed as input to the shielding design calculations." Both in this 24
section and Section 3.1.1 (Materials to be Stored), the information presented is inadequate.
7.2.2 Airborne Radioactive Material Sources (a) What are the references for the various release fractions?
7.3 Radiation Protection Design Features 7.3.1 Installation Design Features Specific activity, physical and chemical characteristics, and expected concen-trations of all sources in Section 7.2 are to be provided.
Other information needed is the design radiation dose rate for the storage area and maintenance and repair' activity, and estimates of the quantity of radioactive materials that might be discharged during storage.
Reference to specific sections of the TSAR where this information may be found would be acceptable.
Indicate how the guidance in Regulatory Guide 8.8 will be followed.
7.3.2 Shielding 7.3~.2.1 Shielding Design Features.
(a) Figure 7.3-2 shows the nominal distance from a cask to the controlled area boundary as 250 ft; 10 CFR Part 72.68 requires that the mimimum distance be 100 m (328 ft). Why was a shorter distance used?
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(b) Provide the atom densities'of the various elements that comprise the cask shield materials presented in Table 7.3-1 (TN-24 Cask Shield Matarials).
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7.3.2.2 Shielding Analysis (a) Why was the fuel region not homogenized to the cylindrical cavity cross-sectional area instead of the cylindrical cross-sectional equivalent of 24 actual assemblies? Wouldn't this approach be more conservative?
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(b) Twenty-four 8.426 square fuel assemblies leads to an equivalent radius of 59.15 cm not 61.08 cm as presented in Figure 7.3-3 (Radial ANISN Model of the TN-24 Cask). Why is there a difference?
(c) Use of the source described in Section 7.2.1 (Characterization of Sources) for the computation of the dose on the side of the cask impl'ies t' hat the Co produced in the structural material.was uniformly distributed along 60 the active fuel length.
Is this actually so?
(d) Figure 7.3-4 (Axial ANSIN Model for the TN-24 Cask) shows regions labeled
" steel hardware" which we assume are representative of the head piece and foot piece regions.
How were the material thicknesses of these regions determined? Furthermore, why are the, material properties of these regions not included in Table 7.3-1 (Tn-24 Cask Shield Materials)?
(e) In the discussion of the axial dose calculations, it is stated that, "a Co source was included in the end fittings." Where are the calculations 60 of the Co source? What was the total source strength in each "end 60 fittings" region?
i (f) In computing the scattered radiation dose for an array of 100 casks, (Page 7.3-5'of the TSAR'), is the point source result based upon an' average single cask multiplied by 80 or are the results based upon the sum of 80 point sources at varying distances? Furthermore, are energy dependence and attenuation neglected and only geometry considered?
(g) Neither the text nor Table 7.3-2 (TN-24 Dose Rates) present results for the cask bottom when the polyethylene disk is in place.
If horizontal storage is an option, then the dose at the cask bottom with the poly-ethylene disk in place should be addressed.
(h) The statement, " Table 7.3-3 also shows that doses at the nominal control-led area-boundary are well within the 25 mrem /yr requirement of 10 CFR 72.67," is incorrect.
Figure 7.3-2 (Nominal ISFSI Layout) shows the nominal distance to the controlled area boundary as 250 ft.
At this 26 L
distance, the dose rate computed for a single cask from Table 7.3-3 (TN-24 Dose Rates at Long Distances) is 114 mrem /yr.
7.4 Estimated Onsite Collective Dose Assessment (a) is'it correct to assume that the doses presented in Table 7.4-1 (Mainte-
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nan.ce and Repair 0perations Annual Exposure) are for a single cask? On what distances are the dose rates of Table 7.4-1 based and.how are the dose rates at those distances calculated?
(b) Where are the estimated dose rates for the replacement of other seals and transducers? Both are listed as subject to procedures contained in Section 7.1.3 (Operational Considerations).
8.
Accident Analysis 8.1 Off-Normal Operations 8.1.1 Event 8.1.1.4 Corrective Action Once again mention is made of the " containment cover" yet no description of this component is provided in the TSAR.
8.1.2 Radiological Impact from Off-Normal Operations Is there any circumstance where replacing the protective cover might involve inhalation of radioactive effluents? If so, then inhalation dose should be addressed.
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8.2 Accidents 8.2.4 Explosion Nearby 8.2.4.2 Accident Analysis Is there a.ny circumstances wh'ere a nearby explosion will dam, age the neutron shielding? If so, the radiological consequences should be addressed.
8.2.5 Fire 8.2.5.2 Accident Analysis (a) Could there be a pressure buildup in the cavity with subsequent leakage of fission product gases?
If this is possible, then the radiological consequences should be addressed.
(b) The claim that charring of the resin material will not lead to a "signifi-cant increase in dose rate" should be substantiated.
8.2.7 Cask Tipping 8.2.7.2 Accident Analysis What is meant by the statement, "the containment would not be breached"? Will the cask always remain sealed against the release of any fission product gases?
If not, then the radiological consequences should be addressed.
8.2.8 Burial or Insulated Cask 8.2.8.2 Accident Analysis Here too, could there be a pressure buildup in the cavity with subsequent leakage of fission product gases? If this is possible, then the radiological consequences should be addressed.
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10 Operating Controls and Limits 10.1 Proposed Operating Controls and Limits 10.1.1 Contents of Operating Controls and Limits (a) With respect to Table'10.1-1 (Operating Limits Summary), how'was the cask tightness limit'of 5 x 10-7 atm/cc-sec determined? The leakage rate from Section 3.3.2.2 (Analysis of Cask Pressures and Leakage Rates) is given.as 6.5 x 10-7 atm/cc-sec. Why is there a difference?
(b) Why not include the 10 CFR Part 72.67 and 72.68 dose equivalent limits as boundary limits with the siting limitations?
10.1.2.1 Cask Int'erface Temperature Terminal Table 10.1-1 indicates an operating limit of 375 C for the fuel cladding.
In order to assess the integrity of the cladding, as requested in Section 3.3.7.1(a) above, the applicant should provide the maximum anticipated pressure in the fuel rods and a temperature decay curve for the spent fuel elements over the life of the 1SFS}.
10.1.2 Bases for Operating Controls and Limits 10.1.2.4 Fuel Characteristics Limits Comments made in Section 3.1.1 (Materials to be Stored) concerning "various I
combinations of burnup, specific power, enrichment, and cooling times" apply here as well.
The limits provided in this subsection are not adequate (see comments on 1
3.1.1).
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s Request for Additional Information Transnuclear, Inc., TN-24, QA 1.
Table 3,4-1'of TN's topical report E-7107, "TN-24 Dry Storage Cask,"
dated August 30, 1985, shows the classification of the components of ti.e cask. Chapter 11. " Quality Assurance Program," of E-7107 should reference this table or include a similar table such that the scope of the QA program is clear in chapter 11.
2.
TN's topical reports E-7107 and E-1473 (Revision 3), " Quality Assurance Program...," both use the term safety-related.
10 CFR 72 (972.80) requires a QA program based on the criteria of Appendix B to Part 50 tar be established and implemented for structures, systems, and components of an ISFSI that are important-to-safety.
10 CFR 72 includes a definition of the term important-to-safety unique to an ISFSI.
It appears that the term safety-related in the two reports meets the definition of important-to-safety in 10 CFR 72, i.e., the terms are used interchangeably.
If you agree with this assumption, please.so document in the report (s).
If you disagree, please clarify your position.
3.
The title of topical report E-1473, " Quality Assurance Program for Design, Manufacture, Test, Use, Maintenance, and Repair for Transport of Radio-active Materials," needs to be changed since the same QA program is to be applied to the TN-24 dry storage cask.
Similarly, the report itself needs to reflect the extension of the QA program to 10 CFR 72 casks.
4.
Page 3 of E-1473 states:
"As shown by the solid line in Fig. 1, he (i.e.,
the QA Engineer) can communicate directly with the President." Clarify to whom (by position title) the QA Engineer reports as regards the QA pr,ogram. The authority and indep.endence of this individual should be,
such that he can direct and control the organization's QA program, can effectively assure the conformance to quality requirements, and is suf-ficiently independent of undue influences and responsibilities for sche-dules and costs. An acceptable organizational structure would have this individual report to at least the same organizational level as the highest line manager directly responsible for performing activities affecting quality.
5.
Describe measures for communi-cating to all responsible organizations and individuals that quality policies and QA program, plans, and procedures are mandatory requirements.
6.
The last paragraph of section 2 of E-1473 (Rev. 3) addresses personnel training and indoctrination. Describe in general terms the specific docu-mentation of completed training and qualification and describe measures which assure that qualified personnel are certified in accordance with applicable codes and standards.
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. 7.
Describe measures which ensure proper selection and accomplishment of design verification by design review, alternate calculation, or qualifi-cation tests. When design reviews are used to verify design adequacy, describe how reviewers' questions and concerns are re. solved and' clarify that the questions, concerns and resolutions are documented. When tests
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are used to verify design adequacy, clarify that a prototype unit'is tested under adverse design conditions.
8.
Describe how TN controls obsolete /s'uperceded documents to prevent their inadvertent use.
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9.
The fifth paragraph.of.section 7 of E-1473 (Rev. 3) states: "The Project QA Engineer shall, inspect and audit contractors and subcontracters...."
Clarify that these. inspect., ions and audits are planned and performed in accordance with written procedures which provide for:
Instructionst5aispecifythecharacteristicsorprocessestobe a.
. inspected / audited and the documentation required b.
Inspections'/ audits.of items whose verification of procurement requirements cannot be detennined upon receipt.
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- 10. Provide a complete as possible listing of special processes involved in the manufacture',' inspection, testing, and repair of the TN-24 dry storage casks arid clarify that special process procedures require recorded evidence of verification of the process.
- 11. The first paraghap5 of section 12 of E-1473 (Rev. 3) states that " measuring devices shall be. calibrated at scheduled intervals...." Clarify that these intervals are based on required accuracy,. precision, purpose, amount of use, stability characteristics, and other conditions which could affect the measurements.
- 12. The fifth paragraph of section 15 of E-1473 (Rev. 3) states that noncon-formance reports are made part of the inspection records. Clarify that, for TN-24 dry storage casks, these reports are forwarded with the casks to the purchaser.
- 13. Describe measures which ensure that (a) significant conditions adverse to quality, (b) the root cause of the conditions, (c) the corrective action taken to remedy the immediate adverse conditions and (d) the corrective action taken to preclude repetition of the adverse conditions are documented and reported to cognizant levels of management for review and assessment.
- 14. Describe measures which ensure that audit team membership includes per-sonnel baving technical expertise in the areas being audited.
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NMSS/ Fuel Cycle Material FCUF FCAF file:
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