ML20206P240
| ML20206P240 | |
| Person / Time | |
|---|---|
| Site: | 07109786 |
| Issue date: | 08/21/1986 |
| From: | Macdonald C NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | |
| Shared Package | |
| ML20206P224 | List: |
| References | |
| NUDOCS 8608270139 | |
| Download: ML20206P240 (10) | |
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Safety Evaluation Report Department of Energy Division of Naval Reactors Model No. S3G Core Basket Disposal Container Assembly Docket No. 71-9786
SUMMARY
By application dated October 24, 1980, as supplemented, Department of Energy, Division of Naval Reactors, requested design approval of the Model No. S3G Core Basket Disposal Container (CBDC) Assembly.
Based on the statements and representations contained in the application and the conditions listed below, we have concluded that the hbdel No. S3G CBDC Assembly meets the performance requirements of 10 CFR Part 71.
REFERENCES 1.
S3G Core Basket Disposal Container Safety Analysis Report for Packaging, WAPD-RE0(C)-122, dated June 1980, as revised (Revision 2, dated May 5, 1986).
2.
Safety Analysis Report for Packaging an S1C Core Basket-Thermal Shield Assembly in the S3G Core Basket Disposal Container, SlC CB-TS, dated August 1983.
3.
00E memorandums G#7627 dated November 16,1983; G#C86-3736 dated May 24,1986, and G#C86-3750 dated July 15, 1986.
DESCRIPTION The package consists of either one irradiated S3G or S1C core basket packaged in an inner, lead-filled container (SSW Core Basket Removal Container (CBRC)) which is placed inside an outer container (S3G CBDC).
The package icighs approximately 172,000 pounds.
The S3G CBDC is a 4-inch thick steel cylinder, 89 inches in outside dianeter,131 inches long, with an 8-inch thick top end plate and a 5-inch thick bottom end plate.
Both end plates are welded to the cylinder with full penetration velds.
The SSW CBRC which will be disposed of along with the S3G CBDC and inner i
core basket is basically a cylindrical shaped container conprised of lead shielding sandwiched between two 304 stainless steel shells. The 1-inch thick inner shell is 60 inches 0.D. and 107.5 inches long. The outer shell is made up of two geometries, a 72.5-inch 0.D., 0.5-inch thick cylindrical shell that measures 66 inches long and joins a truncated conical shell which has a 64-inch 0.D. at the small end.
The two shells are joined by a full thickness penetration weld and a veld backup strap on the inside shell surface. Full penetration welds are also made on both ends of the shells to the top canning and shield ring.
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~ The SSW CBRC will contain either an S3G or S1C core basket.
The irradiated S3G core basket is an Inconel 600 cylindrical shell.
Three, 3-inch thick 304 stainless steel plates are positioned in the core basket prior to removal to provide overhead radiation shielding.
The lower plate is 46.2 inches in diameter.
The upper plates have the same diameter but contain six extensions that fit inside recessed cutouts within the core basket.
The total core basket weight is approximately 9,650 pounds.
The SIC core basket is a 304 stainless steel cylindrical shell positioned inside a 304 stainless steel thermal shield.
The overhead shielding consists of a set of 2-inch thick 304 stainless steel plates attached to the SlC core basket to provide radiation shielding during handling. The core basket weight is approximately 8,523 pounds.
DRAWINGS The packaging is constructed in accordance with Bettis Drawing No.
1527E40 for the S3G Core Basket Assembly and KAPL Drawing No.152D7009 for the S1C Core Basket Assembly.
CONTENTS (1) Type and form of material An irradiated core basket either the S3G or S1C and SSW CBRC. The shipment may include surface contamination in the form of activated corrosion products and for the S3G core basket approximately 8 gallons of residual water.
(2) Quantity of material in package One irraditted core basket and S5W CBRC as described in 5(b)(1).
Surface contamination not to exceed 20.6 curies for the S3G core basket or 7.45 curies for the SIC core basket.
The irradiated S3G core basket not to exceed 131,000 curies; the irradiated SlC core basket not to exceed 20,000 curies.
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STRUCTURAL A.
General Standards for all Packaging Minimum Package Size The package meets the requirements of 10 CFP. $71.43(a) for minimum sizes.
Tamperproof Feature The top plate of the package is closed by 3.0-inch full penetration wel ds.
Thus, no tamperproof devices are mquired.
Positive Closure The package is closed by full penetration wlds.
Thus, it cannot be opened.
Chemical and Galvanic Reaction The package is constructed of such materials that there will be no chemical, galvanic, or other reactions between package components and contents.
General Requirements The package meets the requirements stipulated in 10 CFR $71.43(f) as evidenced by the analysis of each condition under the normal condition of transport.
l Valves or Other Devices The package does not have any valves or other devices to allow radioactive contents to escape.
i B.
Lifting and Tie-Down Standards for All Packages Lifting Devices The application has shown by analysis that the lifting lugs meet the requirements of 10 CFR $71.45(a).
Tie-Down Devices The application has shown by analysis that the tie-down devices (32,1-1/2 UNC-2A SAE Grade 5 bolts) meet the requirements of 10 CFR $71.45(b).
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Normal Conditions of Transport Heat The maximun tenperature of the package is calculated as 229'F and the internal pressure has been conservatively taken as 59.1 psi.
The resulting stresses due to differential thermal expansion and internal pressurization are low compared with the design allowable stresses.
The lead temperature is about 218*F which is below the lead melting temperature (about 620*F).
Thus, the hot environment (heat) requirement has no adverse effects on the package.
Col d An ambient temperature of -40*F does not adversely affect the performance of the package. Because of the high thermal conductivity of lead and steel, no steep thermal gradients exist to cause significant thermal stresses.
The brittle fracture analyses, however, were based on structural mechanics and charpy test results. Al though the approach is different from the procedures recommended in HUREG/CR-151S, the container material s (HY-80 and stainless steel s) are not susceptible to cold tenperature.
In addition, the construction of the package affords multi-layer protection to the payload. Thus, brittle fracture is deemed not a problem for this package.
Reduced External Pressure and Increased External Pressure This regulatory requirement has no significant effects on the package as shown by analysis.
Vibrations The natural frequency of the transport vehicle (railcar) does not lead to a resonant frequency in any of the package components.
Thus, vibrations incident to normal transport should not have any significant effects on package.
Water Spray The package is of all welded steci construction. There are no gasketed joints, aperatures, and valves through which water may gain entrance.
Therefore, the water spray condition will have no effects on the package.
Free Drop The applicant performed detailed hand calculations to show that one foot free drop of the package does not compromise safety.
Because of the massive, all steel welded construction of the package, damage due to the one foot drop is not significant.
The deformation of the S3G CBDC cylinder is calculated to be 0.0739 inches at an equivalent G load of 340 g's.
- Corner Drop Not applicable Compression Hot applicable Penetration The 13-pound cylinder dropped from a height of 40 inches does not possess sufficient energy to damage the container.
D.
Hypothetical Accident Conditions Free Drop The application presents detailed analyses for four drop orientations:
(1) flat top, (2) top corner, (3) side, and (4) flat bottom. The analyses are nostly hand calculations based on simplified assumptions and conventional equations. The top and bottom plate of the S3G CBDC, however, were analyzed using the DUZ-2 computer code for the flat top and bottom drops.
It was shown that critical stresses exceeded the design ultimate stress for the top plate in a bottom end 30-foot drop and al so the bottom plate in a top end 30-fcot d rop. The high stresses in these end plates were the result of extremely large bending moments at the center and also at the edge of the plates. These stresses, however, were computed based on elastic sectional modulus.
If the plastic sectional modulus was used, the stresses would be reduced significantly.
Therefore, it may be concluded that the end plates will not collapse either in a flat top or a flat bottom end drop.
The application did not combine the impact stresses from the 30-foot drop with the concurrent stresses from operating pressure and temperature. The impact analyses were based on an equivalent G load in the range of 1,500 g to 1,700 g's.
As a result, the impact stresses were very large and inclusion of stresses from pressure and temperature would not change the resultant stresses significantly.
The lead slump in a 30-foot top drop could become quite large due to the failure of the top canning of the modified S5W CBRC wall.
However, the applicant performed additional shielding analysis to show that even at the wrst lead slump situation, the package still meets the requirement of 10 CFR $71.51.
_G.
Puncture Puncture damages from the 40-inch free fall upon the 60-inch diameter pin are minor with respect to any physical damages to the package. The structural analysis indicates local yielding of the material at the point of impact but no penetration of the cylindrical wall or the end plates of the S3G CBDC cylinder.
Thermal No significant damages from the 1475*F fire to the package components occurs.
No lead melting within the modified SSW CBRC has been predicted. The staff agrees with the applicant's conclusion that stresses induced by temperature and pressure does not compromise package safety.
Immersion This regulatory requirement does not have any effects on the package.
THERMAL The SlC core basket and thermal shield assembly will be shipped in an SSW CBRC which is itsel f contained within an S3G CBDC.
The SlC core basket and thermal shield are made of stainless steel.
The S5W CBRC is a lead container with stainless steel clad on the inside and outside. A cylindrical carbon steel shield is welded to the outside of the removal container at the bottom, creating an air gap between the removal container and the shield.
All of these components are contained within the S3G CBDC which is a cylindrical container made of HY-80 steel.
Alternately, the applicant may use the S5W CBRC and S3G CBDC to ship an S3G core basket.
The nafor difference between the S1C and S3G core baskets is that the S3G core baskets could contain up to 8 gallons of water.
(There would be no water in the SlC core basket due to the presence of ho,les in the bottom of the core basket.) The presence of this water would result in higher temperatures and pressures vdthin the package during normal and accident conditions. Since the outer components of the package, i.e., the SSW CBRC and S3G CBDC are the same, the applicant has analyzed the thermal accident condition using only the S3G core basket assembly.
This would represent a conservative estimate for the SIC core basket assembly, i
The applicant performed two thermal analyses for the S3G/SSW assembly using the STEDA computer code.
The normal transport conditions were modeled using an m1bient of 130*r (10 CFR Part 71 requires only 100*F) and exposure to solar radiation.
The accident conditions considered a 100*F ambient, solar radiation and exposure of the package to a 1475*F fire environment for 30 minutes.
In each case an internal heat load of 50 watts or 171 Btu /hr was used.
This internal heat load represented the core basket's expected heat generation after a 30-day shutdown.
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~ Normal Conditions of Transport Due to the low heat generation rate in the container, the package temperatures under normal conditions are primarily determined by the absorbed solar flux and the emissivity of the S3G CBDC.
The following temperatures were calculated for normal operating conditions:
Temperature *F SlC S3G Component Core Basket Core Basket S3G CBDC 208 225 Cylindrical shield connected to SSW CBRC 210 275 SSW CBRC 213 300 Core Basket / Thermal Shield 223 325 In this temperature range, there were no appreciable problems with either thermal stresses or material properties.
Accident Conditions The thernal analysis for accident conditions was performed for the S3G core basket.
This represents a conservative estimate for the S1C assembly for the reasons previously stated.
The S3G assembly was modeled with and without the effect of air gaps under the assumption that the air gaps could become filled with water for the S3G assembly under accident conditions. The temperatures for the SlC assembly would be expected to be closer to those calculated with the air gaps since no water is present.
The results of the analysis are given below:
S3G Temperatures (*F) with air without air Component gaps gaps Core Sasket 272 419 SSW CD6tC Inner Clad 269 419 Lead 269 429 Outer Clad 269 438 Cylindrical Shell (SSW CBRC) 386 457 S3G CBDC 819 662
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- The SSW CBRC's lead shielding for both the S3G and Slc core basket assemblies remain well below the melting point of lead and no loss of radiation shielding would occur.
Internal Pressure i
An average temperature of 434*F was used to calculate the increase in internal pressure for the S3G core basket assembly.
Since this temperature was obtained using the model without air gaps, it can also conservatively be used for the calculation of the SIC core basket assembly's internal pressure increase.
The total pressure developed within the S3G CBDC is due to:
(1) steam. pressure from trapped internal water 3
(2) thermal expansion of trapped air.
c The maximum internal pressure for the S3G CBDC assembly containi.ng the S3G core basket is approximately 191 psia (176 psig), with 167 psi of that resulting from superheated steam.
The maximum pressure for the S3G CBDC assembly containing the SlC core basket would be approximately 24 psia (9 psig).
4 Summary The applicant has demonstrated the S3G CBDC/SSW CBRC shipping package for transporting SlC and S3G core barrels meet the thermal requirements of 10 CFR Part 71.
CONTAll#1ENT The primary containment boundary for the shipment of either the SlC or S3G core basket, the S3G CBDC, consists of a 4.0-inch thick high strength steel cylinder, a 5.0-inch ~ thick bottom plate, and a 4.0- to 8.0-inch thick top plate. Both the top and bottom plates are full penetration -
welded to the cylinder.
There are no penetrations into the primary containment vessel itsel f and no seals or gaskets are used in the S3G C BDC.
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_ The major sources of radioactivity within the assembly are the irradiated core baskets and the activated corrosion products adhering to both the core baskets and the SSW CBRC.
The inside surface of the SSW CBRC is contaminated with loose activated corrosion products accumulated fona
" crud" loosened during previous shipboard to disposal container handling of irradiated core barrels.
It has been estimated that residual contamination on both the core basket and SSW CBRC is approximately 20 curies (for -
each).
The crud / corrosion deposits are tightly caked on both the core basket and SSW CBRC and would not be available for release unless dislodged.
Even if 100% of the material were dislodged during a catastrophic event such as a 30-foot drop, the loosened material would anount to less than 0.1% of the packages total radioactivity.
Hone of the radioactivity from the irradiated core baskets themselves (greater than 99.9% of the total) would be subject to leakage as the baskets would remain intact even during hypothetical accident conditions.
In addition, since the S3G CBDC would not rupture or puncture during hypothetical accident conditions, no radioactive material would escape since the S3G CBDC is completely welded shut and contains no outside penetrations, seals, or gaskets.
The S3G CBDC/SS1 CBRC package meets the containment requirements of 10 CFR $71.51.
SHIELDING Department of Energy has demonstrated using the SPAN-5 shielding program that the S3G CBDC/S5U CBRC assembly satisfies 10 CFR $71.73, the hypothetical accident condition that an external dose rate udll be less than one rem per hour at 1 meter from the cask surface. For a 25.1-inch lead slump leading to an annular void between the inner and outer shells, a gamma dose rate of 827 mrem /hr was calculated 3-feet from the package surface at nidplane.
A naw gamma source was calculated for the S3G CBDC/SSW CBRC package derived on a more accurate flux case history during irradiation resulting in a uniform source reduction by 9% of the previously submitted accident analysi s.
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, OPERATING, ACCEPTANCE, AND MAINTENANCE General operating procedures for use of the package are provided in Section 7 of the application.
General acceptance and maintenance programs are described in Section 8 of the application.
CONDITIONS 1.
Shipment of an irradiated S3G core basket must be made no earlier than 75 days after reactor shutdown.
2.
Shipment of an irradiated SIC core basket must be made no earlier than 60 days after reactor shutdoe:n.
CONCLUSION Based on our review, the statements and representations contained in the application and the conditions listed above, we find that the Model No.
S3G Core Basket Disposal Container Assembly meets the requirements of 10 CFR Part 71.
Charles E. MacDonald, Chief Transportation Certification Branch Division of Fuel Cycle and Material Safety, HMSS Date:
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