ML19257A339
| ML19257A339 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 12/31/1979 |
| From: | GEORGIA POWER CO. |
| To: | |
| Shared Package | |
| ML19257A336 | List: |
| References | |
| NUDOCS 8001030778 | |
| Download: ML19257A339 (10) | |
Text
Edwin I. Hatch Nuclear Plant, Units 1 & 2 December 1979 Spent Fuel Pool Modification INSERTION INSTRUCTIONS Page Instruction Table of Contents Page i (Book)
Replace 4-7 Replace 4-8 Add 4-9 Add Tables:
4-5 Add 4-6 Add Figures:
4-11 Add Response to Questions:
Q1-1 Replace Q8-1 Replace 1671 287 8001030 7 78
TABLE OF CONTENTS Section Title Page 1.0 Introduction.
1-1 2.0 Overall Description.
2-1 3.0 Design Bases...............
3-1 4.0 Mechanical and Structural Considerations.
4-1 4.1 Seismic Analysis.
4-1 4.2 Stress Analysis..
4-3 4.3 Fuel Bundle / Module Impact Evaluation...........
4-7 4.4 Effects of Increased Loads on the Fuel Pool Liner and 34 5
Structures........................
4-8 5.0 Material Considerations...
5-1 6.0 Installation....
6-1 7.0 Nuclear Considerations...................
7-1 7.1 Neutron Multiplication Factor.
7-1
- 7. 2 Input Parameters.................
7-1 7.3 Geometry, Bias, and Uncertainty.
7-2 7.4 Postulated Accidents..
7-5 8.0 Thermal Hydraulic Considerations.
8-1 8.1 Description of the Spent Fuel Pool Cooling System.
8-1 8.2 Heat Loads and Pool Temperatures for Present Storage Capacity..........
8-2 8.3 Heat Loads and Pool Temperatures for Increased Storage Capacity..............
8-3 8.4 Loss of Spent Fuel Pool Cooling.
8-6 8.5 Local Fuel Bundle Thermal Hydraulics.
8-7 8.6 Radiological Impact of Spent Fuel Pool Boiling.
8-10 9.0 Cost Benefit Assessment.
9-1 9.1 Need for Increased Storage Capacity.
9-1 9.2 Alternative to Increasing Storage Capacity 9-2 9.3 Capital Costs.
9-5 9.4 Resource Commitment.
9-5 9.5 Environmental Impact of Expanded Spent Fuel Storage.
9-6 10.0 Radiological Evaluation.
10-1 10.1 Spent Resin Waste.
10-1 10.2 Noble Gases....
10-1 10.3 Gamma Isotopic Analysis for Pool Water.
10-2 10.4 Dose Levels Over and Along the Sides of the Pool.
10-2 10.5 Airborne Radioactive Nuclides.
10-2 10.6 Radiation Protection Program.
10-2 10.7 Disposal of Present Spent Fuel Racks 10-3 10.8 Impact on Radioactive Effluents...
10-3 -l2 i
) ()/ ]
2 @ 8 Amend. 2 9/79 Amend. 3 10/79 Amend. 4 11/79 Amend. 5 12/79
The loads experienced under a stuck fuel assembly condition are less than those calculated for the seismic condition and have therefore not been included as a load combination.
4.3 Fuel Bundle / Module Impact Evaluation An analysis was performed to evaluate the effect of an impact load that is possible because of gaps between the fuel bundle and the fuel storage module.
In the seismic analysis for the Hatch high density spent fuel storage module (results in Table 4-2), gaps were not considered and the fuel bundle was treated as an integral part of the module in addition to the hydrodynamic mass due to surrounding water.
A gapped element model was prepared to study the effect of im-pact loads on the module. This model is shown in Figure 4-11.
The distinct feature of this model is that the fuel bundle is separated from the module and is free to vibrate within the con-fines of the storage position in the module. The fuel bundle is pinned supported at the base and the entire module is submerged 5
under water and free to slide.
For comparison purposes regarding the impact load effect, a lumped element model was also constructed.
The lumped element model'is identical to the gapped element model shown in Figure 4-11 except that the gaps between the fuel bundle and the module are ignored.
The objectives of this evaluation are:
a.
to assess the difference in maximum internal forces in the module as determined from a gapped element model and a lumped element model, and b.
to assess the effect of impact loads on the maximum sliding displacement of the module.
To evaluate gap effects on rigid body displacements, the two models were subjected to a coristant 1.09 base acceleration for a period of 0.8 seconds. This acceleration was applied for two cases, correspond-ing to friction coefficients of 0.145 and 0.2.
The use of a constant 1.0g base acceleration was mandated by the lack of a definitive time history to use in conjunction with rigid body displacements.
Gap effects on internal forces were evaluated by subjecting both models to the Hatch time history. This was done for three cases: p = 0.145, p = 0.2, and p+= (fixed base).
The results of these analyses are presented in Tables 4-5 and 4-6 for rigid body displacements and internal forces, respectively.
Table 4-5 shows the displacement ratio between the gapped and the lumped element model.
It indicates that there are no significant differences between the rigid body displacements as determined from the gapped and lumped element models for both p = 0.145 and u = 0.2.
Thus it can be concluded that gap effects on the rigid body motions can be neglected and that the results provided in Table 4-2 are ade-quate for design purposes. Table 4-6 indicates that the internal 1671 289 4-7 Amend. 5 12/79
forces (or spring loads) in the module determined from the gapped models are significantly less than the corresponding forces in the lumped models for the two cases p = 0.145, and p = 0.2.
For the case where n+= this situation is reversed, however, and the intern-al force in the lumped model exceeds the internal force in the gapped model.
Thus it can be concluded that where rigid body motion is permitted and friction forces are within the range of interest, the internal forces are conservatively determined from the lumped model.
4.4 Effects of Increased Loads on the Fuel Pool Liner and Structures 3
The Unit 1 and Unit 2 spent fuel pool structure and liner plate have adequate capacity to carry the increased loads imposed by the 4
new high density spent fuel storage racks.
5 The spent fuel pool structure for each unit was evaluated for the new loads based on the following criteria:
1.
" Code Requirements of Nuclear Safety Related Concrete Structures", The ACI 349-76 Code.
2.
3.
USNRC Standard Review Plan, Section 3.8.4.II.
4.
USNRC Operating Technical Position for Review and Acceptance of Spent Fuel Storage and Handling Applications.
Based on the above criteria, the following is a listing of the primary loads that were considered in the structural evaluation:
1.
The dead weight of the structural elements (D).
2.
The live loads acting on the structural elements (L).
3.
The hydrostatic load due to the water in the pool (F).
4.
A three component OBE seismic load (E ).
g 5.
A three component SSE seismic load (Ess)*
6.
A thermal loading based on normal operating conditions - pool water t mperature of 150*F and ambient air temperature of 90*F (T ).
7.
A thermal loading based on accident conditions - pool water temperature of 212*F and ambient air temperature of 90*F (Tf).
8.
A thermal loading based on normal operating conditions - pool water temperature of 150*F and ambient air temperature of 110*F (T ).
g 1671 290 Amend. 3 10/79 4-8 Amend. 4 11/79 Amend. 5 12/79
9.
A thermal loading based on accident conditions - pool water temperature of 212*F and ambient air temperature of 110*F (T )'
a The following seven loading combinations that produce the most severe loading to this type of structure were used in the evalua-tion:
1.
U = 1.4 (D) + 1.7 (L) + 1.4 (F) + 1.9 (E )
g 2.
U = (D) + (L) + (F) + (Ess) + (
}
3.
U = (D) + (L) + (F) + (Ess) + (T )
g 4.
U = (D) + (L) + (F)
(Ess) + (
)
5.
U = (D) + (L) + (F) + (Ess) + (T )
a 6.
U = 0.75 [1.4 (D) + 1.7 (L) + 1.4 (F) + 1.9 (E ) + 1.7 (T )]
5 g
2 7.
U = 0.75 [1.4 (D) + 1.7 (L) + 1.4 (F) + 1.9 (E ) + 1.7 (T ))
g A three-dimensional mathematical model was developed for each spent fuel pool structure. Each mathematical model is composed of plate /
shell elements, beam elements, truss elements, and boundary ele-ments to idealize the existing structure.
Structural properties for the elements were selected based on insitu conditions.
The analysis was performed using a computer code named "BSAP".
This computer code is a modified version of SAP IV which is in the public domain. The analysis war broken into two parts.
- First, each structure was analyzed for load combination 1 using gross concrete structural properties. This will verify that each structure will carry the mechanical loading and place an upper bound on the structure's stiffness.
Second, each structure was analyzed for all seven loading combinations listed above using cracked concrete and reinforcing steel structural properties.
This will verify that each structure will carry the mechanical as well as the thermal loading combinations, placing a lower bound on the structural stiffness. The results of the analyses, forces, moments and shears for each loadir.g combination and analysis cond'.-
tion were evaluated based on " strength criteria" for each of the fuel pool elements.
The evaluation shows that the fuel pool structure for each unit meets the design criteria for the conditions stated.
1671 291 4-9 Amend. 5 12/79
TABLE 4-5 Normalized Rigid Body Displacements Of Lumped And Gapped Models Friction Coefficient Gapped Element Model/
u Lumped Element Model 0.145 1.02 0.2 1.02 1671 292 Amend. 5 12/79
TABLE 4-6 Spring Forces In Lumped And Gapped Models Friction Coefficient Gapped Model Lumper. Model (p)
Force (lbs.)
Force (lbs.)
5 5
0.145 0.489 x 10 0.915 x 10 5
5 0.2 0.592 x 10 1.20 x 10 6
6 p+=
2.09 x 10 1.38 x 10 (fixed base) 1671 293 Amend. 5 12/79
+U
- U 2
3 k 1 3
W///<'
GD
~
1 4
/
-h 1
2
/
k
/
4
+U 3
Mass Definitions:
Generalized base mass Generalized channel-beam mass Generalized fuel-bundle mass Fixed point Element Definitions:
1 Channel beam element (nodes 1 & 2) 2 Fuel bundle element (nodes 1 & 2) 3 Gapped, hydrodynamic element (nodes 2 & 3) 4 Elastic-plastic spring element (nodes 1 & 4) 1671 294 Figure 4-11 Gapped Element Model Amend. 5 12/79
QUESTION 1 Discuss the effects of the increased loads due to the new rack structures on the fuel pool liner and structures.
RESPONSE
The response has been incorporated into Section 4.4.
l5 1671 295 Q1-1 Amend. 3 10/79 Amend. 5 12/79
QUESTION 8 During seismic events (horizontal and vertical), part of the fuel bundle inertial forces is transferred directly to the tube wall or the fuel support plate through the clearance gaps.
Indicate how these impactive motions have been considered in the analysis along with the effects of fuel storage rack rocking and sliding on the pool floor.
Provide the numerical values for these impactive factors (dynamic amplification factors) and justifications.
RESPONSE
The response has been incorporated into Section 4.3.
l5 1671 296 Q8-1 Amend. 3 10/79 Amend. 5 12/79