ML18047A607
| ML18047A607 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 10/08/1982 |
| From: | Vandewalle D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| TASK-03-07.B, TASK-3-7.B, TASK-RR IEB-79-02, IEB-79-04, IEB-79-2, IEB-79-4, NUDOCS 8210130334 | |
| Download: ML18047A607 (12) | |
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consumers Power company General Offices: 212 Welt Michigan Avenue, Jackson, Ml 49201 * (617) 788-0660 October 8, 1982 Mr Dennis M Crutchfield, Chief Operating Reactors Branch No 5 Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-255 - LICENSE DPR
- PALISADES PLANT - SEP TOPIC III-7.B, DESIGN CODES, DESIGN CRITERIA AND LOAD COMBINATIONS In a letter dated August 17, 1982, Consumers Power Company committed to pro-vide our evaluations of a number of open items as identified in the NRC's February 12, 1982 letter regarding SEP Topic III-7.B, Design Codes, Design Criteria and Load Combinations, for the Palisades Plant.
This letter responds to this commitment.
The attached report, which encompasses Consumers Power Company evaluations of the NRC's SER (February 12, 1982 NRG letter), addresses all but one of the is-sues identified by the Franklin Research Institute.
The remaining open item is an addition to the ACI-349 Code (Appendix B) on steel embedment.
Appen-dix B provides comprehensive requirements for the design of embedment using anchor heads, expansion anchors, grouted anchors and inserts.
Some of these requirements are merely formal statements of what has been the industry prac-tice for some time.
The impact on perceived safety margin due to the ACI-349 code addition has not yet been determined.
The obvious problem is the large guantity of steel em-bedments used at the Plant, both in terms of types, connection methods and number.
A casual review of Plant drawings leaves the impression tpat for em-bedments transmitting heavy loads (ie, other than platforms, walkways and lad-ders), Nelson studs are predominantly used.
In some cases, headed bolts or bent bars made out of rods are used.
For supports attached to the walls and floor slabs which obviously carry heavy loads (eg, steam generator, pressuri-zer and primary coolant pump supports), the embedments extend beyond the far-face reinforcement.
For primary coolant pump support, for instance, that is through a 5 1 0 11 slab.
With regard to expansion anchor bolts, Consumers Power Company has performed exhaustive work associated with IE Bulletins 79-02 and 79-04 for accessible ocl082-0123a-43-71 l
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bolts.
The results of the work should be considered in the overall assessment.
Consumers Power Company is presently reviewing the steel embedments issue in more detail and intends to propose a plan of action for its resolution by December 31, 1982.
2 Consumers Power Company would also like to expand upon the enclosed report re-garding two items.
The first item involves a change to B&PV Code Section III, Division 2.
Subsection CC of this code provides rules for the design of con-crete containments, both prestressed and reinforced.
One of the code change items identified by the FRC report, CC-3532.1.2, is significant only for rein-forced containments.
Palisades containment structure, of course, is postten-sioned.
Others (eg, CC-3421.6 and CC-3421.7), when applied to a prestressed structure, results in a "c" rating.
The second item involves a change in AISC Code (1.14.2.2) on tension members.
This code change must be considered in conjunction with Section 1.5.11.
For Grade A-36 steel used at Palisades, a comparison of the design criteria based on the 1963 and 1980 code indicates that tension members design to this ear-lier code always have greater margin of safety.
Nuclear Licensing Administrator CC Administrator, Region III, USNRC NRC Resident Inspector - Palisades oc1082-0123a-43-71
SEP Topic III-7.B CONSUMERS POWER cmtP ANY RESPONSE TO US NRC SEP TOPIC III-7.B Design Codes, Design Criteria and Loading Combinations I.
INTRODUCTION The following report summarizes the results of evaluations made concern-ing the Palisades Plant structures in compliance with the intent of the Nuclear Regulatory Commission's (NRG) Systematic Evaluation Program (SEP), Topic III-7.B, "Design Codes, Design Criteria and Load Combinations."
The presentation follows the same format as Franklin Research Center (FRC) Report, TER-C5257-324.
Only those items that were marked with questionable ratings were elaborated.
II.
RESULTS OF EVALUATION This evaluation emphasizes qualitat-i-ve--assessment of the Plant struc-tures because quantitative assessment would require full-scale reanaly-sis of all structural components.
Such reanalysis is physically and economically unwarranted.
Where questions were raised in the FRC report regarding specific loading criteria addressed in the Palisades Final Safety Analysis Report (FSAR), an effort was made to review the original design, because the FSAR contains only design criteria, not design details.
A.
DESIGN LOAD TABLES (FRC REPORT, SECTION 10.3)
- 1.
Containment Structure
- a.
Live Load (L)
The severe weather loads are far less critical than earth-quake, tornado and tornado missile loads, which are being evaluated under separate SEP topics.
- b.
Soil Pressure (H)
Soil pressure, which only exists over a small area around the containment east side, is small and acts in an opposite direction from other primary loads.
Soil pressure, there-fore, does not affect the overall structural capability of the containment.
- c.
Earthquake Load (E')
nul082-0123a-43-71 Earthquake load was considered under SEP Topic III-6, "Seismic Design Considerations," and evaluated in 1
SEP Topic III-7.B NUREG/CR-1833, UCRL-53015, "Seismic Review of the Palisades Nuclear Power Plant Unit 1 as Part of the Systematic Evalu-ation Program." It was concluded that the containment structure can withstand a safe shutdown earthquake (SSE) event.
- d.
Tornado Load CW')
The primary loads that dictate the design of the contain-ment stru.cture are the earthquake and pressure loads.
Analysis showed that the structural capacities of the con-tainment structure resulting from the above considerations greatly exceed those required for the tornado and tornado missile loads.
Tornado and tornado missile loads are reviewed under separate SEP Topics III-2, and III-4.A, respectively.
- e.
Impulse Loads (Y, Y., Y) r J
m High-energy piping (listed under Palisades FSAR Sec-tion 5.4.3) has been analyzed for postulated pipe break conditions.
Pipe restraints and pipe whip barriers have been provided at postulated pipe break locations.
Pipe break effects inside containment are currently evaluated under SEP Topic III-5.A.
- 2.
Auxiliary Building - Control Room, Diesel Generator and Switch-gear Rooms
- a.
Live Load (L)
The final safety evaluation for severe weather loads con-tained in SEP Topic II-2.A shows that Palisades design loads used in the original design are adequate.
SEP Topic III-3.B concerns only the flooding condition and has no bearing on parapet roof loading.
In addition, snow loading is not the controlling load case for roof design.
- b.
Soil Pressure and Hydrostatic Pressure (H)
Soil pressure and hydrostatic pressure were considered in the original design.
- c.
Pressure Load and Thermal Load (P, T )
a a
nu1082-0123a-43-71 There are no postulated pipe breaks in these areas.
These loading components do not apply.
2
SEP Topic III-7.B
- d.
Earthquake Load CE')
Refer to Subsection II.A.1.c.
- e.
Pipe and Impulse Loads CR, Y, Y., Y) a r
J m
There are no postulated pipe breaks in these areas.
These loads do not apply.
- 3.
Auxiliary Building - Spent Fuel Pool and Its Enclosure
- a.
Earthquake Load CE')
Refer to Subsection II.A.1.c.
- b.
Tornado Loads CW').
Refer to SEP Topics III-2 and III-4.A.
Tornado missile loads were not the dominant load case for the concrete portion of the spent fuel pool.
The spent fuel pool enclosure was not designed for tornado missile loads.
- c.
Impulse Loads CY, Y., Y) r J
m
/
These load cases are not applicable because there are no pipe breaks postulated in these areas.
- d.
Live Load (L)
Refer to Subsection II.A.2.a.
- 4.
Auxiliary Building - New Fuel Area, Pump Rooms and Radwaste Treatment Area
- a.
Live Load (L)
Refer to Subsection II.A.2.a.
- b.
Earthquake Load CE')
Refer to Subsection II.A.1.c.
- c.
Pipe Rupture Loads (Y, Y., Y, P, T, R )
r J
m a
a a
nu1082-0123a-43-71 Tii.ere are no pipe breaks postulated in the pump room area.
However, in the main steam and main feedwater penetration rooms, pipe restraints have been provided for high-energy lines to mitigate the consequences of pipe breaks.
Safety margins of the Plant structures will not be affected by the code changes.
3
SEP Topic III-7.B
- 5.
Intake Structure
- a.
Live Load (L)
Refer to Subsection II.A.2.a.
- b.
Earthquake Load (E')
Refer to SEP Topic III-6.
- 6.
Turbine Building - Auxiliary Feedwater Pump Enclosure
- a.
Soil Pressure (H)
Soil Pressure was considered in the original design.
- b.
Earthquake Load CE')
Refer to SEP Topic III-6.
- c.
Pipe Rupture Loads (Y, Y., Y, T, P, R) r J
m a
a a
No pipe break was postulated inside the auxiliary feedwater pump room; therefore, these loads are not applicable.
B.
LOAD COMBINATION TABLES (FRC REPORT, SECTION 10. 4)
- 1.
Containment Structure
- a.
Load Combination 8 (R )
a The specific design details for loading component R cannot a
be located in the original design calculation.
However, R a is only a localized point loading.
Consideration of R a will not infringe upon the structural integrity of the con-tainment structure because sufficient margin exists from considering the other critical uniform load (1.5Pa).
Fur-thermore, the containment was designed with adequate heat sink in addition to the spray system to control the thermal load during accident conditions.
Load R is not expected a
to be significant.
- b.
Load Combination 14 [R + R (Y, Y., Y )]
a r
r J
m nul082-0123a-43-71 Inside the containment structure, pipe restraints have been provided at all major pipe break locations to mitigate the pipe break effects.
The impact from R + R is deemed a
r 4
SEP Topic III-7.~
insignificant.
In addition, Load Combination 14 is less critical than Load Combination 10.
- 2.
Containment Liner Plate
- a.
.Other than achieving strain compatibility with concrete containment, there is no load transferred to the contain-ment liner.
Therefore, the structural integrity of the liner plate is ensured if the structural integrity of the concrete containment is maintained.
- 3.
Auxiliary Building - Control Room Diesel Generator and Switch-gear Rooms
- a.
Load Combination 1 is inaccurate.
The load factors used in the original design are 1.5D + 1.aL.
- b.
Load Combination 10 is less critical than Load Combina-tion 9.
- c.
There are no postulated pipe breaks in these areas.
There-fore, Load Combination 13 does not apply.
- 4.
Auxiliary Building - Spent Fuel Pool and Its Enclosure
- a.
Load Combination 10 The tornado missile load is not the controlling load case for the concrete portion of the spent fuel pool.
This load was reviewed under SEP Topic III-4.
- b.
Load Comination 13 Impulse loads are not applicable to the spent fuel pool.
- c.
The spent fuel pool enclosure was not designed for tornado loads.
This structure was reviewed under SEP Topics III-2 and III-4.A.
- 5.
Auxiliary Building - New Fuel Area, Pump Rooms and Radwaste Treatment Area
- a.
Load Combination 10 nu1082-0123a-43-71 Tornado and tornado missile loads do not* apply to these areas because they are enclosed by other reinforced con-crete structures.
5
SEP Topic III-7.B
- b.
Load Combination 13 Refer to Subsection II.A.4.c.
- 6.
Turbine Building
- a.
Load Combination 10 Tornado load was considered in the original design.
- b.
Load Combination 13 No pfpe break was postulated inside the auxiliary feedwater pump room.
The load combination is less severe than other load combinations.
C.
TYPE OF STRUCTURAL ELEMENT (FRC REPORT, SECTION 13)
In this section, inapplicable code changes will be pointed out.
The specific structural elements that do not exist at the Palisades Plant will be identified and eliminated from the listing in the FRC report:
- 1.
Beams
- a.
Shear Connectors in Composite Beams There were no composite structures in the Plant designed to the 1963 AISC code.
However, partial composite design was employed for the baler room roof to account for uplift pressure generated by the tornado, in accordance with the 1971 code.
Currently, a new addition is being built above the baler room, which will become an interior structure.
Therefore, this item is not applicable to the Palisades Plant.
- b.
Composite Beams With Formed Steel Deck The main purposes for the combined use of steel beams and steel deck at the Palisades Plant were to facilitate con-struction and to eliminate the need for additional form-works.
Structural steel beams were primarily designed to support the construction loads, except those addressed in the preceding Section C.1.a.
Therefore, the code change will have no significant impact on the safety margin of the Plant structure.
- c.
Hybrid Girders No hybrid girders exist in the Plant.
nu1082-0123a-43-71 6
SEP Topic III-7.B
- 2.
Compression Elements In the 1963 edition of the AISC specification appendix, Sec-tion 1.9 gives the limiting width-thickness ratios (b/t) for different structural shapes, Those limiting ratios, which are the lower bound ratios stipulated in Appendix C of AISC 1980 edition, are easy to follow and require no reduction in stress.
Provisions were made in the 1963 code to allow for higher b/t, provided that *special design consideration was imposed.
How-ever, it has not been the common industrial design practice to compensate for possible small material savings by using a more sophisticated design procedure.
Furthermore, structural shapes addressed under Subsection 1.9.12 of the AISC code had not been used as the primary load supporting members in the Palisades Plant.
Therefore, the safety margin of the Plant structures has not been affected.
- 3.
Tension Members No major structural members, except some secondary truss mem-bers, are axially loaded at the Palisades Plant.
However, all the tension truss members are weld connected.
Bolted connec~
tions are employed only for lateral bracings between trusses.
Therefore, the code changes addressed under Subsection 1.14.2.3 of the AISC code will not affect the safety margin of the Plant structures.
- 4.
Connections
- a.
Review of design documents indicates that both welded and bolted connections were used.
Furthermore, structural steel beams were primarily designed to carry construction loads rather than being designed as major load carrying members.
It was also found that the 1963 code gives more conservative connection strength using ASTM 307 bolts.
However, with ASTM 325 bolts, as used at the Palisades*
Plant, only a few lighter weight wide flange beams for each size may not be conservative.
In common design practice for beam selection, the limitation on lateral unsupported length tends to direct the designer to avoid lateral weak-ness by choosing a slightly heavier beam, which would nor-mally possess more than adequate web thickness for the compatible connection.
Therefore, the safety margin of the Plant structures has not been affected.
- b.
The restrained member connections were used only for pipe whip restraints in the Palisades Plant.
The review of pipe supports/restraints ls outside the scope of this SEP topic.
nul082-0123a-43-71 7
SEP Topic III-7.B
- 5.
Member Designed To Operate in an Inelastic Region All structural steel members were designed to function elasti-cally in the Plant.
The provision of AISC Manaul, Subsec-tion 2.9, does not apply.
- 6.
Short Brackets and Corbels The allowable *shear stress, 2¢1~ = 1.71~; was used in the c
c original design, which is more conservative th9n-;t;J1e limiting allowable shear stress, 3.72.;rr-, obtained from equation 11.28*
c of ACI 349-76, Section 11.13.2, for f' /f = 0.075, a/d = 1 and c
y Nu/Vu= 0.2 (Nu is usually negligible).
Therefore, the provi-sion stated in Section 11.13.2 is automatically met.
- 7.
Shear Walls Used as a Primary Load Carrying Member The stress conditions addressed under Section 11.16 of ACI 349-76 were reviewed under a separate SEP topic.
- 8.
Precast Concrete Structural Elements, Where Shear Is Not a Mea-sure of Diagonal Tension No precast concrete structural elements were used as part of any safety-related structures.
Therefore, this provision does not apply to the Palisades Plant.
- 9.
Concrete Regions Subject to High Temperature
- a.
The only high-temperature sources are high-temperature pip-ing and possible pipe breaks.
There is no high-temperature piping embedded inside the concrete structure.
Exposed high-energy lines are properly insulated.
During a pipe break event, localized high temperature dissipates within seconds.
Other temperature variations within the Plant do not warrant concern over structural integrity.
Therefore, this item does not apply.
- 10.
Columns With Spliced Reinforcement No columns are subject to stress reversal at the Palisades Plant.
The provision stated in Section 7.10.3 of ACI 349-76 does not apply.
- 11.
Containment and Other Elements Transmitting In-Plane Shear Stress This item has been deemed insignificant in accordance with NUREG/CR-2583, UCRL-53033.
nu1082-0123a-43-71 8
SEP Topic III-7.B
- 12.
Region of Shell Carrying Normal Loads The only shell structure at the Palisades Plant is prestressed concrete containment.
The applicable section of ACI 318-63 for shear is Section 2610 of Chapter 26, not Section 1707 of Chap-ter 17, which was cited in Appendix B of the Palisades FSAR.
Due to the presence of prestressing force, the entire concrete containment shell is under compression, except at the junction of the shell and the basemat under certain loading combinations (FSAR Table 5-1).
The provision stated in ACI 318-63 concern-ing ultimate shear is 3.5/£'"".
This value is less than the c
lower bound figure stipulated in CC-3421.6, ASME Code, Sec-tion III, Division 2 (4~), because f and fh are in c
m compression at all times.
This criterion is applicable only to nonprestressed concrete structures.
- 13.
Region of Shell Under Torsion No torsional moments exist in the region of the containment shell, except at major penetrations.
However, torsion at major penetrations is also insignificant in comparison with other primary loads.
Furthermore, additional shear reinforcements have been placed around.the penetrations.
Therefore, the con-sideration of torsion will not adversely impact the integrity of the containment structure.
- 14.
Elements Subject to Biaxial Tension Where reinforcements are required by design, adequate embed-ments shall be provided.
Development lengths provided at the Palisades Plant (24d) are generally more conservative than those based upon ACI 318-77 for the same grade of reinforcing steel, except for the few larger bars.
In addition, develop-ment length of 30d was provided at the beam-wall connection and rebars greater than #9 in the containment wall, even for Grade 40 steel.
Furthermore, for prestressed concrete contain-ment, all the primary loads are taken by prestressed tendons.
The reinforcements provided are mainly as temperature rebars.
Therefore, the structural integrity of the containment will not be affected by the code change.
The required development lengths for various grades of rein-forcements used at the Palisades Plant are tabulated in the following table:
nul082-0123a-43-71 9
e SEP Topic III-7.B ACI 318-77 231\\/16d 29Ab/16d Original Design Rebar F = 40 ksi f = 40 ksi f = 40 ksi y
y y
Size f' = 5 ksi f' = 3 ksi 24d 30d
-c
-c
- 4 12 inches 12 inches 12 inches 15 inches
- 5 12 ditto 12 ditto 15 ditto 19 ditto
- 6 12 II 13 II 18 II 23 II
- 7 14 II 17 II 21 II 26 II
- 8 18 II 23 II 24 II 30 II
- 9 23 II 29 II 27 II 34 II
- 10 29 II 37 II 30 II 38 II
- 11 36 II 45 II 34 II 42 II Where:
Ab = bar area in square inches d = diameter of the bar in inches
- 15.
Brackets and Corbels This item is a repetition of Item 6 above).
III.
CONCLUSION Specific evaluation effort made for this SEP topic and the results of the evaluations associated with other SEP topics seem to indicate strongly that the code change is not expected to change the safety mar-gin of the Palisades Plant structures.
Of the 19 items listed in the FRC report, 18 i~ems were found to be ei-ther inapplicable or to have no impact on the safety margin, according to the latest code requirements.
An action plan for the resolution of the remaining open item on steel embedment is currently being developed.
nul082-0123a-43-71 10