ML19351F289
| ML19351F289 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 11/04/1980 |
| From: | William Jones OMAHA PUBLIC POWER DISTRICT |
| To: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| IEB-80-11, NUDOCS 8101120161 | |
| Download: ML19351F289 (5) | |
Text
CENTRAL FILES PDR:HQ LPDR ii
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Omaha Public Power District STATE 1623 MARNEY OMAMA. NESRASMA 66102 TELEPHONE $36 4000 AREA CODE 402
- Icvember k, 1980 g
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$2 s.
Mr. K. V. Seyfrit, Director L1 U. S. :luelear Regulatory Cc==ission T:
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Office of Inspection and Enforcement j'
Eerien I7 5'
615 Eyan Plaza Drive N
5 Suite 1000
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S Arlington, Texas 76011
Reference:
Docket No. 50-285
Dear Mr. Seyfrit:
In response to IE Eulletin 80-11, Iten 2.b., the Omaha Public Power District is forwarding the attached report. The attached report supple-ments the District's first submittal in response to the bulletin, dated July 7, 1980, and co=pletes our response to all bulletin requirements.
Sincerely,
'4. C. Jones Division Manager Production Operations
'4CJ/KJM/TLP:j==
Attachment ec:
U. S. Nuclear Regulatory Co==ission Cffice of Inspection and Enforcement
'4ashington, D. C.
20555 leBoeuf, Lamb, Leiby a MacEae 1333 New Ha=pshire Avenue, :I.
'4.
'4ashington, D. C.
20036 Subscribed and sworn to before te this day of
, 1980.
Notary Public saning monar-siese d me.na Culms C. WOOD sa##*"s.wam 3 i o 1120 \\ bl
2.b.
Sub=it a written report upon completion of the re-evaluation progra=.
The report shall include the following infor=ation.
Recuest (1)
Describe, in detail, the function of the masonry valls, the configurations of these valls, the type and strengths of the
=aterials of which they are constructed (=ortar, grout, concrete and steel), and the reinforcement details (hori: ental steel, vertical steel, and =asonry ties for multiple vythe construction).
A vythe is considered to be (as defined by ACI Standard 531-1979) "each centinuous vertical section of a vall, one masonry unit or grouted space in thickness and 2 in. mini =um in thick-ness."
Respense All of the 42 valls under censideration function as partitions only. None are load-bearing valls and none are shear valls.
All of the Type I and II valls extend from supporting concrete floor structure to the underside of concre'ce slabs and/or bea=s above.
?/pe I and II valls are hollow concrete casonry units with ortar in all horizontal and vertical joints and were constructed under specifications which included the following requirements:
Concrete Masonry Units - ASIM C90, Type P-II Mortar - AS31 C270, ?ype N Joint Eeinforcine - Truss type, 3/16" dia=eter side wires and No. 9 diagonal wires, galvanized, 16 inctes on center Vertical Ears - ASTM 615-68, Grade 40 Vertical Joints
" Running bond" Installatien - Flumb, true to lines, full mortar joints, 3/8" joints, 400F minimum ambient temperature Type III valls are used for shielding valls and are constructed of solid concrete units stacked with no =ortar.
A more detailed description of the use of the 42 valls was provided-in Table 1 attached to the
-District's letter dated July 7, 1980.
Request (ii)
Describe the construction practices employed in the construction of these valls and, in particular,- their adequacy. in preventing significant voids or other weaknesses in any =ortar, grout, or concrete fill.
-2 i
Response
The Type I and II valls vere constructed using local building procedures. However, no quality control was utilised, or at least documented.
However, a close visual examination of the valls was performed. Based on r_n examination of the valls, it has been cencluded that they =ay be evaluated on the basis of the specified req". ire =ents below, with one exceptien.
The exception is that the integrity of the valls under load should not be presu=ed to depend on continuity of horizontal joint reinforcing.
Recuest (iii)
The re-evaluation report should include detailed justificatien for the criteria used.
References to exitting codes or test data may be used if applicable for the : dant conditions.
The re-evaluation should specifically address the following:
(a)
All postulated loads and load combinations should be evaluated against the corresponding re-evaluation accept-ance criteria.
The re-evaluation should consider the loads from safety and non-safety-related attach =ents, differential floor displacement and thermal effects (or detailed justification that these can be considered self limiting and cannot induce brittle failures), and the effects of any potential cracking under dynamic loads.
Describe in detail the methods used to account for these factors in the re-evaluation and the adequacy of the acceptance criteria for both in-plane and out-of-plane loads.
(b)
The techanis: for load transfer into the masonry walls and ccatulated failure modes should be reviewed.
For multiple vythe valls in which ec=posite behavior is relied upon,.
desc~'.be the methods and acceptance criteria used to asa re that these valls vill behave as composite valls, especially with regard to shear and tension transfer at the wythe interfaces.
'Jith regard to local loadings such as piping and equipment support reactions, the acceptance criteria should assure that the loads are adequately transferred into the vall, such that any assumptions regarding the behavior of the valls are appropriate.
Include the potential for block pullout and the necessity -
for tensile stress transfer through bond at the vythe interfaces.
Fesnonse It has been concluded that only seismic loads which are dependent on the = ass and properties of the valls and which act in a direction normal to the vall surfaces need to be considered.
Trs methods used to censider the stability of the valls under seismic loads presume that cracking could occur.
The effects of differential fleor move-
=ent and te=perature -hanges are, therefore, not considered zicnificant.
, Re-evaluation Criteria and Conclusions The FSAR ground acceleration values are 0.03 g fer the " design earthquake" and 0.17 g for the "taximum hypothetical earthquake".
These values correspond to 1979 Uniforn Building Code (U.S.C.) earthquake enes 2 and 3, respectively.
The max 1=un earthquake intensity experi-enced at the site in the period for which there are records of any kind probably occurred in Nove=ber of 1877 in connection with a shock near Lincoln, Nebraska.
The site intensity is believed to have been about Modified Mercalli V.
(See FSAR) The U.3.C. earthquake zone which corresponds to M.M. V intensities is :ene 1.
The approximate ground acceleration from M.M. V intensity is 0.015 g.
The FSAR ground ac-celeration values are, therefore, approximately 5 and 11 times the probable ground acceleration experienced during the Novetter 1877 earthquake.
The 1979 U.S.C. requires that " interior non-bearing valls and partitions" be designed for " lateral forces in accordance with the following formula":
p = ZIC W (eq. 12-8, p. 131)
F pp where F is the lateral force on the vall, Z is a numerical coefficient p
dependent on the :ene, I is the occupancy Importance Factor, C is 0.30, p
and W is the dead load of the vall.
The values for Z are:
p Zone 1 - 3/16 Zone 2 - 3/8 Zone 3 - 3/h The value of I for " essential facilities" is 1.50.
The coefficient (ZIC ) values are therefore:
p Zone 1 - 0.08hh Zone 2 - 0.1688 Zone 3 - 0.3375 Eased on an analysis using ordinary principles of mechanics and certain naterial properties derived from the 1979 U.3.C. for valls constructed without "special inspection", the followin; conclusions have been reached:
(a)
All Types I and II valls vill sustain the lateral forces specified by the 1979 U.S.C. for Zone 3 with no signi-ficant loss of function and with no damage to safety related systems and equipment.
(b)
All Type III valla vill sustain the lateral forces speci-fled by the 1979 U.S.C. for Zone 2 with no significant loss of function and with no damage to safety relatei syste..s and equipment.
_h-(c)
Of the 20 Type III valls, 13 vill sustain the lateral forces specified by the 1979 U.S.C. for Zone 3 with no significant loss of function and with no da= age to safety related systems and equipment.
The equivalent static forces derived from the 1979 U.S.C. are understood to be intended for use along with certain other related U.3.C. requirements, especially the requirements for vall reinforcing in Zones 2 and 3 The requirements for vall reinforcing are understood to bv related to the desirability of ductile behavior.
It has been concluded that all the valls will survive an earthquake having an intensity about five times greater than the November 1877 intensity and vill also survive the Operating Easis Earthquake and that the valls should, therefore, be considered acceptable for a reasonable period of time.
However, it has also been concluded that seven of the unreinforced shield valls may not survive a safe shutdown earthquake; therefore, these valla vill be provided with supplemental support.
The District vill provide the Co==ission with its schedule for i=plementing these modifications by December 15, 1960.