ML20155C202
| ML20155C202 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 09/29/1988 |
| From: | Bradham O SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | Hayes J NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NUDOCS 8810070283 | |
| Download: ML20155C202 (4) | |
Text
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10CFR50.36 gigcergas sectric a on comp ny g.s.ggagem gin,sgescmes Nucine operations SCEAG
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September 29, 1988 Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555 Attention: Mr. J. J. Hayes, Jr.
SUBJECT:
Virgil C. Summer Nuclear Station Docket No. 50/395 Operating License No. NPF-12 "Cor.tainment Structural Integrity" Surveillance Requirements
Reference:
September 16, 1986 SCE&G to Mr. H. R. Denton letter and September 14, 1988 NRC meeting with Mr. J. J. Hayes, Jr., Mr. C. P. Tan, and Mr. H. Ashar Gentlemen:
South Carolina Electric & Gas Company (SCE&G) agrees to the 7 quest made by Mr.
C. P. Tan as a condition for the approval of our September 16, 1986 request fJr change to "Containment Structural Integrity" Technical Specifications (3.6.1.6).
SCE&G will revise the Technical Specifications Bases (3/4.6.1.6) to include the reference to Surveillance 'iest Procedure STP-160.001, "Containment Tendon Test,"
Attachment I, for the purpose of specifying the tendons to be inspected and establishing the base values and normalizing factors for those tendons, see Enclosure.
If you should have any additional questions, please advise.
Very truly yo rs, O. S. Bradham 1
l WRH/0SB: led Enclosure c:
D. A. Nauman/J. G. Connelly, Jr./0. W. Dixon, Jr./T. C. Nichols, Jr.
E. C. Roberts W. A. Williams, Jr.
G. O. Percival J. Nelson Grace R. L. Prevatte J. J. Hayes, Jr.
J. B. Knotts, Jr.
General Managers H. G. Shealy C. A. Price /R. M. Campbell, Jr.
NSRC R. B. Clary RTS (TSP 860010)
M0!
K. E. Nodland NPCF J. C. Snelson file (813.20)
Su 258 HMsb P
Enclosure to Document Control Desk Letter Page 1 of 3
, September 29, 1988 CONTAINMENT SYSTEMS BASES 3/4.6.1.4 INTERNAL PRESSURE
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The limitations on reactor building internal pressure ensure that 1) the reactor building structure is prevented from exceeding its design negative pressure differential with respect to the outside atmosphere of 3.5 psig and l
- 2) the reactor building peak pressure does not exceed the design pressure of 57 psig during steam line break conditions.
The maximun peak pressure expected to be obtained from a steam line break event is 47.1 psig.
The limit of 1.5 psig for initial positive containment pressure will limit the total pressure to 47.1 psig which is less than design pressure and is consistent with the accident analyses.
3/4.6.1.5 AIR TEMPERATURE The limitations on reactor building average air temperature ensure that the overall containment average air temperature does not exceed the initial
=
temperature condition assumed in the accident analysis for a steam line break accident.
3/4.6.1.6 REACTOR BUILOING STRUCTURAL INTEGRITY This limitation ensures that the structural integrity of the containment will be maintained comparable to the original design standards for the life of l
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the facility.
Structural integrity is required to ensure that the containment will withstand the maximum pressure of 47.1 psig in the event of a steam line break accident.
The measurement of containment tendon lift off force, the I
tensile tests of the tendon wires, the visual examination of tendons, anchorages and exposed interior and exterior surfaces of the containment, and the Type A leakage test are sufficient to demonstrate this capability.
The tendon lif t off forces are evaluated to ensure that 1) the rate of I
tendon force loss is within predicted limits, and 2) a minimum required prestress level exists in the containment.
In order to assess the rate of force loss, the lift off force for a tendon is compared with the force predicted for the tendon times a reduction factor of 0.95.
This resulting force is referred to as the 95% Base Value.
The predicted tendon force is equal to the original stressing force minus losses due to elastic shortening of the tendon, stress relaxation of the tendon wires, and creep and shrinkage of the concrete.
The 5% reduction un I,he predicted force is intended to compensate for both uncertainties in the prediction techniques for the losses and for inaccuracies in the lift-off force measurements.
a SUMMER - UNIT 1 B 3/4 6-2 Amendment No. 49
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Enclosure to Document Control Desk Letter Page 2 of 3
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, September 29, 1988 CONTAINMENT SYSTEMS BASES REACTOR BUILDING STRUCTURAL INTEGRITY (Continued)
In order for the tendon ifft off force to be indicative of the level of prestress force in the containment, each measured force must be adjusted for the known differences which exist among the tendons due to original stressing force and elastic shortening loss.
of a Normalizing Factor (NF (t)).This adjustment is accomplished through the use which results in the Normalized Lift Off Force.This factor is added to the lift off force, 4
given by:
The Normalizing Factor is NF (t) = {F,y,(o) - F (o)} {1 -
I*O 9
9 0
s 2N
[F,y,(o) - F (o)) is the group average lock-off force at original stressing, 4
minus the original stressing force for the specific tendon.
SR(t) is stress relaxation (percent) which occurs at time t after original stressing.
AFf,isthetotalelasticshorteningtendonforceloss.
7 n is the stressing sequence comprising the specific tendon.
a k
N is the total number of stressing sequences for the group of tendons i
1 which comprise the specific tendons, i
i i refes to the specific tendon.
t refers to the time after original stressing of the current inspection
) Ls tav-period.
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A ss.e. r The surveillance requirements for demonstrating the containment's structural g integrity are in compliance with the recommendations of Proposed Revision 3 to Regulatory Guide 1.35, "Inservice Inspection of Ungrouted Tendons in Prestressed Concrete Containments," April 1979, except that in place of the Lower Limit and 90% Lower Limit defined by these Regulatory Guides, the 95% Base Value and 90%
i Base Value, respectively, are used.
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x.j SUMMER - UNIT 1 B 3/4 6-2a
e Enclosure to Document Control Desk Letter l
Page 3 of 3 September 29, 1988 Insert "A" The Base Values and Normalizing Factors of tendons selected for surveillances 4 through 10 are listed in Enclosure 8 of Attachment I to the Virgil C.
Summer Nuclear Station Surveillance Test Procedure STP-160.001, "Containment Tendon Test," Revision 2.
Based on experience from the first three tendon surveillances, STP-160.001 may have to be revised to add Base Values and Normalizing Factors for additional or alternate tendons not previously listed, but are required for a particular surveillance. The revision level of STP-160.001, as listed above, need not be updated in this Technical Specification where a change to Enclosure 8 of Attachment I only adds Base Values and Normalizing Factors for tendons not previously listed, but were used as additional or alternates for a particular surveillance.
Base Values and Nonnalizing Factors listed in Enclosure 8 of Attachment I of STP-160.001 will not be revised prior to NRC approval, t
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