ML20237C454
| ML20237C454 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 12/14/1987 |
| From: | HOUSTON LIGHTING & POWER CO. |
| To: | |
| Shared Package | |
| ML20237C439 | List: |
| References | |
| NUDOCS 8712210321 | |
| Download: ML20237C454 (2) | |
Text
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ATTACHMENT )
. ST.HL AE. ;2%
I CONTAINMENT SYSTEMS PAGE I OF 2 l
SURVEILLANCE REQUIREMENTS (Continued) b.
Performing tendon detensioning, inspections, and material tests on a previously stressed tendon from each group (inverted U and hoop).
A randomly selected tendon from each group shall be completely.
'detensioned in order to identify broken or damaged wires and deter-j mining that over the entire length of the removed wire that:
i (ra.
c+
ar<
1)
The tendon wires have net undwgone corrosion, cracks, ora d physical damage." excess of th:t alie-ed by A5TM A421-77.
1 2)
There are not changes in the presence or physical appearance of the sheathing filler grease, and 3)
A minimum tensile strength of 240,000 psi;(guaranteed ultimate strength of the tendon material) for at least three wire samples
{
(one from each end and one at mid-length) cut from each removed j
wire.
Failure of any one of the wire samples to meet the mini-mum tensile strength test is evidence of abnormal degradation of the containment structure.
.)
Performing tendori retensioning of those tendons detensioned for c.
inspection to their observed lif t-off force with a tolerance limit of +6%.
During retensioning of these tendons, the changes in load
{
and elongation should be measured simultaneously at 20%, 60%, and 100%
of the maximum jacking force.
If the elongation corresponding to a specific load differs by more than 5%.from that recorded during installation, an investigation should be made to ensure that the difference is not related to wire failures or slip of wires in anchorages; d.
Assuring the observed lift-off stresses exceed the average minimum design value given below, which are adjusted to account for elastic and time dependent losses; and Inverted U 126 ksi Hoop:
Cylinder 128 ksi Dome 123 ksi
- Verifying the OPERABILITY of the sheathing filler grease by:
e.
1)
No voids in excess of 5% of the net duct volume i, 2)
Minimum grease coverage exists for the different parts of the anchorage system, and 3)
The chemical properties of the filler material are within the tolerance limits as specified by the manufacturer.
8712210321 871214
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PDR ADOCK 05000498 P
PDR SOUTH TEXAS - UNIT 1 3/4 6-10
ATTACHMENT I CONTAINMENT SYSTEMS
^
E BASES 3/4.6.1.5 AIR TEMPERATURE The limitations on containment average air temperature ensure that the over -
all containment average air temperature does not exceed the initial temperature
]
condition assumed in the. safety analysis for a LOCA or steam line break-i accident.
Measurements shall be made by fixed instruments, prior to determin-
~
ing the average air temperature.
3/4.6.1.6 CONTAINMENT 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 the facility.
Structural integrity is required to ensure that the containment will with-stand the maximum pressure of 37.5 psig in the event of a LOCA or steam line break accident.
The measurement of containment tendon lif t-off force, the 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.
LssW The Surveillance Requirements for demonstrating the containment's structural integrity are in compliance with the recommendations of wnes Regulatory Guide 1.35, " Inservice 5=R L of Ungrouted Tendons in Prestressed Concrete 2
Containment Structures," WhM, and proposed Regulatory Guide 1.35.1, " Deter--
mining Prestressing Forces for Inspection of Prestressed Concrete Containments,"
April 1979.
The required Special Reports from any engineering evaluation of containment abnormalities shall :nclude a description of the tendon condition, the condition of the concrete >(espc.ially at tendon anchorages), the inspection procedures, the tolerances on cracking, the results of the engineering evaluation, and the correc-tive actions taken.
3/4.6.1.7 CONTAINMENT VENTILATION SYSTEM The 48-inch containment purge supply and exhaust isolation valves are i
required to be sealed closed during plant operations since these valves have not been demonstrated capable of closing during a LOCA or steam line break accident.
Maintaining these valves sealed closed during plant operation ensures that exces-sive quantities of radioactive materials will not be released via the Containment Purge System.
To provide assurance that these containment valves cannot be inad-vertently opened, the valves are sealed closed in accordance with Standard Review Plan 6.2.4 which includes mechanical devices to seal or lock the valve closed, or prevents power from being supplied to the valve operator.
The use of the containment purge lines is restricted to the 18-inch purge
)
supply and exhaust isolation valves since, unlike the 48-inch valves, the 18-inch 1
valves are capable of closing during a LOCA or steam line break accident.
There-SOUTH TEXAS - UNIT 1 B 3/4 6-2 J
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