ML18012A398

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Proposed Tech Specs Bases Change to 3/4.6.1.4 & 3/4.6.1.6 Changing Calculated Peak Pressure for MSLB Event
ML18012A398
Person / Time
Site: Harris Duke Energy icon.png
Issue date: 10/08/1996
From:
CAROLINA POWER & LIGHT CO.
To:
Shared Package
ML18012A394 List:
References
NUDOCS 9610160203
Download: ML18012A398 (2)
v • d • e


Text

.. 3/4..6 CONTAINMENT YSTEMS BASES 3/4.6. 1 PRIMARY CONTAINMENT 3/4.6.1. 1 CONTAINMENT INTEGRITY Primary CONTAINMENT INTEGRITY ensures that the release of radioactive materials from the containment atmosphere will be restricted to those leakage paths and associated leak rates assumed in the safety analyses.

This restriction, in conjunction with the leakage rate limitation, will limit the SITE BOUNDARY radiation doses to within the dose guideline values of 10 CFR Part 100 during accident conditions.

3/4.6. 1.2 CONTAINMENT LEAKAGE The limitations on containment leakage rates ensure that the total containment leakage volume wi 11 not exceed the value assumed in the safety analyses at the peak accident

pressure, P,.

As an added conservatism, the measured overall integrated leakage rate is further limited to less than or equal to 0.75 L,.

during performance of the periodic test, to account for possible degradation of the containment leakage barriers between leakage tests.

The surveillance testing for measuring leakage rates is consistent with the requi rements of Appendix J of 10 CFR Part 50.

A one time extension of the test interval specified in Surveillance Requirement 4.6. 1.2.a is allowed for performance of the third Type A test of the first 10-year service period during Refueling Outage No. 7.

3/4.6. 1.3 CONTAINMENT AIR LOCKS The limitations on closure and leak rate for the containment air locks are required to meet the restrictions on CONTAINMENT INTEGRITY and containment leak rate.

Surveillance testing of the air lock seals provides assurance that the overall air lock leakage will not become excessive due to seal damage during the intervals between air lock leakage tests.

3/4.6. 1.4 INTERNAL PRESSURE The limitations on containment internal pressure ensure that:

(1) the containment structure is prevented from exceeding its design negative pressure differential with respect to the outside atmosphere of -2 psig, and (2) the containment peak pressure does not exceed the design pressure of 45 psig.

The maximum peak pressure expected to be obtained from a postulated main steam line break event is 41.2 psig using a value of 1.9 psig for initial positive containment pressure.

However, since the instrument tolerance for containment ressure is 1.32 psig and the high-one setpoint is 3.0 psig, the pressure imit was reduced from the high-one setpoint by slightly more than the tolerance and was set at 1.6 psig.

This value will prevent spurious safety injection signals caused by instrument drift during normal operation.

The

-1" wg was chosen to be consistent with the initial assumptions of the accident analyses.

HNP-96-064 SHEARON HARRIS - UNIT 1 B 3/4 6-1

'96iOi60203 96f008 I

i PDR ADQCK 05000400 P

PDR I

COtPAINMENT SYSTEMS BASES 3/4.6. 1. 5 AIR TEMPERATURE The limitations on containment average air temperature ensure that the overall containment average air temperature does not exceed the initial temperature condition assumed in the safety analysis for a LOCA or steam line break accident.

Measurements shall be made at all listed locations, whether by fixed or portable instruments, prior to determining 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 withstand the maximum pressure of a postulated main steam line break accident (41.2 psig).

A visual inspection in conjunction with the Type A leakage tests is sufficient to demonstrate this capability.

3/4.6. 1. 7 CONTAINMENT VENTILATION SYSTEM The 42-inch containment preentry purge makeup and exhaust isolation valves are required to be sealed closed during plant operations in MODES 1, 2, 3 and 4 since these valves have not been demonstrated capable of closing during a

LOCA or steam line break accident.

Maintaining these valves sealed closed during these MODES ensures that excessive quantities of radioactive materials will not be released via the Pre-entry Containment Purge System.

To provide assurance that these containment valves cannot be inadvertently 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 Normal Containment Purge System is restricted to the 8-inch purge makeup and exhaust isolation valves since, unlike the 42-inch valves, the 8-inch valves are capable of closing during a

LOCA or steam line break accident.

Therefore.

the SITE BOUNDARY dose guideline of 10 CFR Part 100 would not be exceeded in the event of an accident during normal containment PURGING operation.

The'otal time the Normal Containment Purge System isolation valves may be open during MODES 1. 2. 3, and 4 in a calendar year is a function of anticipated need and operating experience.

Only safety-related reasons:

e.g..

containment pressure control or the reduction of airborne radioactivity to facilitate personnel access for surveillance and maintenance activities, may be used to justify the opening of these isolation valves during MODES 1, 2, 3, and 4.

Leakage integrity tests with a maximum allowable leakage rate for containment purge makeup and exhaust supply valves will provide early indication of resi 1-ient material seal degradation and will allow opportunity f'r repair before SHEARON HARRIS - UNIT 1 B 3/4 6-2 HNP-96-064

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