ML20079G208
| ML20079G208 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 06/02/1982 |
| From: | VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | |
| Shared Package | |
| ML20079G201 | List: |
| References | |
| NUDOCS 8206080355 | |
| Download: ML20079G208 (4) | |
Text
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VYNPS mm cno 23 0 O-hCD 3.7 LIMITING CONDITIONS FOR OPERATION 4.7 SURVEILLANCE REQUIREMENTS OO n t) c.
Reactor operation may continue for (4) A drywell to suppression Eg o
fifteen (15) days provided that at chamber leak rate test shall least one position alarm circuit for demonstrate that with an go each vacuum breaker is operable and initial differential pressure 72mo each suppression chamber - drywell of not less than 1.0 psi, the
$$dM vacuum breaker is physically verified differential pressure decay to be closed immediately and daily rate shall not exceed the thereafter.
equivalent of the leakage rate through a 1-inch orifice.
7.
If Specifications 3.7.A.1 through 3.7.A.6 cannot be met, an orderly shutdown shall be initiated immediately and the reactor shall be in a cold shutdown condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
4 8.
Oxygen Concentration a.
The primary containment atmosphere 8.
Oxygen Concentration shall be reduced to less than 4 percent oxygen with nitrogen gas when The primary containment oxygen in Run mode except as specified in concentration shall be measured and Specification 3.7. A.8.b and 3.7. A.8.c.
recorded on a weekly basis.
b.
Within the 24-hour period after placing the reactor in the Run mode, the containment atmosphere oxygen concentration shall be reduced to less than 4 percent and maintained in this condition. Deinerting may commence 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> prior to shifting the mode switch out of the Run mode.
129
vtars 3.7 LIMITING CONDITIONS FOR OPERATION 4.7 SURVEILLANCE REQUIREMENTS c.
The containment atmosphere oxygen 9.
Drywell/ Suppression Chamber d/p concentration (as noted in 3.7.A.8.a) may be increased to greater than 4 a.
The differential pressure between the percent oxygen for the purposes of drywell and suppression chamber shall containment inspection and minor be recorded once per shif t.
maintenance, provided that the conditions required by Specification b.
The operability of the low 3.7.A.8.a are re-established within 24 differential pressure alarm shall be hours.
verified once per week.
9.
Drywell/ Suppression Chamber d/p a.
Differential pressure between the drywell and suppression chamber shall be maintainedJtl.7 psi except as specified in 3.7.A.9.b and 3.7. A.9.c below.
b.
The21.7 psi differential pressure shall be established within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> subsequent to placing the reactor in the Run mode. The differential pressure may be reduced to 41.7 psi 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> prior to commencing a cold shutdown.
c.
The differential pressure may be reduced to41.7 psi for a maximum of four (4) hours (period to begin when the AP is reduced to 41.7) during required operability testing of the HPCI system pump, the RCIC system pump, the drywell-suppression chamber vacuum breakers, and the suppression chamber-reactor building vacuum breakers and SBGTS testing. The differential pressure may be reduced to 41.7 psi for a maximum of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> for the purposes of containment inspection and minor maintenance per 129a Specification 3.7.A.8.c.
A VYNPS 3.7 LIMITING CONDITIONS FOR OPERATION 4.7 SURVEILLANCE REQUIREMENTS 10.
If the specification of 3.7.A.8 or 3.7.A.9 cannot be met, and the required conditions cannot be restored within the subsequent six (6) hour period, an orderly shutdown shall be initiated and the reactor shall be l
in a Hot Shutdown condition in six (6) hours and a Cold Shutdown condition in six (6) hours and a Cold Shutdown condition in the following eighteen (18) hours.
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129b e
VYNPS Basis 3.7.A. (cont'd) is based on the requirement of 10CFR50.44 on the recommendation of the Advisory Tha' requirement to inert the containment I
Committee on Reactor Safeguards. This recommendation, in turn, is based on the assumption that several percent of the zirconium in the core will undergo a reaction with steam during the loss-of-ccolant accident. This reaction would release sufficient hydrogen to result in a flammable concentration in the primary containment building. The oxygen concentration is, therefore, kept below 4% (except for minor maintenance / inspection) to minimize the possibility of hydrogen combustions.
Deinerting Primary Containment for on-line containment entries is permitted for up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> for emergency maintenance / inspections based on the following:
1.
On-line containment entries are short in duration and few in number. Therefore, hydrogen protection, provided by inerting, is insignificant 1y affected by these entries.
1 2.
Brief on-line containment entries for minor repairs and inspection, typically enhance reactor safety and perfo rmance.
General Electric has estimated that less than 0.1% of the zirconium would react with steam following a loss-of-coolant due 1
to operation of emergency core cooling equipment. This quantity of zirconium would not liberate enough hydrogen to form a combustible mixture.
a Standby Gas Treatment System and Secondary Containment System c.
The secondary containment is designed to minimize any ground level release of radioactive materials which might result from a serious accident. The reactor building provides eecondary containment during reactor operation, when the drywell is sealed and in service; the reactor building provides primary containment when the reactor is shutdown and the drywell is open, as during refueling.
Because the secondary containment is an integral part of the complete containment system, secondary containme,nt'is required at all-times that primary containment is required except, however, for initial fuel 1,oading an,d-low power physics testing.
The Standby Gas Treatment System s designed to filt'er and exhaust the reactor building atmosphere to the stack during secondary containment isolation conditions, with a minigum release of radioactive materi.als from the reactor building to s
the environs. To ensure that the Standby Gas Treatment System will be effective in removing radioactive contaminants from,-
the reactor building air, the system is tested periodically to meet the intent of ANSI N510r1975.
Both standby gas treatment fans are designed to aptomatical)y start upon containment isolation and th maintsin the reactor building pressure to approximately a negative 0.15-in'ch water gauge pressure; all leakage should be in-leakage. SHould the fan fail to start, the redundant alternate fan and f;11ter system is designed to start automatically. Each of the two fans has 100% capacity. This substantiates the availability'of the operable circuit and results in no added risk; thus, reactor operation or refueling operation 'can continue. If neither circuit is operable, the plant is brought to a condition where the system is not required.
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