ML042050277
| ML042050277 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 07/22/2004 |
| From: | NRC/NRR/DLPM/LPD1 |
| To: | |
| References | |
| TAC MC1674 | |
| Download: ML042050277 (4) | |
Text
LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS 3.7 CONTAINMENT SYSTEMS (Cont) 4.7 CONTAINMENT SYSTEMS (Cont)
A. Primary Containment (Cont) A. Primary Containment (Cont)
- 7. Containment Atmosphere Dilution 7. Containment Atmosphere Dilution
- a. Within the 24-hour period after a. The post-LOCA containment placing the reactor in the Run Mode atmosphere dilution system shall be the Post - LOCA Containment functionally tested once per operating Atmosphere Dilution System must cycle.
be operable and capable of b. The level in the liquid N2 storage tank supplying nitrogen to the shall be recorded weekly.
containment for atmosphere dilution. If this specification cannot c. Not used.
be met, the system must be d. Once per month each manual or I restored to an operable condition power operated valve in the CAD within 30 days or the reactor must system flow path not locked, sealed be at least in Hot Shutdown within or otherwise secured in position shall 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. be observed and recorded to be in its
- b. Within the 24-hour period after correct position.
placing the reactor in the Run Mode, the Nitrogen Storage Tank shall contain a minimum of 1500 gallons of liquid N2. If this specification cannot be met the minimum volume will be restored within 30 days or the reactor must be in at least Hot Shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
Amendment No. 5H 206 3/4.7-1 0
LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS 3.7 CONTAINMENT SYSTEMS (Cont.) 4.7 CONTAINMENT SYSTEMS (Cont.)
B. Standby Gas Treatment System and B. Standby Gas Treatment System and Control Room High Efficiency Air Control Room High Efficiency Air Filtration Filtration System System
- a. Except as specified in 3.7.B.1.c or a. 1. At least once per operating cycle, 3.7.B.1.e below, both trains of the it shall be demonstrated that standby gas treatment shall be pressure drop across the operable when in the Run, Startup, combined high efficiency filters and and Hot Shutdown MODES, during charcoal adsorber banks is less movement of irradiated fuel than 8 inches of water at 4000 cfm.
assemblies in the secondary containment, and during movement 2. At least once per operating cycle, of new fuel over the spent fuel pool, demonstrate that the inlet heaters and during CORE ALTERATIONS, on each train are operable and are and during operations with a capable of an output of at least 20 potential for draining the reactor kW.
vessel (OPDRVs), 3. The tests and analysis of or Specification 3.7.B.1.b. shall be performed at least once per operating cycle or following the reactor shall be in cold painting, fire or chemical release in shutdown within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. any ventilation zone
- b. 1. The results of the in-place cold communicating with the system DOP tests on HEPA filters shall while the system is operating that show >99% DOP removal. The could contaminate the HEPA filters results of halogenated or charcoal adsorbers.
hydrocarbon tests on charcoal 4. At least once per operating cycle, adsorber banks shall show automatic initiation of
>99.9% halogenated hydrocarbon removal.
Amendment NoA 5,42, 50, 51, 52,112, 144, 151, 161, 170,187, 19 206 3/4.7-1 1
BASES:
3/4.7 CONTAINMENT SYSTEMS (Cont)
A. Primary Containment (Cont) wetwell pressure differential to keep the suppression chamber downcomer legs clear of water significantly reduced suppression chamber post LOCA hydrodynamic loads. A pressure of 1.17 psid is required to sufficiently clear the water legs of the downcomers without bubbling nitrogen into the suppression chamber at the 3.00 ft.
downcomer submergence which corresponds to approximately 84,000 ft.3 of water.
Maximum downcomer submergence is 3.25 ft. at operating suppression chamber water level. The above pressure differential and submergence number are used in the Pilgrim I Plant Unique Analysis.
Post LOCA Atmosphere Dilution In order to ensure that the containment atmosphere remains inerted, i.e. the oxygen-hydrogen mixture below the flammable limit, the capability to inject nitrogen into the containment after a LOCA is provided. A minimum of 1500 gallons of liquid N2 in the storage tank assures that a three-day supply of N2 for post-LOCA containment inerting is available. Since the inerting makeup system is continually functioning, no periodic testing of the system is required.
The Post-LOCA Containment Atmospheric Dilution (CAD) System is designed to meet the requirements of AEC Regulatory Guides 1.3, 1.7 and 1.29, ASME Section IlIl, Class 2 (except for code stamping) and seismic Class I as defined in the PNPS FSAR.
In summary, the limiting criteria are:
- 1. Maintain hydrogen concentration in the containment during post-LOCA conditions to less than 4%.
- 2. Limit the buildup in the containment pressure due to nitrogen addition to less than 28 psig.
- 3. To limit the offsite dose due to containment venting (for pressure control) to less than 300 Rem to the thyroid.
By maintaining at least a 3-day supply of N2 on site there will be sufficient time after the occurrence of a LOCA for obtaining additional nitrogen supply from local commercial sources. (1)The system design contains sufficient redundancy to ensure its reliability. Thus, it is sufficient to test the operability of the whole system once per operating cycle.
(1) As listed in Pilgrim Nuclear Power Station Procedure No. 5.4.6 "Post Accident Venting".
Revision 133/4.7-8
BASES:
3/4.7 CONTAINMENT SYSTEMS (Cont)
Due to nitrogen addition, the pressure in the containment after a LOCA will increase with time. Under the worst expected conditions the containment pressure will reach 28 psig in approximately 45 days. If and when that pressure is reached, venting from the containment shall be manually initiated per the requirements of 10CFR50.44. The venting path will be through the Standby Gas Treatment system in order to minimize the off site dose.
B.1 Standby Gas Treatment System The Standby Gas Treatment System is designed to filter and exhaust the reactor building atmosphere to the stack during secondary containment isolation conditions. Upon containment isolation, both standby gas treatment fans are designed to start to bring the reactor building pressure negative so that all leakage should be in leakage. After a preset time delay, the standby fan automatically shuts down so the reactor building pressure is maintained approximately 1/4 inch of water negative. Should one system fail to start, the redundant system is designed to start automatically. Each of the two trains has 100%
capacity.
High Efficiency Particulate Air (HEPA) filters are installed before and after the charcoal adsorbers to minimize potential release of particulates to the environment and to prevent clogging of the iodine adsorbers. The charcoal adsorbers are installed to reduce the potential release of radioiodine to the environment. The in-place test results should indicate a system leak tightness of less than 1 percent bypass leakage for the charcoal adsorbers and a HEPA filter efficiency of at least 99 percent removal of cold DOP particulates. The laboratory carbon sample test results should indicate a methyl iodide removal efficiency of at least 95 percent for expected accident conditions. The specified efficiencies for the charcoal and particulate filters is sufficient to preclude exceeding 10CFR100 guidelines for the accidents analyzed. The analysis of the loss of coolant accident assumed a charcoal adsorber efficiency of 95% and TID 14844 fission product source terms, hence, installing two banks of adsorbers and filters in each train provides adequate margin. A 20 kW heater maintains relative humidity below 70% in order to ensure the efficient removal of methyl iodide on the impregnated charcoal adsorbers.
Considering the relative simplicity of the heating circuit, the test frequency of once/operating cycle is adequate to demonstrate operability.
Air flow through the filters and charcoal adsorbers for 15 minutes each month assures operability of the system. Since the system heaters are automatically controlled, the air flowing through the filters and adsorbers will be <70% relative humidity and will have the desired drying effect.
Revision 13314.7-9