ML20062G624
| ML20062G624 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 01/02/1979 |
| From: | Daltroff S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Ippolito T Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7901100236 | |
| Download: ML20062G624 (3) | |
Text
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PHILADELPHIA ELECTRIC COMPANY 2301 M ARKET STREET P.O. BOX 8699 PHILADELPHI A. PA.19101 swittes L. caLTnorr atactnec Pn o som f
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January 2, 1979
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Docket Nos.:
_5.0-- 2 7 7-50-278 F
Mr. Thomas A.
Ippolito, Chief Operating Reactors Branch #3 Division of Operating Reactors United States Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Ippolito:
This is in response to your letter to E. G.
Bauer, Jr.,
dated November 29, 1978 on the subject of containment purging during normal plant operation and safety actuation signal circuits which incorporate manual override features.
Your concerns addressed p rimarily to PWR containment purging.
A discussion of your concerns as the-y pertain to Peach Bottom Units 2 and 3 follows:
The Containment Atmospheric Control System and Containment Atmospheric Dilution System are utilized to control the containment atmosphere during normal plant operations and post-loss-of-coolant accident (LOCA), respectively.
The portions of these systems used for containment venting are shared.
All vent lines discharge to the Standby Gas Treatment System (SGTS).
The torus and drywell are each provided with two 18 inch diameter penetrations for deinerting during shutdowns, l
ventilation during outages, and inerting during startups.
These 18 inch penetrations are each previded with two system isolation valves.
The butterfly valves used in this service are designed to maintain a tight seal against design post-LOCA containment pressures.
These isolation valves may be operated from the control room during normal plant operations and are automatically closed upon receipt of a containment isolation signal.
The l
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Mr.
T.
A.
Ippolito
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4 containment isolation signal to these valves cannot be bypassed or over-ridden.
In addition to the above 18 inch penetrations, the torus and drywell are each provided with small lines f or cont rolled purging / venting during plant operation and post-LOCA.
These small lines are either one inch or two inch in diameter.
Each is provided with two 1 inch system isolation valves (either two globe valves or a globe and a check).
The valves used in this i
service are designed for very rapid closure and tight seal against design post-LOCA containment pressures.
The globe isolation valves may be operated from the control room during normal operation and are automatically closed upon receipt of a containment isolation signal.
For post-LOCA venting, these isolation valves may be opened by taking the reactor mode switch out of the RUN position and utilizing keylocked bypass switches.
This override of the isolation signal is alarmed in the control room.
Operating experience has shown that it has been necessary to periodically purge / vent the containments during normal plant operation to control containment pressure, maintain l
torus-to-drywell differential pressure, and/or maintain an a
inert atmosphere.
Drywell venting during normal power operation is accomplished either through the one inch vent valves or by
" Batching" through the 18-inch valves such that at no time are both 18-inch valves open.
It is important to note that an isolation signal to the 18 inch valves cannot be manually overriden.
All purging and venting is through the Standby Gas i
Treatment System as required by Te.?hnical Specification.
Acceptance Criteria 8 of Standard Review Plan 6.2.4 addresses general requirements for containment purging and venting during operation (hot shutdown, hot stanoby, startup and power operation) and refers to Branch Technical Position CSB 6-4 for additional guidance.
The design and operation of the PBAPS
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containment atmospheric systems using the one inch valves and the
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18 inch valves in the " Batching" mode meet the intent of all BTP requirements and far exceed the design requirements at the time of system design and construction.
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The Peach Bottom Units 2 and 3 Technical Specifications presently require that containment be inerted during operation.
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Recent NRC and industry evaluations indicate that containment-inerting is not likely requ' ired.
Philadelphia Electric Company is presently developing the necessary justification for deleting the containment inerting requirement at Peach Bottou.
Deletion of the inerting requirement will substantially reduce the l
necessity to utilize-the 18 inch valve flow path during-startup l
and shutdown and will greatly reduce all purging requirements.
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In light of the above Philadelphia Electric Company, as t
per page 3, paragraph (2) of your letter, will submit a Technical-l
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Mr..T.
A.
Ippolito Page 3
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Specification change limiting the use of the 18 inch valve flow path (i.e. both valves open simultaneously) during operation.
We anticipate completion of the required analyses-and submittal of an Technical Specification change by March 15, 1979.
- Further, pending submittal of our Technical Specification change request and your review of our justification, we propose limiting the use of the 13 inch valve flow path (i.e. both valves open simultaneously) during operation to 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> per year.
Additionally, as was requested by your letter, the design of all isolation actuation circuits which incorporate a manual override feature at Peach Bottom Atomic Power Station Units 2 and 3 have been reviewed.
During our investigation, it was determined that overriding one isolation actuation signal does not cause the bypass of any other safety actuation signal, that sufficient physical features are provided to facilitate adequate administrative controls, and that the use of each manual override is annunciated at the system level for every system impacted.
Should you require any additional information or have 4
any questions, please contact us.
Very truly yours, s
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