ML20198D905
| ML20198D905 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 11/06/1985 |
| From: | Daltroff S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8511130059 | |
| Download: ML20198D905 (4) | |
Text
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PHILADELPHIA ELECTRIC COMPANY 23O1 M ARKET STREET P.O. BOX 8699 PHILADELPHIA. PA 19101 SHIELDS L. D.s LTROFF sjeEE"/.U'Eo,.
November 6, 1985 Docket Nos. 50-277 50-278 Mr.. John F.
Stolz, Chief Operating Reactors Branch #4 Division of. Licensing U.S. Nuclear Regulatory Commission Washington, D.C.
20555
SUBJECT:
Peach Bottom Atomic Power Station Safety-Grade Pneumatic Supply System for Containment Purge / Vent Valve Inflatable Seals and Controls
REFERENCE:
Correspondence dated March 20, 1985 G.
E. Gears, NRC, to Philadelphia Electric Company
Dear Mr. Stolz:
This letter confirms a proposal to install a new
-pneumatic supply system for.certain valves as described to the NRR staff in an October 29, 1985 telephone conversation.
The prc.aosal responds to a request from the NRC (referenced letter) to improve the long-term availability of the safety-grade pneumatic supply system for the containment purge / vent valve inflatable seals and controls following an accident coincident with a-loss of the normal plant instrument air system.
The proposed modification and an appropriate testing requirement are as follows:
Proposed Modification:
The Containment Atmospheric Control System (CACS) purge and vent line isolation valves consist of 9 butterfly valves on each unit equipped with an inflatable seal between the disc and seat.
The Containment Atmospheric Dilution System (CADS) vent system utilizes 6 air operated valves on two trains per unit j
whose operation is required to control post-accident combustible gas-concentrations in the containment.
Individual safety-grade I
ol high pressure gas cylinders are presently installed for each c
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- Mrs John
- F.iStolz:
November 6, 1985 cp Page 2
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in
-valve described above in parallel with the non-safety-grade
' instrument air, supply.
~ A modification is propose'd to utilize the existing CADS
' liquid nitrogen-storage tank to _ supply a source of pneumatic
' pressure.to the CACS and CADS valves, replacing the individual tbottle supplies.
A hard-piped safety-grade pneumatic supply
'would be installed to each of these valves.
The pneumatic, supply would come ' rom-the vapor space of f the existing safety-grade CADS nitrogen tank though a pressure reducing station.
During
/
-normal' operations, manifold presure would be maintained by the plant _iastrument air system.
A sketch (Figure 1) of the proposed system design ~ is attached.
Proposed Surveillance Requirements The.following surveillance requirement is proposed to
- demonstrate the operability of this new supply system.
"The valve operator and inflatable' seal. safety-grade pneumatic-supply system shall:be demonstrated operable for the CACS and CADS isolation valves by:-
1.
Verifying at least once per day that the backup nitrogen supply inventory is adequate for maintaining the
. operability. of the. valves,
n
'2.
Once per operating-cycle, conduct a' functional test that
. demonstrates - the operability of.the backup nitrogen supply system upon loss of the normal supply system.
A leak rate test of the supply system is not deemed to be necessary since 'all portions of the supply system are '
pressurized _ continuously by either the normal or backup pneumatic. supply when the valves 'are required to be operational.
All but minor leaks would be'. evident by' observation or loss of CADS nitrogen inventory.
Minor leaks are not a1 safety concern since the storage tank is accessible duringt a severe accident and can be recharged from liquid '
nitrogen trucks.
As stated in the October 29,~1985 telecon, the integrated pneumatic supply system will be installed within two fyears:following NRC approval of-this proposal.
A license amendment application will be submitted within six months following NRC approval of the modification.
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- Mr.. John F.~S'ablz-November 6,'1985 6-Page 3 i,
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,Should you have any questions regarding this matter, y. 3 :.
' l please=do not hesitate-to contact-us.:
4 "g-Very truly yours, t
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Attachment
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I T.'P.
Johnson, Resident-Site. Inspector
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n FIGURE 1 PEACH BOTTOM ATOMIC POWER STATION. UNITS 2 8 3 PROPOSED PNEUMATIC SUPPLY SYSTEM FOR CONTAINMENT l;
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PURGE & VENT ISOLATION VALVES I~~T~
hl l
@ Xn i
CAD LIQUID i
i r n NITROGEN TANK i
s 6
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f-SET AT I
80 PSI t
if SET AT i
T0 175 PSI l
UNIT 3 AW8IENT i
VAPORIZER l
I EXISTING I NEW i
CONTROL UNIT 2 R00W INSTR.
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X N
HITR0 GEN GAS HEADER (NOTE 2)
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(NOTE 1)
F' da l
NON 'O O'
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USER t
(TYP.)
NOTE 1 NOTE 2 NITROGEN GAS HEADER SERVICES:
SINGLE HEADER DESIGN.
- 1. UNITS 2 & 3 CAC & CAD SYSTEM SINGLE ACTIVE FAIL'JRE PROOF CONTAINWENT ISOLATION VALVES CONTROLS (TOTAL :30)
- 2. UNITS 2 & 3 CAD SYSTEW VENT LINE CONTROL VALVES (TOTAL :4) 1
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