ML20004C948
| ML20004C948 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 06/01/1981 |
| From: | Tramm T COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8106080069 | |
| Download: ML20004C948 (3) | |
Text
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N' Commonwealth Edison
\\'.
. One First National Pla21 Ch cago. tilinofs
~~ ).1 ~ Address Reply 13: Post Ottica Box 7G7 Chicago, Illinois 60690 June 1,
1981
'Mr. Harold-R. Denton, Director Of f ice of Nu' clear Reactor ' Regul at io;i -
U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
Zicn-Station Units 1 and 2 Fire Protection NRC Docket Nos. 50-?95 and 50-304-Reference (a):
February 20, 1981 letter from D. G. Eisenhut letter f rom D. G. Eisenhut to All PWR Licensees
Dear Mr. Denton:
of reference (a) identified additional information requireo for NRC review.of Zion's alternative shutdown Cdpability following a fir'e.
Attachment A to this letter contains the information identified in Item 2 of Enclosure 2.
.A very large effort is necessary to provide the information requested i n Item i of Enclosure 2.
That information will be provided by August 1, 1981.
Please address questions regarding this matter to this office.
One (1) sign o original and thirty-nine (39) copies of this letter are provided fo. your use.
Very truly yours, b ke f T. R. Tramm Nuclear Licensing Administrator Pressurized Water Reactors Attachment cc:
Zion Resident inspector i
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Information Requested in Enclosure 2 of February 20, 1981 Letter from D. G.
Eisenhut 2.
The residual. heat: removal system is gener' ally a low pressure system.that interf aces with the high.perssure primary coolant system.
To' preclude a LOCA through this' interface, we. require D
-compliance with the recommendations of Branch Technical;Positon-RSB 5-1.
Thus, this interf ace most liekly. consists of two reoundant ano independent motor-operated valves.
Tnese two motor-operated valves and their assoicated cable may be subject to a. single tire h'azard.
It is our. concern that this single fire.could'cause the-two valve's to open'resulting in a fire-init^ateo LOCA through the subject high-low pressure interface.
To assure that this interface and other high-low pressure interf aces are ~ adequately protected f rom the ef f ects of-single fire, we require the following information:
A.
Identify each high-low pressure interf ace that uses redundant electrically controlled devices (such as two series motor-operated valves) to isolate or preclude rupture of any primary coolant boundary.
B.
Identify the device's essential cabling (power and control) and describe the cable routing (by fire area) from sourse t
to termination.
C.
loent-ify each location where the identified cables are separated by less than a wall having a three-hour fire rating from cables for the redundant device.
D.
For the areas identified in item 2.C above (if any),
provide the bases and justification as to the acceptability of the existing design or any proposed modifications.
Response
A.
The only Zion high-low pressure interface is in the RHR suction line from the loop A hot leg.
This line is isolated by normally closed motor-operated valves MO-RH8701 and M0-RH8702, located in the containment building outsioe and inside the missile barrier, respectively.
B.
The respective power and control cables to these valves are as follows:
Valve Power Cables Control Cables Unit 1 M0V-RH8701 10499 and 10500 16570 H0V-RH8702 10501 and 10515 16574 Unit 2 MOV-RH8701 20499 and 20500 26570 MOV-RH8702 20501 and 20515 26574
.e D
'V.
V The-cable' routings by fire zones are given below:
10499:
1.h-1, 1.4-1 10500:
13.3-1, 3.1-1, 5.1-1 10501:
1.3-1, 1.2-1, 1.4-1 10515:
3.2-1, 3.1-1, 5.2-1 16570:
2.0, 3.2-1, 3.1-1, 5.1-1 b,
16574:
2.0, 3.2-1, 3.1-1, 5.2-1
-20499:
1.2-2, 1.4-2 20500:
3.3-2, 3.1-2, 5.1-2 20501:
1.3-2, 1.2-2, 1.4-2 20515:
~3.3-2, 3.1-2, 5.2-2 26570:
2.0, 3.2-2, 3.1-2, 5.1-2
-26574:
2.0, 3.2-2, 3.1-2, 5.2-2 Identification of Fire Zones for Unit 1 1.2-1 Containment Annular Area 1.3-1 Containment SG and RC pump area 1.4-1 Containment Operating F!oor 2.0 Main Control Room 3.1-1 Outer Cable Spreading Room 3.2-1 Inner Cable Spreading Room 3. 3 - 1.
Penetration Vault 5.1-1 DC 18 SWGR Room 5.2-1 DG 1A SWGR Room C.
Wherever the cables for both valves RH-8701 ar.d RH 8702 are in the-same fire zone, the cables are separated by distance only.
D.
The present design and installation of the RHR isolation valves is adequate.
A postulated fire destroying these cables would cause the valve to fail as is, i.e.,
in the normally closed position.
Fire-induced electrical short
-circuits would blow the fuses at the MCC, also disabling the valves in the closed position.
The control to MOV-RH8701 ano MOV-RH8702 is electrically interlocked out with Reactor Coolant System pressure greater than 425 psi and/or recirculation mode of safety injection.
Overpressure protection for the. low pressure RHR line is-provided by mechanical relief valve RH-8708 inside containment, which is set at 600 psig and which discharges to the Pressurizer Relief Tank.
The RHR line can be isolated outside the containment by valves M0-RH8700A and B, whi;h are accessible for manual operation, if necessary.
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