Information Notice 1979-32, Separation of Electrical Cables for HPCI and ADS
| ML070220250 | |
| Person / Time | |
|---|---|
| Site: | 05000000 |
| Issue date: | 12/21/1979 |
| From: | NRC/IE |
| To: | |
| References | |
| IE-79-032, NUDOCS 7910250511 | |
| Download: ML070220250 (3) | |
791/OZ5O 51/
UNITED STATES
SSINS No.: 6870
NUCLEAR REGULATORY COMMISSION
Accession No:
OFFICE OF INSPECTION AND ENFORCEMENT
7910250511 WASHINGTON,
D.C.
20555 December21,
1979 IE Information Notice No.
79-32
SErARATION OF ELECTRICAL CABLES FOR HPCI AND ADS
This notice contains information on boiling water reactors (BWR's)
regarding the
routing of high pressure coolant injection (HPCI)
system and automatic depres- surization system (ADS)
cables in the same cable tray.
Such routing violates
design criteria for separation of these safety systems.
This potential cable
separation problem for BWR's is highlighted as a result of our review of recent
Licensee Event Reports (LER's):
Hatch Units I & 2, Brunswick Unit 1, and
James A. FitzPatrick (See references for LER identification).
Des(ciption of Circumstances:
The Hatch LER's state that tht NSSS supplier (Genera7 Electric) contacted plant
management about possible irregularities in cable separation between HPCI and ADS.
Plant engineering personnel subsequently confirmed that separation criteria per
design notes were not met because HPCI ;ystem inboard steam supply isolation
valve cables were routed with ADS contro& cables.
The architect-engineer (AE)
was notified of the HPIC/ADS cable separation problem and they are formulating a
design chinge to provide for proper cable separation.
Other; immediate corrective
action was not provided in the LER.
The Brunswick LER states that cables for the HPCI system steam sipply inboard
isolation valve are located in sections of cable tray containing ADS cables.
Also, their analysis of those cables revealed that if the isolation valve were in the
wrong position, then a failure at a tray section containing these cables might
result in a combination of cable failures which could impair the operability of
both the HPCI ,nd
ADS systems.
The problem is common to both units at Brunswick.
The AE,
United Engineers and Constructors, is said to be preparing plant modifi- cations to provide sufficient isolation of HPCI and ADS cables.
The licensee
stated that a review of emergency core cooling systems (ECCS)
and their primary
containment isolation valves is being performed to verify that no other cable
separation problems exist.
Also, the cable separation criterion for HPCI and ADS
systems is to be redefined in the cable s.eparation specifications to prevent
future recurrences of this event.
The FitzPatrick plant staff was informed of the HPCI/ADS cable routing problem by
the AE,
Stone and Webster, following a fire hazard analysis conducted by the AE.
Six cables which could affect the control of the steam supply inboard isolation
valve for the HPCI system are located in the same cable trays as some ADS cables.
Initial corrective action by the licensee to preclude spurious closure of the HPCI
system inboard steam supply isolation valve was to de-energize the valve by
racking out the breaker.
In addition, for purposes of primary containment
isolation, the outboard valve was maintained in its normal, closed position
IE Information Notice No.
79-3Z
DecemberVJ,
1979 and checked daily.
However, re-evaluation of the initial corrective action- indicated the preferred method of assuring operability of both the ECCS and
primary containment isolation functions would be to provide additional protection
against a fire which might Involve cables of both the HPCI and ADS, and to restore
the inboard isolation valve to a fully operable condition.
Accordingly, FitzPatrick initiated an hourly patrolling fire watch and restored the inboard
isolation valve to a fully opera;,?* :ndition.
The hourly patrolling fire watch
parallels that required by Techniical Specifications when early warning protection
against a potential fire must be taken due to inadequate or inoperable fixed
detection systems.
The FitzPat-ick plant staff was also informed by Stone and Webster that other
(third party) caoles (not identified in the LER) could affect the operation
of the inboard isolation valve for the [PCI steam supply due to their proximity
The licensee has decided to re-route the cables
of concern to correct both problems, and states that a preliminary design
modification has been completed.
Conclusions
Our review indicates that lack of separation of HPCI and ADS cables is a possible
generic -roblem for all BWR4's and that earlier designs may also be affected.
Permanent resolution of this problem, corrective action in the meanwhile, and
separation from other systems such as RCIC or i-solation condenser are under
consideration by the NRC.
It is anticipated that further NRC evaluations will
result in issuance of an IE Circular, Bulletin, or NRR genet ic letter in the
near future which will recommend or request specific applicant or licensee
actions.
This Information Notice is provided to inform licensees of a possible significant
matter.
If you have questions regarding this matter, please contact the Director
of the appropriate NRC Regional Office.
No written response to this Information Notice is required.
References:
1.
Hatch 1, LER #79-056/0]T-0, dated September 11, 1979
2.
Hatch 2, LER #79-098/DIT-O,
dated September 11, 1979
3.
Brunswick 1, LER #79-068/OIT-0, dated October 9, 1979
4.
FitzPatrick, LER #79-056/OIT-0, dated October 9, 1979
5.
FitzPatrick, LER #79-056/OIT-1, dated November 19, 1979
IE Information Notice No.
79-32 December 21,
1979
RECENTLY ISSUED
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79-31
79-30
79-29
79-28
79-27
79-12A
79-26
79-25
79-24
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Use of Incorrect Amplified
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Reporting of Defects and
Noncompliance,
Loss of NonSafety-Relatcd
Reactor Coolant System
Instrumentation During
Operation
Overloading of Structural
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Loads
Steam Generator Tube
Ruptures At Two PWR
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Attempted Damage To New
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Integrity
Reactor Trips At Turkey
Point Units 3 And 4
Overpressurization Of
Containment Of A PWR Plant
After A Main Steam Line
Break
Emergency Diesel Generator
Lube Oil Coolers
Qualification of Control.
Systems
11/16/79
All power reactor facilities
11/16/79
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11/16/79
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power reactors with an
12/13/79
All holders of power reactor
12/6/79
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vendors inspected by LCVIP
11/5/79
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