Information Notice No.: 79-32, Separation of Electrical Cables for HPCI and ADS
IN79032
December 18, 1979
MEMORANDUM FOR: B. H. Grier, Director, Region I
J. P. O'Reilly, Director, Region II
J. G. Keppler, Director, Region III
K. V. Seyfrit, Director, Region IV
R. H. Engelken, Director, Region V
FROM: Norman C. Moseley, Director, Division of Reactor
Operations Inspection, Office of Inspection and
Enforcement
SUBJECT: Information Notice No. NO.: 79-32, SEPARATION OF
ELECTRICAL CABLES FOR HPCI AND ADS
The subject document is transmitted for issuance on December 21, 1979. The
Information Notice should be issued to all power reactor facilities holding
operating licenses and construction permits.
Also enclosed is a draft copy of the transmittal letter.
Norman C. Moseley, Director
Division of Reactor Operations
Inspection
Office of Inspection and Enforcement
Enclosures:
1. Draft Transmittal Letter
2. IE Information Notice
No. 79-32
CONTACT: W. R. Mills, IE
49-28180
.
(Transmittal letter for Information Notice No. 79-32 to each holder of an
NRC Operating License and Construction Permit.)
Information Notice No. 79-32
Addressee:
This Information Notice is provided as an early notification of a possibly
significant matter. No specific action or response is requested at this
time. However, we anticipate that further NRC evaluations will result in
issuance of an IE Circular, Bulletin, or NRR Generic Letter in the near
future which will recommend or request specific applicant or licensee
actions. If you have any, questions regarding the matter, please contact the
Director of the appropriate NRC Regional Office.
Sincerely,
Signature
(Regional Director)
Enclosure:
1. IE Information Notice
No. 79-32
2. List of Recently Issued
Information Notices
.
UNITED STATES SSINS No.: 6870
NUCLEAR REGULATORY COMMISSION Accession No:
OFFICE OF INSPECTION AND ENFORCEMENT 7910250511
WASHINGTON, D.C. 20555
December 21, 1979
Information Notice No. 79-32
SEPARATION 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
depressurization 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 1 & 2,
Brunswick Unit 1, and James A. FitzPatrick (See references for LER
identification).
Description of Circumstances:
The Hatch LER's state that the NSSS supplier (General 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 system
inboard steam supply isolation valve cables were routed with ADS control
cables. The architect-engineer (AE) was notified of the HPIC/ADS cable
separation problem and they are formulating a design change 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 supply
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 and ADS systems. The
problem is common to both units at Brunswick. The AE, United Engineers and
Constructors, is said to be preparing plant modifications 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 separation
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
.
Information Notice No. 79-32 December 21, 1979
Page 2 of 2
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 patrol fire watch
and restored the inboard isolation valve to a fully operable condition. The
hourly patrolling fire watch parallels that required by Technical
Specifications when early warning protection against a potential fire must
be taken due to inadequate or inoperable fixed detection systems.
The FitzPatrick plant staff was also informed by Stone and Webster that
other (third party) cables (not identified in the LER) could affect the
operation of the inboard isolation valve for the HPCI steam supply due to
their proximity to both HPCI and ADS cables. 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 problem 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 isolation
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
generic 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/OIT-O, dated September 11, 1979
2. Hatch 2, LER #79-098/OIT-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
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