Information Notice 1988-60, Inadequate Design and Installation of Watertight Penetration Seals
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C.
20555
August 11, 1988
NRC INFORMATION NOTICE NO. 88-60:
INADEQUATE DESIGN AND INSTALLATION OF
WATERTIGHT PENETRATION SEALS
Addressees
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose
This information notice is being provided to alert addressees to potential
problems resulting from inadequate design and installation of penetration
seals whereby the seals may not provide watertight barriers between redun- dant safe shutdown trains. It is expected that recipients will review this
information for applicability to their facilities and consider actions, as
appropriate, to avoid similar problems. However, suggestions contained in
this information notice do not constitute NRC requirements; therefore, no
specific action or written response is required.
Description of Circumstances
On June 3, 1988, with Vogtle Unit 1 at 100 percent power, an inadvertent
pressurization of the fire protection system caused 1/4 to 1/2 inch of
water to accumulate around cable penetrations on the B train cable spreading
room floor.
The water then seeped through the floor into the control room
below. The water entered various process panel cabinets causing a spurious
pressurizer high level signal and alarm.
The spurious signal also resulted
in a pressurizer level deviation signal that caused the pressurizer backup
heaters to cycle on and off.
In addition, the water caused a pressurizer
power-operated relief valve to open.
Discussion:
During the review of this event, the licensee identified an unanalyzed con- dition in which a postulated fire in the B train cable spreading room, with
either actuation of the sprinkler system and/or manual fire suppression
activities, could result in a loss of functions required for safe shutdown
as follows: loss of control room train B and auxiliary shutdown panel via
8808003>
)
`'A-N 88-60
August 11, 1988 the fire, and loss of control room train A via water leaking into control
room panels. A second auxiliary shutdown panel (not required by the NRC)
would still be available; however, no indication would be available since
the indication circuits on that panel are not isolated from the control
room.
Testing showed that the water seeped between the concrete floor and the
penetration embedded steel angle (see Figure 1, attached). The licensee
applied a silicone sealant around the perimeter of all the floor pene- trations where the concrete and the angle iron meet.
Testing showed that
the sealant was watertight.
The licensee found through additional testing that there was a second leak
path within the cable bundles penetrating the foam sealant material. If
a large number of cables are so tightly massed that foam does not completely
surround the individual cables, leakage can occur along the cables.
The
licensee applied sealant around and between individual cables and at the
interface of the foam and the steel angle where foam shrinkage can cause
a gap.
Through testing, the licensee showed that a penetration seal with limited
conductors penetrating the silicone seal material is watertight.
As an
additional precaution, an elastomer cap was placed over the seal to protect
the foam and sealant from damage by water impingement in the event of fire
suppression activity (see Figure 2, attached).
The licensee began a review to determine whether there were other seals that, because of leakage, could cause an unanalyzed event.
The review located all
instances in which a room containing one train of safe shutdown equipment was
located above another room containing the redundant train of safe shutdown
equipment. The licensee broadened the scope of review to include other con- ditions in which leakage could affect safety-related equipment.
General Design Criterion 3 in Appendix A to 10 CFR 50 states, in part:
"Fire
detection and fighting systems of appropriate capacity and capability shall be
provided and designed to minimize the adverse effects of fires on structures, systems, and components important to safety.
Firefighting systems shall be
designed to assure that their rupture or inadvertent operation does not sig- nificantly impair the safety capability of these structures, systems, and
components." The NRC has identified numerous occurrences of system inter- action between fire suppression systems and systems important to safety.
"Actuation of Fire Suppression System Causing Inoperability of Safety-Related
Equipment" was the subject of Information Notice 83-41.
The scenario at
Vogtle Unit 1 is of particular significance in that it could involve the
potential loss of redundant and auxiliary safe shutdown trains.
August 11, 1988 No specific action or written response is required by this information notice.
If you have questions about this matter, please contact the technical contact
listed below or the Regional Administrator of the appropriate NRC regional
office.
ar esE. Rossi , Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
D. Oudinot, NRR
(301) 492-1174 Attachments:
i. Figure 1, Penetration Seal Leakage Path
2. Figure 2, Proposed Typical Seal Repair
(Upper Cable Spreading Room)
3. List of Recently Issued NRC Information Notices
I
Attachment 1
August 11, 1
SILICONE
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Attachment 3
August 11,
1988 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
88-04,
Supplement 1
Inadequate Qualification
arid Documentation of Fire
Barrier Penetration Seals
8/9/88
All holders of OLs
or CPs for nuclear
power reactors.
88-59
88-58
88-57
88-56
88-55
Main Steam Isolation Valve
Guide Rail Failure at
Waterford Unit 3
Potential Problems with
ASEA Brown Boveri ITE-51L
Time-Overcurrent Relays
Potential Loss of Safe
Shutdown Equipment Due to
Premature Silicon Controlled
Rectifier Failure
Potential Problems with
Silicone Foam Fire Barrier
Penetration Seals
Potential Problems Caused
by Single Failure of an
Engineered Safety Feature
Swing Bus
8/9/88
8/8/88
8/8/88
8/4/88
8/3/88
All holders of OLs
or CPs for nuclear
power reactors.
All holders of OLs
or CPs for nuclear
power reactors.
All holders of OLs
or CPs for nuclear
power reactors.
All holders of OLs
or CPs for nuclear
power reactors.
All holders of OLs
or CPs for nuclear
power reactors.
88-54
Failure of Circuit Breaker
Following Installation of
Amptector Direct Trip
Attachment
7/28/88
All holders of OLs
or CPs for nuclear
power reactors.
88-53
Licensee Violations of NRC
Regulations, Which Led to
Medical Diagnostic
Misadministrations
7/28/88
All manufacturers and
distributors of radio- pharmaceuticals for
human use, nuclear
pharmacies, and
medical licensees.
OL = Operating License
CP = Construction Permit
August 11,
1988 No specific action or written response is required by this information notice.
If you have questions about this matter, please contact the technical contact
listed below or the Regional Administrator of the appropriate NRC regional
office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
D. Oudinot, NRR
(301) 492-1174 Attachments:
1. Figure 1, Penetration Seal Leakage Path
2. Figure 2, Proposed Typical Seal Repair
(Upper Cable Spreading Room)
3. List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCE
- EAB:NRR
DOudinot:db
8/3/88
- EAB:NRR
DFischer
8/3/88
- TECH: ED
BCalure
8/3/88
- C:EAB:NRR
WLanning
8/4/88
- C:OGCB:NRR
CHBerlinger
8/4/88 CERossi i
8/ 5/88
IN 88- August , 1988 The licensee found through additional testing that there was a second
leak path within the cable bundles penetrating the foam sealant material. If
a large number of cables are so tightly massed that foam does not completely
surround the individual cables, leakage can occur along the cables. The
licensee applied sealant around and between individual cables and at the inter- face of the foam and the steel angle where foam shrinkage can cause a gap.
Through testing, the licensee showed that a penetration seal with limited
conductors penetrating the silicone seal material is watertight. As an
additional precaution, an elastomer cap was placed over the seal to protect
the foam and sealant from damage by water impingement in the event of fire
suppression activity (see Figure 2, attached).
The licensee began a review to determine whether there were other seals
that, because of leakage, could cause an unanalyzed event. The review located
all instances in which a room containing one train of safe shutdown equipment
was located above another room containing the redundant train of safe shutdown
equipment.
The licensee broadened the scope of its review to include other
conditions in which leakage could affect safety-related equipment.
General Design Criterion 3 in Appendix A to 10 CFR 50 states, in part:
"Fire
detection and fighting systems of appropriate capacity and capability shall be
provided and designed to minimize the adverse effects of fires on structures, systems, and components important to safety.
Firefighting systems shall be
designed to assure that their rupture or inadvertent operation does not
significantly impair the safety capability of these structures, systems, and
components." NRC has identified numerous occurrences of system interaction
between fire suppression systems and systems important to safety.
"Actuation of
Fire Suppression System Causing Inoperability of Safety-Related Equipment' was
the subject of Information Notice 83-41.
This scenario is of particular
significance in that it could involve the potential loss of redundant and
auxiliary safe shutdown trains.
No specific action or written response is required by this information
notice. If you have questions about this matter, please contact one of the
technical contacts listed below or the regional administrator of the
appropriate NRC regional office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Attachments: List of Recently Issued NRC Information Notices
Technical Contacts: D. Oudinot, NRR
(301) 492-1174
- SEE PREVIOUS CONCURRENCE
D
X ,
- EAB:NRR
- EAB:NRR *TECH:ED
C:EAB:NRR
C: GCB:NRR D:DEA:NRR
DOudinot:db DFischer BCalure
WLanning
CHBe/linger CERossi
/
/88
/ /88
/
/88 i/ i/88 gi/'/88
/
/88
IN 88- August , 1988 Testing showed that the water seeped between the concrete floor and the
penetration embedded steel angle (see Figure 1, attached). The licensee applied
a silicone sealant around the perimeter of all the floor penetrations where the
concrete and the angle iron meet. Testing showed that the silicone caulk
modification was watertight.
The licensee found through additional testing that there was a second
leak path within the cable bundles penetrating the foam sealant material.
If
a large number of cables are so tightly massed that foam does not completely
surround the individual cables, leakage can occur along the cables.
The
licensee applied sealant around and between individual cables and at the inter- face of the foam and the steel angle where foam shrinkage can cause a gap.
Through testing, the licensee showed that a penetration seal with limited
conductors penetrating the silicone seal material is watertight.
As an
additional precaution, an elastomer cap was placed over the seal to protect
the foam and sealant from damage by water impingement in the event of fire
suppression activity (see Figure 2, attached).
The licensee began a review to determine whether there were other seals
that, because of leakage, could cause an unanalyzed event.
The review located
all instances in which a room containing one train of safe shutdown equipment
was located above another room containing the redundant train of safe shutdown
equipment. The licensee broadened the scope of its review to include other
conditions in which leakage could affect safety-related equipment.
General Design Criterion 3 in Appendix A to 10 CFR 50 states. in part:
"Fire
detection and fighting systems of appropriate capacity and capability shall be
provided and designed to minimize the adverse effects of fires on structures, systems, and components important to safety.
Firefighting systems shall be
designed to assure that their rupture or inadvertent operation does not
significantly impair the safety capability of these structures, systems, and
components."
NRC has identified numerous occurrences of system interaction
between fire suppression systems and systems important to safety.
"Actuation of
Fire Suppression System Causing 1noperability of Safety-Related Equipmentt was
the subject of Information Notice 83-41.
This scenario is of particular
significance in that it could involve the potential loss of redundant and
auxiliary safe shutdown trains.
No specific action or written response is required by this information
notice. If you have questions about this matter, please contact one of the
technical contacts listed below or the regional administrator of the
appropriate NRC regional office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Attachments:
List of Recently Issued NRC Information Notices
Technical Contacts: D. Oudinot, NRR
(301) 492-1174 CAD, -
EAB:NRR T j D
C:EAB:NRR
C:OGCB:NRR
D:DOEA:NRR
- Ftdinot
- dbDFischer
Iuie
WLanning
CHBerlinger CERossi
& / /88 r/3 /88 T1/. /88
/
/88
/
/88
/
/88