Information Notice 1990-78, Previously Unidentified Release Path from Boiling Water Reactor Control Rod Hydraulic Units: Difference between revisions

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| issue date = 12/18/1990
| issue date = 12/18/1990
| title = Previously Unidentified Release Path from Boiling Water Reactor Control Rod Hydraulic Units
| title = Previously Unidentified Release Path from Boiling Water Reactor Control Rod Hydraulic Units
| author name = Rossi C E
| author name = Rossi C
| author affiliation = NRC/NRR
| author affiliation = NRC/NRR
| addressee name =  
| addressee name =  
Line 14: Line 14:
| page count = 11
| page count = 11
}}
}}
{{#Wiki_filter:UNITED STATES NUCLEAR REGULATORY
{{#Wiki_filter:UNITED STATES


COMMISSION
NUCLEAR REGULATORY COMMISSION


===OFFICE OF NUCLEAR REACTOR REGULATION===
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555 December 18, 1990 NRC INFORMATION


NOTICE NO. 90-78: PREVIOUSLY
WASHINGTON, D.C. 20555 December 18, 1990
NRC INFORMATION NOTICE NO. 90-78:   PREVIOUSLY UNIDENTIFIED RELEASE PATH FROM


UNIDENTIFIED
BOILING WATER REACTOR CONTROL ROD HYDRAULIC


RELEASE PATH FROM BOILING WATER REACTOR CONTROL ROD HYDRAULIC UNITS
UNITS


==Addressees==
==Addressees==
:
:
All holders of operating
All holders of operating licenses or construction permits for boiling water


licenses or construction
reactors (BWRs).
 
permits for boiling water reactors (BWRs).


==Purpose==
==Purpose==
: This information
:
This information notice is intended to alert addressees to potential problems


notice is intended to alert addressees
pertaining to a previously unidentified release path from the control rod drive


to potential
hydraulic systems in boiling water reactors that may lead to design basis


problems pertaining
accident radiation doses significantly exceeding the values specified in the


to a previously
Final Safety Analysis Report. It is expected that recipients will review the


unidentified
information for applicability to their facilities and consider actions, as


release path from the control rod drive hydraulic
appropriate, to avoid similar problems. However, suggestions contained in this


systems in boiling water reactors that may lead to design basis accident radiation
information notice do not constitute NRC requirements; therefore, no specific


doses significantly
action or written response is required.


exceeding
==Description of Circumstances==
:
In June 1989, a design review for unmonitored release paths at Washington


the values specified
Nuclear Power Plant Unit 2 resulted in the discovery of a previously unidenti- fied radiation release path in the control rod drive hydraulic system. This


in the Final Safety Analysis Report. It is expected that recipients
path is postulated to result from the following sequence of conditions. The


will review the information
two control rod drive pumps are shut down following a design basis accident.


for applicability
There is a break outside of the reactor building (secondary containment) in


to their facilities
the non-seismically qualified piping or tankage to which the control rod


and consider actions, as appropriate, to avoid similar problems.
hydraulic system is connected (see Figure 1). Reactor coolant leaks past the


However, suggestions
double seals in any of the 185 control rod drives and the valves in their


contained
associated hydraulic control units. The leakage flows back through one or


in this information
more of the four headers connecting each of the 185 hydraulic control units to


notice do not constitute
the common control rod drive (CRD) pump header. The leakage then flows through


NRC requirements;
the CRD pump header and the control rod drive pumps to the break or the conden- sate storage tank located outside of the reactor building.
therefore, no specific action or written response is required.Description


of Circumstances:
Much of the pathway to the condensate storage tank lies outside of the reactor
In June 1989, a design review for unmonitored


release paths at Washington
building and includes piping that is not seismically qualified. In addition, this piping passes close to the air intakes for the control room ventilation


Nuclear Power Plant Unit 2 resulted in the discovery
system. Consequently, a failure of the supply piping for the drive pumps


of a previously
s3                                                                -1D8W-        /'C


unidenti-fied radiation
IN 90-78 December 18, 1990 during an accident would not only greatly increase the potential external


release path in the control rod drive hydraulic
release, but could increase the radiation dose to the control room operators.


system. This path is postulated
General Electric-Nuclear Energy performed calculations for the newly postulated


to result from the following
release path for a design basis accident with concurrent failure of the


sequence of conditions.
non-seismically qualified supply piping for the control rod drive system at


The two control rod drive pumps are shut down following
Washington Nuclear Power Plant Unit 2. The calculations incorporated the


a design basis accident.There is a break outside of the reactor building (secondary
source terms specified in Regulatory Guide 1.3 and assumed that 10% of the


containment)
iodine would escape as a gas from the liquid release. These calculations
in the non-seismically


qualified
produced a 30-day thyroid dose for control room operators of 121 rem per gpm of


piping or tankage to which the control rod hydraulic
leakage, a 30-day thyroid dose at the outer boundary of the low-population zone


system is connected (see Figure 1). Reactor coolant leaks past the double seals in any of the 185 control rod drives and the valves in their associated
of 86 rem per gpm of leakage, and a 2-hour thyroid dose at the exclusion zone


hydraulic
boundary of 36 rem per gpm of leakage. A generic communication discussing this


control units. The leakage flows back through one or more of the four headers connecting
concern was sent by General Electric-Nuclear Energy to each BWR utility in


each of the 185 hydraulic
July 1989.


control units to the common control rod drive (CRD) pump header. The leakage then flows through the CRD pump header and the control rod drive pumps to the break or the conden-sate storage tank located outside of the reactor building.Much of the pathway to the condensate
Discussion:
For the control rod hydraulic systems at General Electric boiling water reac- tors, the inboard isolation for the primary containment is provided by the


storage tank lies outside of the reactor building and includes piping that is not seismically
double seals in the control rod drives, and the outboard isolation for the


qualified.
primary containment is provided by valves within the hydraulic control units.


In addition, this piping passes close to the air intakes for the control room ventilation
However, past leak tests of the rod drive seals that were performed by General


system. Consequently, a failure of the supply piping for the drive pumps s3 -1D8W- /'C
Electric produced a maximum of 5 gpm per drive. Leakage from the hydraulic


IN 90-78 December 18, 1990 during an accident would not only greatly increase the potential
control units can also be significant.


external release, but could increase the radiation
As shown in Figure 1, four paths lead from each of the 185 hydraulic control


dose to the control room operators.
units to the common CRD pump header. Three of these paths, the accumulator


General Electric-Nuclear
charging header, the drive header and the cooling header include check valves


Energy performed
to prevent the return of water from the hydraulic units. In addition, water


calculations
escaping through the accumulator charging header must leak through the insert


for the newly postulated
side scram valve, and water escaping through the drive header must leak through


release path for a design basis accident with concurrent
one of the directional control valves. However, the check valve in the exhaust


failure of the non-seismically
header is oriented so as to permit the flow of water back to the CRD pump header.


qualified
The exhaust water then flows via the CRD pump header back to the reactor vessel


supply piping for the control rod drive system at Washington
(or, as at Washington Nuclear Power Plant Unit 2, to the reactor water cleanup


Nuclear Power Plant Unit 2. The calculations
system) along with the excess pump flow. Therefore, only one normally closed


incorporated
valve prevents water that is leaking out of each of the 185 control rod drives


the source terms specified
from returning through the associated exhaust header to the CRD pump header.


in Regulatory
During startup testing at Limerick Unit 1, and at Susquehanna Unit 1, the total


Guide 1.3 and assumed that 10% of the iodine would escape as a gas from the liquid release. These calculations
leakage from all of the hydraulic control units combined was measured at 5 gpm


produced a 30-day thyroid dose for control room operators
and 11 gpm, respectively. Both of these reactors include additional check valves


of 121 rem per gpm of leakage, a 30-day thyroid dose at the outer boundary of the low-population
at the discharge of the control'rod drive pump (area A in Figure 1). A partial


zone of 86 rem per gpm of leakage, and a 2-hour thyroid dose at the exclusion
audit by the NRC staff indicates that many of the newer BWR plants have check


zone boundary of 36 rem per gpm of leakage. A generic communication
valves installed in the discharge pipe of the control rod drive pumps. However, this audit also showed that other BWR plants, mostly the earlier ones, did not


discussing
have such check valves. The control rod drive system for BWR/6 plants is de- signed with a testable check valve and a motor-operated isolation valve. There- fore, this pathway is applicable to pre-BWR/6 plants only.


this concern was sent by General Electric-Nuclear
Ie


Energy to each BWR utility in July 1989.Discussion:
IN 90-78 December 18, 1990 Combining the General Electric dose calculations for the postulated path with
For the control rod hydraulic


systems at General Electric boiling water reac-tors, the inboard isolation
the leak rates measured from the hydraulic units at either Limerick or


for the primary containment
Susquehanna produces dose rates significantly in excess of the values in the


is provided by the double seals in the control rod drives, and the outboard isolation
Final Safety Analysis Report. Independent calculations by the NRC staff pro- duced offsite dose values that were comparable to the General Electric results.


for the primary containment
Radiation release by this path is not possible as long as the control rod drive


is provided by valves within the hydraulic
pumps are kept running. However, continued operation of these pumps following


control units.However, past leak tests of the rod drive seals that were performed
an accident cannot be assured, particularly if the non-seismically qualified


by General Electric produced a maximum of 5 gpm per drive. Leakage from the hydraulic control units can also be significant.
suction piping were to fail.


As shown in Figure 1, four paths lead from each of the 185 hydraulic
This problem was resolved at Washington Nuclear Power Plant Unit 2 by the


control units to the common CRD pump header. Three of these paths, the accumulator
installation of two check valves in series in the common discharge pipe from


charging header, the drive header and the cooling header include check valves to prevent the return of water from the hydraulic
the control rod drive pumps (at area A in Figure 1) to prevent backflow out of


units. In addition, water escaping through the accumulator
the reactor building (secondary containment). The Washington Nuclear Power


charging header must leak through the insert side scram valve, and water escaping through the drive header must leak through one of the directional
Plant Unit 2 installation includes provisions for leak testing the valves and


control valves. However, the check valve in the exhaust header is oriented so as to permit the flow of water back to the CRD pump header.The exhaust water then flows via the CRD pump header back to the reactor vessel (or, as at Washington
a leak rate criterion of 0.01 gpm was established for these valves.


Nuclear Power Plant Unit 2, to the reactor water cleanup system) along with the excess pump flow. Therefore, only one normally closed valve prevents water that is leaking out of each of the 185 control rod drives from returning
This information notice requires no specific action or written response. If


through the associated
you have any questions about the information in this notice, please contact one


exhaust header to the CRD pump header.During startup testing at Limerick Unit 1, and at Susquehanna
of the technical contacts listed below or the appropriate NRR project manager.


Unit 1, the total leakage from all of the hydraulic
Division of Operational Events Assessment


control units combined was measured at 5 gpm and 11 gpm, respectively.
Office of Nuclear Reactor Regulation


Both of these reactors include additional
Technical Contacts:  Charles R. Nichols, NRR


check valves at the discharge
(301) 492-0854 Donald C. Kirkpatrick, NRR


of the control'rod
(301) 492-1849 Attachments:
1. Figure 1. BWR Control Rod Drive System


drive pump (area A in Figure 1). A partial audit by the NRC staff indicates
2. List of Recently Issued NRC Information Notices


that many of the newer BWR plants have check valves installed
Note: At Washington Nuclear Power


in the discharge
Plant, Unit 2, the control rod drive


pipe of the control rod drive pumps. However, this audit also showed that other BWR plants, mostly the earlier ones, did not have such check valves. The control rod drive system for BWR/6 plants is de-signed with a testable check valve and a motor-operated
return water Is piped to the reactor w


isolation
water cleanup system


valve. There-fore, this pathway is applicable
SvITE..t.                                                .... \SECONDONDARY


to pre-BWR/6 plants only.
OAin4Z(                      EXHAUST            CWHIOL VALV(S                CONTAINMENT


Ie IN 90-78 December 18, 1990 Combining
~I ~>*PCV                                      "(E


the General Electric dose calculations
S                CU


for the postulated
OUTSIDE OF                                        DRV


path with the leak rates measured from the hydraulic
BUILDINGA-H


units at either Limerick or Susquehanna
AREA


produces dose rates significantly
A                                                    SCIM VALVIE


in excess of the values in the Final Safety Analysis Report. Independent
6TaLQUT1                            COTROL4MmuMRG


calculations
RMOO140MIX        ROD


by the NRC staff pro-duced offsite dose values that were comparable
To              OTHE


to the General Electric results.Radiation
CONTARNEN R-OD                                                        -.                     I.-AJ___
                                                                                                                  CrI


release by this path is not possible as long as the control rod drive pumps are kept running. However, continued
DRIVEPUMPSM


operation
0
                                                                                                                    ~j


of these pumps following an accident cannot be assured, particularly
c


if the non-seismically
Figure 1. BWR CONTROL ROD DRIVE SYSTEM


qualified suction piping were to fail.This problem was resolved at Washington
Attachment 2 IN 90-78 December 18, 1990 LIST OF RECENTLY ISSUED


Nuclear Power Plant Unit 2 by the installation
NRC INFORMATION NOTICES


of two check valves in series in the common discharge
Information                                    Date of


pipe from the control rod drive pumps (at area A in Figure 1) to prevent backflow out of the reactor building (secondary
Notice No.              Subject                Issuance      Issued to


containment).
90-77          Inadvertent Removal of Fuel    12/12/90 All holders of OLs or


The Washington
Assemblies from the Reactor              CPs for pressurized- Core                                    water reactors (PWRS).


Nuclear Power Plant Unit 2 installation
88-23,        Potential for Gas Binding of 12/10/90    All holders of OLs or


includes provisions
Supp. 3        High-Pressure Safety Injection          CPs for pressurized- Pumps During A Loss-Of-Coolant          water reactors (PWRs).


for leak testing the valves and a leak rate criterion
Accident


of 0.01 gpm was established
90-76          Failure Of Turbine Overspeed    12/7/90  All holders of OLs or


for these valves.This information
Trip Mechanism Because Of                CPs for nuclear power


notice requires no specific action or written response.
Inadequate Spring Tension                reactors.


If you have any questions
90-75          Denial Of Access To Current    12/5/90  All Michigan holders


about the information
Low-Level Radioactive Waste              of NRC licenses.


in this notice, please contact one of the technical
Disposal Facilities


contacts listed below or the appropriate
90-74          Information on Precursors To    12/4/90  All holders of OLs or


NRR project manager.Division of Operational
Severe Accidents                        CPs for nuclear power


===Events Assessment===
reactors.
Office of Nuclear Reactor Regulation


Technical
90-73          Corrosion Of Valve-To-          11/29/90 All holders of OLs or


Contacts:
Torque Tube Keys In                      CPs for nuclear power
Charles R. Nichols, NRR (301) 492-0854 Donald C. Kirkpatrick, NRR (301) 492-1849 Attachments:
1. Figure 1. BWR Control Rod Drive System 2. List of Recently Issued NRC Information


Notices
Spray Pond Cross Connect                reactors.


Note: At Washington
Valves


Nuclear Power Plant, Unit 2, the control rod drive return water Is piped to the reactor w water cleanup system SvITE..t.
90-72          Testing of Parallel Disc        11/28/90 All holders of OLs or


.... \SECONDONDARY
Gate Valves In Europe                    CPs for nuclear power


OAin4Z( EXHAUST CWHIOL VALV(S CONTAINMENT
reactors.


~I ~>*PCV "(E S CU OUTSIDE OF DRV BUILDINGA-H
90-71          Effective Use of Radi-          11/6/90  All NRC licensees


===AREA A SCIM VALVIE 6TaLQUT1 COTROL4MmuMRG===
ation Safety Committees                  authorized to use by- to Exercise Control Over                product material for
RMOO140MIX


ROD To OTHE CONTARNEN
Medical Use Programs                    medical purposes.


R-OD I.-AJ___ -. CrI DRIVEPUMPSM
90-70          Pump Explosions Involving      11/6/90  All uranium fuel


~j 0 c Figure 1. BWR CONTROL ROD DRIVE SYSTEM
Ammonium Nitrate                        fabrication and


Attachment
conversion facilities.


2 IN 90-78 December 18, 1990 LIST OF RECENTLY ISSUED NRC INFORMATION
90-38,         License and Fee Require-        11/6/90  All fuel facility and


NOTICES Information
Supp. 1        ments for Processing Fin-                materials licensees.


Date of Notice No. Subject Issuance Issued to 90-77 88-23, Supp. 3 90-76 90-75 90-74 90-73 90-72 90-71 90-70 90-38, Supp. 1 Inadvertent
ancial Assurance Submittals
 
Removal of Fuel Assemblies
 
from the Reactor Core Potential
 
for Gas Binding of High-Pressure
 
Safety Injection Pumps During A Loss-Of-Coolant
 
Accident Failure Of Turbine Overspeed Trip Mechanism
 
Because Of Inadequate
 
Spring Tension Denial Of Access To Current Low-Level
 
Radioactive
 
===Waste Disposal Facilities===
Information
 
on Precursors
 
To Severe Accidents Corrosion
 
Of Valve-To-Torque Tube Keys In Spray Pond Cross Connect Valves Testing of Parallel Disc Gate Valves In Europe Effective
 
Use of Radi-ation Safety Committees
 
to Exercise Control Over Medical Use Programs Pump Explosions
 
Involving Ammonium Nitrate License and Fee Require-ments for Processing
 
Fin-ancial Assurance
 
Submittals


for Decommissioning
for Decommissioning


12/12/90 12/10/90 12/7/90 12/5/90 12/4/90 11/29/90 11/28/90 11/6/90 11/6/90 11/6/90 All holders of OLs or CPs for pressurized- water reactors (PWRS).All holders of OLs or CPs for pressurized- water reactors (PWRs).All holders of OLs or CPs for nuclear power reactors.All Michigan holders of NRC licenses.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 NRC licensees authorized
OL = Operating License


to use by-product material for medical purposes.All uranium fuel fabrication
CP = Construction Permit


and conversion
IN 90-78 December 18, 1990 Combining the General Electric dose calculations for the postulated path with


facilities.
the leak rates measured from the hydraulic units at either Limerick or


All fuel facility and materials
Susquehanna produces dose rates significantly in excess of the values in the


licensees.
Final Safety Analysis Report. Independent calculations by the NRC staff pro- duced offsite dose values that were comparable to the General Electric results.


OL = Operating
Radiation release by this path is not possible as long as the control rod drive


License CP = Construction
pumps are kept running. However, continued operation of these pumps following


Permit
an accident cannot be assured, particularly if the non-seismically qualified


IN 90-78 December 18, 1990 Combining
suction piping were to fail.


the General Electric dose calculations
This problem was resolved at Washington Nuclear Power Plant Unit 2 by the


for the postulated
installation of two check valves in series in the common discharge pipe from


path with the leak rates measured from the hydraulic
the control rod drive pumps (at area A in Figure 1) to prevent backflow out of


units at either Limerick or Susquehanna
the reactor building (secondary containment). The Washington Nuclear Power


produces dose rates significantly
Plant Unit 2 installation includes provisions for leak testing the valves and


in excess of the values in the Final Safety Analysis Report. Independent
a leak rate criterion of 0.01 gpm was established for these valves.


calculations
This information notice requires no specific action or written response. If


by the NRC staff pro-duced offsite dose values that were comparable
you have any questions about the information in this notice, please contact one


to the General Electric results.Radiation
of the technical contacts listed below or the appropriate NRR project manager.


release by this path is not possible as long as the control rod drive pumps are kept running. However, continued
Origina Signkd IN


operation
Charles E Rossi


of these pumps following an accident cannot be assured, particularly
Charles E. Rossi, Director


if the non-seismically
Division of Operational Events Assessment


qualified suction piping were to fail.This problem was resolved at Washington
Office of Nuclear Reactor Regulation
 
Nuclear Power Plant Unit 2 by the installation
 
of two check valves in series in the common discharge
 
pipe from the control rod drive pumps (at area A in Figure 1) to prevent backflow out of the reactor building (secondary
 
containment).
 
The Washington
 
Nuclear Power Plant Unit 2 installation
 
includes provisions
 
for leak testing the valves and a leak rate criterion
 
of 0.01 gpm was established
 
for these valves.This information
 
notice requires no specific action or written response.
 
If you have any questions
 
about the information
 
in this notice, please contact one of the technical


contacts listed below or the appropriate
Technical Contacts:    Charles R. Nichols, NRR


NRR project manager.Origina Signkd IN Charles E Rossi Charles E. Rossi, Director Division of Operational
(301) 492-0854 Donald C. Kirkpatrick, NRR


===Events Assessment===
(301) 492-1849 Attachments:
Office of Nuclear Reactor Regulation
1. Figure 1. BWR Control Rod Drive System


Technical
2. List of Recently Issued NRC Information Notices


Contacts:
*12/11/90
Charles R. Nichols, NRR (301) 492-0854 Donald C. Kirkpatrick, NRR (301) 492-1849 Attachments:
                                                                NJDi*C/OGCB:DOEA:NRR
1. Figure 1. BWR Control Rod Drive System 2. List of Recently Issued NRC Information
 
Notices*12/11/90 NJDi *C/OGCB:DOEA:NRR


CHBerlinger
CHBerlinger


12/L~/jW 111/09/90*OGCB:DOEA:NRR
12/L~/jW 111/09/90
*OGCB:DOEA:NRR *SPLB:DST:NRR    *C/SPLB:DST:NRR        *D/U ST:NRR *RPB:ADM


*SPLB:DST:NRR
DCKirkpatrick CRNichols        CMcCracken              AThadani    TechEd


*C/SPLB:DST:NRR
08/17/90      08/20/90        09/24/90                10/30/90    08/06/90
DOCUMENT NAME:   IN 90-78


*D/U ST:NRR *RPB:ADM DCKirkpatrick
IN 90-XX


CRNichols
August xx, 1990 for these and other plants produced offsite dose values that were comparable


CMcCracken
to the General Electric results and that could also significantly exceed the


AThadani TechEd 08/17/90 08/20/90 09/24/90 10/30/90 08/06/90 DOCUMENT NAME: IN 90-78 IN 90-XX August xx, 1990 for these and other plants produced offsite dose values that were comparable
values specified in the Final Safety Analysis Report. Radiation release by


to the General Electric results and that could also significantly
this path is not possible as long as the control rod drive pumps are kept


exceed the values specified
running. However, continued operation of these pumps following an accident


in the Final Safety Analysis Report. Radiation
cannot be ensured, particularly if the non-seismically qualified suction piping


release by this path is not possible as long as the control rod drive pumps are kept running. However, continued
were to fall.


operation
This problem was resolved at Washington Nuclear Power Plant Unit 2 by the


of these pumps following
installation of two check valves in series in the common discharge pipe from


an accident cannot be ensured, particularly
the control rod drive pumps to prevent back flow out of the secondary contain- ment. The Washington Nuclear Power Plant Unit 2 installation includes provisions


if the non-seismically
for leak testing the valves. Washington Nuclear Power Plant Unit 2 planned to


qualified
establish a leak rate criterion for these valves of 0.01 gpm.


suction piping were to fall.This problem was resolved at Washington
The control rod drive system for BWR/6 plants is designed with a testable


Nuclear Power Plant Unit 2 by the installation
check valve and a motor-operated isolation valve, therefore this pathway is


of two check valves in series in the common discharge
applicable to only pre-BWR/6 plants.


pipe from the control rod drive pumps to prevent back flow out of the secondary
This information notice requires no specific action or written response. If


contain-ment. The Washington
you have any questions about the information in this notice, please contact the


Nuclear Power Plant Unit 2 installation
technical contact listed below or the appropriate NRR project manager.


includes provisions
Charles E. Rossi, Director


for leak testing the valves. Washington
Division of Operational Events Assessment


Nuclear Power Plant Unit 2 planned to establish
a leak rate criterion
for these valves of 0.01 gpm.The control rod drive system for BWR/6 plants is designed with a testable check valve and a motor-operated
isolation
valve, therefore
this pathway is applicable
to only pre-BWR/6 plants.This information
notice requires no specific action or written response.
If you have any questions
about the information
in this notice, please contact the technical
contact listed below or the appropriate
NRR project manager.Charles E. Rossi, Director Division of Operational
===Events Assessment===
Office of Nuclear Reactor Regulation
Office of Nuclear Reactor Regulation


Technical
Technical Contacts:   Charles R. Nichols, NRR
 
Contacts:  
Charles R. Nichols, NRR (301) 492-0856 Donald C. Kirkpatrick, NRR (301) 492-1849 Attachments:
1. Figure of Control Rod Hydraulic
 
System 2. List of Recently Issued NRC Information
 
Notices Document Name: UNIDENTIFIED
 
RELEASE PATH IN*SEE PREVIOUS CONCURRENCES
 
D/DOEA:NRR
 
C/OGCB:DOEA:NRR
 
===CERossi CHBerlinger===
10/ /90 10/ /90 OGCB:DOEA:NRR
 
SPLB:DST:NRR
 
C/SPLB:DST:NRR
 
D/DST:NRRK4 RPB:ADM DCKirkpatrick*
CRNichols*
CMcCracken*
AThadani TechEd*08/17/90 08/20/90 09/24/90 10M /90 08/06/90
1990 Page 3 f 3 Combining


the General Electric dose calculations
(301) 492-0856 Donald C. Kirkpatrick, NRR


for the postulated
(301) 492-1849 Attachments:
1. Figure of Control Rod Hydraulic System


path with the leak rates measured from the hydraulic
2. List of Recently Issued NRC Information Notices


units at either Limerick or Susquehanna
Document Name:  UNIDENTIFIED RELEASE PATH IN


produces dose rates significantly
*SEE PREVIOUS CONCURRENCES


in excess of the values specified in the Final Safety Analysis Report. Independent
D/DOEA:NRR    C/OGCB:DOEA:NRR


calculations
CERossi      CHBerlinger


by the NRC staff produced offsite dose values that were comparable
10/  /90    10/  /90
OGCB:DOEA:NRR      SPLB:DST:NRR    C/SPLB:DST:NRR      D/DST:NRRK4 RPB:ADM


to the General Electric results and that could also significantly
DCKirkpatrick*      CRNichols*      CMcCracken*        AThadani      TechEd*
08/17/90            08/20/90        09/24/90            10M /90      08/06/90


exceed the values specified
1990
                                                                Page 3 f 3 Combining the General Electric dose calculations for    the postulated path with


in the Final Safety Analysis Report. Radiation
at  either  Limerick or


release by this path is not possible as long as the control rod drive pumps are kept running. However, continued operation
the leak rates measured from the hydraulic units in excess  of the values specified


of these pumps following
Susquehanna produces dose rates significantly        calculations    by the NRC staff


an accident cannot be assured, particularly
in the Final Safety Analysis Report. Independent to the General Electric


if the non-seismically
produced offsite dose values that were comparable the values specified in the


qualified
results and that could also significantly exceed by this path is not possible


suction piping were to fail.This problem was resolved at Washington
Final Safety Analysis Report. Radiation release running. However, continued


Nuclear Power Plant Unit 2 by the installation
as long as the control rod drive pumps are kept cannot be assured, particularly


of two check valves in series in the common discharge
operation of these pumps following an accident were to fail.


pipe from the control rod drive pumps (at area A) to prevent backflow out of the reactor building secondary
if the non-seismically qualified suction piping


containment.
This problem was resolved at Washington Nuclear    Power Plant Unit 2 by the


The Washington
installation of two check valves in series  in the  common discharge pipe from


Nuclear Power Plant Unit 2 installation
the control rod drive pumps (at area  A) to prevent  backflow out of the reactor


includes provisions
building secondary containment. The Washington Nuclear      Power Plant Unit 2 and a leak rate


for leak testing the valves and a leak rate criterion
installation includes provisions for leak testing the valves


of 0.01 gpm was established
criterion of 0.01 gpm was established for these valves.


for these valves.This information
or written response. If


notice requires you have any questions
This information notice requires no specific action


about the of the technical
in this notice, please contact one


contacts listed no specific action or written response.
you have any questions about the information appropriate NRR project manager.


If information
of the  technical contacts listed below or the


in this notice, please contact one below or the appropriate
Charles E. Rossi, Director


NRR project manager.Charles E. Rossi, Director Division of Operational
Division of Operational Events Assessment


===Events Assessment===
Office of Nuclear Reactor Regulation
Office of Nuclear Reactor Regulation


Technical
Technical Contacts:   Charles R. Nichols, NRR
 
Contacts: Charles R. Nichols, NRR (301) 492-0854 Donald C. Kirkpatrick, NRR (301) 492-1849 Attachments:
1. Figure 1. BWR Control Rod Drive System 2. List of Recently Issued NRC Information
 
Notices Document Name: RELEASE PATH NOTICE D/DOEA:NRR
 
CERossi 11/ /90*D/DST:NRR
 
AThadani 10/30/90 ok 1vko .*C/OGCB:DOEA:NRR
 
CHBerlinger


11/09/90*RPB:ADM TechEd 08/06/90*OGCB:DOEA:NRR
(301) 492-0854 Donald C. Kirkpatrick, NRR


===DCKirkpatrick===
(301) 492-1849 Attachments:
08/17/90*SPLB:DST:NRR
  1. Figure 1. BWR Control Rod Drive System


CRNichols 08/20/90*C/SPLB:DST:NRR
2. List of Recently Issued NRC Information Notices


CMcCracken
Document Name:  RELEASE PATH NOTICE                                ok      1vko .


09/24/90
D/DOEA:NRR *C/OGCB:DOEA:NRR
IN 90-XX August xx, 1990 this path is not possible as long as the control rod drive pumps are kept running. However, continued


operation
CERossi      CHBerlinger


of these pumps following
11/  /90    11/09/90
                                  *C/SPLB:DST:NRR      *D/DST:NRR    *RPB:ADM


an accident cannot be ensured, particularly
*OGCB:DOEA:NRR *SPLB:DST:NRR                                        TechEd


if the non-seismically
DCKirkpatrick CRNichols        CMcCracken            AThadani


qualified
08/20/90        09/24/90              10/30/90      08/06/90
    08/17/90


suction piping were to fail.This problem was resolved at Washington
IN 90-XX


Nuclear Power Plant Unit 2 by the installation
August xx, 1990 this path is not possible as long as the control rod drive pumps are kept


of two check valves in series in the common discharge
running. However, continued operation of these pumps following an accident


pipe from the control rod drive pumps to prevent back flow out of the secondary
cannot be ensured, particularly if the non-seismically qualified suction piping


contain-ment. The Washington
were to fail.


Nuclear Power Plant Unit 2 installation
This problem was resolved at Washington Nuclear Power Plant Unit 2 by the


includes provisions
installation of two check valves in series in the common discharge pipe from


for leak testing the valves. Washington
the control rod drive pumps to prevent back flow out of the secondary contain- ment. The Washington Nuclear Power Plant Unit 2 installation includes provisions


Nuclear Power Plant Unit 2 planned to establish
for leak testing the valves. Washington Nuclear Power Plant Unit 2 planned to


a leak rate criterion
establish a leak rate criterion for these valves of 0.01 gpm.


for these valves of 0.01 gpm.This information
This information notice requires no specific action or written response. If


notice requires no specific action or written response.
you have any questions about the information in this notice, please contact the


If you have any questions
technical contact listed below or the appropriate NRR project manager.


about the information
Charles E. Rossi, Director


in this notice, please contact the technical
Division of Operational Events Assessment


contact listed below or the appropriate
NRR project manager.Charles E. Rossi, Director Division of Operational
===Events Assessment===
Office of Nuclear Reactor Regulation
Office of Nuclear Reactor Regulation


Technical
Technical Contacts:   Charles R. Nichols, NRR
 
Contacts: Charles R. Nichols, NRR (301) 492-0856 Donald C. Kirkpatrick, NRR (301) 492-1849 Attachments:
1. Figure of Control Rod Hydraulic
 
System 2. List of Recently Issued NRC Information


Notices Document Name: UNIDENTIFIED
(301) 492-0856 Donald C. Kirkpatrick, NRR


RELEASE PATH IN*SEE PREVIOUS CONCURRENCES
(301) 492-1849 Attachments:
1. Figure of Control Rod Hydraulic System


OGCB:W EA:NRR DOrirkpathick
2. List of Recently Issued NRC Information Notices


08/e 9/90 VC<SPLB:DST:NRR
Document Name: UNIDENTIFIED RELEASE PATH IN


CRNichols 08AV2/9M;*^
*SEE PREVIOUS CONCURRENCES
CISPLB:DST:NRR


CMcCracken
D/DOEA:NRR   C/OGCB:DOEA:NRR
 
OF/p/90 D/DOEA:NRR
 
CERossi 08/ /90 D/DST:NRR AThadani 408/ /90 V1 C/OGCB:DOEA:NRR
 
CHBerlinger


08/ /90*RPB:ADM TechEd 08/06/90
CERossi      CHBerlinger
IN 90-XX August xx, 1990 The Washington


Nuclear power installation
08/ /90      08/ /90
OGCB:W EA:NRR SPLB:DST:NRR    CISPLB:DST:NRR      D/DST:NRR    *RPB:ADM


includes provisions
DOrirkpathick CRNichols      CMcCracken          AThadani      TechEd


for leak testing the valves. Washington
08/e 9/90VC< 08AV2/9M;*^      OF/p/90            408/ /90        08/06/90
                                                V1


Nuclear Power has established
IN 90-XX


a very low leak rate criterion
August xx, 1990 The Washington Nuclear power installation includes provisions for leak testing


for these valves (.01 gpm was indicated).
the valves. Washington Nuclear Power has established a very low leak rate


A partial check by the NRC staff indicates
criterion for these valves (.01 gpm was indicated). A partial check by the NRC


that many of the newer BWR plants already have check valves installed
staff indicates that many of the newer BWR plants already have check valves


in the control rod drive pump discharge
installed in the control rod drive pump discharge pipe. However, this check


pipe. However, this check also showed that other BWR plants, mainly the earlier ones, did not have such check valves.This information
also showed that other BWR plants, mainly the earlier ones, did not have such


notice requires no specific action or written response.
check valves.


If you have any questions
This information notice requires no specific action or written response. If


about the information
you have any questions about the information in this notice, please contact the


in this notice, please contact the technical
technical contact listed below or the appropriate NRR project manager.


contact listed below or the appropriate
Charles E. Rossi, Director


NRR project manager.Charles E. Rossi, Director Division of Operational
Division of Operational Events Assessment


===Events Assessment===
Office of Nuclear Reactor Regulation
Office of Nuclear Reactor Regulation


Technical
===Technical Contact:===
 
Contact: Charles R. Nichols, NRR (301) 492-0854 Attachments:
1. Figure of Control Rod Hydraulic


System 2. List of Recently Issued NRC Information
===Charles R. Nichols, NRR===
                    (301) 492-0854 Attachments:
1. Figure of Control Rod Hydraulic System


Notices Document Name: UNIDENTIFIED
2. List of Recently Issued NRC Information Notices
 
RELEASE PATH IN D/DOEA:NRR
 
CERossi 08/ /90 D/DST:NRR AThadani 08/ /90 C/OGCB:DOEA:NRR
 
CHBerlinger


08/ /90 RPB:ADM TechEd J ai P 08/C /90 OGCB:DOEA:NRR
Document Name: UNIDENTIFIED RELEASE PATH IN


SPLB:DST:NRR
D/DOEA:NRR  C/OGCB:DOEA:NRR


DCKirkpatyi
CERossi      CHBerlinger


.- CRNichols 08/' /9 xF 08/ /go C/SPLB:DST:NRR
08/ /90      08/ /90
OGCB:DOEA:NRR SPLB:DST:NRR    C/SPLB:DST:NRR     D/DST:NRR    RPB:ADM


CMcCracken
DCKirkpatyi .-CRNichols      CMcCracken         AThadani    TechEd J ai P


08/ /90}}
08/' /9    xF 08/ /go        08/ /90            08/ /90      08/C /90}}


{{Information notice-Nav}}
{{Information notice-Nav}}

Latest revision as of 04:04, 24 November 2019

Previously Unidentified Release Path from Boiling Water Reactor Control Rod Hydraulic Units
ML031130145
Person / Time
Site: Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant  Entergy icon.png
Issue date: 12/18/1990
From: Rossi C
Office of Nuclear Reactor Regulation
To:
References
IN-90-078, NUDOCS 9012120148
Download: ML031130145 (11)
v • d • e


UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 December 18, 1990

NRC INFORMATION NOTICE NO. 90-78: PREVIOUSLY UNIDENTIFIED RELEASE PATH FROM

BOILING WATER REACTOR CONTROL ROD HYDRAULIC

UNITS

Addressees

All holders of operating licenses or construction permits for boiling water

reactors (BWRs).

Purpose

This information notice is intended to alert addressees to potential problems

pertaining to a previously unidentified release path from the control rod drive

hydraulic systems in boiling water reactors that may lead to design basis

accident radiation doses significantly exceeding the values specified in the

Final Safety Analysis Report. It is expected that recipients will review the

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

In June 1989, a design review for unmonitored release paths at Washington

Nuclear Power Plant Unit 2 resulted in the discovery of a previously unidenti- fied radiation release path in the control rod drive hydraulic system. This

path is postulated to result from the following sequence of conditions. The

two control rod drive pumps are shut down following a design basis accident.

There is a break outside of the reactor building (secondary containment) in

the non-seismically qualified piping or tankage to which the control rod

hydraulic system is connected (see Figure 1). Reactor coolant leaks past the

double seals in any of the 185 control rod drives and the valves in their

associated hydraulic control units. The leakage flows back through one or

more of the four headers connecting each of the 185 hydraulic control units to

the common control rod drive (CRD) pump header. The leakage then flows through

the CRD pump header and the control rod drive pumps to the break or the conden- sate storage tank located outside of the reactor building.

Much of the pathway to the condensate storage tank lies outside of the reactor

building and includes piping that is not seismically qualified. In addition, this piping passes close to the air intakes for the control room ventilation

system. Consequently, a failure of the supply piping for the drive pumps

s3 -1D8W- /'C

IN 90-78 December 18, 1990 during an accident would not only greatly increase the potential external

release, but could increase the radiation dose to the control room operators.

General Electric-Nuclear Energy performed calculations for the newly postulated

release path for a design basis accident with concurrent failure of the

non-seismically qualified supply piping for the control rod drive system at

Washington Nuclear Power Plant Unit 2. The calculations incorporated the

source terms specified in Regulatory Guide 1.3 and assumed that 10% of the

iodine would escape as a gas from the liquid release. These calculations

produced a 30-day thyroid dose for control room operators of 121 rem per gpm of

leakage, a 30-day thyroid dose at the outer boundary of the low-population zone

of 86 rem per gpm of leakage, and a 2-hour thyroid dose at the exclusion zone

boundary of 36 rem per gpm of leakage. A generic communication discussing this

concern was sent by General Electric-Nuclear Energy to each BWR utility in

July 1989.

Discussion:

For the control rod hydraulic systems at General Electric boiling water reac- tors, the inboard isolation for the primary containment is provided by the

double seals in the control rod drives, and the outboard isolation for the

primary containment is provided by valves within the hydraulic control units.

However, past leak tests of the rod drive seals that were performed by General

Electric produced a maximum of 5 gpm per drive. Leakage from the hydraulic

control units can also be significant.

As shown in Figure 1, four paths lead from each of the 185 hydraulic control

units to the common CRD pump header. Three of these paths, the accumulator

charging header, the drive header and the cooling header include check valves

to prevent the return of water from the hydraulic units. In addition, water

escaping through the accumulator charging header must leak through the insert

side scram valve, and water escaping through the drive header must leak through

one of the directional control valves. However, the check valve in the exhaust

header is oriented so as to permit the flow of water back to the CRD pump header.

The exhaust water then flows via the CRD pump header back to the reactor vessel

(or, as at Washington Nuclear Power Plant Unit 2, to the reactor water cleanup

system) along with the excess pump flow. Therefore, only one normally closed

valve prevents water that is leaking out of each of the 185 control rod drives

from returning through the associated exhaust header to the CRD pump header.

During startup testing at Limerick Unit 1, and at Susquehanna Unit 1, the total

leakage from all of the hydraulic control units combined was measured at 5 gpm

and 11 gpm, respectively. Both of these reactors include additional check valves

at the discharge of the control'rod drive pump (area A in Figure 1). A partial

audit by the NRC staff indicates that many of the newer BWR plants have check

valves installed in the discharge pipe of the control rod drive pumps. However, this audit also showed that other BWR plants, mostly the earlier ones, did not

have such check valves. The control rod drive system for BWR/6 plants is de- signed with a testable check valve and a motor-operated isolation valve. There- fore, this pathway is applicable to pre-BWR/6 plants only.

Ie

IN 90-78 December 18, 1990 Combining the General Electric dose calculations for the postulated path with

the leak rates measured from the hydraulic units at either Limerick or

Susquehanna produces dose rates significantly in excess of the values in the

Final Safety Analysis Report. Independent calculations by the NRC staff pro- duced offsite dose values that were comparable to the General Electric results.

Radiation release by this path is not possible as long as the control rod drive

pumps are kept running. However, continued operation of these pumps following

an accident cannot be assured, particularly if the non-seismically qualified

suction piping were to fail.

This problem was resolved at Washington Nuclear Power Plant Unit 2 by the

installation of two check valves in series in the common discharge pipe from

the control rod drive pumps (at area A in Figure 1) to prevent backflow out of

the reactor building (secondary containment). The Washington Nuclear Power

Plant Unit 2 installation includes provisions for leak testing the valves and

a leak rate criterion of 0.01 gpm was established for these valves.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact one

of the technical contacts listed below or the appropriate NRR project manager.

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Charles R. Nichols, NRR

(301) 492-0854 Donald C. Kirkpatrick, NRR

(301) 492-1849 Attachments:

1. Figure 1. BWR Control Rod Drive System

2. List of Recently Issued NRC Information Notices

Note: At Washington Nuclear Power

Plant, Unit 2, the control rod drive

return water Is piped to the reactor w

water cleanup system

SvITE..t. .... \SECONDONDARY

OAin4Z( EXHAUST CWHIOL VALV(S CONTAINMENT

~I ~>*PCV "(E

S CU

OUTSIDE OF DRV

BUILDINGA-H

AREA

A SCIM VALVIE

6TaLQUT1 COTROL4MmuMRG

RMOO140MIX ROD

To OTHE

CONTARNEN R-OD -. I.-AJ___

CrI

DRIVEPUMPSM

0

~j

c

Figure 1. BWR CONTROL ROD DRIVE SYSTEM

Attachment 2 IN 90-78 December 18, 1990 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

90-77 Inadvertent Removal of Fuel 12/12/90 All holders of OLs or

Assemblies from the Reactor CPs for pressurized- Core water reactors (PWRS).

88-23, Potential for Gas Binding of 12/10/90 All holders of OLs or

Supp. 3 High-Pressure Safety Injection CPs for pressurized- Pumps During A Loss-Of-Coolant water reactors (PWRs).

Accident

90-76 Failure Of Turbine Overspeed 12/7/90 All holders of OLs or

Trip Mechanism Because Of CPs for nuclear power

Inadequate Spring Tension reactors.

90-75 Denial Of Access To Current 12/5/90 All Michigan holders

Low-Level Radioactive Waste of NRC licenses.

Disposal Facilities

90-74 Information on Precursors To 12/4/90 All holders of OLs or

Severe Accidents CPs for nuclear power

reactors.

90-73 Corrosion Of Valve-To- 11/29/90 All holders of OLs or

Torque Tube Keys In CPs for nuclear power

Spray Pond Cross Connect reactors.

Valves

90-72 Testing of Parallel Disc 11/28/90 All holders of OLs or

Gate Valves In Europe CPs for nuclear power

reactors.

90-71 Effective Use of Radi- 11/6/90 All NRC licensees

ation Safety Committees authorized to use by- to Exercise Control Over product material for

Medical Use Programs medical purposes.

90-70 Pump Explosions Involving 11/6/90 All uranium fuel

Ammonium Nitrate fabrication and

conversion facilities.

90-38, License and Fee Require- 11/6/90 All fuel facility and

Supp. 1 ments for Processing Fin- materials licensees.

ancial Assurance Submittals

for Decommissioning

OL = Operating License

CP = Construction Permit

IN 90-78 December 18, 1990 Combining the General Electric dose calculations for the postulated path with

the leak rates measured from the hydraulic units at either Limerick or

Susquehanna produces dose rates significantly in excess of the values in the

Final Safety Analysis Report. Independent calculations by the NRC staff pro- duced offsite dose values that were comparable to the General Electric results.

Radiation release by this path is not possible as long as the control rod drive

pumps are kept running. However, continued operation of these pumps following

an accident cannot be assured, particularly if the non-seismically qualified

suction piping were to fail.

This problem was resolved at Washington Nuclear Power Plant Unit 2 by the

installation of two check valves in series in the common discharge pipe from

the control rod drive pumps (at area A in Figure 1) to prevent backflow out of

the reactor building (secondary containment). The Washington Nuclear Power

Plant Unit 2 installation includes provisions for leak testing the valves and

a leak rate criterion of 0.01 gpm was established for these valves.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact one

of the technical contacts listed below or the appropriate NRR project manager.

Origina Signkd IN

Charles E Rossi

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Charles R. Nichols, NRR

(301) 492-0854 Donald C. Kirkpatrick, NRR

(301) 492-1849 Attachments:

1. Figure 1. BWR Control Rod Drive System

2. List of Recently Issued NRC Information Notices

  • 12/11/90

NJDi*C/OGCB:DOEA:NRR

CHBerlinger

12/L~/jW 111/09/90

  • OGCB:DOEA:NRR *SPLB:DST:NRR *C/SPLB:DST:NRR *D/U ST:NRR *RPB:ADM

DCKirkpatrick CRNichols CMcCracken AThadani TechEd

08/17/90 08/20/90 09/24/90 10/30/90 08/06/90

DOCUMENT NAME: IN 90-78

IN 90-XX

August xx, 1990 for these and other plants produced offsite dose values that were comparable

to the General Electric results and that could also significantly exceed the

values specified in the Final Safety Analysis Report. Radiation release by

this path is not possible as long as the control rod drive pumps are kept

running. However, continued operation of these pumps following an accident

cannot be ensured, particularly if the non-seismically qualified suction piping

were to fall.

This problem was resolved at Washington Nuclear Power Plant Unit 2 by the

installation of two check valves in series in the common discharge pipe from

the control rod drive pumps to prevent back flow out of the secondary contain- ment. The Washington Nuclear Power Plant Unit 2 installation includes provisions

for leak testing the valves. Washington Nuclear Power Plant Unit 2 planned to

establish a leak rate criterion for these valves of 0.01 gpm.

The control rod drive system for BWR/6 plants is designed with a testable

check valve and a motor-operated isolation valve, therefore this pathway is

applicable to only pre-BWR/6 plants.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Charles R. Nichols, NRR

(301) 492-0856 Donald C. Kirkpatrick, NRR

(301) 492-1849 Attachments:

1. Figure of Control Rod Hydraulic System

2. List of Recently Issued NRC Information Notices

Document Name: UNIDENTIFIED RELEASE PATH IN

  • SEE PREVIOUS CONCURRENCES

D/DOEA:NRR C/OGCB:DOEA:NRR

CERossi CHBerlinger

10/ /90 10/ /90

OGCB:DOEA:NRR SPLB:DST:NRR C/SPLB:DST:NRR D/DST:NRRK4 RPB:ADM

DCKirkpatrick* CRNichols* CMcCracken* AThadani TechEd*

08/17/90 08/20/90 09/24/90 10M /90 08/06/90

1990

Page 3 f 3 Combining the General Electric dose calculations for the postulated path with

at either Limerick or

the leak rates measured from the hydraulic units in excess of the values specified

Susquehanna produces dose rates significantly calculations by the NRC staff

in the Final Safety Analysis Report. Independent to the General Electric

produced offsite dose values that were comparable the values specified in the

results and that could also significantly exceed by this path is not possible

Final Safety Analysis Report. Radiation release running. However, continued

as long as the control rod drive pumps are kept cannot be assured, particularly

operation of these pumps following an accident were to fail.

if the non-seismically qualified suction piping

This problem was resolved at Washington Nuclear Power Plant Unit 2 by the

installation of two check valves in series in the common discharge pipe from

the control rod drive pumps (at area A) to prevent backflow out of the reactor

building secondary containment. The Washington Nuclear Power Plant Unit 2 and a leak rate

installation includes provisions for leak testing the valves

criterion of 0.01 gpm was established for these valves.

or written response. If

This information notice requires no specific action

in this notice, please contact one

you have any questions about the information appropriate NRR project manager.

of the technical contacts listed below or the

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Charles R. Nichols, NRR

(301) 492-0854 Donald C. Kirkpatrick, NRR

(301) 492-1849 Attachments:

1. Figure 1. BWR Control Rod Drive System

2. List of Recently Issued NRC Information Notices

Document Name: RELEASE PATH NOTICE ok 1vko .

D/DOEA:NRR *C/OGCB:DOEA:NRR

CERossi CHBerlinger

11/ /90 11/09/90

  • C/SPLB:DST:NRR *D/DST:NRR *RPB:ADM
  • OGCB:DOEA:NRR *SPLB:DST:NRR TechEd

DCKirkpatrick CRNichols CMcCracken AThadani

08/20/90 09/24/90 10/30/90 08/06/90

08/17/90

IN 90-XX

August xx, 1990 this path is not possible as long as the control rod drive pumps are kept

running. However, continued operation of these pumps following an accident

cannot be ensured, particularly if the non-seismically qualified suction piping

were to fail.

This problem was resolved at Washington Nuclear Power Plant Unit 2 by the

installation of two check valves in series in the common discharge pipe from

the control rod drive pumps to prevent back flow out of the secondary contain- ment. The Washington Nuclear Power Plant Unit 2 installation includes provisions

for leak testing the valves. Washington Nuclear Power Plant Unit 2 planned to

establish a leak rate criterion for these valves of 0.01 gpm.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Charles R. Nichols, NRR

(301) 492-0856 Donald C. Kirkpatrick, NRR

(301) 492-1849 Attachments:

1. Figure of Control Rod Hydraulic System

2. List of Recently Issued NRC Information Notices

Document Name: UNIDENTIFIED RELEASE PATH IN

  • SEE PREVIOUS CONCURRENCES

D/DOEA:NRR C/OGCB:DOEA:NRR

CERossi CHBerlinger

08/ /90 08/ /90

OGCB:W EA:NRR SPLB:DST:NRR CISPLB:DST:NRR D/DST:NRR *RPB:ADM

DOrirkpathick CRNichols CMcCracken AThadani TechEd

08/e 9/90VC< 08AV2/9M;*^ OF/p/90 408/ /90 08/06/90

V1

IN 90-XX

August xx, 1990 The Washington Nuclear power installation includes provisions for leak testing

the valves. Washington Nuclear Power has established a very low leak rate

criterion for these valves (.01 gpm was indicated). A partial check by the NRC

staff indicates that many of the newer BWR plants already have check valves

installed in the control rod drive pump discharge pipe. However, this check

also showed that other BWR plants, mainly the earlier ones, did not have such

check valves.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contact:

Charles R. Nichols, NRR

(301) 492-0854 Attachments:

1. Figure of Control Rod Hydraulic System

2. List of Recently Issued NRC Information Notices

Document Name: UNIDENTIFIED RELEASE PATH IN

D/DOEA:NRR C/OGCB:DOEA:NRR

CERossi CHBerlinger

08/ /90 08/ /90

OGCB:DOEA:NRR SPLB:DST:NRR C/SPLB:DST:NRR D/DST:NRR RPB:ADM

DCKirkpatyi .-CRNichols CMcCracken AThadani TechEd J ai P

08/' /9 xF 08/ /go 08/ /90 08/ /90 08/C /90


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