ML073450262

UNITED STATES 

NUCLEAR REGULATORY COMMISSION 

OFFICE OF NUCLEAR REACTOR REGULATION 

WASHINGTON, DC 20555-0001 

March 19, 2008 

NRC INFORMATION NOTICE 2008-02: FINDINGS IDENTIFIED DURING COMPONENT 

DESIGN BASES INSPECTIONS 

ADDRESSES

All holders of operating licenses for nuclear power reactors, except those who have 

permanently ceased operations and have certified that fuel has been permanently removed 

from the reactor vessel. 

PURPOSE

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to inform 

addressees of issues identified during recent component design bases inspections (CDBIs) 

regarding the capability of selected components to perform their design bases safety functions. 

The NRC expects 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 IN are not NRC requirements; therefore, no specific action or written response is required. 

BACKGROUND

Starting in January 2006, CDBIs replaced safety system design and performance capability 

(SSDPC) inspections in the baseline inspection program of the Reactor Oversight Process. 

Unlike SSDPC inspections, CDBIs are not limited to one or two systems. Instead, CDBIs verify 

that design bases have been correctly implemented for selected risk-significant and low-margin 

components and that operating procedures and operator actions are consistent with design and 

licensing bases. This is to ensure that selected components are capable of performing their 

intended safety functions. Inspectors also review the initial design and subsequent 

modifications to verify that important design features have not been altered or disabled during a 

modification. The basis for the change from SSDPC inspections to CDBIs is described in 

SECY-05-0118, “Results of the Pilot Program to Improve the Effectiveness of Nuclear 

Regulatory Commission Inspections of Engineering and Design Issues,” dated July 1, 2005, 

available through the Agencywide Documents Access and Management System (ADAMS) 

Accession No. ML051390465. 

DESCRIPTION OF CIRCUMSTANCES

Following is a summary of the findings identified by CDBIs from their initiation in January 2006, 

through September 2007. This summary also includes several findings that were identified 

during the pilot CDBI inspection performed in 2004. The areas of concern were identified in 

SECY-05-0118. Enclosure 1 lists the referenced NRC inspection reports. The specific CDBI 

findings can be accessed under ADAMS Accession No. ML080670419. 
IN 2008-02 

Page 2 of 6 

(1) Potential Air Entrainment and Vortexing of Safety-Related Fluid Systems

NRC inspectors identified instances where design deficiencies could have led to air entering 

safety-related water systems, potentially resulting in damage to pumps and a degradation or 

loss of system function. The majority of these design issues were related to inappropriate 

setpoint calculations for refueling water storage tank and condensate storage tank (CST) level 

instruments. These level instruments, and associated alarms, are used either to stop 

safety-related pumps or to realign their suctions to alternate water supplies. The failure to stop 

operating pumps or to transfer their suctions can result in the ingestion of gas from these tanks 

which could cause degraded system performance and would eventually cause damage to the 

pumps. In some cases, both trains of a redundant safety-related system could be affected by 

this design deficiency. The potentially affected systems for pressurized-water reactors included 

auxiliary feedwater, containment spray, high pressure safety injection, and low pressure safety 

injection/residual heat removal (RHR). The potentially affected systems for boiling-water 

reactors included high pressure core spray and reactor core isolation cooling. 

The level setpoint issues included: (a) the use of inappropriate methodology to predict the 

onset of vortexing in tanks, (b) the failure to allow for the time required for the transfer of the 

pump suctions to be completed (operator response times and valve stroke times), and (c) the 

failure to correctly translate analysis results into operating procedures. One case involved the 

failure to account for instrument uncertainty, resulting in potentially inadequate vortexing margin 

for the RHR pumps during reactor coolant system mid-loop operation. Another case involved 

failure to account for the potential effect of air entrainment on the level instrument sensing lines. 

Some deficiencies involved the existence of air in the suction piping associated with safetyrelated pumps. This stemmed from the failure to ensure that the piping was full of water 

following testing or maintenance activities. One case involved a system design inadequacy that 

created the potential for air intrusion into operating auxiliary feedwater (AFW) pumps, potentially 

resulting in a common mode failure of the AFW system. The AFW pump discharge pressure 

trip design was not in compliance with the plant licensing basis because it could not be shown 

that the AFW pumps would trip prior to pump damage, due to air ingestion if the CSTs or 

suction piping failed during a seismic or tornado event. 

(2) Emergency Diesel Generators

NRC inspectors identified instances where the emergency diesel generators (EDGs) loading 

calculations failed to account for the increased electrical load resulting from EDG operation at 

the maximum frequency allowed by technical specifications. The operation of rotating 

equipment at higher speeds (resulting from higher electrical frequencies) would result in 

increased EDG loads under accident conditions. In some cases, the EDG capacity margin was 

found to be small compared to the potential load increase. 

Other EDG deficiencies included: (a) failure to verify that fuel oil testing results were within 

specified limits, (b) failure to correctly determine tube plugging limits for associated heat 

exchangers, (c) failure to account for all potential electrical loads in analyses, (d) failure to verify 

fuel transfer equipment was rated for the required temperature, and (e) inadequate procedures 

related to ground faults and tornado depressurization. 
IN 2008-02 

Page 3 of 6 

(3) Testing

NRC inspectors identified instances where test acceptance criteria failed to ensure the 

capability of the equipment to perform its function under the most limiting conditions. Examples 

included the acceptance criteria for valve and pump surveillance tests as well as design 

requirements and safety-related battery tests that did not include appropriate minimum voltage 

acceptance criteria. NRC inspectors identified deficiencies in test programs for molded case 

circuit breakers. Other test deficiencies included: (a) failure to account for EDG underfrequency in pump test acceptance criteria, (b) failure to appropriately account for instrument 

uncertainties, (c) failure to ensure adequate test equipment, (d) failure to account for valve 

pressure locking effects, and (e) failure to verify the minimum containment cooling coil fouling 

factor assumed in analyses. 

(4) Cooling Water Systems

NRC inspectors identified instances where the licensee did not demonstrate that systems were 

capable of performing their intended safety function under the most limiting conditions. One 

finding involved the failure to appropriately account for service water strainer plugging in the 

flow calculation. Another finding was that system design calculations did not reflect the 

maximum strainer pressure drop allowed by the plant operating procedures, resulting in 

potentially non-conservative analyses. 

Other issues included: (a) failure to evaluate the potential loss of a non-safety-related service 

water valve positioner, (b) failure to adequately evaluate the potential effects on system 

performance of a closed valve that was leaking significantly, (c) failure to address maximum 

component cooling water piping temperatures in the pump room heat up calculation, (d) 

modification to remove four fans from the safety-related screenhouse ventilation system without 

adequately verifying the adequacy of remaining fans, and (e) potential plugging of emergency 

(auxiliary) feedwater flow control valves when aligned to the service water system, which served 

as a backup water supply. 

Procedure deficiencies included: (a) failure to verify by testing that adequate flow was provided 

to an essential service water cooling tower, (b) inadequate operating procedures to perform time 

critical operations after the loss of component cooling water, and (c) plant procedures that would 

have allowed a plugged strainer to be bypassed without an evaluation of the potential impact on 

downstream equipment. 

(5) Station Blackout

NRC inspectors identified deficiencies related to plant operation after a postulated loss of all 

alternating current (AC) power. This scenario may require equipment to operate in off-normal 

conditions and may require the use of non-safety-related equipment to maintain the plant in a 

safe condition for the design basis coping duration. The identified deficiencies included: (a) 

failure to perform analyses or have adequate procedures to ensure that building temperatures 

would be acceptable for the operation of equipment credited for coping with a station blackout, 

(b) failure to perform coping analyses that covered the entire coping duration, (c) failure to 

address the degraded reliability of a non-safety-related gas turbine, and (d) failure to perform an 

evaluation to support a procedure change that substituted manual actions for automatic actions 
IN 2008-02 

Page 4 of 6 

during a station blackout event in accordance with Title 10 of the Code of Federal Regulations

(10 CFR), Section 50.59, “Changes, Tests and Experiments.” 

(6) Motor Operated Valves

NRC inspectors identified where licensees failed to identify the maximum differential pressures 

across containment sump isolation valves, and analyze the ability of the valves to open with 

these pressures. The postulated scenario involves the pressurization of the piping between 

these valves and the suction of the safety injection/RHR pumps after an accident where the low 

pressure pumps are not injecting flow. The failure of these valves to open could result in a loss 

of long term emergency core cooling. In addition, inspectors identified where a licensee failed 

to use adequate methodology to determine if a motor-operated valve (MOV) could be 

susceptible to pressure locking phenomenon. 

NRC Inspectors identified deficiencies including non-conservative inputs to MOV voltage 

calculations, and incorrect control logic for containment isolation valves. NRC inspectors also 

identified deficiencies in MOV overload protection, as described in section (9) of this IN. 

(7) Operability Evaluations

NRC inspectors identified deficiencies including the failure to identify degraded conditions and 

perform operability evaluations, the failure to identify past operability issues for potential 

reportability, and the failure to perform adequate operability evaluations for degraded conditions. 

One licensee failed to promptly identify and correct a long-standing condition involving an 

inadequate safety analysis dose calculation, and failed to maintain previously imposed 

compensatory measures that were credited in plant analyses. 

(8) Standby Batteries and Direct Current Electrical Distribution Systems

NRC inspectors identified deficiencies in the 125 volts direct current (Vdc) system voltage drop 

calculations including: (a) failure to include acceptance criteria for end use equipment such as 

circuit breakers, (b) failure to analyze an alternate supply for the 125 Vdc system, (c) improper 

methodology for determining first minute voltage, (d) failure to consider effect of accident 

temperatures on cable resistance, and (e) failure to use conservative design inputs for battery 

inter-cell resistance and battery terminal voltage. Deficiencies were identified in battery sizing 

calculations involving failure to correctly model battery loads and charger restoration 

procedures. 

NRC inspectors identified instances of improper battery and battery charger maintenance 

including failure to follow procedures for cleaning battery terminals, inadequate procedures for 

cleaning spilled electrolyte, use of a non-safety-related battery charger without proper isolation, 

failure to periodically energize a spare battery charger, improper torque values for battery 

terminals, and ineffective corrective action for high battery inter-cell resistance. NRC inspectors 

also identified instances of inadequate battery testing listed under section (3) of this IN. 
IN 2008-02 

Page 5 of 6 

(9) Alternating Current Auxiliary Power Systems

NRC inspectors identified instances of deficiencies in voltage calculations for AC auxiliary power 

systems. These included: (a) lack of motor starting studies, (b) use of incorrect brake 

horsepower, (c) using incorrect assumption for voltage drop in cables, and (d) errors in control 

circuit analyses for motor control centers. NRC inspectors identified instances where 

calculations for offsite power availability were inadequate including failure to analyze all offsite 

sources, and failure to properly analyze a modified transformer. 

NRC inspectors also identified problems with motor overload protection including failure to 

provide overload protection for a deep well pump, continuously bypassing overload devices for 

several safety-related motors including MOVs, and failure to verify the adequate sizing of fan 

motor overload devices. 

(10) Circuit Breakers

NRC inspectors identified instances of improper maintenance of circuit breakers involving failure 

to follow vendor maintenance recommendations. Other findings related to circuit breakers 

included failure to use the correct short circuit rating in a design calculation, and numerous 

testing deficiencies described under the “Testing” topic of this IN. 

DISCUSSION

This IN provides examples in which the design basis was not correctly implemented for certain 

systems and components as required by 10 CFR Part 50, Appendix B, Criterion III, “Design 

Control.” The issues often involved the capability of the plant system or component to perform 

its intended safety function under the most limiting conditions (e.g., pressure, temperature) 

assumed in the plant design and licensing basis. In some cases, the issues were original 

design deficiencies that had not been adequately addressed. In other cases, these design 

deficiencies were introduced as a result of plant design changes, calculation revisions, and/or 

changes to operating and test procedures. Some of the design basis discrepancies resulted in 

technical specification required systems and components being declared inoperable. There 

were also instances where the licensee did not incorporate the requirements and acceptance 

limits contained in applicable design documents into test procedures, as required by 10 CFR 

Part 50, Appendix B, Criterion XI, “Test Control.” The issues discussed in this IN often involved 

plant systems and components with low design margin. Systems and components are 

designed and operated, as described in the current licensing basis, with design margins and 

engineering margins of safety to ensure, among other things, that some loss of quality does not 

mean immediate failure to meet a specified function. The current licensing basis includes 

commitments to specific codes and standards, design criteria, and some regulations that also 

dictate margins. Many licensees add conservatism so that a partial loss of quality does not 

affect their commitments for design and operational margin. The loss of conservatism that is 

not credited in the current licensing basis does not affect operability or functionality. The issues 

discussed in this IN often involved the failure to account for factors, or the use of improper 

assumptions (i.e., not using the most limiting conditions) that could reduce or eliminate the 

available design margin. 

The NRC and its licensees rely on calculations and analyses that predict the performance of the 

facility under various accident sequences. Design deficiencies have the potential of affecting 
IN 2008-02 

Page 6 of 6 

redundant systems and components and introducing common mode failures that were not 

considered in accident or transient analyses. The plant risk assessment model assumes the 

capability of safety systems and components to perform their intended safety function 

successfully. Therefore, the accuracy of these design basis calculations and analyses has 

become increasingly important as the industry and NRC implement risk-informed regulatory 

initiatives. 

CONTACT

This IN requires no specific action or written response. Please direct any questions about this 

matter to the technical contact listed below. 

 /RA/ 

Michael J. Case, Director 

Division of Policy and Rulemaking 

Office of Nuclear Reactor Regulation 

Technical Contact: Donald Norkin, NRR/DIRS 

301-415-2954 

E-mail: dpn@nrc.gov

Enclosure: NRC Inspection Report References 
IN 2008-02 

Page 6 of 6 

redundant systems and components and introducing common mode failures that were not 

considered in accident or transient analyses. The plant risk assessment model assumes the 

capability of safety systems and components to perform their intended safety function 

successfully. Therefore, the accuracy of these design basis calculations and analyses has 

become increasingly important as the industry and NRC implement risk-informed regulatory 

initiatives. 

CONTACT

This IN requires no specific action or written response. Please direct any questions about this 

matter to the technical contact listed below. 

 /RA/

Michael J. Case, Director 

Division of Policy and Rulemaking 

Office of Nuclear Reactor Regulation 

Technical Contact: Donald Norkin, NRR/DIRS 

301-415-2954 

E-mail: dpn@nrc.gov

Enclosure: NRC Inspection Report References” 

Distribution: IN Reading File 

ADAMS Accession Number: ML073450262 

OFFICE IRIB:DIRS TECH EDITOR BC:IRIB:DIRS D:DIRS 

NAME DNorkin HChang TKobetz FBrown 

DATE 02/28/2008 12/19/2007 3/4/2008 3/7/2008 

OFFICE LA:PGCB PGCB:DPR BC:PGCB:DPR D:PGCB:DPR 

NAME CHawes DBeaulieu MMurphy MCase 

DATE 03/12/2008 3/11/2008 03/19/2008 03/19/2008 

OFFICIAL RECORD COPY 
Enclosure 

NRC INSPECTION REPORT REFERENCES 

[Note: A brief description of the specific CDBI findings from the below inspection reports is 

available at ADAMS Accession No. ML080670419.] 

Plant NRC Inspection Report (IR) Number ADAMS No.

Byron Units 1 and 2 IR 05000454/2006009; 05000455/2006009 ML070120571 

Callaway IR 05000483/2006009 ML070560002 

Catawba Units 1 and 2 IR 05000413/2007006; 05000414/2007006 ML071490122 

Donald C. Cook Units 1 and 2 IR 05000315/2007002; 05000316/2007002 ML071060236 

Comanche Peak Units 1 and 2 IR 05000445/2006009; 05000446/2006009 ML070360606 

Dresden Units 2 and 3 IR 05000237/2007006; 05000249/2007006 ML071830531 

Duane Arnold IR 05000331/2006007 ML061580073 

Edwin I. Hatch Units 1 and 2 IR 05000321/2006007; 05000366/2006007 ML062370129 

Fermi IR 05000341/2007003 ML072540412 

Ginna IR 05000244/2007006 ML073060346 

Grand Gulf IR 05000416/2006008 ML061070259 

Hope Creek IR 05000354/2006015 ML070190243 

Indian Point Units 2 and 3 IR 05000247/2007007; 

IR 05000286/2007006 

ML070890270 

ML080320244 

James A. Fitzpatrick IR 05000333/2007006 ML072430509 

Kewaunee IR 05000305/2005002 

IR 05000305/2007006 

ML050950237

ML071550470 

McGuire Units 1 and 2 IR 05000369/2006007; 05000370/2006007 ML061740013 

Monticello IR 05000263/2006009 ML062190468 

Nine Mile Point, Units 1 and 2 IR 05000220/2006008; 05000410/2006008 ML063350016 

Oyster Creek IR 05000219/2007006 ML071870171 

Oconee Units 1, 2, and 3 IR 05000269, 05000270, 05000287/2006006 ML061180004 

Palisades IR 05000255/2006009 ML070440439 

Peach Bottom Units 2 and 3 IR 05000277/2006009; 05000278/2006009 ML061520381 

Pilgrim IR 05000293/2006006 ML061800215 

Point Beach Units 1 and 2 IR 05000266/2006006; 05000301/2006006 ML063200093 

Prairie Island Units 1 and 2 IR 05000282/2007007; 05000306/2007007 ML072180551 

Quad Cities Units 1 and 2 IR 05000254/2006003; 05000265/2006003 ML063330597 

Robinson IR 05000261/2007006 ML071100274 

Saint Lucie IR 05000335/2007006; 05000389/2007006 ML073090538 

Salem Units 1 and 2 IR 05000272/2006006; 05000311/2006006 ML060930500 

San Onofre Units 2 and 3 IR 05000361/2006009; 05000362/2006009 ML063420342 

Seabrook Station IR 05000443/2007006 ML071590071 

Shearon Harris IR 05000400/2006007 ML063400335 

Three Mile Island Unit 1 IR 05000289/2007006 ML070920411 

Virgil C. Summer IR 05000395/2004009 

IR 05000395/2006008 

ML050060203

ML062080036 

Vogtle Units 1 and 2 IR 05000424/2007006; 05000425/2007006 ML072050572 

Vermont Yankee IR 05000271/2004008 

IR 05000271/2006007 

ML043340269

ML062720159 

Waterford IR 050003822007007 ML071940133 

Watts Bar IR 05000390/2007006 ML071100271 

Wolf Creek IR 05000482/2007006 ML072880678