Changes in Technical Specification Surveillance Intervals to Accommodate a 24-Month Fuel Cycle (Generic Letter 91-04)

April 2, 1991


TO:       ALL HOLDERS OF OPERATING LICENSES OR CONSTRUCTION PERMITS FOR 
          NUCLEAR POWER REACTORS

SUBJECT:  CHANGES IN TECHNICAL SPECIFICATION SURVEILLANCE INTERVALS TO 
          ACCOMMODATE A 24-MONTH FUEL CYCLE (Generic Letter 91-04)


Improved reactor fuels allow licensees to consider an increase in the 
duration of the fuel cycle for their facilities.  The staff has reviewed 
requests for individual plants to modify surveillance intervals to be 
compatible with a 24-month fuel cycle.  Enclosure 1 provides generic 
guidance for preparing such license amendment requests. 

Technical specifications (TS) that specify an 18-month surveillance interval 
could be changed to state that these surveillances are to be performed once 
per refueling interval.  The notation for surveillance intervals would then 
be changed to include the definition of a "Refueling Interval" with the 
existing "R" notation for surveillances that are generally performed during 
a refueling outage.  The frequency for the interval indicated by this 
notation would also be changed from 18 months to "At least once every 24 
months."  The provision to extend surveillances by 25 percent of the 
specified interval would extend the time limit for completing these 
surveillances from the existing limit of 22.5 months to a maximum of 30 
months.  

The interval for conducting steam generator (SG) inservice inspections 
(ISIs) is worthy of special consideration in extending the surveillance 
intervals to be compatible with a 24-month fuel cycle.  The frequency of SG 
tube ruptures and their possible effect on safety has prompted the staff to 
provide an alternative with which to extend the existing 24-month interval 
requirements for ISIs.  This alternative provides conservative methods for 
verifying SG integrity, including increasing the number of tubes in the 
sample for an inspection based upon the TS category of the results from the 
previous inspection.  In some cases, the results of previous inspections may 
warrant analyzing SG tube integrity and reducing the TS limit on leakage 
between the primary and secondary coolant systems.  Finally, an extension of 
the inspection interval would not be appropriate if the results of the 
previous inspection of SG tube integrity were in the lowest (C-3) category. 

Licensees must address instrument drift when proposing an increase in the 
surveillance interval for calibrating instruments that perform safety 
functions including providing the capability for safe shutdown.  The effect 
of the increased calibration interval on instrument errors must be addressed 
because instrument errors caused by drift were considered when determining 
safety system setpoints and when performing safety analyses.  Enclosure 2 
describes information required to address the effect that instrument drift 
caused by an increased calibration interval can have on safety. 

For other 18-month surveillances, licensees should evaluate the effect on 
safety of the change in surveillance intervals to accommodate a 24-month 
fuel 



9103270310
.

Generic Letter 91-04                - 2 -                   April 2, 1991 



cycle.  This evaluation should support a conclusion that the effect on 
safety is small.  In addition, licensees should confirm that historical 
maintenance and surveillance data do not invalidate this conclusion.  
Licensees should confirm that the performance of surveillances at the 
bounding surveillance interval limit provided to accommodate a 24-month fuel 
cycle would not invalidate any assumption in the plant licensing basis.  In 
consideration of these confirmations, the licensees need not quantify the 
effect of the change in surveillance intervals on the availability of 
individual systems or components. 

The TS changes do not alter the required 24-month testing interval for 
performing Type B and C tests under the current testing requirements of 
Appendix J to Part 50 of Title 10 of the Code of Federal Regulations (10 CFR 
Part 50).  The U.S. Nuclear Regulatory Commission (NRC) is considering 
changes to Appendix J that would accommodate a 24-month fuel cycle.  
However, it is anticipated that licensees will desire an extension of the 
current 24-month testing interval of Appendix J to accommodate a 24-month 
fuel cycle instead of a unit shutdown to perform these tests.  An increase 
in the testing interval for Type B and C tests will require a request for an 
exemption from the Appendix J requirements.  Licensees desiring an exemption 
from the 24-month testing interval should provide supporting leak testing 
data to demonstrate that the requested test interval would not provide 
unacceptable results.  Enclosure 3 provides guidance on the information 
needed to support a request for an exemption to the Type B and C test 
interval requirements in Appendix J. 

The enclosed guidance is provided to support proposed TS changes and a 
request for an exemption to Appendix J requirements for licensees that plan 
to adopt a 24-month fuel cycle.  Proposed amendments that deviate from this 
guidance will lengthen the time required to complete the review.  Please 
contact the NRC project manager or the contact indicated below if you have 
questions on this matter. 

Any response to the NRC suggestion for TS changes is voluntary.  Therefore, 
any action taken in response to the guidance provided in this generic letter 
is not a backfit under 10 CFR 50.109.  Likewise, an Office of Management and 
Budget clearance is not required. 

                                   Sincerely,


                                   James G. Partlow
                                   Associate Director for Projects
                                   Office of Nuclear Reactor Regulation

Enclosures: 
As stated

Contact:  Tom Dunning, OTSB/NRR
          (301) 492-1189
          
          
.

Generic Letter 91-04                                           Enclosure 1 

         GUIDANCE ON PREPARATION OF A LICENSE AMENDMENT REQUEST FOR
   CHANGES IN SURVEILLANCE INTERVALS TO ACCOMMODATE A 24-MONTH FUEL CYCLE 

DISCUSSION 

Licensees are planning to use improved reactor fuels because of the 
significant economic benefits associated with a longer fuel cycle.  A longer 
fuel cycle increases the time interval between refueling outages and the 
performance of the associated technical specification (TS) surveillance 
requirements.  This guidance addresses TS changes to accommodate a 24-month 
fuel cycle for those surveillances that are performed at each 18-month or 
other refueling outage interval. 

The NRC staff has reviewed a number of requests to extend 18-month 
surveillances to the end of a fuel cycle and a few requests for changes in 
surveillance intervals to accommodate a 24-month fuel cycle.  The staff has 
found that the effect on safety is small because safety systems use 
redundant electrical and mechanical components and because licensees perform 
other surveillances during plant operation that confirm that these systems 
and components can perform their safety functions.  Nevertheless, licensees 
should evaluate the effect on safety of an increase in 18-month surveillance 
intervals to accommodate a 24-month fuel cycle.  This evaluation should 
support a conclusion that the effect on safety is small.  Licensees should 
confirm that historical plant maintenance and surveillance data support this 
conclusion.  Also, licensees should confirm that assumptions in the plant 
licensing basis would not be invalidated on the basis of performing any 
surveillance at the bounding surveillance interval limit provided to 
accommodate a 24-month fuel cycle.  In consideration of these confirmations, 
the licensees need not quantify the effect of the change in surveillance 
intervals on the availability of individual systems or components. 

TECHNICAL SPECIFICATION CHANGES 

Licensees should propose TS changes to accommodate a 24-month fuel cycle by 
modifying 18-month surveillances to indicate that they are to be performed 
". . . at least once each REFUELING INTERVAL."  In addition, the proposed  
changes should modify the surveillance interval notation in Table 1.1 in the 
Definitions Section of the TS to include the term "REFUELING INTERVAL" along 
with the "R" notation to define the frequency for surveillances that are 
specified to be performed once each refueling interval.  (Capitalization of 
the term "refueling interval" is used in the TS to designate a defined 
term.)  The proposed TS change should modify the frequency for this 
surveillance interval notation from "At least once per 18 months" to "At 
least once per 24 months" to define the nominal frequency for surveillances 
that are specified to be performed each refueling interval or with the "R" 
notation.  The bounding time interval for these surveillances would then be 
30 months under the provision of TS 4.0.2 that allows a surveillance to be 
extended by 25 percent of the specified interval.  

Licensees may omit the TS qualification that an 18-month surveillance is to 
be performed "during shutdown" when specifying the surveillance interval as 
". . . at least once per REFUELING INTERVAL."  Because the terms "Hot" and 
"Cold Shutdown" are defined in the TS as operating modes or conditions, the 
added restriction to perform certain surveillances during shutdown may be 
mis-interpreted.  This restriction ensures that a surveillance would only be 
.

Generic Letter 91-04                - 2 -                      Enclosure 1 



performed when it is consistent with safe plant operation.  However, this 
consideration is valid for other surveillances that are performed during 
power operation, plant startup, or shutdown, but is not addressed by 
restricting the conduct of  these surveillances.  

The staff concludes that the TS need not restrict surveillances as only 
being performed during shutdown.  Nevertheless, safety dictates that when 
refueling interval surveillances are performed during power operation, 
licensees give proper regard for their effect on the safe operation of the 
plant. If the performance of a refueling interval surveillance during plant 
operation would adversely affect safety, the licensee should postpone the 
surveillance until the unit is shut down for refueling or is in a condition 
or mode that is consistent with the safe conduct of that surveillance. 

The NRC provided an updated basis for TS 4.0.2 in Generic Letters (GLs) 
87-09, "Sections 3.0 and 4.0 of Standard Technical Specifications on the 
Applicability of Limiting Conditions for Operation and Surveillance 
Requirements," and 89-14, "Line-Item Improvements in Technical 
Specifications - Removal of the 3.25 Limit on Extending Surveillance 
Intervals."  However, the TS changes to accommodate a longer fuel cycle will 
also alter the basis for TS 4.0.2.  Therefore, licensees should update the 
Bases Section of TS 4.0.2 to be consistent with these TS changes and 
particularly with respect to the safe conduct of refueling interval 
surveillances.  The changes to the associated paragraph of the previous 
guid-ance on the Bases Section of TS 4.0.2 are underlined, as follows: 

     It also provides flexibility to accommodate the length of a fuel 
     cycle for surveillances that are specified to be performed at 
     least once each REFUELING INTERVAL.  It is not intended that this 
     provision be used repeatedly as a convenience to extend surveillance 
     intervals beyond that specified for surveillances that are 
     not performed once each REFUELING INTERVAL.  Likewise, it is not 
     the intent that REFUELING INTERVAL surveillances be performed 
     during power operation unless it is consistent with safe plant 
     operation.  The limitation of Specification 4.0.2 is . . .

Licensees should incorporate these changes to the Bases Section of TS 4.0.2 
where they have been modified as identified in GLs 87-09 and 89-14.  
Otherwise, the Bases Section should be updated to reflect the intent of this 
guidance.  The proposed amendment request should include a copy of the 
updated Bases Section for TS 4.0.2. 

The surveillance interval for performing the second inservice inspection of 
steam generators is currently specified with a bounding time limit of 24 
calendar months after the previous inspection.  The interval for subsequent 
inspections may be extended to a maximum of 40 months if the results from 
two consecutive inspections, excluding the preservice inspection, are within 
the C-1 Category or if two consecutive inspections demonstrate that 
previously observed degradation has not continued and no additional 
degradation has occurred.  However, for plants having inspection results in 
the C-2 Category from inspections of steam generators (SGs) during either of 
the two previous inspections, the bounding interval for the next inspection 
would be 24 months from the last inspection.  

.

Generic Letter 91-04                - 3 -                      Enclosure 1 



A 24-month inspection interval may not coincide with the next refueling 
outage when operating on a 24-month fuel cycle, particularly if any outage 
time is accumulated over the duration of the fuel cycle or if startup for 
the next fuel cycle is delayed following the completion of a SG inspection.  
Therefore, the staff developed an alternative to compensate for any delay 
that could cause the interval for SG inspections to occur near the end of a 
24-month fuel cycle but before the refueling outage. The alternative 
includes the following:  (1) an increase in the sample size of tubes 
examined during the previous inspection, (2) a suitable analysis of the 
integrity of SG tubes if the results of either of the two previous 
inspections were in the C-2 Category, and (3) a more restrictive limit for 
leakage between the primary and secondary coolant systems for operation 
beyond 24 months after the previous inspection.  These considerations 
provide an acceptable basis with which to permit the next inspection 
interval to be compatible with the 30-month bounding limit for refueling 
interval surveillances if the results of either of the two previous 
inspections were not in the C-3 Category. 

The current TS requirements permit inspections to be conducted at 40-month 
intervals if the results of two previous inspections are in the C-1 
Category. However, this may not provide a practical alternative for 
facilities that would operate on a 24-month fuel cycle.  The inspection 
results would be in the C-2 Category if only one defective tube were found 
during either of the two previous inspections, and this would preclude the 
use of the provision for extending the inspection interval to 40 months. 

The alternatives for the TS section on SG inspection frequencies are shown 
underlined based on the current STS requirements. 

4.4.5.3  Inspection Frequencies - The above required inservice inspections 
of steam generator tubes shall be performed at the following frequencies: 

     a.   The first inservice inspection shall be performed after 6 
          Effective Full Power Months but within 24 calendar months of 
          initial criticality.  Subsequent inservice inspections shall be 
          performed at intervals of not less than 12 nor more than 24 
          calendar months after the previous inspection.  If 20 percent of 
          the tubes were inspected and the results were in the C-1 Category 
          or if 40 percent of the tubes were inspected and were in the C-2 
          Category during the previous inspection, the next inspection may 
          be extended up to a maximum of 30 months in order to correspond 
          with the next refueling outage if the results of the two previous 
          inspections were not in the C-3 Category.  However, if the results 
          of either of the previous two inspections were in C-2 Category, an 
          engineering assessment shall be performed before operation beyond 
          24 months and shall provide assurance that all tubes will retain 
          adequate structural margins against burst throughout normal 
          operating, transient, and accident conditions until the end of 
          the fuel cycle or 30 months, which ever occurs first.  If two 
          consecutive inspections, not including the preservice inspection, 
          result in all inspection results falling within the C-1 Category 
          or if two consecutive inspections demonstrate that previously 
          observed degradation has not continued or no additional 
          degradation has occurred, the inspection interval may be extended 
          to a maximum of once per 40 months;  

.

Generic Letter 91-04                - 4 -                      Enclosure 1 



     b.   If the results of the inservice inspection of a steam generator 
          conducted in accordance with Table 4.4.2 at 40-month intervals 
          fall into Category C-3, the inspection frequency shall be 
          increased to at least once per 20 months.  The increase in 
          inspection frequency shall apply until the subsequent inspections 
          satisfy the criteria of Specification 4.4.5.3a.; the interval may 
          then be extended to a maximum of once per 30 or 40 months, 
          as applicable; 

     c.   (no change to unscheduled inservice inspection requirements.); and

     d.   
          The provisions of Specification 4.0.2 do not apply for extending 
          the frequency for performing inservice inspections as specified in
          Specifications 4.4.5.3a. and b.

The staff added TS 4.4.5.3d. to clarify its position that the provision of 
TS 4.0.2 does not apply to extend SG inspection intervals because TS 
4.4.5.3a. addresses those conditions under which the 24-month surveillance 
interval for SG tube inspections may be extended and TS 4.4.5.3b. addresses 
conditions under which the surveillance interval for inspections shall be 
reduced to at least once every 20 months. 

Licensees should update the Bases Section of TS 3/4.5.4 to clarify the 
intent of the engineering assessment of SG tube integrity addressed in the 
above addition to TS 4.4.5.3a. by adding the following: 

     An engineering assessment of steam generator tube integrity will 
     confirm that no undue risk is associated with plant operation beyond 24 
     months of the previous steam generator tube inspection.  To provide 
     this confirmation, the assessment would demonstrate that 
     all tubes will retain adequate structural margins against burst during 
     all normal operating, transient, and accident conditions until the end 
     of the fuel cycle.  This evaluation would include the following 
     elements: 
     
     1.   An assessment of the flaws found during the previous inspection.

     2.   An assessment of the maximum flaw size that can be expected before 
          the end of the current fuel cycle or 30 months, which ever comes 
          first, and the corresponding structural margins relative to the 
          criteria of Regulatory Guide 1.121, "Bases for Plugging Degraded 
          PWR Steam Generator Tubes."

     3.   An update of the assessment model, as appropriate, based on 
          comparison of the predicted results of the steam generator tube 
          integrity assessment with actual inspection results from previous 
          inspections.

Along with the above alternative for inspection intervals, the following 
addition to the TS section on reactor coolant system operational leakage is 
required and shown underlined for the current STS requirements. 

.

Generic Letter 91-04                - 5 -                      Enclosure 1 



3.4.6.2  Reactor Coolant System leakage shall be limited to: 

     a. & b.  (No change.) 
     
     c.   1 GPM total reactor-to-secondary leakage through all steam 
          generators not isolated from the Reactor Coolant System and [500] 
          gallons per day through any one steam generator not isolated from 
          the Reactor Coolant System.  For plant operation beyond 24 months 
          from the previous steam generator tube inspection when the results 
          of either of the two previous inspections are in the C-2 Category 
          as defined by Specification 4.4.5.2, the leakage through any one 
          steam generator not isolated from the Reactor Coolant System shall 
          not exceed 100 gallons per day,

     d. & e.  (No change.) 
.

Generic Letter 91-04                                           Enclosure 2 


              GUIDANCE FOR ADDRESSING THE EFFECT OF INCREASED 
                 SURVEILLANCE INTERVALS ON INSTRUMENT DRIFT 
                      AND SAFETY ANALYSIS ASSUMPTIONS 

Discussion 

The U.S. Nuclear Regulatory Commission (NRC) staff determined that licensees 
should address the issue of instrumentation errors caused by drift in order 
to justify an increase in surveillance intervals to accommodate a 24-month 
fuel cycle.  Licensees must evaluate the effects of an increased calibration 
interval on instrument errors in order to confirm that drift will not result 
in instrument errors that exceed the assumptions of the safety analysis.  
Instrument drift affects the capability of a system to perform its safety 
function and is a consideration for determining safety system setpoints.  
The amount of instrument drift that occurs over a long interval between 
calibrations may not be readily available from the instrument vendor.  
However, operating experience and available vendor data can provide insights 
on the increase in instrument errors that could occur with an increased 
calibration interval.  These insights, with a program to monitor and assess 
the long-term effects of instrument drift, can provide the basis for 
increasing the refueling outage related calibration intervals for 
instruments that perform safety functions. 

Justification for Increased Calibration Intervals 

Licensees should address a number of issues to provide an acceptable basis 
for increasing the calibration interval for instruments that are used to 
perform safety functions.  The NRC staff has identified a specific action 
that licensees should address for each of these issues in order to justify a 
proposed increase in the calibration interval.  A summary of the applicable 
issue is provided after each of the following actions. 

     1.  Confirm that instrument drift as determined by as-found and as-left 
     calibration data from surveillance and maintenance records has not, 
     except on rare occasions, exceeded acceptable limits for a calibration 
     interval.

The surveillance and maintenance history for instrument channels should 
demonstrate that most problems affecting instrument operability are found as 
a result of surveillance tests other than the instrument calibration.  If 
the calibration data show that instrument drift is beyond acceptable limits 
on other than rare occasions, the calibration interval should not be 
increased because instrument drift would pose a greater safety problem in 
the future.  

     2.  Confirm that the values of drift for each instrument type (make, 
     model, and range) and application have been determined  with a high 
     probability and a high degree of confidence.  Provide a summary of the 
     methodology and assumptions used to determine the rate of instrument 
     drift with time based upon historical plant calibration data.  

The licensee should have a body of as-found and as-left calibration data 
that permits the determination of the rate of instrument drift with time 
over the calibration interval.  This data should allow the determination of 
instrument drift for those instruments that perform safety functions. 

.

Generic Letter 91-04                - 2 -                      Enclosure 2 



     3.  Confirm that the magnitude of instrument drift has been determined 
     with a high probability and a high degree of confidence for a bounding 
     calibration interval of 30 months for each instrument type (make, model 
     number, and range) and application that performs a safety function.  
     Provide a list of the channels by TS section that identifies these 
     instrument applications.  

The magnitude of the instrument drift error that occurs over a longer 
interval is an important consideration to justify an extension of the 
calibration interval for instruments that perform safety functions.  
Licensees need to identify the applications where the calibration interval 
for these instruments depends upon the length of the fuel cycle and could be 
as long as 30 months (the extension limit for this calibration interval).  
Licensees should determine the projected value of the instrument drift error 
that could occur over a 30-month interval for each of these applications. 

     4.  Confirm that a comparison of the projected instrument drift errors 
     has been made with the values of drift used in the setpoint analysis.  
     If this results in revised setpoints to accommodate larger drift 
     errors, provide proposed TS changes to update trip setpoints. If the 
     drift errors result in a revised safety analysis to support existing 
     setpoints, provide a summary of the updated analysis conclusions to 
     confirm that safety limits and safety analysis assumptions are not 
     exceeded.  

Licensees should ensure that the projected value of instrument drift for an 
increased calibration interval is consistent with the values of drift errors 
used in determining safety system setpoints.  These setpoints ensure that 
the consequences of accidents and anticipated transients are bounded within 
the assumptions of the safety analysis.  If the allowance for instrument 
drift that was used to establish trip setpoints for safety systems would be 
exceeded, licensees should establish new trip setpoints for safety systems.  
Instrument Society of America (ISA) Standard, ISA-A67.04-1982, "Setpoints 
for Nuclear Safety-Related Instrumentation Used in Nuclear Power Plants," 
provides a methodology for evaluating instrument drift.  The NRC endorsed 
this standard in Regulatory Guide 1.105, "Instrument Setpoints for 
Safety-Related Systems."  If a new setpoint must be used to ensure that 
safety actions will be initiated consistent with the assumptions of the 
safety analysis, this will require a TS revision to reflect a new trip 
setpoint value.  If the combination of instrument drift errors and current 
trip setpoints is not consistent with existing safety analysis assumptions, 
licensees should perform a new safety analysis to confirm that safety limits 
will not be exceeded with the increased drift associated with longer 
calibration intervals. 

     5.  Confirm that the projected instrument errors caused by drift are 
     acceptable for control of plant parameters to effect a safe shutdown 
     with the associated instrumentation.

Licensees should determine the effect of instrument errors on control 
systems used to effect a safe shutdown.  Licensees must confirm that the 
instrument errors caused by drift will not affect the capability to achieve 
a safe plant shutdown. 

.

Generic Letter 91-04                - 3 -                      Enclosure 2 



     6. Confirm that all conditions and assumptions of the setpoint and 
     safety analyses have been checked and are appropriately reflected in 
     the acceptance criteria of plant surveillance procedures for channel 
     checks, channel functional tests, and channel calibrations.

Licensees should take care to avoid errors or oversights when establishing 
acceptance criteria for plant surveillance procedures that are derived from 
the assumptions of the safety analysis and the results of the methodology 
for determining setpoints.  The NRC staff experience is that licensees have 
encountered problems when asked to confirm that instrument drift and other 
errors and assumptions of the safety and setpoint analyses are consistent 
with the acceptance criteria included in plant surveillance procedures.  
This review should include channel checks, channel functional tests, and the 
calibration of channels for which surveillance intervals are being 
increased. 

     7.  Provide a summary description of the program for monitoring and 
     assessing the effects of increased calibration surveillance intervals 
     on instrument drift and its effect on safety.

Finally, licensees should have a program to monitor calibration results and 
the effect on instrument drift that will accompany the increase in 
calibration intervals.  The program should ensure that existing procedures 
provide data for evaluating the effects of increased calibration intervals.  
The data should confirm that the estimated errors for instrument drift with 
increased calibration intervals are within the limits projected.  

In summary, licensees can provide a justification for increased surveillance 
intervals for instrument channel calibration by addressing each of the items 
noted herein. 


.

Generic Letter 91-04                                           Enclosure 3


    GUIDANCE ON INFORMATION NEEDED TO SUPPORT AN EXEMPTION TO APPENDIX J 
           OF 10 CFR PART 50 TO ACCOMMODATE A 24-MONTH FUEL CYCLE 

BACKGROUND 

The NRC staff is developing changes to Appendix J to 10 CFR Part 50 to 
resolve a number of problems that have been encountered with this 
regulation.  These changes include revising the surveillance interval for 
performing Type B and C leak testing in order to accommodate a longer fuel 
cycle.  However, until such changes are incorporated in the regulation, the 
current 24-month surveillance interval for Type B and C tests would likely 
require a plant shutdown to perform Appendix J leak testing before the 
completion of a 24-month fuel cycle.   To temporarily solve this limitation, 
the NRC staff has prepared guidance on information needed to support an 
exemption to the requirements of Appendix J until the regulation is revised 
to accommodate a 24-month fuel cycle. 

DISCUSSION 

The NRC staff guidance on revising surveillance intervals specified in TS 
provides a bounding time limit of 30 months to accommodate a 24-month fuel 
cycle.  The exemption to Appendix J will require that a 25-percent increase 
in the 24-month surveillance interval for Type B and C leak tests be granted 
in order to be compatible with the change in the TS surveillance intervals 
that accommodate a 24-month fuel cycle.  The NRC staff concludes that 
licensees should address two issues to justify an exemption to Appendix J in 
order for the NRC to grant a request to extend the surveillance interval of 
Type B and C tests up to 30 months.  

The first issue is a possible reduction in the combined leakage limit for 
Type B and C tests based upon an increase in the margin to the TS allowable 
leakage limit which is proportional to the proposed increase in the 
surveillance interval.  The acceptance criterion for Type B and C leak tests 
is a combined leakage rate for all penetrations and valves that are subject 
to Type B and C tests that shall be less than 0.6 of La, where La is the 
maximum allowable leakage rate that is specified in the TS.  This 
constitutes a margin of 40 percent of La.  Licensees should use leak test 
data to demonstrate that this margin will be preserved with the proposed 
increase in the test interval, or should consider proposing an acceptance 
criterion limit of less than 0.6 of La for Type B and C tests as a TS 
change. 

The second issue is that there should be a reasonable basis for licensees to 
conclude that containment leakage will be maintained within acceptable 
limits based upon the extrapolation of the results of past Type B and C leak 
tests to account for an increase in the surveillance interval up to 30 
months.  The exemption request should include a summary of the methodology 
used and results obtained that support this conclusion. 

In summary, licensees can provide a justification for an exemption to 
Appendix J by addressing each of the issues noted herein.