ML17229A466
| ML17229A466 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 08/13/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML17229A465 | List: |
| References | |
| NUDOCS 9709080091 | |
| Download: ML17229A466 (14) | |
Text
gP,R 8500
++*++
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFET V LUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION OF THE SECO D 10-YEAR INTERVAL INSERVICE INSPECTION PROGRAM PLAN RE VEST FOR RELIEF NO.
14 FOR LORIDA POWER AND LIGHT COMPANY S
UCIE PLANT UNIT 2 DOCKET NUMBER 50-389
- 1. 0, INTRODUCTION The Technical Specifications (TS) for St. Lucie Plant, Unit 2 states that the inservice inspection (ISI) of the American Society of Mechanical Engineers (ASHE) Code Class 1, 2, and 3 components shall be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel Code and applicable addenda as required by 10 CFR 50.55a(g),
except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i).
The 10 CFR 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by the U. S. Nuclear Regulatory Commission (NRC), if (i) the proposed alternatives would provide an acceptable level of quality and safety or (ii) compliance with the specified requirements would result in hardship or unusual difficultywithout a compensating increase in the level of quality and safety.
Pursuant to 10 CFR 50.55a(g)(4),
ASHE Code Class 1, 2, and 3 components (including supports) shall meet the requirements, except the design and access provisions and the pre-service examination requirements, set forth in the ASME
- Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components," to the extent practical within the limitations of design,
- geometry, and materials of construction of the components.'he regulations require that inservice examination of components and system pressure tests conducted during the first 10-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) 12 months prior to the start of the 120-month interval, subject to the limitations and modifications li'sted therein.
The applicable edition of Section XI of the ASHE Code for the St. Lucie Plant, Unit 2, second 10-year ISI interval is the 1989 Edition.
Pursuant to 10 CFR 50.55a(g)(5), if the Florida Power and Light Company (licensee) determines that conformance with an examination requirement of Section XI of the ASHE Code is not practical for its facility, information shall be submitted to the Commission in support of that determination and a
request made for relief from the ASHE Code requirement.
After evaluation of
~NCLOSUR 970908009X 9708XS PDR ADQCK 05000389 8
the determination, pursuant to 10 CFR 50.55a(g)(6)(i),
the Commission may grant relief and may impose alternative requirements that are determined to be authorized by law, will not endanger life, property, or the common defense and
- security, and are otherwise in the public interest, giving due consideration to the burden upon the licensee that could result if the requirements were imposed.
By letter dated November 20, 1995, the licensee submitted a revised version of Request for Relief 14 for the St. Lucie, second 10-year inspection interval.
In addition, the licensee provided additional information in its letter dated March 13, 1997.
Request for Relief 14, was originally submitted and evaluated as part of the St.
Lucie second 10-year program plan, and was left unresolved in an NRC safety evaluation dated May 4,
- 1995, due to inadequate justification for the licensee's rescheduling of examinations.
- 2. 0 EVALUATION The staff, with technical assistance from its contractor, the Idaho National Engineering and Environmental Laboratory has evaluated the information provided by the licensee in support of its Second 10-Year ISI Interval Program Plan Request for Relief No.
14 for St. Lucie Plant, Unit 2.
Based on the information submitted, the staff adopts the contractor's conclusions and recommendations presented in the Technical Letter Report (TLR) attached.
For Request for Relief No.
14, the Code requires that the sequence of component examinations established during the first inspection interval be repeated during each successive inspection interval.
In addition, the Code requires a distribution of examinations in accordance with IWX-2400, Inspection Schedule.
The licensee has proposed an alternative to Code requirements by rescheduling examination areas for the second inspection interval to reduce the radiation exposure and burden associated with distributing the examinations of major components by inspection period.
This approach is intended to focus on one component or zone at a time so that redundant insulation removal can be minimized during the inspection interval.
In addition, the licensee proposed to substitute scheduled welds with similar welds in order to reduce radiation exposure.
The Code scheduling philosophy requires periodic examination of selected areas to assure continued system operability and integrity.
Modifying the schedule of examination areas for the second 10-year interval provides the licensee a
means to reduce radiation exposure while enhancing the overall efficiency of the ISI program.
Considering that the purpose of ALARA is to maintain radiation levels "as low as reasonably achievable,"
ISI program changes that reduce radiation exposure without compromising quality and safety are prudent.
There are two technical considerations associated with this request.
The first is the time duration between examinations, which are performed at intervals of approximately 10 years.
This aspect is controlled by the successive examination requirement of the Code (IWX-2420).
The second consideration is the distribution of examinations within the inspection interval, which is governed by IWX-2412 (Inspection Program B) for the
0
3 St. Lucie Plant.
By adhering to the sequence of examinations established during the first 10-year interval, the same insulation would have to be removed two or more times during each inspection interval.
This greatly increases the potential for damage to the insulation, while causing excessive radiation exposure to plant personnel.
As a result, imposition of the Code scheduling and sequencing requirements would create an undue burden on the licensee.
The licensee has proposed, in lieu of the Code requirements, to group the examinations of certain components within a single period to reduce radiation exposure.
To accomplish this, the licensee altered, the sequence of examinations established during the first 10-year interval.
The licensee has provided tables summarizing the rescheduling of examinations by examination category for the second 10-year interval.
These tables indicate that a
majority of the components will be examined during the same period as during the first interval.
For those areas where the schedule was adjusted, the number of components examined later in the interval is offset by those examined earlier.
Although the time between examinations will exceed 10 years for some components, the delayed examination of these components is being compensated for by the examination of other components for which the duration is less than 10 years.
This results in a new sequence of examinations that allows the licensee to achieve its goal of reducing radiation without compromising the level of quality and safety.
The staff determined that this new sequence is an acceptable alternative to reduce the burden of staging the automated tool'ore than once in a given interval.
However, distribution of all Examination Category B-D welds within the interval would require delaying steam generator (SG) examinations into the third period for SG "B", which would mean 14 to 17 years would elapse between examinations.
As a compromise, the licensee has proposed the examination of six examination Category B-D welds on'SG "A" during the third period while examining the SG "B" welds during the second period.
Although thi's results in a slight variation in the scheduling requirements of Inspection Program B of the Code, the staff determined that the distribution is adequate for detecting patterns of degradation that may occur.
Therefore, reasonable assurance of the structural integrity of the subject components will be provided.
The licensee has also proposed to select substitute welds of similar configuration when a significant reduction in radiation exposure can be achieved.
The licensee has committed to meet Program B scheduling requirements and will meet the selection requirements of the Code (i.e.,
terminal ends and high stress welds) whenever-possible.
Si,nce the licensee can reduce exposure while maintaining the scheduling and selection requirements of the Code, the staff finds this portion of the licensee's proposed alternative acceptable.
3.0 CONCLUSION
The licensee has proposed rescheduling of examination areas for the second inspection interval, which will establish a new sequence of examinations while reducing radiation exposure and enhancing the overall'fficiency of the ISI program.
The staff has evaluated the licensee's proposed alternative and concludes that the proposed scheduling changes will provide reasonable assurance of the structural integrity of the affected
- systems, and that imposing the scheduling and sequencing requirements of the Code would.cause an undue hardship without a compensating increase in the level of quality and safety.
Therefore, the licensee's proposed alternative contained in Request for Relief No.
14 is authorized pursuant. to 10 CFR 50.55a(a)(3)(ii).
Attachment:
Technical Letter Report Principal Contributor:
T. McLellan August 13, 1997
TECHNICAL LETTER REPORT ON THE SECOND 10-YEAR INSERVICE INSPECTION INTERVAL EUS 0
FLORIDA OWER AND LIGHT CONPANY ST.
LUCIE PLANT UNIT 2 DOCKET NUMBER 50-389
- 1. 0 INTRODUCTION Request for Relief 14, originally submitted and evaluated as part of the St. Lucie second 10-year program plan, was left unresolved in an NRC safety evaluation report dated Hay 4,
- 1995, due to inadequate justification for the licensee's rescheduling of examinations.
By letter dated November 20, 1995, Florida Power and Light Company (FPL) submitted a revised version of Request for Relief 14 for the St. Lucie, second 10-year inspection interval.
In response to a March 14,
- 1996, conference call, the licensee provided additional information in a letter dated March 13, 1997.
The Idaho National Engineering and Environmental Laboratory (INEEL) staff has evaluated the subject request for relief in the following section.
2.0 EVALUATION The Code of record for the St.
Lucie Plant, Unit 2, second 10-year inservice inspection interval, which began August 8, 1993, is the 1989 Edition of Section XI of the ASHE Boiler and Pressure Vessel Code.
The information provided by the licensee in support of the request for relief from Code requirements has been evaluated and the basis for disposition is documented below.
ATTACHMENT
e uest fo Relic 4
IWB-4 a
d C-24 2
Ins ect o
o ra B
e cent e
Re u' e ts W - 420 d
C-2420 e
e ce o
Co onent Examinations Established Durin the First Ins ection Interval Code Re uirement:
IWB-2412 and IWC-2412 specify the minimum/maximum
,percent of examinations that may be completed/credited each period.
IWB-2420 and IWC-2420 require that the sequence of component examinations established during the first inspection interval be repeated during each successive inspection interval, to the extent practical.
icensee's P
o osed Alternative:
Pursuant to 10 CFR 50.55a(a)(3)(ii),
FPL proposed to adjust the sequence of examinations established within the first inspection interval for the Reactor Pressure
- Vessel, Steam Generator, and Pressurizer such that all major examinations are performed at one time within a specified'inspection
- period, Where practical, the sequence of examinations has been adjusted within the same examination category (Shutdown Cooling Water Heat Exchanger, Regenerative Heat Exchanger, etc.) to minimize the variation in the percentage requirements of Inspection Program B.
The alternative can be summarized as follows:
Reactor Pressure Vessel A'll required examinations will be performed during the second inspection period, in conjunction with the 10-year automated examination activity, with the exception of the examination of the shell-to-flange weld from the seal side and the threads in the flange which will be. conducted in the first period.
Reactor Pressure Vessel Closure Head - All required examinations will be performed in the first inspection period.
Steam Generator (primary and secondary sides)
All required examinations will be performed in the second inspection period, except the Examination Category B-D nozzle-to-vessel welds.for Steam Generator A, which will be examined during the third period.
Pressurizer
- All required examination will be performed in the first inspection period.
Shutdown Cooling Water Heat Exchanger - All required examinations will be performed in the third inspection period.
Regenerative Heat Exchanger - All required examinations will be performed in the second inspection period.
In lieu of the percentage requirements of IWB-2412-1 and IWC-2412-1, FPL proposes the following variations:
Examination
.'Cate or B-A
- B-B B-D B-F B J **
B H ***
B-G-2 C-A C-B C-C 1st; Period 16X - 34X'
- 23X 4-44X'2 33X 10 32X 56 31X
-:1 - 50X 9 29X
.2: 13X 0-OX 6 - 30X 2nd Perio'd 50X - -67X 20 100X
'5 - 100X
'-'I 18 83X ll 67X 65 67X 1
100X 8 54X 6 - 53X 4
50X ll 85X 3rd Period-
'100X -100X..
0 100X 0
100X 6
100X 10 100X 58 100X 0 100X 10 100X 7
100X 4 - 100X 3 - 100X Note: Shaded blocks identify variation from the percentage requirements of Section XI~
Deferral of inspection to the end of interval permissible by IWB-2500-1.
The numbers identified above reflect circumferential weld examinations only.
Later editions of XI allows less than 3 items in a category to be examined in any two periods.
Li n
sis for he Pro Al rn iv (as stated):
"Since FPL began performing in-service examinations, the rules for radiation exposure, safety, and the selection and scheduling of in-service examinations have changed significantly. Examinations in the first in-service inspection interval on Class 1 and 2 components and systems were performed in accordance with the 1980 Edition through the Winter 1980 Addenda of Section XI prorated for the interval.
"Vessels, unlike piping systems are unique in that examination areas include several Examination Categories, Examination Item Numbers, and in the case of steam generators cover two Code Classes (Class 1 and Class 2 respectively).
Equal distribution of examinations over three inspection periods on individual vessels (Steam Generators, Pressurizer, etc,), are complicated due to their unique size, reduction in required examination items and multiple Examination Categories.
Equal distribution imposes an undue hardship in the areas of radiation exposure, personnel
access, multiple job interference, and adds additional cost without providing a significant increase in the quality and safety of the plant.
"Previous Examination Results - The St. Lucie previous nondestructive examination (NDE) results performed on these same components during the first inspection interval have not identified any flaws that exceeded the acceptance criteria of Section XI, or'identify results that would warrant consideration of not adjusting the sequence of the examinations, therefore modifying the ISI schedule would have no effect on the safe operation of the plant.
"Radiation - 10 CFR 20.1101(b) mandates FPL to reduce radiation exposure to as low as reasonably achievable.
In order to satisfy this requirement and other new regulations, FPL must re-evaluate every aspect of every job. Adjusting the sequence of examinations will allow FPL to minimize the amount of work being conducted in radiation areas, meet safety requirements, ALARArequirements, and still meet the intent of Section XI.
"Insulation - Vessel insulation is of a size and shape that the removal process of examination area insulation usually requires a substantial amount of additional insulation to be removed.
Adhering to the sequence of examinations established
. during the first interval would require FPL to remove and reinstall the same insulation and scaffolding on two or more occasions.
Removal, storage and reinstallation of the insulation greatly increases the chances of insulation damage and includes additional man-rem and cost associated with the need for personnel to prepare and examine components in essentially the same area several times.
The radiation exposure, time, and manpower required to perform these tasks can be significantly reduced by changing the sequence of examinations and changing the areas to be examined.
"Cost Reduction - The cost associated with preparing vessels for selected examinations on the same component, within each inspection period in order to specifically satisfy the percentage requirements of Section XI, is an economic hardship, without a substantial compensating increase in the quality or safety of the unit.
"Examination Schedules - While it is desirable to have examination schedules move forward in the interval (less than 10 years between successive examinations), the wording of Inspection Program B makes this difficult. A review of Inspection Program 8 requirements show that it is weighted toward moving examinations to the end of the interval (opposite from USNRC desires.)
The maximum examinations allowed for credit during the 1st period is 34/. If the minimum examinations were performed during the 1st period (16/) and the maximum examined during the 2nd period (67'k), then 51 /o of the interval exams'ould be performed during the 2nd period.
This same thought process can be applied to the 3rd period.
When a sample size in a category is small, Inspection Program B requires examinations to be scheduled later in the interval.
Since St. Lucie ISI examinations were originally scheduled one-third each period, it is not possible to move examination schedules forward without scheduling others later in the interval.
"Inspec'tion Program B allows up to 50% of the 10 year examinations to be
~
performed during the 2nd or 3rd periods.
Allowing this same latitude during the 1st period would enable FPL to perform examinations with a more efficient schedule, reduce radiation exposure and costs, and meet USNRC desires to have the time frame between successive examinations not exceed 10 year intervals.
"Substitutions - Examination items scheduled may be substituted for items not previously scheduled in order to reduce the radiation levels.
All substitutions will meet the selection criteria of the applicable Examination Category, (Le. terminal ends, high stress welds, etc.), and shall meet the percentage requirements of inspection program "B"
~ Such changes will be noted in the summary report submittal.
"Tables 14-1 through 14-10 provide listings of items selected for adjustment by Examination Category and provides specific percentages to be achieved during the inspection interval and within each inspection period.
"Table 14-11 provides a Category summary for all Code Categories."
tn the March 13, 1997, submittal, the licensee provided the following information regarding substitutions and the scheduling of the RPV and Class 1 nozzle-to-vessel
~
"FPL will schedule substitute welds for examination in accordance with Section XI selection and scheduling requirements.
When substitute welds are selected, they will be similar in configuration to those originally scheduled, if possible.
Terminal end welds and high stress welds will be selected, if available.
The substituted welds will be on the same or similar lines as close as possible to the originally scheduled welds.
Substitute welds will be selected only when a significant reduction in overall exposure or costs can be achieved, or the originally scheduled weld is no longer accessible or has been removed from service.
Program 8 requirements will be followed.
"FPL will perform the required RPV examinations during the scheduled March 1999 refueling outage.
This schedule will have FPL performing the examinations 10 years after the March 1989 outage.
"FPL has reviewed the originally submitted schedule to determine the effect of moving the RPV examinations forward by one period.
By doing this, Program B
requirements would be exceeded by having too many examinations scheduled during the second period.
The. review showed the pressurizer welds were examined during the first period.
The pressurizer examinations met the maximum requirements of Program B and Code Category 8-D for the first period.
Steam Generator A and 8 (with 12 B-D areas) are scheduled for the second period and the RPV, examinations (with 12 B-D areas) for the third period to meet the Program B requirements.
By moving the RPV examinations forward one period, 100% of the Category B-D examinations would be completed by the end of the second period, with no examinations scheduled for the third peiiod.
In order to correct this, the steam
generator examinations would have to be moved to the third period.
However, steam generator B was already delayed one period.
By delaying it a second period, it would mean 14 to 17 years between examinations.
FPL felt these examinations should not be delayed any further.
For steam generator A, FPL can delay one period and still be approximately 10 years between examinations.
This would still result in the second period having more examinations scheduled than allowed by Program B, but is a reasonable alternative that will not affect the safety and quality of the plant.
FPL plans to use the following schedule:
,,. ':Category B-D Examination'Schedule'::-',,'i,'.'",:,.">>:.'.:;.";:
,, Co'mponent, Number of areas
- Peiiod':..":
- '-"RPV.'='-
Steam Generator Pressurizer "12.'2 12
.:.0:.
0 12
'- 12
.0 0'::-
.Totals
'-36 12 = 33ojS '18=83'6
= 100/o Evaluation: The Code requires that the sequence of component examinations established during the first inspection interval be repeated during each successive inspection interval.
In addition, the Code requires a distribution of examinations in accordance with IWX-2400, Inspection Schedu/e.
The licensee has proposed rescheduling examination areas for the second inspection interval to reduce the radiation exposure and burden associated with distributing the examinations of major components by inspection period.
This approach is intended to focus on one component or zone at a time so that redundant insulation removal can be minimized during the inspection interval.
In addition, the licensee proposed to substitute scheduled welds with similar welds in order to reduce radiation exposure.
The Code scheduling philosophy requires periodic examination of selected areas to assure continued system operability and integrity. Modifying the schedule of examination areas for the second 10-year interval provides the licensee a fneans to reduce radiation exposure while enhancing the overall efficiency of the inservice inspection program.
Considering that the purpose of ALARAis to maintain radiation levels as low as reasonably achievable, ISI program changes that reduce radiation exposure without compromising quality and safety are prudent.
There are two technical considerations associated with this request.
The first is the time duration between examinations, which are performed at intervals of approximately 10 years.
This aspect is controlled by the successive examination requirement of the Code (IWX-2420). The second consideration is the distribution of examinations within the inspection interval, which is governed by IWX-2412 (Inspection Program B) for the St. Lucie Plant.
By adhering to the sequence of examinations established during the first 10-year interval, the same insulation would have to be removed two or more times during each inspection interval. This requires many man-hours from skilled workers and greatly increases the potential for damage to the insulation, while causing excessive radiation exposure to plant personnel.
As a result, imposition of the Code scheduling and sequencing requirements would create an undue burden on the licensee.
At St. Lucie, the licensee has proposed a compromise with the Code requirements that will allow them to group the examinations of certain components within a single period to reduce radiation exposure.
To accomplish this, the licensee altered the sequence of examinations established during the first 10-year interval. The licensee has provided tables summarizing the rescheduling of examinations by examination category for the second 10-year interval. These tables indicate that a majority of the components will be examined during the same period as during the first interval.
For those areas where the schedule was adjusted, the number of components examined later in the interval is offset by those examined earlier.
Although the time between examinations will exceed 10 years for some components, the delayed examination of these components is being compensated for by the examination of other components for which the duration is less than 10 years.
This results in a new sequence of examinations that allows the licensee to achieve its goal of reducing radiation without compromising the level of quality and safety.
To reschedule the examination of components while minimizing the duration between examinations, the licensee modified the distribution of examinations among inspection periods for major components.
For example, the licensee has scheduled the examination of the RPV, including 12 Examination Category B-D welds, during the second period.
Since the duration between examinations does not exceed 10 years, this has been found to be an acceptable alternative to reduce the burden of
staging the automated tool more than once in a given interval.
However, distribution of all Examination Category 8-D welds within the interval would require delaying steam generator examinations into the third period for Steam Generator (SG) "8",
which would mean 14 to 17 years would elapse between examinations.
As a compromise, the licensee has proposed the examination of six examination Category 8-D welds on SG "A"during the third period while examining the SG "8" welds during the second period.
Although this results in a slight variation in the scheduling requirements of Inspection Program 8 of the Code, the INEEL staff believes that the distribution is adequate for detecting patterns of degradation that may occur.
Therefore, reasonable assurance of the structural integrity of the subject components will be provided.
The licensee has also proposed to select substitute welds of similar configuration when a significant reduction in radiation exposure can be achieved.
The licensee has committed to meet Program 8 scheduling requirements and will meet the selection requirements of the Code (i.e., terminal ends and high stress welds) whenever possible.
Since the licensee can reduce exposure while maintaining the scheduling and selection requirements of the Code, the INEEL staff finds this portion of the licensee's proposed alternative acceptable.
The licensee has proposed rescheduling of examination areas for the second inspection interval, which will establish a new sequence of examinations while reducing radiation exposure and enhancing the overall efficiency of the inservice I
inspection program.
The INEEL staff has evaluated the licensee's proposed alternative and concludes that the proposed scheduling changes will provide reasonable assurance of the structural integrity of the affected systems, and that imposing the scheduling and sequencing requirements of the Code would cause an undue hardship without a compensating increase in the level of quality and safety, Therefore, it is recommended that the licensee's proposed alternative be authorized pursuant to 10 CFR 50.55a(a)(3)(ii).