ML20206G356
| ML20206G356 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 03/30/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20206G338 | List: |
| References | |
| TAC-62811, TAC-62812, NUDOCS 8704140524 | |
| Download: ML20206G356 (10) | |
Text
c, UNITED STATES
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g NUCLEAR REGULATORY COMMISSION y,
t WASHINGTON, D. C. 20555 A
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SAFETY EVALUAT'ON BY THE OFFICE OF NUCLEAR REACTOR REGULATION i
RELATED TO AMENDMENT NO. 69 TO FACILITY OPERATING LICENSE NO. NPF-2 i
AND AMENDMENT NO. 61 TO FACILITY OPERATING LICENSE NO. NPF-R ALARAMA POWER COMPANY
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JOSEPH M. FADLFY NUCLEAR PLANT UNIT NOS. 1 AND ?
DOCKET NOS. 50-348 AND 50-364 INTRODUCTION By letter dated September 2, 1986, Alabama power Company (the licensee) requested changes in the Technical Specifications on snubber visual inspection frequency requirements for Joseph M. Farley Nuclear Plant Units 1 and P.
The proposed revision redifies the existing snubber visual inspection frequency schedule from one that is independent of the snubber population size to one that is dependent on a snubber population of 200 The proposed revision is based on a statistical methodology that would maintain a similar level of snubber reliability as the existino visual inspection frecuency schedule. The a
staff met with the licensee on November 20, 1986 to discuss the licensee's proposal. Based on discussions with the staff, the licensee submitted revised versions of the proposed changes by letters dated February 9, and 25, 1987 and j
supplementary snubber failure data by letter dated February 27, 1987.
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in the February 9, 1987 submittal, the licensee advised that plant shutdowns for inspections of all snubbers would be recuired by April 20, and July 18, 1987, for Units 1 and 2, respectively. On that basis, we considered these potential shutdowns for inspections of snubbers as the basis of one-time emergency i
changes the pending completion of a long-time study of the new methodology proposed. Therefore, in the February 25, lo87 submittal, the licensee limited i
the reauested Technical Specification changes to a one-time change that would be in effect until the startup from the next refueling outages at Farley Units I and 2.
The next refuelina outages for Farley Units 1 and 2 are currently scheduled for March 1988 (eighth refueling outage for Farley Unit 1) and I
September 1987 (fifth refueling outaae for Farley Unit 2), respectively.
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Furthermore, in Attachment 5 of the February 9, 1987 submittal, the licensee requested that two of the inoperable snubbers found during the October 10M visual inspection at Farley Unit 1 not be considered in detemining the sub-sequent snubber visual inspection period.
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O!SCUSSION AND EVALUATION Our discussion and evaluation of the snubber visual inspection schedule and of the inoperable snubbers reported follows.
I SNUPPER VISUAL INSPECTION SCHEDULE The basis for the proposed snuhber visual inspection schedule was submitted by the licensee in the September 2, 1986 letter. A statistical methodology was used in deriving the proposed snubber visual inspection schedule. Based on the assumed statistical frodel, the proposed visual inspection schedule will provide a 954. confidence level that at least 90% of the snubbers in the plant are operable as detemined by visual examinations.
It is noted that the existing Technical Specifications require both visual and functional tests of snubbers. The licensee proposed changes in the snubber visual inspection schedule only.
The existing snubber visual inspection schedule is independent of the snubber population size. However, methodology used for the proposed snubber visual inspection schedule depends on the snubber population size. The licensee used a snubber population size of 200 in deriving the snubber visual inspection schedule in the February 9, 25, and 27,1987 submittals. The snubber population sizes for Farley Units 1 and 2 are summarized in Table 1.
The existing snubber visual inspection reouirements in the Technical Specifications allow grouping of snubbers into " accessible" and " inaccessible" snubbers during reactor operation. The proposed snubber visual inspection schedule would not change this groupino definition. Table I shows that the smallest number of snubbers, either accessible or inaccessible, in Farlev Units 1 and 2 is ?37.
Thus, it is acceptable for the licensee to assume a snubber population size of 200 in derivino the snubber visual inspection schedule for inaccessible and accessible snubbers in Farley Units 1 and 2.
The proposed snubber visual inspection schedule was revised by letter dated February 25, 1987. Ry letter dated February 27, 1987, the licensee provided a history and compilation of of snubbers at each unit. Table 2 shows a comparison of the existino and the proposed snubber visual inspection schedules for Farley Units 1 and 2.
It is observed thit both the existing and the proposed inspec-tion schedules depend on the current inspection period and the number of inoperable snubbers found by visual examinations.
A comparison of the snubber reliabilities obtained from existing and proposed snubber visual inspection schedules was submitted by licensee letter dated February 9, 1987 Table 3 shows a summary of the confidence and reliability levels of snubbers as detemined by visual examinations for the existing and proposed snubber visual inspection schedules. The same statistical model assumed in deriving the proposed inspection schedule was assumed for the existing inspection schedule for calculating the snubber reliability. Using the same statistical model provided a consistent basis for the comparison of the existing and the proposed inspection schedules. A snubber group size of
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. 200 was assumed for both the existino and the proposed inspection schedules.
The reliability level was calculated by reouiring a confidence level of at least 95%. Because the proposed visual inspection schedule was revised by letter dated February 25, 1987, some reliability values were diffe ent from what the actual values would be. This is indicated in a footnote io Table 3.
Specifically, for a current inspection period of 18 months, one fewer inoperable snubber is allowed for "next inspection periods" of 6,12, and 18 months by the revised inspection schedule in the February 25, 1987 submittal as compared with the inspection schedule in the February 9, 1987 submittal.
Because fewer inoperable snubbers are allowed in the revised inspection schedule, the actual snubber reliability is expected to exceed the values in Table 3 for these cases.
From Table 3, it is observed that the statistical methodology used in deriving the proposed inspection schedule maintains a reliability level of at least 90%
in the proposed inspection schedule. The proposed visual inspection schedule has a reliability greater than 90% at a 18-month current inspection period as discussed in the previous paragraph. The existing inspection schedule has a reliability of over 95% at a 18-month current inspection period, which decreases to a reliability of only 75% at a 1-month current inspection period.
From Table 3, it is observed that the snubber reliability level of the proposed visual inspection schedule exceeds that of the existing inspection schedule for current inspection periods of less than or equal to 6 months.
From Table 2, it is observed that this increase in snubber reliability is achieved by allowing fewer inoperable snubbers in the proposed inspection schedule as compared with the existing inspection schedule for current inspection periods of less than or equal to 6 months. Because a short inspection period is reouired for a plant with a poor history of snubber failures, the. proposed visual inspection schedule would provide a higher level of snubber reliability for such a plant when compared with the existing inspection schedule.
Conversely, from Table 3, it is observed that the snubber reliability level of the proposed visual inspection schedule is slightly less than that of the existing inspection schedule for current inspection periods of greater than 6 months. From Table 2, it is observed that this decrease in snubber reliability is due to the allowance of more inoperable snubbers in the proposed inspection schedule as compared with the existing inspection schedule for current inspection periods of creater than 6 months. Because a long inspection period is allowed for a plant with few prior snubber failures, the proposed visual inspection schedule would result in a slight decrease in snubber reliability for such a plant when compared with the existing inspection schedule.
These changes in t. ubber reliability are considered acceptable until startup from the next refueling outages since the decrease in reliability is slight for long inspection periods, and since snubber reliabilities have been calculated on the basis of a snubber ropulation size smaller than the smallest snubber group size for Farley Units 1 and 2.
4 INOPERABLE SNt'PPERS IN VISUAL EXAMINATIONS In Attachment 5 of the February 9,1987 submittal, the licensee requested that two of the inoperable snubbers found during the October 1986 (sevepth refueling outage for Farley Unit 11 visual inspection at Farley Unpt I not be considered in determining the subsequent snubber visual inspection period.
The licensee indicated that hydraulic snubber Mark Numbers RC-R91 and RC-R219 were found with empty fluid reserviors and with the fluid port uncovered.
Both snubbers failed the functional test in their as-found conditions. Since then, both snubbers were completely rebuilt and found acceptable by functional testing.
During the rebuild, the snubber conditions were documented which indicated that the snubbers had been damaged since the last visual inspection performed at the sixth refueling outage.
Specifically, snubber RC-PQ1 was found to have bent snubber reservoir trounting brackets, and snubber RC-R219 was found to have bent fittings connecting the hydraulic cylinder to the reservoir tubing.
The licensee concluded that the cause of the bending was accidental and the bent parts were replaced.
The staff finds that snubbers RC-P91 and RC-R219, which were found inoperable in Farley Unit 1, were isolated failures with clearly established causes of failure which were remedied. Thus, in accordance with the intent of existing Technical Specifications, these two inoperable snubbers should not be counted as inoperable in detemining the subsequent snubber visual inspection period.
SAFETY StfMMARY The staff has reviewed and evaluated the licensee's requests. We have concluded that the proposed snubber visual inspection schedule submitted in the letter dated February 25, 1987 provides a level of snubber reliability similar to that of the existing inspection schedule when compared on a consistent statistical basis usino the proposed statistical model and a snubber population size of 200. The snubber population size of POO is selected because it is less than the smallest snubber group size for Farley Units 1 and 2 and results in a conservative inspection schedule based on the statistical methodology. Thus, the proposed one-time Technical Specification changes that will be in effect until the startup from the next refueling outages at Farley Units 1 and 2 are acceptable.
Furthermore, we have concluded that two of the inoperable snubbers (i.e., RC-R91 and RC-R219) found during the October 1986 visual inspection at Farley Unit I should not be counted as inoperable in determining the subseouent snubber visual inspection period.
FINDING OF EXTSTENCE OF EMERGENCY SITUATION 10 CFR 50.91/a)(51 provides the necessary requirements for issuing an amendment when the Comission finds that an emergency situation exists and failure to act in a timely way would result in derating or shutdown of a nucifar plant.
The Comission expects its licensees to: apply for license amendments in a timely fashion; not abuse the emergency provisions by failing to make a timely application for the amendment and thus itself creating the emergency; provide j
an explanation as to why the emergency situation occurred; and why it could not have been avoided.
As noted above, the licensee applied for the amendment by letter dated September 2,1986, with a projected need date of February 27, 1987.
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Therefore, the application was timely enouch to preclude the plant shutdowns noted subsecuently in the licensee letter dated February 9, 1987
- However, the NRC staff review of the request for a pemanent, generic change to standard TSs based on the proposed statistical methodology would require a more detailed I
study of the proposal. On this basis, the NRC staff proposed acceptance of the I
change on a one-time basis. The licensee responded on February 25, 1987, l
requesting the one-time TS chance. Although the initial application was timely, as a result of staff action during the course of the review the applicant l
was requested to reduce its request to a one-time only change. Promptly upon notification by the staff, the applicant submitted its revised request on February 25, 1987, which did not provide sufficient time to enable the staff to provide its usual notice. We consider this action to be a necessary emergency action to preclude shutdowns of both units for surveillance tests of inaccessible I
snubbers. The emergency situation is considered unavoidable because of the extensiveness of the long tem study which became evident to the MC staff late in the review process.
1 FINAL NO SIGNIFICANT HA7ARDS CONSIDERATION i
1 The Comission has provided standards for detemining whether a significant hazards consideration exists (10 CFR 50.92(c)l. A proposed amendment to an operating license for a facility involves no significant hazards consideration l
if operation of the facility in accordance with the proposed amendment would l
not (1) involve a significant increase in the probability or consequences of an accident previously evaluatedt (2) create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) involve a significant reduction in a margin of safety.
The NRC staff has reviewed the proposed change in accordance with 10 CFP 50.92(c) and has detemined that the change does not:
(1) involve a significant increase in the probability or consequences of an accident previously evaluated because snubber operability will not be affected and a plant shutdown (transient) will not occur just to visually inspect the inaccessible snubbers in mid-cycle on both units.
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(?) Create the possibility of a new or different kind of accident than previously evaluated because extending the surveillance interval does not physically alter the plant or change parameters governing nomal plant operation.
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(3) Involve a significant reduction in a margin of safety because the visual inspection interval, although increased from that currently required, maintains a confidence level which would provide adequate assurance that the snubber system will adequately perform its design function.
i Based on the foregoina, the Comission has concluded that the stanhards of 10 CFR 50.92 are satisfied. Therefore, the Commission has made a final determination that the proposed amendment does not involve a significant q
hazards consideration.
i ENVIRONMENTAL CONSIDERATION These amendments involve a change in surveillance requirements and in the installation or use of the facilities components located within the restricted i
areas as defined in 10 CFR 20. The staff has determined that these amendments
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involve no significant increase in the amounts, and no significant change in the types, of any affluents that may be released off-site and that there is no 4
j significant increase in individual or cumulative occupational radiation exposure.
The Comission has previously issued a proposed finding that these amendments I
involve no significant hazards consideration and there has been no public coment j
en such findino. Accordingly, these amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of these amendments.
CONCLUSION l
We have concluded, based on the considerations discussed above, that:
l (1) there is reasonable assurance that the health and safety of the i
public will not be endancered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Comission's regulations and the issuance of these amendments will not i
be inimical to the comon defense and security or to the health and j
safety of the public.
Dated:
March 30, 1987 j
Principal Contributor:
- 5. Lee ll E. Reeves l
Attachments j
Tables I, 2 and 3
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ATTACHMENT l
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TABLE 1 FARLEY UNITS 1 AND 9 SAFETY-RELATED SNURRER POPULATIONS 1
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Snubber Type Farlev l' nit 1 Farley Unit 2 Inaccessible Accessible inaccessible Accessible
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l Hydraulic 343 188 175 189 Mechanical 243 63 256 48 l
Total 586 251 431 737 i
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TABLE ?
SlWARY OF EXISTING AND PROPOSED SNUBBER VISUAL INSPECTION SCHEDULFS 4
k Inspection Nex) lod (Months)
Current Inspection Number of Inonerable Snubbers Peg
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Period (Months)
Existing Program Propo5ed Procram t
i 18 + 25f 0
0,1,2 18 + 25%
1 3
12 i PST
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4 6 T PS%
l 3,4 5,6 4 7 25%
i 5,6,7 7
2 T 25%
i 8 or more 8 or more 1 7 ?5%
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12 + 25%
0 0,1 18 + 25%
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2,3 12 T 25%
))
2 4
6 T 25%
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3,4 5
4 7 25%
l 5,6,7 6,7 2725%
j 8 or more 8 or more 1{25%
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6 + O!!
O,1 0
12 + 25%
j 2
1 6 7 75%
l 3,4 2
4 7 25%
j 5,6,7 3,4 2 i ?5%
1 8 or more 5 or more 1.7 25%
4 + 25%
0,1,2 0
6 + 25%
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3,4 1
4 i P5%
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5,6,7 2
2725%
8 or more 3 or more 1725%
i 0,1,2,3,4 0
4 + 25%
2 + 25%
5,6,7 1
? i 25%
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8 or more 2 or more 1{?5%
I 1 + 25%
0,1,2,3,4,5,6,7 0
2 + 25%
8 or more 1 or more 1 7 25%
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TABLE 3 SUMMAPY Or SNUBBER RELIABILITIEF OBTAINED FROM EXISTING AND PROPOSED SNUBRER VISUAL INSPECTION SCur00LES BASED ON A SNUBBEP GR0llP SIZE OF 200*
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Current Existino Progran Proposed Program Next Inspection Cerfidence Reliability Confidence RelfabilitV Inspection Period Level level level Level Period (Months)
(%)
(%)
(%)
(4)
(Months)
IR + ?5%
97.3 95.5 97.0**
90.5**
18 + 25%
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96.1 95.5 95.2**
92.5**
I? 7 ?S%
97.4 96.5 96.4**
95.0**
6 7 25%
97.7 96.5 96.3 96.0 4 7 25%
l 95.9 97.5 95.9 97.5 2 7 ?51 1 7 25%
................................................................. 7...........
I? + 25%
96.5 94.0 95.7 91.5 18 + PS%
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97.4 43.5 97.0 90.5 12 T 25%
96.1 95.5 45.6 94.0 6 I PS%
96.6 95.5 96.4 95.0 4 T 25%
96.4 96.5 96.4 96.5 2 7 25%
1 7 25%
..................................................................T...........
6 + 25%
96.7 89.0 96.4 9'.5 12 + 25%
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96.0 97.0 97.4 93.5 6775%
95.?
92.5 95.2 94.5 A 7 25%
96.3 94.0 96.6 95.5 2 7 25%
1 7 75%
4 + PS%
96.7 PQ.0 96.6 94.0 6 + 25%
05.5 89.5 47.4 93.5 4 7 25%
97.1 91.5 96.1 95.5 2 7 25%
1 _7 25%
2 + 25%
45.6 81.5 96.4 92.5 4 + 25%
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96.7 85.5 97.4 93 5
? 7 75%
g ; p$g 1 + ?5%
95.6 75.0 96.4 92.r
? + 75%
3 7 P5%
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(Table 3tobecontinuedonthenextpage.)
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TARLE 3 (Continued)
SUMMARY
OF SNURBER RELIABILITIES ORTAINED FROM EXISTING AND PROPOSED SNURBER VISUAL INSPECTION SCHEDULES BASED ON A SNUBBER GPOUP SIZE OF 200*
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The reliability level was calculated by requiring a confidence level of at least 95%.
For conservatism in the reliability estimation, the minimum allowable current inspection period (i.e, using the -25% option),
the maximum allowable next inspection period (i.e., usino the +25%
option), and the maximum number of allowable inoperable snubbers (e.g.,
using 7 incperable snubbers if 5, 6, or 7 inoperable snubbers are allowed) were assumed.
The confidence and reliability levels shown were calculated based on allowino one more inoperable snubber than presented in Table ?.
- Thus, the actual reliability level will exceed the value shown.
The reliability level was calculated conservatively usino the maximum number of allowable inoperable snubbers. Because there is no upper bound on the number of allowable inoperable snubbers for this case, no reliability calculation was perfonned.
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