ML20080F372
| ML20080F372 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 01/05/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20080F370 | List: |
| References | |
| NUDOCS 9501200217 | |
| Download: ML20080F372 (6) | |
Text
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UNITED STATES 5
NUCLEAR REGULATORY COMMISSION k * *,
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wassiscrow, o.c. rous-coos SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 158 TO FACILITY OPERATING LICENSE NO. NPF-6 ENTERGY OPERATIONS. INC.
ARKANSAS NUCLEAR ONE. UNIT NO. 2 DOCKET NO. 50-368
1.0 INTRODUCTION
By letter dated November 29, 1994, as supplemented by letters dated December 20 and 21, 1994, Entergy Operations, Inc., the licensee, submitted a request to change the technical specifications for Arkansas Nuclear One, Unit 2 (ANO-2). The requested amendment revises, in part, Technical Specifications 4.4.5.0 and 4.4.5.2.b.3, Table 4.4-2, and Bases 3/4.4.5. The proposed changes to the technical specifications would permit, in part, the licensee to implement an alternate expansion criteria for the steam generator tube inspections to be performed during the 2P95-1 outage in January 1995.
The requested amendment also makes several administrative changes to remove inconsistencies and a misspelling introduced in previous amendments to the technical specifications. The proposed inspection scope and expansion criteria for the steam generator tubing are designed to address a specific type of degradation mechanism, that is, circumferential cracking at the expansion-transition region.
The licensee's letters of December 20 and 21,1994, provided additional clarifying information with respect to its proposed inspection scope and expansion criteria that did not change the initial proposed no significant i
hazards consideration determination.
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2.0 BACKGROUND
1 In March 1992, ANO-2 shut down as a result of a primary-to-secondary leak of approximately 0.25 gallons per minute. During the performance of eddy current examinations of the steam generator tubing during this outage (2F92), the 3
licensee discovered a number of circumferential cracks at the expansion-transition which is located near the top of the tubesheet. The licensee decided to pull several tubes to characterize the root cause of failure. As a result of the pulled tube metallurgical examinations and rotating pancake coil (RPC) inspections at the expansion-transition, the licensee concluded that the plant could be operated safely until the scheduled refueling outage in the Fall of 1992 (approximately four-months of operation).
During the 1992 refueling outage (2RS), the licensee detected additional circumferential indications on a number of tubes at the expansion-transition 9501200217 950105 PDR ADOCK 05000368 P
location. The licensee pulled several tubes for metallurgical examination I
during the outage and also performed an in-situ pressure test of the most degraded tube detected as characterized by the RPC probe. The licensee concluded that all detected circumferential indications were capable of meeting the structural criteria of Regulatory Guide 1.121. The licensee also concluded, based on the distribution of indications detected, that the plant could be safely operated for six-months prior to the next inspection.
During the scheduled plant shutdown in the Spring of 1993 (2P93-1), the licensee examined the expansion-transition location of approximately 6000 tubes with an RPC probe. These examinations were concentrated in a region of i
the steam generator tube bundle where the majority of circumferential cracking l
had been detected previously. Based on the inspection findings from this outage and other considerations, the licensee concluded that the plant could be operated safely for the remainder of the cycle, approximately 10-months.
The licensee concluded that a 10-month operating cycle was acceptable based, in part, on 100-percent RPC probe inspection in the area of interest (i.e.,
approximately 70-percent of.the total tube population was inspected at the expansion-transition with the RPC probe).
All the detectable indications were repaired (i.e., plugged or sleeved).
An assessment that concluded that none of the detected cracks exceeded Regulatory Guide 1.121 acceptance criteria based on RPC data after 6-months of operation.
l An analysis which determined the required through-wall depth necessary to sustain Regulatory Guide 1.121 pressure loads.
A projection of the total number of tubes expected to be detected at the end of a 10-month operating interval.
Improved eddy current testing data analysis guidelines and f
acquisition techniques.
i Enhanced primary-to-secondary leak rate monitoring including the use of Nitrogen-16 monitors.
L Improvements in the secondary water chemistry program.
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Lowering of the primary coolant hot leg temperature.
Evaluation of operator response to single and multiple steam generator tube ruptures (with a concurrent main steam line break I
(MSLB) in some instances) during simulator training exercises.
l Subsequent to the Spring 1993 outage (2P93-1), the plant was operated for l
approximately 10-months after which a refueling outage inspection of the steam f
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-3 generator tubing was performed (i.e., 2R10). This outar,e commenced in the March 1994 time-frame. During 2R10, the licensee inspected 100% of the tubes with an RPC probe at the expansion-transition location. Based on ar.
evaluation of the inspection findings and other considerations, the licensee concluded that the plant could be operated safely for approximately 10-months until a scheduled outage in January 1995 (i.e., 2P951).
As a result of these previous inspection findings, the licensee is proposing to modify their technical specifications to permit them to focus their inspection efforts during 2P95-1 in the area of the steam generator where circumferential cracking has historically been observed.
3.0 PROPMED REVISIONS TO THE TECHNICAL SPECIFICATIONS The following revisions to the technical specifications are being proposed by the licensee:
1.
Correcting a reference in Technical Specification 4.4.5.2.b.3 to specify that the reference for the definition of tube inspection is in Technical Specification 4.4.5.4.a.9.
2.
Deleting a one-time exemption includerl as Footnote I to Table 4.4-2.
3.
Correcting a misspelled word in Table 4.4-2.
4.
Correcting an inconsistency in Bases 3/4.4.5 to allow an unserviceable tube to be either plugged or repaired.
5.
Adding a note to Technical Specification 4.4.5.0 which states that:
the surveillance requirements of Specification 3.4.5 do not apply to a.
the special steam generator tube inspection to be performed during the 2P95-1 outage scheduled to begin on January 6,1995; b.
the scope and expansion criteria for this inspection are specified in correspondence to the ERC submitted under separate cover; the scope and criteria shall be approved by the NRC prior to exiting c.
Mode 5; and d.
the results of this inspection shall be reviewed by the Plant Safety Committee prior to resumption of plant operation and reported to the NRC within 30 days of resumption of plant operation 4.0 EVALUATION 4.1 Minor Administrative Chanaes The licensee has proposed to correct several minor administrative errors in the technical specifications. The staff's evaluation of these changes are provided below.
. 4 The staff finds that correcting the reference to " tube inspection" in Technical Specification 4.4.5.2.b.3 from 4.4.5.4.a.8 to 4.4.5.4.a.9 is appropriate since the reference to Technical Specification 4.4.5.4.a.8 references a section of the technical specifications pertaining to an unserviceable condition of a tube rather than the inspection of the tube. The proposed technical specification change is acceptable.
The staff finds that deleting footnote 1 of Table' 4.4-2 which references a one time exemption to the C-3 inspection requirements as a result of not inspecting two tubes during 2R9 is appropriate since the tubes have subsequently been inspected and the permitted interval of applicability of this footnote has expired. As a result, the proposed technical specification change is acceptable.
The staff finds that changing the spelling of the word "mininum" to " minimum" in Table 4.4-2 is appropriate. As a result, the proposed technical specification change is acceptable.
The staff finds that changing Technical Specification Bases 3/4.4.5 to clarify that a tube may be either plugged or repaired in cases when the plant is shutdown as a result of primary-to-secondary leakage in excess of the technical specification limits is acceptable since tube repair (i.e.,
sleeving) was approved for ANO-2 as a result of the issuance of Amendment No. 133 on April 22, 1992.
4.2 Inspection Scope and Expansion Criteria By letter dated November 29, 1994, the licensee proposed to exempt all special steam generator tube inspections (e.g., inspections conducted at frequencies shorter than those specified in the technical specifications, inspections with defined scopes for examinations of a specific area of interest, etc.) from the surveillance requirements of Specification 3.4.5.
Based upon subsequent discussions with the NRC, the licensee narrowed the focus of the proposed amendment in a letter dated December 20, 1994.
The licensee's revised submittal provides a one-time exemption to the requirements of Specification 3.4.5 for the special steam generator tube inspection to be performed during the 2P95-1 outage scheduled to begin on January 6,1995.
Specifically, the licensee has proposed to add a note to Technical Specification 4.4.5.0 which states that (1) the surveillance requirements of Specification 3.4.5 do not apply to the special steam generator tube inspection to be performed during the 2P95-1 outage scheduled to begin on January 6,1995,(2) the scope and expansion criteria for this inspection are specified in correspondence to the HRC submitted under separate cover, (3) the scope and criteria shall be approved by the NRC prior to exiting Mode 5, and (4) the results of this inspection shall be reviewed by the Plant Safety Committee prior to resumption of plant operation and reported to the NRC within 30 days of resumption of plant operation.
By letter dated December 21, 1994, the licensee submitted their proposed scope and expansion criteria for the special steam generator tube inspection to be performed during 2P95-1. The scope of the 2P95-1 steam generator tube
. inspection includes performing RPC inspections of approximately 5000 tubes in both steam generators in the sludge pile region at the hot-leg expansion-transition location.
The licensee may also use ultrasonic probes to size selected indications detected with the RPC probe.
The licensee's proposed expansion criteria for the 2P95-1 inspection is as follows:
If a circumferential crack indication is found on the periphery of the inspection zone in either steam generator, the zone at the location of the flaw will be expanded to bound the detected indication by two tubes.
Should more than one circumferential crack indication be found on the periphery of the inspection zone of a steam generator, the periphery of the entire sample area will be expanded by two tubes.
The peripheral expansion will be continued until no further indications are found.
As noted above, the inspections to be performed during 2P95-1 are designed to monitor the progression of circumferential cracking at the expansion-transition location on the steam generator tubing which is located near the top of the tubesheet. Historically, circumferential cracking at ANO-2 has primarily been observed at the expansion-trar.sition location in an area of the hot-leg portion of the steam generator commonly referred to as the sludge pile region.
Since the proposed inspection scope essentially includes 100% of the tubes in the area of interest, that is the region where circumferential cracking has historically been observed, the staff finds the initial RPC inspection scope and the proposed expansion criteria to be acceptable for 2P95-1. The expansion criteria provides added confidence that if circumferential cracking starts to occur outside the initial inspection boundary that it will be detected.
The staff notes that the licensee will repair all tubes exhibiting circumferential indications that are detected during the 2P95-1 outage.
l Authorized repair techniques are those delineated in Specification 3.4.5.
l Based on the evaluation provided above, the staff finds the proposed changes to the technical specifications to be acceptable.
Furthermore, the staff
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finds the proposed inspection scope and expansion criteria delineated in the I
licensee's letter dated December 21, 1994, to be appropriate for 2P95-1.
5.0 STATE CONSULTATION
f In accordance with the Commission's regulations, the Arkansas State official was notified of the proposed issuance of the amendment. The State official had no comments.
6.0 ENVIRONMENTAL CONSIDERATION
l The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements.
The NRC staff has determined that the amendment involves no significant increase in the amounts, and no
. significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a pro-posed finding that the amendment involves no significant hazards consideration and there has been no public connent on such finding (59 FR 62416).
Accordingly, the amendment meets 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 the amendment.
7.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors:
K. Karwoski Date: January 5, 1995 l