ML20056A790
| ML20056A790 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 07/24/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20056A789 | List: |
| References | |
| NUDOCS 9008090200 | |
| Download: ML20056A790 (3) | |
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UNITED STATES
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- C NUCLEAR REGULATORY COMMISSION 4
WA SHINGTON, D. C. 20$$5 g... f SAFETY EVALUATION SY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.13470 FACILITY OPERATING LICENSE NO. DPR-51 ENTERGY OPERATIONS. INC.
ARKANSAS NUCLEAR ONE. UNIT NO. 1 DOCKET NO. 50-313 i
-INTRODUCTION By letter dated October 19, 1989, as su 22, 1990, Arkansas Power and Light Company (AP&L)pplemented by letter dated May requested an amendment to the Technical Specifications appended to Facility Operating License No. DPR-51 for Arkansas NuclearOne, Unit 1(ANO-1). The proposed amendment would revise the Technical Specifications-(TS) by. changing the TS 3.1.6.3.b limiting condition for operation (LCO) for reactor coolant system leakage. Specifically, the current 1.0 gpm limit on total primary-to-secondary leakage would be changed to an explicit 500 gallons per day (0.347 gpm) limit from any one steam generator.
In addition, TS 4.18.4.c.1 would be revised to include additional unscheduled inservice inspections whenever leakage occurs in excess of the limit in TS 3.1.6.3.b in lieu of. the radioiodine activity limits in the secondary coolant per TS 3.10.
The change-to TS 4.18.4.c.1 would also provide an alternative inspection sample to the random inspection specified in TS Table 4.18-2 when the leakage is in the steam generator lane or wedge regions.
The Standard Technical Specifications (STS)-for Babcock & Wilcox plants (NUREG-0103) specify both a 1.0 gpm limit for total primary-to-secondary
- leakage ~and a 500 gallon per day (gpd) limit (e.g. 0.35 gpm) for leakage from each individual steam generator. The 1.0 gpm total leakage limit was intended
.to ensure that the dosage contribution from steam generator tube leakage would be a small fraction of 10 CFR Part 100 limits during design basis accidents.
L The 500 gpd limit was intended to ensure that leaking steam generator tubes I -
would not burst under the spectrum of normal operating and upset conditions.
Presently, the ANO-1 Technical Specifications. include only the 1.0 gpm limit 1
for total primary-to-secondary leakage.
AP&L's May 22, 1990, supplement provided clarifying information, including correction of typographical errors, and did not alter the action noticed, or affect the initial determination published, in the Federal Register on
. February 21, 1990.
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9008090200 900724 l;
PDR ADOCK 05000313 P
2 EVALVATION In Generic Letter 85-02, the NRC staff recommended that all licensees of all pressurized water reactors adopt TS limits that were at least as restrictive as that detailed in the STS.
Based on this recommendation, Amendment No. 115 was issued which incorporated only the 1.0 gpm total leakage limit and thus, established an ANO-1 TS leak rate limit which was within the envelop of the limits existing at several other B&W plants.
AP&L proposes to replace the 1.0 gpm total primary-to-secondary leakage limit -
with the 500 gpd limit per steam generator since the 500 gpd limit bounds the requirements for the 1.0 gpm limit. The 500 gpd limit corresponds to the expected steam generator tube leakage resulting from the maximum-sized crack which would not be expected to fail under worst case pressure differential loadings associated with the design basis main steam line or feedwater line
- breah, Since the 500 gpd (0.35 gpm) limit per each of the two steam generators pre-Les a more restrictive limit than the 1.0 gpm total leak rate limit, the taff agrees that this change is acceptable.
w" TS 4.18.4.c.1 requires that a steam generator inservice inspection (ISI) be conducted whenever the secondary coolant activity exceeds 0.17 Ci/gm limit per TS 3.10.
The TS 3.10 limit was based on a postulated accident with an initial assun.ption of 1.0 gpm steam generator tube leakage such that tLe dose contribution from tube leakage would be well within the 10 CfR Part 100 limits.
The proposed change would replace that secondary coolant activity initiator of the steam generator ISI with the proposed 500 gpd leak rate limit from TS 3.1.6.3.b.
Since the activity limit corresponds to a leakage rate that is in excess of the proposed 500 gpd per steam generator limit, the staff agrees that the change would be more conservative.
The staff also finds that the proposal to allow, as an option, the performance
-of a 1001 151 of the affected region of steam generator tubes in lieu of the random inspection specified in TS Table 4.18-2 for primary-to-sccondary leakage originating in the lane or wedge regions to be acceptable. The purpose of the
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3% random sample inspection of the population of all tubes in the steam generator is to determine the probability of similar degradation within the steam generator.
However, the lane and wedge regions have been observed to have been the most susceptible areas for steam generator tube cegradation in the Once-Through SteamGenerators(OTSG). The tubes plugged to date at ANO-1 have been predominately in the lane region and adjacent wedge regions.
Thus, if a leak should be observed in these regions, a complete inspection of this more suspect section would prove more appropriate, and have a higher success of finding similarly degraded tubes, than a 3% random sample inspection. This alternative sample method will also require all the tubes in the same group in the other OTSG to be inspected if the results of the complete inspection discussed above fall in the C-3 category (more than 10% of the total tubes inspected are degraded tubes or more than 1% of the inspected tubes are defective), since a C-3 inspection result in one OTSG raises concerns regarding the integrity of 1
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the other OTSG. This inspection of the other OTSG upon a C-3 inspection result is also consistent with Table 4.18-2 and consistent with TS approved on other plants where a complete inspection of the suspect region may be performed in lieu of a 3% random sample inspection.
The additional inspection of the other OTSG upon a C-3 inspection result of a 100% ISI of the affected region in the first OTSG was not proposed by AP&L in the October 19, 1989, application. However, this was discussed with AP&L and it was agreed to by AP&L-that the. additional inspection and its corresponding changes to the proposed amendment are a logical extension and clarification of the original application, and are appropriate. AP&L formally adopted the staff's suggestion in their May 22, 1990, supplement and corrected other typographical errors which the staff finds to be appropriate. Thus the changes are acceptable.
ENVIRONMENTAL CONSIDERATION The amendment involves a change in a requirement with respect to the installa-tion or use of a facility component locoted within the restricted area as defined in 10 CFR Part 20 and changes in surveillance requirements. The staff has determined that the emendment 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 exposures. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR Section 51.22(c)(9). Pursuantto10CFR51.22(b),noenvironmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
CONCLUSION The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the will not be endangered by operation in the proposed manner,-and (2) public such activities will be conducted in compliance with the Commission's regulations, and the issuance of the amendment will not be inimical to the common defense ano security or to the health and safety of the public.
Date:
July 24,1990 Principal Contributors:
E. Murphy, EMCB l
T. Alexion. PDIV-1 l
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