ML15112B004
| ML15112B004 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 03/30/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML15112B003 | List: |
| References | |
| NUDOCS 8104090021 | |
| Download: ML15112B004 (3) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION oo WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 94 TO FACILITY OPERATING LICENSE NO. DPR-38 AMENDMENT NO. 94 TO FACILITY OPERATING LICENSE NO. DPR-47 AMENDMENT NO. 91 TO FACILITY OPERATING LICENSE NO. DPR-55 DUKE POWER COMPANY OCONEE NUCLEAR STATION, UNITS NOS. 1, 2 AND 3 DOCKETS NOS. 50-269, 50-270 AND 50-287 Introduction By letter dated July 15, 1980, the Duke Power Company (the licensee or DPC) submitted proposed changes to the Station's common Technical Specifications (TSs) that would revise the steam generator tube inspection program.
Background
The request proposes to change the steam generator tube unscheduled inspection requirements, after a primary-to-secondary leak, in TS 4.17.4.d as follows:
(1) when the leaking tube is located within one, two, or three rows of the inspection lane (region where tube degradation unique to this area has been observed), all the tubes in this group in only the affected steam generator need be inspected (Currently the TSs are not explicit in this regard.); (2) when the leaking tube is not in the three rows of the open inspection lane, an inspection will be performed in accordance with Table 4.17-1, which defines the scope of the general inservice inspection program, except that the licensee has proposed a 3% initial inspection sample rather than the 6% now specified in the table when a single generator is inspected in a two steam generator plant such as an Oconee Unit.
Evaluation The licensee is proposing that the steam generator tube inspection requirements after a primary-to-secondary tube leak as specified in TS 4.17.4.d be modified to indicate the following:
(1) when the leaking tube is located within three rows of open inspection lane (areas where tube degradation previously has been observed),
all the tubes in this group in only the affected steam generator need be inspected; (2) when the leaking tube is not in the three rows of the open inspection lane, an inspection will be performed in accordance with the general inspection program defined in Table 4.17-1 except that the initial sample size be reduced from 6% to 3% of the total number of tubes in the tube bundle when a single generator is inspected in a two generator plant. Each item is separately evaluated below.
(1) Affected Steam Generator The proposal to limit an inspection to the leaking steam generator when a leak is found in the open inspection lane will both reduce personnel radiation exposure 81040o90
-2 associated with inspections and provide adequate assurance of steam generator integrity.
In keeping with the Commission's policy to reduce radiation exposures to levels as low as reasonably achievable (ALARA), we conclude that the proposed TS is acceptable. If the results of the special inspection should fall into the C-3 category, Note (2) of Section 4.17.3.c states that inspection of the same area in the other steam generator will be required.
Since the proposed TS explicitly states that only the affected steam generator need be inspected, it should also indicate that if the results from the special inspection fall into the C-3 category, additional inspections shall be performed in the same tube group in the other steam generator.
In conclusion, we find the provision to inspect only the leaking steam generator after a primary-to-secondary tube leak does not reduce the effectiveness of the overall unscheduled steam generator tube inspection program. Therefore, the proposal is acceptable with the condition that changes be made to agree with Note (2) of Section 4.17.3.c.
The TS therefore is changed as follows:
If the leaking tube is in a Group as defined in Section 4.17.3.b, all of the tubes in this Group in this steam generator will be inspected. If the results of this inspection fall into the C-3 category, additional inspections will be performed in the same Group in the other steam generator.
(2) Initial SampI e Size With regard to the proposed change in the general inspection program, we disagree with reducing the initial inspection sample size for a single generator from the currently required level of 6% to 3% of the total number of tubes in the tube bundle in. the affected steam generator of a two steam generator plant.
We find that the licensee did not provide an adequate technical basis to support his conclusion that the 6% initial inspection sample requirement is excessive. Because our past experience has indicated that steam generator leakage is usually indicative of cor rosion progress in a steam generator, we believe that the 6% initial inspection sample size is necessary to.preclude the possibility of overlooking significant tube degradation and consequently to reduce the potential for unscheduled outages. In addition, we do not believe that a 6% initial inspection sample will result in a sub stantial increase in the radiation exposure as compared to 3% initial inspection sample, since most exposure to radiation occurs when opening a steam generator. In view of the above, we conclude that the initial sample size, as stated in the current Oconee TSs, provides reasonable assurance to the health and safety of the public without incurring needless personnel exposure and should remain unchanged.
Environmental Consideration We have determined that the amendments do not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that'the amendments involve an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR §51.5(d)(4),
that an environmental impdct statement, or negative declaration and environ mental impact appraisal need not be prepared in connection.with the issuance of these amendments.
-3 Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the amendments do not involve a significant increase in the probability or consequences of accidents previously considered and do not involve a signi ficant decrease in a safety margin, the amendments do not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulations and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Dated: March 30, 1981