ML18054A814
| ML18054A814 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 06/19/1989 |
| From: | Berry K CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEB-89-001, IEB-89-1, NUDOCS 8906290095 | |
| Download: ML18054A814 (5) | |
Text
General Offices:
1945 West Parnall Road, Jackson, Ml 49201 * (517) 788-1636 June 19, 1989 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT -
RESPONSE TO NRC BULLETIN 89 FAILURE OF WESTINGHOUSE STEAM GENERATOR TUBE MECHANICAL PLUGS Kenneth W Berry Director Nuclear Licensing NRC Bulletin 89-01, Failure of Westinghouse Steam Generator Tube Mechanical Plugs, dated May 15, 1989, requires a determination of whether certain mechanical plugs supplied by Westinghouse are installed in Palisades steam generators.
If so, implement an action plan to ensure the plugs will continue to provide assurance of Reactor Coolant System pressure boundary integrity under normal operating, transient and postulated accident conditions.
Cons~mers Power Company's response to the Bulletin is provided herein.
Requested Action 1.
Addressees are requested to verify that information contained in References 1 and 2 relating specifically to their plant is correct for plugs supplied from heat numbers 3279, 3513, 3962, and 4523.
The specific information to be verified is the numb~r of Westinghouse mechanical plugs installed in the hot and cold legs broken down by steam generator number, heat number, and date of installation.
If information from these references is incorrect, appropriate corrections should be identified.
Addressees are requested to state if their plants have not installed Westinghouse mechanical plugs from the subject heats.
Response
Reference 1, Westinghouse Report WCAP-12244 and WCAP-12245, "Steam Generator Tube Plug Integrity Summary Report," Revision 1, April 1989 was reviewed.
The information is correct and consistent with Palisades' plant records.
Palisades Plant does have Westinghouse mechanical plugs from heat 3513.
Additionally, Reference 2, Westinghouse letter dated May 1, 1989, "Steam Generator Tube Plug Integrity Update" was also reviewed.
This report is not applicable to Palisades' mechanical tube plugs.
OC0689-0138-NL04 8906290095 80%886~55 PDR ADOCK
~
PNU G
Nuclear Regulatory Commission Palisades Plant Response to Bulletin 89-01 June 19, 1989 Requested Action 2.a) 2 Steam generator tube plug lifetim~ for plugs from heats 3279, 3513, 3962, and 4523 should be estimated using the methodology from References 1 and 2 and should be based on the Millstone Unit 2 benchmark subject to any corrections per item 1 above.
Lifetime estimates in Reference 2 for plugs fabricated from heat 4523 are based on the Farley Unit 2 benchmark.
These estimates should be adjusted to reflect the Millstone Unit 2 benchmark using the methodology described in Section 4.1.2 of Reference 1.
Response
Remaining life estimates have been calculated for plugs from heat No 3513 for Palisades using Reference 1 and Millstone Unit 2 as a benchmark.
This evalua-tion indicated that with continued operation of Palisades at 80 percent power, the potential growth rate for tube plug circumferential cracking similar to the defect at North Anna, will be within specified guidelines through October 10, 1989.
Requested Action 2.b)
Addressees should implement appropriate remedial actions (i.e., repair and/or replacement) for all plugs whose estimated lifetimes in 2a, above do not extend to the next refueling outage.
If operation is planned beyond a refueling outage that represents the last outage before any plug exhausts the predicted lifetime, an alternative schedule with the appropriate technical justification should be submitted to the NRC at least 30*days before the end of this refueling outage.
Response
Based on the remaining life estimates, Palisades has committed to an October 1989 maintenance outage during which Westinghouse PIP (Plug in a Plug) repair will be performed on 215 target plugs (reference Consumers Power Company letter dated May 11, 1989 to NRC, Item 1).
The 215 target plugs consist of all installed hot leg plugs of heat No 3513 and are broken down as follows:
S/G "A" Hot Leg -
37 plugs S/G "B" Hot Leg -
178 plugs Requested Action 2.c)
Prior to any plug repairs or replacement, addressees are reminded that their responsibilities under ALARA require analysis of the various plug repair or replacement methods available to determine which method will result in the lowest overall personnel radiation exposure while still remaining cost-effective.
In choosing a plug repair or replacement method, the licensee should consider the accessibility of the plugs and the dose reduction benefit of using robotic manipulators.
Prior to plug repair or replacement, the OC0689-0138-NL04
r Nuclear Regulatory Commission Palisades Plant Response to Bulletin 89-01 June 19, 1989 licensee should consider steam generator decontamination and/or local shielding to reduce working area dose rates.
Response
3 Currently, Palisades plans on performing the PIP repair utilizing a remote manipulator.
Due to the design of the Palisades steam generators, some "hands on" repairs may be necessary as the current manipulator development cannot reach the entire tube sheet.
If manipulator modifications are in place in time for the Palisades outage, then all repairs will be made remotely.
This plan minimizes exposure for the current outage.
The probability that future cracking of the suspect tubes could result in additional steam *generator repair outages with the associated exposure has been considered, but were judged to be of little significance or low probability since steam generator replacement is planned to occur within the next few years.
Requested Action 2.d)
\\Installation of Westinghouse mechanical plugs from heats 3279, 3513; 3962, and 4523 should be discontinued.
Response
No further installations of Westinghouse mechanical plugs from suspect heats will occur.
Requested Action 2.e)
Westinghouse mechanical plugs removed from steam generators, regardless of heat number, should be examined for PWSCC on a sample basis for each heat.
Addressees should maintain a record of these examinations and the results should be provided to Westinghouse to improve the database concerning the susceptibility of plugs to PWSCC.
Response
Palisades removed ten (10) Westinghouse mechanical plugs from the "B" steam generator hot leg in September 1988.
Eight (8) of the plugs were sent to Westinghouse for metallurgical evaluation.
The results of that testing are contained in Westinghouse Reports WCAP-12225, WCAP-12227 and summarized in WCAP-12244.
This information is maintained at the Palisades site and also at Westinghouse offices.
The current planned repair method will not remove any additional tube plugs.
Requested Action 3.
Remedial actions at plants where the steam generator tubes are partially-depth-expanded within the tubesheet as described above may be deferred on a one-time OC0689-0138-NL04
I Nuclear Regulatory Commission Palisades Plant Response to Bulletin 89-01 June 19, 1989 basis to the next scheduled refueling outage, if the outage that immediately follows receipt of this bulletin ends before October 1, 1989.
Response
Requested Action 3. is not applicable to Palisades.
Requested Action 4.
4 Remedial actions for "sentinel related" mechanic_al-plugs described above may be def erred on a one time basis to the next refueling outage if the outage that immediately follows receipt of this bulleti_n ends before October 1, 1989.
Response_
Requested Action 4. is not applicable to Palisades.
Kenneth W Berry Director, Nuclear Licensing CC Administrator, Region III, USNRC NRC Resident Inspector - Palisades OC0689-0138-NL04
CONSUMERS POWER COMPANY Palisades Plant Docket 50-255 - License DPR-20 RESPONSE TO NRC BULLETIN 89-01 At the request of the Commission and pursuant to the Atomic Energy Act of 1954 and the Energy Reorg2nization Act of 1974, as amended, and the Commission's Rules and Regulations thereunder, Consumers Power Company submits our response to 1TR.C Bulletin 89-01 dated May 15, 1989, entitled, "Failure of Westinghouse Steam Generator Tube Mechanical Plugs."
Consumers Power Company's response is da*ted June 19,
- 1989.
- CONSUMERS POWER COMPAJ\\1Y Sworn and subscribed to before me this 19th day of June 1989.
Elaine E Buehrer, Notary Public Jackson County, Michigan My commission expires October 31, 1989 OC0689-0138-NL04