ML20049J348
| ML20049J348 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse, Oconee, Crystal River, 05000000 |
| Issue date: | 03/09/1982 |
| From: | Crouse R TOLEDO EDISON CO. |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| 793, NUDOCS 8203150147 | |
| Download: ML20049J348 (3) | |
Text
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Docket No. 50-3l.6 SEgWr9 p
TOLEDO EDISON License No. NPF-3 g, g15 g v
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u Serial No. 793
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Mr. Darrell G. Eisenhut, Director Division of Licensing Office of Nuclear Reactor Regulation United States Nuclesr Regulatory Commission Washington, D.C.
20555
Dear Mr. Eisenhut:
The Regulatory Response Group for Babcock and Wilcox nuclear steam supply system owners met with you and your staff on March 8,1982 in the NRC Bethesda offices. This letter is in direct response to your meeting request to provide justification for continued operation of the Davis-Besse Nuclear Power Station Unit No. 1 in the light of recent makeup system injection line cracks discovered at the Crystal River and Oconee Nuclear Generating Stations.
Toledo Edison has reviewed all the information available to date and concludes that the continued operation of Davis-Besse, until its refueling outage scheduled to commence on March 13, 1982, presents no significant additional risk to the public health and safety.
This conclusion was reached after evaluating the available information in light of the basic functions performed by these lines. These are:
I.
Reactor Coolant System Boundary - loss of integrity could result in up to a 2*n inch break condition in the reactor coolant system.
II.
The make up system line doubles as a high pressure injection system flow path to the reactor coolant system.
The particular factors of interest in the review are identified below:
A.
Inspection related (based on inspections performed at Crystal River 3, Oconee 2 & 3 and TMI-1.)
1.
The actual pipe and valve cracking observed to date has only been found on double-duty lines.
These are lines that provide makeup system as well as high pressure injection system water to the reactor coolant system.
Aoi 1 gio THE TOLEDO EOISON COMPANY EOISON PLAZA 300 MADISON AVENUE TOLEDO OH10 43G52 8203150147 820309 PDR ADOCK 05000346 P
Docket No. 50-346 License No. NPF-3 Serial No. 793 March 9, 1982 Page 2 Toledo Edison utilizes only one of the four high pressure injection system lines in a double-duty role. The as-built arrangement of these lines is consistent with the original B&W and ASHE design criteria.
Plant emergency procedures currently instruct the operators how to control and monitor flow through these lines to insure adequate core cooling water to the reactor coolant system. On March 5, 1982, the Training Department formally disseminated information on the problems found at other utilities and re-emphasized the associated Davis-Besse operating procedures to all licensed operators and shift technical advisors.
2.
All currently known safe-end cracking has been accompanied by physically loose thermal sleeves. Although no specific cause and effect relationship has yet been established, in one potential scenario these sleeves must be loose to allow the crack initiation mechanism to be present.
In March 1977, prior to operation of DB-1, two of these thermal sleeves were identified as loose. Three of the sleeves were physically re-rolled in place. Re-rolling the fourth sleeve proved not required. This line is an HPI-only line.
3.
Detailed examiniation to date identifies the safe-end cracks as longitudinal, random, transgranular and fatigue related due to thermal cyclic stress.
Film and oxide deposits indicate slow propagation over a period of greater than one year.
The actual time Davis-Besse has operated is significantly l
less than the other B&W units.
Due to the slow crack propagation any leaking conditions would be monitored as unidentified reactor coolant system leakage to the containment vessel.
B.
Time related Toledo Edison is taking Davis-Besse out-of-service by March 13, 1982. The four remaining days of service are incrementally small and, therefore, limit the probability of pipe failure prior to shutdown and inspection.
On March 4, 1982, the Company Nuclear Review Board (CNRB) discussed this issue extensively. Again today this offsite safety review board has been updated on its status. The CNRB concurs with the current actions planned by the Company allowing continued operation until March 13, 1982.
e Docket No. 50-346 License No. NPF-3 Serial No. 793 March 9, 1982 Page 3 As discussed with you in the meeting, this activity is considered important enough to continue dissemination of information through the Regulatory Response Group. We shall keep you informed of any changes in our position.
Very truly yours, f/k =-_2
/
RPC:TJM: lab cc:
DB-1 Resident Inspector James G. Keppler, Region III Administrator b/4