ML20247Q162
| ML20247Q162 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 09/19/1989 |
| From: | Trevors G NEBRASKA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CNSS895931, NUDOCS 8909280119 | |
| Download: ML20247Q162 (2) | |
Text
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COOPER NUCLEAR ST ATioN s
Nebraska Public Power District
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CNSS895931 September 19, 1989 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. -20555
Subject:
Alternate Rod Insertion System Cooper: Nuclear Station.
NRC Docket No. 50-298/DPR-46
References:
- 1) Letter, W. O. Long to G. A. Trevors, dated September 23, 1987, " Safety Evaluation Report on Cooper Nuclear Station Compliance with ATWS Rule 10CFR50.62 Releting to ARI and RPT Systems...
-2) Letter, W. O. Long to G. A. Trevors, dated January 8, 1987, "ATWS Rule (10CFR50.62)".
Gentlemen:.
'i Reference 1) transmitted the staff's safety evaluation of the District's Alternate Rod Insertion (ARI) design submittal which was being reviewed to verify compliance with 10CFR50.62. Two of the ARI criteria reviewed and found acceptable in Reference 1) were system function' time and completion of the protective action once initiated. These criteria stated that:
1.
All control rods will begin-insertion within 15 seconds of ARI initiation.
2.
All control rods will reach their full-in position within 25 seconds of the ARI initiation signal.
3)
.The ARI will have a seal-in' feature for 30 to 35 seconds to ensure completion of the protective action once it is initiated.
- Acceptance testing of the installed ARI system showed that not all rods began inserting within 15 seconds of the ARI initiation and that some rods did not reach their full-in position within 25 seconds. The maximum full-in rod insertion time found during acceptance testing was 29.2 seconds after ARI
- initiation. -This was measured using either the position indication of the SCRAM inlet and outlet valves or the rod drift light, both contained on the full core. display, as indication of initit.2 rod movement.
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September 19, 1989 Page 2 Deviations from the 15 and 25 second rod insertion motion performance are discussed in the BWR Owners Group Topical Report NEDE-31096-P-A also submitted in response to 10CFR50.62. Reference 2) enclosed a copy of the staff's safety evaluation of this report and stated that the District may reference NEDE-31096-P-A in support of its submittals. The Topical Report states that one of the ARI design basis requirements is for the scram air header to be depressurized in sufficient time after the initiatior, signal to ensure that all rods will be fully inserted by the time the Scram Discharge Volume (SDV) is full. Under tb-AFT design objectives, the report states that deviations from the 15 and 15 seccad rod insertion design objectives can be shown to be acceptable bar on plant unique SDV fill time calculations and assessments of other design esfectives t ihat are met if full rod insertion occurs within approximately 60 seconds of ARI initiation).
A plant specific SDV fill time evaluation was performed for Cooper Nuclear Station prior to the site ARI acceptance test.
It allows 34.5 seconds for full rod insertion to occur following an ARI initiation before SDV fill up takes place. Attendant with this is a 29.5 second allowable time for start of rod insertion after ARI initiation. All rod T.imes evaluated during ARI acceptance testing met the stipulated criteria.
In addition, completion of the Protective Action criteria remained satisfied since all rods were fully inserted before the ARI lock-out feature would allow manual reset of ARI (30-35 seconds after ARI initiation).
The District requests NRC concurrence that the ARI system function time criteria has been met at Cooper Nuclear Station based on the above provided information and that the ARI Safety Evaluation Report contained in Reference
- 1) be supplemented ts documentation of this acceptance.
The District also eequests that the time interval for the ARI seal-in feature as described in the Safety Evaluation Report be changed to 35 to 40 seconds to allow a greater margin between the time it takes for all rods to insert and the time that the ARI seal-in feature resets. After receipt of the supplemented Safety Evaluation Report, the District will change the ARI seal-in feature time accordingly.
If you have any questions, please call.
G. A.
frevors Division Manager of Nuclear Support GAT:GRS:sg cc:
U.S. Nuclear Regulatory Commission Region IV Arlingtou, TX 76011 NRC Resident Office Cooper Nuclear Station
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