ML20029C270
| ML20029C270 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 03/21/1991 |
| From: | Pelletier J VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| BVY-91-30, GL-88-14, NUDOCS 9103270088 | |
| Download: ML20029C270 (3) | |
Text
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VERMONT YANKEE NUCLEAR POWER CORPORATION N
Ferry Road, Brattleboro, VT 05301-7002 7
PWW c
2 1991 Vice President. Engineering e
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(802) 257 5271 United States Nuclear Regulatory Commission Document Control Desk Washington, D.C.
205b5 Referencess a.
Licensee No. DPR-28 (Docket No. 50-271) b.
Letter, USNRC to VYNPC, NVY 89-54, Inspection Report dated 3/20/89 c.
General Electric Specification 22A1265 Design Specification - Reactor Containment d.
Vermont Yankee Final Safety Analysis (FSAR' e.
General Electric Specification 22A2856 Des:.gn Specification - Atmospheric Control, Primary Containment f.
Vermont Yankee Safety Evaluation Report, dated 6/1/71 g.
10CFR50, Appendix A, General Design Criteria No. 56 h.
Vermont Yankee Technical Specification i.
- Letter, VYNPC to USNRC, FVY 86-80, dated 8/26/86; Proposed Change No. 134 j.
- Letter, VYNPC to USNRC, BVY 90-00h, dated 1/16/90 k.
- Letter, VYNPC to USNRC, DVY 90-016, dated 2/15/90 1.
- Letter, USNRC to. VYNPC, NVY 91-06, dated 1/23/91 m.
General Electric Specification 22A1132AL Design Specification - Containment Isolation Systems n.
Letter, BWROG to Primary Representatives, OG91-123-01, dated 2/12/91
. Subject Vermont Yankee Torus to Reactor Building Vacuum Breaker Operability
Dear Sir:
During an evaluation performed in accordance with NRC Generic
. Letter 88-14 Instrument Air System Problems, a' potential design deficiency w1th the Torus-to-Reactor Building Vacuum Breakers was identified.
In Reference Vermont Yankee provided the NRC the results. of a review of the(k), ign bases and-_ operability status of des the vacuum breakers.
This submittal concluded that the current design of these vacuum breakers met the licensing bases of the plant, and the vacuum breakers were subsequently declared operable.-
By recent letter dated January 23 1991, (Reference (1)], the evaluation NRC has concluded that our was incorrect, and as containment isolation valves, the vacuum breakers should be fully safety grade, including a fully qualified air supply, and requested 9103270088 910321 PDR ADOCK 05000271
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f VERMONT YANKEE NUCLEAR POWER CORPORATION United States Nuclear Regulatory Commission Page 2 a response to this finding.
The this letter is to provide the NRC with Vermont Yankee' purpose of s assessment regarding the NRC evaluation described in Reference (1).
1)
Did the licensee have sufficient technical basis for exiting the action statement for containment isolation?
Vermont Yankee does not agree with the NRC's assessment of this issue.
Upon receipt of Reference (1),
Vermont Yankee initiated further review of the original design bases documents identified in Reference (k) as well as other design documents.
Additional documentation which identifies this penetration as an exception to normal isolation requirements is found in Reference (m).
This design specification states in Section 3.2.2 that,
" Class D valves are on process lines that do not directly communicate with the reactor vescol, but penetrate the primary containment and communicate with the primary containment free space.
These lines require two valves in series, both of them outside the primary containment.
Both valves shall close automatically on isolation signal.
Both valves shall receive the isolation closure signal even if normally closed during reactor operation." Section 3.2.4 goes on to state that, "The fourth class of valves are exceptions to the above definitions.
These valves are referenced in Appendix A by their class designations followed by an
'X' suffix; for example, A-X."
A review of Appendix A of this specification identifies that valves 16-19-11A6B are considered class D-X valves, which clearly identifies them as exceptions to the requirements for normal class D valves.
Aaditionally, this appendix identifies no isolation signal to these valves, even thcugh these valves are normally closed during operation.
This reinforces the fact that those valves were considered exceptions to class B isolation valves and were expected to open on loss of air (i.e.,
no isolation signal required).
Therefore, Vermont Yankee believes tnnt sufficient technical basis existed for exiting the action statement for containment isolation.
2)
Are the licensee's actions acceptable for meeting GDC 56 requirements for containment isolation?
Vermont Yankee does not agree with the NRC's assessment of this issue.
As identified above, and in Reference (k), this line is an oiception to the requirement for (2) containment isolation valves.
GDC 56 general'.y requires isolation valves unless it can be demonstrated that the lines (2) are acceptable on some other defined basis.
Therefore, Vermont Yankee believes the existing valve arrangement is an acceptable variation to the containment isolation design criteria and that this configuration meets the original design basis requirements of GDC 56.
The NRC evaluation does not address this aspect of GDC 56.
3)
Should the butterfly valve air supply be "backfitted" to be safety grade to assure reliable closure of the isolation valves?
Vermont Yankee does not agree with the NRC's assesument of this issue.
Ab stated above, Vermont Yankee believes that the existing configuration is in conformance with our original design basis.
As stated in Reference (k), Vermont Yankee believes that the swing check valves provide a
highly reliable means to
VERMONT YANKEE NUCLE AR POWER CORPORATION United States Nuclear Regulatory Commission Page 3 accomplish the containment isolation function.
Therefore, Vermont Yankee believes that any requirement to supply a fully qualified air supply to these valves should be considered under the backfit rules.
4)
Should a generic backfit determination be performed, in conjunction with GL 88-14, to evaluate the cost benefit of providing a safety grade air supply to the upstream containment isolation valves?
Region I has several other BWRs with the same design f(eatures for the vacuum breaker system.
In addition, one BWR has installed a seismically qualified safety grade air supply in order to ensure a reliable safety function.)
As stated above, Vermont Yankee believes that the existing configuration is in conformance with the original design basis.
Therefore, any required modification should be considered under the backfit rules.
Should the butterfly valves llA and B be deleted from 5) the TS Table for containment i(solation v)alve surveillance or otherwise not considered to be containment isolation valves?
Vermont Yankee believes that the butterfly valves provide an aaditional degree of isolation under most circumstances.
Their inclusion within TS surveillance requirements provides additional assurance of satisfactory operation.
Accordingly, Vermont Yankee believes that the subject butterfly valves should remain in the Technical Specifications.
Vermont Yankee had the BWR Owners Group (BWROG cont.act the primary representatives of other BWR Mark I utilitie)s to identify any other plants which may be affected by this issue (Reference (n)).
We are considering Joining with other affected BWRs via the BWROG in a joint offort to resolve this issue with the NRC.
Very truly yours, SPA Q ames P.
Pelletier Vice President, Engineering cc:
USNRC Region I Administrator USNRC Resident Inspector - VYNPS USNRC Project Manager - VYNPS STATE OF VERMONT
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