ML17284A398
| ML17284A398 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 05/26/1988 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17284A397 | List: |
| References | |
| NUDOCS 8806280331 | |
| Download: ML17284A398 (8) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATIO SUPPORTING AMENDMENT NO. 58 TO FACILITY OPERATING LICENSE NO.
NPF-21 WASHINGTON PUBLIC POWER SUPPLY SYSTEM WPPSS NUCLEAR PROJECT N0.2 DOCKET NO. 50-397
1.0 INTRODUCTION
By letter dated January 5,
1988 (G02-88-002)
Washington Public Power Supply System (WPPSS) requested an amendment to the WNP-2 Technical Specifications related to automatic isolation of a valve on the residual heat removal system intake line.
Specifically, WPPSS proposed to transfer control of valve RHR-V-8 to the alternate remote shutdown panel, thereby bypassing the automatic isolation controls of that valve.
By letter dated February 12, 1988 the licensee described more completely the interlocks which would be bypassed and measures which would be taken to preclude inadvertent operation of the valve from the alternate remote shutdown panel.
By letter dated March 15 the licensee provided a revision to the proposed wording for the Technical Specifications.
This was for clarity and did not represent a substantive change.
2.0 DISCUSSION The purpose of transferring control of the valve to the alternate remote shutdown panel is to eliminate the potential for a control room fire to open spuriously both motor-operated Residual Heat Removal (RHR) system suction line isolation valves (RHR-V-8 and RHR-V-9). These valves, which are in series, constitute a high/low pressure interface whenever reactor pressure is greater than the pressure at which the low pressure side of the line is designed (220 psig).
The valves are kept closed during power operation and are remote manually opened at other times if needed (e.g.,
normal shutdown cooling).
The high/low pressure interface is further protected by pressure interlocks provided for these valves (the interlock logic for the valves is housed in two control room panels).
At reactor pressures above the shutdown range permissive (135 psig) interlocks will ensure. the line isolation (i.e.,
will prevent opening of the valves or will close the valves if they are open).
When the reactor pressure is such that these valves constitute a
high/low pressure interface,.possible spurious opening of both the valves due to a control room fire and consequent breach of the associated high/low pressure interface should be avoided.
Appropriate fire protection procedures should be implemented to ensure that at least one of these two valves cannot spuriously open due to such a fire.
8806280331 880526 PDR ADOCK 05000397 PDR
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The licensee's resolution of this concern proposed in the January 5 and February 12, 1988 submittals can be summarized as follows:
1.
To ensure that the control for valve RHR-V-8 is unaffected by a
control room fire when the reactor pressure is greater than 135 psig, the valve transfer switch located at the Alternate Remote Shutdown Panel (ARSP) will be placed in the "Emergency" position during plant Operational Conditions I, 2 and 3 (power operation, start up and hot shutdown respectively).
This will result in bypassing the interlocks associated with the normal shutdown cooling mode isolation actuation instrumentation and consequently bypassing the corresponding automatic isolation signals (reactor pressure above shutdown range permissive, shutdown flow high, and reactor vessel water level low) for the valve.
2.
The valve control switch located at the ARSP will be kept in the "Closed" position prior to transfer of its control from the control room to the ARSP to ensure that the valve 'does not open upon actuation of the valve transfer switch, 3.
A two position (Enable-Disable) key-lock switch will be installed at the ARSP and it will be locked with the valve in the closed position to prevent inadvertent opening of the valve from the ARSP.
A contact from this switch will be wired in series with the ARSP RHR-V-8 control switch ("Open" control contact).
The key will be administratively controlled.
4.
RHR-V-8 position indication will continue to be available continuously in the control room during normal plant operation.
5.
During plant Operational Conditions 2 and 3 (startup and hot shutdown),
if needed, transfer of the valve control back to the control room and additional opening of the valve from the control room will be permissible, provided the reactor pressure is less than 135 psig.
Such a re-transfer will result in reestablishment of the valve interlocks and associated automatic isolation signals for the normal shutdown cooling.
6.
There will be no change in the existing availability of interlocks and automatic isolation signals for valve RHR-V-9.
7.
The plant procedures will be revised as appropriate to implement the above approach.
The submittals included licensee's proposed changes to WNP-2 Technical Specification (TS) Tables 3.3.2-1, "Isolation Actuation Instrumentation,"
and 3.6.3-1, "Primary Containment Isolation Valves," as they apply to the valve RHR-V-8.
A footnote is to be added to each table to indicate that the automatic isolation capability for valve RHR-V-8 would not be available when control is transferred to the ARSP.
The footnotes delineate the conditions under which the inter locks are bypassed and the conditions under which control of RHR-V-8 is transferred back to the control romm reestablishing the interlocks.
- 3. 0 EVALUATION The staff has determined that while the valve control is transferred to the ARSP, the valve will be closed.
Its spurious opening due to a control room fire will thus be prevented.
Inadvertent opening from the ARSP wil1 be minimized since such opening will require acquiring the administratively controlled key, changing the key-lock switch from "Disable" to "Enable"
- position, and changing the valve control switch from "Close" to "Open" position.
The staff has also determined that bypassing the RHR-V-8 valve interlocks and automatic isolation signals during the time when the valve control remains at the ARSP will not compromise the intent and purpose for which these are provided, namely to ensure the isolation of the normal shutdown cooling suction line under adverse reactor conditions.
This is because the valve will be ensured to remain in an isolated condition, when its interlocks and automatic isolation signals are bypassed.
The staff therefore finds that the propsed changes to the Technical Specifications will have no significant adverse safety impact but will allow resolution of a significant safety concern.
The staff notes that in the June 3, 1987 and August 20, 1987 submittals, the licensee committed to complete necessary modifications and implement the approach chosen for permanent resolution of the high/low pressure interface concern by the end of the 1988 refueling outage.
- 4. 0 ENVIRONMENTAL CONSIDERATION Pursuant to 10 CFR 51.32, an environmental assessment has been published (53 FR 18939) in the Federal Re ister on May 25, 1988.
The Commission has determined that tlie issuance o
this amendment will not have a
significant effect on the quality of the human environment.
5.0 CONTACT WITH STATE OFFICIAL The State of Washington advised that they did not have any comment.
- 6. 0 CONCLUSION The changes proposed by the licensee have been reviewed by the staff and have been found to be acceptable because they will resolve staff concern over potential safety problems resulting from a control room fire and because there is adequate assurance that there will be no greater potential for spurious or inadvertent breeching of the pressure interface with control of the valve transfered to the alternate remote shutdown panel.
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The Commission has issued a Notice of Consideration of Issuance of Amendment to Facility Operating License and Opportunity for Hearing which was published in the Federal Re ister (53 FR 8291) on Parch 14, 1988.
No request for hearing o~r pet tion for eave to intervene was filed following this notice.
Me have concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed
- manner, and (2) such activities will be conducted in compliance with the Commissions's regulations and (3) the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors:
T. Chadrasekaran S.
Rhow Dated:
May 26, 1988
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