ML17284A461
| ML17284A461 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 07/27/1988 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17284A460 | List: |
| References | |
| TAC-68897, NUDOCS 8808040246 | |
| Download: ML17284A461 (8) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO.
61 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 July 25, 1987 the Washington Public Power Supply System proposed a change to Tables 3.3.7.5-1 and 4.3.7.5-1 of the Technical Specifications for WNP-2.
The first table sets forth operability require-ments for accident monitoring instrumentation.
The second table sets forth surveillance requirements.
Specifically with regard to Safety/Relief Valve Position indicators it is required that there be two instrument channels per valve and that a minimum of one channel per valve be operable.
With less than two channels per valve operable the licensee must restore the inoperable channel to operable status within seven days or be in at least hot shutdown within the next twelve hours.
On Wednesday, July 20, 1988 at 4:38 pm hours (PDT), the licensee declared the acoustic monitor channel for relief valve MS-RV-1B inoperable due to loss of position indication.
This placed the licensee in the seven day action period with repair of the channel or plant shutdown required by Wednesday July 27, 1988.
The licensee has determined that the plant will be required to be shut down and cooled down to repair or replace the acoustic monitor to restore the channel to operability.
The proposed change permits continued operation of the plant with one channel (the acoustic monitor) for the specified relief valve inoperable until the next refueling outage, scheduled for no later than May 15, 1989, or until the first forced outage prior to that date which is of sufficient duration to effect repair/r eplacement.
Table 4.3.7.5-1 of the technical specifications will be changed to specify daily surveillance of the remaining operable channel until the acoustic monitor channel is restored to an operable condition.
The licensee has determined that the loss of position indication does not reduce the capability of the safety relief valve to perform its intended function.
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l 2.0 EVALUATION TMI Action Plan Item II.D.3 "Direct Indication of Relief and Safety-valve Position" requires that "Reactor coolant system relief and safety valves shall be provided with a -positive indication in the control room derived from a reliable valve-position detection device or a reliable indication of flow in the discharge pipe."
The technical specifications for WNP-2 require two instrumentation channels for providing this information on valve position.
One channel utilizes an acoustic monitor.
The second channel utilizes thermocouples to detect a temperature increase indicative of flow past the valve.
The staff in its review of the licensee's evaluation considered the basis for the TMI Action Plan requirement and the continued capability at WNP-2 to satisfy the requirement and the continued capability at WNP-2 to satisfy the requirement with the inoperable acoustic monitor position indicator.
The staff concurs that the capability of the relief valve to perform its safety function is not impaired by the loss of position indication.
The review has focused on the capability of the alternatives for providing accurate position indication in the absence of the acoustic monitor.
The licensee has proposed the following mitigating and compensatory measures to provide assurance that the valve position is reliably detected and indicated:
(I)
The second instrumentation channel for valve position utilizes tail pipe temperature.
Tail pipe temperature indication is monitored and recorded.
An increase in temperature would indicate that the valve is open and steam is entering the suppression pool via the tail pipe.
This indication has remained capable of indicating valve actuation since the failed monitor was identified.
Channel checks of the temperature recorder are currently performed monthly per Technical Specification 3/4.3.7.5.
Until MS-RV-IB is declared
- operable, the tail pipe temperature surveillance will be performed daily instead of monthly.
The acoustic monitor channel was alarmed.
A control room annunciator is available that alarms on high tail pipe temperature (greater than 250 degrees Fahrenheit).
An annunciator response procedure addressing the tail pipe temperature alarm will be revised to uniquely identify appropriate actions for MS-RV-IB.
(2)
Suppression Pool temperature indication is available and is set to alarm at 85 degrees Fahrenheit.
An increase in suppression pool temperature would indicated an open SRY.
(3)
Suppression Pool level indication is available and is set to alarm at one half inch above Normal Level (466.25 feet).
An increase in suppression pool level would indicated an open SRV.
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(4)
Other plant parameters are affected by an SRV actuation and are available as confirmation.
Examples are main turbine governor valve position indication change, generator output change, main turbine steam flow change and the resultant reactor pressure perturbation.
3.0 EMERGENCY CIRCUMSTANCES Failure of the acoustic monitor has only recently been identified.
The licensee declared the monitor inoperable at 4:38 p.m.
PDT on Wednesday, July 20, 1988.
This could not have been anticipated.
The licensee has determined that repair will require that the reactor be shut down and cooled down in order to permit drywell entry.
The licensee has therefore requested an emergency temporary change to the Technical Specifications to allow continued operation until the next outage of adequate duration to make the needed repairs.
At the latest, this will be the next refueling
- outage, scheduled to begin prior to May 15, 1989.
4.0 FINAL NO SIGNIFICANT HAZARDS DETERMINATION The Commission's regulations in 10 CFR 50.92 state that the Coranission may make a final determination that a license amendment involves no significant hazards consideration if operation of the facility in accordance with the amendment would not:
(I)
Involve a significant increase in the probability or consequence of an accident previously evaluated; or (2)
Create the possibility of a new or different kind of accident from any accident previously evaluated; or (3)
Involve a significant reduction in a margin of safety.
Based on the availability of alternative methods to determine whether safety relief valve MS-RV-1B is open or closed, and on the compensatory action being taken to perform the surveillance of the operable channel daily instead of monthly and to provide an alarm on that operable
- channel, we have determined that the amendment meets the above criteria.
The requested amendment does not:
(I) involve a significant increase in the probability or consequences of an accident previously evaluated because inadvertent opening of a safety relief valve was analysed in FSAR Section 15.1.4.
With the compensatory measures
- noted, the inoperability of the acoustic monitor position indicator does not affect the probability or consequence of inadvertent valve operation; or (2) create the possibility of a new or different type of accident than previously evaluated because the confirmatory devices identified above under the discussion of compensatory actions will allow the operator to recognize that a relief valve is not closed; or (3) involve a significant reduction in a margin of safety because more frequent surveillance of the single channel (daily as opposed to monthly when two channels were operable) should enhance the reliability of the thermocouple channel and compensate for the inoperability of the acoustic monitor channel.
Accordingly, we concluded that the license amendment involves no significant hazards consideration.
5.0 STATE CONSULTATION
The State of Washington was provided a copy of the license amendment application on July 25, 1988 and was advised by NRC staff the application would be processed on an emergency basis.
- 6. 0 ENVIRONMENTAL CONSIDERATION This amendment involves a change in the installation and use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes in surveillance requirements.
The staff has determined that this amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b),
no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.
Principal Contributor:
Robert B. Samworth Dated:
July 27, 1988
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