ML20031E300
| ML20031E300 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 10/07/1981 |
| From: | Daltroff S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20031E301 | List: |
| References | |
| NUDOCS 8110150348 | |
| Download: ML20031E300 (4) | |
Text
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PHILADELPHIA ELECTR!C COMPANY 2301 M ARKET STREET P.O. BOX 8699 1881 1981 PHILADELPHI A PA.19101 SMIE LDS L. D ALTROFF ELacTaic pac c som October 7, 1981 Re: Docket Nos. 50-277 50-278 Mr. John F.
Stolz, Chief Operating Reactors Branch #4 Division of Licensing U.S. Nuclear Regulatory Commission Washington, DC 20555
SUBJECT:
Correspondence dated September 1,
- 1981, J.
F.
Stolz, NRC to E.
G.
Bauer, Jr.,
Philadelphia Electric Company
Dear Mr. Stolz:
This letter provides the information you requested for your contractor in the referenced letter regarding Philadelphia Electric Company's application for amendment to the Peach Bottom Atomic Power Station Technical Specification.
The application was submitted on October 14, 1980, at the request of the NRC to provide surveillance requirements for scram discharge volume (SDV) vent and drain valves and LCO/ surveillance requirements for RPS and control rod block SDV limit switches.
The requests and our responses are provided sequentially as follows:
I.
Request: Provide technical bases why the licensee proposed surveillance requirement to stroke test the scram discharge volume drain and vent valves every 3 months should not be changed to once every 31 days.
00\\
l 5i i 0110150348 811007 i PDR ADOCK 05000277 P
Mr. John F. Stolz Pcga 2
Response
The Model Technical Specifications, submitted to the licensees in the July 7, 1980 letter requesting an amendment requiring SDV drain and vent valve stroking, specified a 120 day frequency.
Philadelphia Electric's proposed amendment specified a more conservative frequency of every 3 months.
The Model Technical Specifications, referenced in the September 1, 1981 letter, is a later revision (Fall 1980, revision 3).
A monthly surveillance test would be appropriate for designs lacking redundant valves.
However, Philadelphia Electric Company is in the process of adding a second valve in series on each SDV drain and vent line.
The modification involves quality aesured, environmentally and seismically qualified components.
Each valve in series is fed from independent power sources to assure line isolation in the event of a single failure.
We believe a stroke test every 3 months is sufficient to ensure isolation capabilities in a redundant valve design.
Testing every month will only nerve to add to the proliferation of surveillance testing, procedures and paperwork, thus distracting personnel from more essential tasks.
Further justification for the proposed quarterly testing frequency are the permanent modifications, described in a letter frc.a S.
L.
Daltroff to D.
G. Eisenhut dated December 16, 1980, that will connect the SDV directly to the instrument volume with new piping equal in cross sectional area.
The modifications will provide adequate hydraulic coupling to ensure proper drainage.
There will be no dependence on the vent and drain system for the proper detection of water, and additional discharge volume will be provided as added margin for scram capability.
Additionally, monthly testing on a redundant valve design is inconsistent with the testing philosophy presented in the Standard Technical Specifications (Nureg 0123, rev. 3, page 3/4 4-8) for react.or coolant system pressure isolation valves.
For example, most primary containment valves are required to be stroke tested only once per 18 months.
II.
Request: Provide reference to that section of the Technical Specifications which indicates compliance with the following j
provisions of the Model Technical Specifications.
SDV level switch design based on a 1 out of 2 logic.
a.
b.
SDV level switches calibrated every refueling cycle.
-a s-sa---
Mr. John F. Stolz Pega 3 i
Response
copies of the Peach Bottom Technical Specifications, pages 38, 39, 44, and 46 are enclosed to document compliance with the Model Technical Specificaticns.
III. Request: Specify "2" minimum operable channels per trip function for the SDV high water level control rod with drawal blocks
Response
j We specified "one" minimum operable channel per trip function on page 73 of the proposed amendment because the Peach Bottom design consists of only one channel for the rod block feature associated with high SDV water level.
Six level switches on the scram discharge volume, set at ',hree different water levels, guard against operation of the reactor without sufficient free volume present in the scram discharge volume to receive the scram discharge water in the event of a scram.
At the first (lowest) level, one level switch initiates an alarm for operator action.
At the second level, another level switch initiates a rod withdrawal block to prevent further withdrawal of any control rod.
At the third (highest) level, four level switches (two for each Reactor Protection System trip system) initiate a scram to shut down the reactor while sufficient free volume is available to receive the scram discharge.
The modification to the SDV piping, described in our response to item I above, will provide a 40% increase in the discharge volume.
This improvement has the effect of substantially increasing the sensitivity of the instrument volume water detection system.
The addition of another level switch to provide a total of two channels for a control rod withdrawal block would have a negligible impact on the probability that the lack of sufficient free volume in the scram discharge volume would go undetected.
We believe the current alarm / rod block / scram control circuitry involving six level switches provides the necessary protection.
IV.
Request: Provide a technical bases for not providing " scram trip bypassed" instrumentation.
Response
Peach Bottom has the control rod withdrawal block feature when the SDV scram trip is bypassed.
A manual keylock switch located in the control room permits the operator to bypass the scram
-e-
Mr. Jchi F. Stolz Page 4 discharge volume high level scram trip if the mode switch is in Shutdown or Refuel.
This bypass allows the operator to reset the Reactor Protection System, so that the system is restored to operation while the operator drains the SDV.
Additionally, the bypass initiates a control rod block.
An annunciator in the control room indicates the bypass condition.
A functional test for the scram trip bypassei-control rod block feature was not proposed in our amendment application due to the simplicity of the design.
No relays are involved, only manual switch contacts.
Should you consider a functional test to be necessary, we would propose a once per refueling cycle frequency in lieu of the monthly test recommended in the Model Technical Specifications referenced in the July 7, 197.0 letter (D.
G.
Eisenhut to All Operating BWR's).
The once per refueling cycle frequency is appropriate for this feature based on its minor safety significance and the simplicity of its design.
If you have any questions regarding the above or need additional information regarding the Technical Specification on the SDV control systems, please contact Willian Birely, (215) 841-5048.
Very truly yours, suK v
Enclosure