ML19210A624
| ML19210A624 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 11/11/1977 |
| From: | Reid R Office of Nuclear Reactor Regulation |
| To: | Herbein J METROPOLITAN EDISON CO. |
| References | |
| NUDOCS 7910300658 | |
| Download: ML19210A624 (4) | |
Text
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November 11, 1977 Docket File V
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NRC POR L PDR Gray File Docket No.: 50-269 ORB #4 Rdg am GZwetzig Metropolitan Eoison Company GZech ATTN: Mr. J. G. Herbein Attorney, OELD Vice President TCarter P. O. Box 542 OI&E (3)
Reading, Pennsylvania 19603 DEisenhut TBAbernathy Gentlenen:
JRBuchanan ACRS (16)
The NRC staff has conpleted a preliminary review of the overpressure protection system for Three Mile Island Unit No.1.
We have founo that the system currently installed in combination with the proposed changes does not meet all the criteria established by the NRC.
Your proposed system maintains a gas blanket or Dubble in the pressurizer at all times, in conjunction with a single low pressure setpoint relief valve. This design has certain advantages over other concepts because failure of an operator to manually enable the low pressure setpoint of the relief valve does not totally defeat protection against a pressure transient. The staff M s concluded that your proposed system adecuately accommodates all postulated overpressure transients with the exception of an inadvertent initiation of safety injection by the high pressure injection (HPI) pump.
Based on your analyses we have identified HPI as the limiting eass addition overpressure transient. Operation of the HPI pump, which is capable of delivering flow against full system operating pressure, is required whenever a reactor coolant pucp is in operation. Since the discharge of the HPI pump is isolated from the reactor coolant system by a single injection valve, a single error or equipoent failure could open the injection valve and initiate a pressure increase in the primary system.
If failure of the single low setpoint power operated relief valve is then assumed as the single failure following initiation of the event, your analysis shows that operator action is required within five minutes to maintain primary systen pressure below Appendix G limits. This is not in accordance with HRC criteria for operator action :rbich prohibits the assumption of operator inter-vention for ten minutes, and which requires the assua:ption of a single
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Fetropolitan Edison Cormany '
f ailure following the initial f ailure or error which is postulated to cause the transient. Si'.;ce your proposed systen does not fully satisfy our established criteria we require that you propose systeS modificatons that will provide overpressure protection in full con-formance with hRC criteria, and that you provide a schedule and a value-impact assessacnt to make all necessary hardware changes.
It is also the NRC position that to assure proper alignment of the overpressure protection systen during plant cooldown, an enabling alarm nust be provided which monitors the system enabling switch and the position of the isolation valve upstream of the PORY.
Your previous submittals do not provide detailed electrical circuit and logic diagrams of the overpressure protection system to facilitate a thorough review. Please provide the following:
1.
RCS overpressure protection system diagram; 2.
Logic Diagram; 3.
Control Circuitry Diagram; 4.
Instrument Loop Diagram; 5.
Annunciator System Schematic; and 6.
Overpressure Protection Control Display and Layout.
In addition to the items discussed above, the staff bas identified several concerns related to PORY maintenance and HPI testing for the currently proposed system.
If the PORY requires maintenance the upstream isolation valve would need to be closed thereby removing the single relief valve from service. Therefore the staff will require Technical Specifications which stipulate that when the reactor vessel temperature is below the minimum value for which the vessel can be fully pressurized the PORY nay be removed from s2rvice for a short period of time only if:
(1) charging punps are out of service and all HPI injection valves are closed and power removed, or (2) the vessel head is re-moved. Regarding HPI testing, the staff will require that your pro-cedures state that the HPI valve be allowed to be cycled only if all HPI pumps are out of service, or vessel temperature is above the minimum value for which the vessel can be fully pressurized, or the reactor vessel head is removed.
z Netropolitan Edison Coopany.
We will require that your Technical Specifications identify tne system enabling temperature and the PORY setpoint.
In addition, you should propose specifications related to systen testing.
These maintenance and testing restrictions should be examined to assura compatibility with present Technical Specification require-ments regarding the operability and periodic testing of ECC and emergency boration systems. Also, since the impact of the proposed Technical Specifications will be considerec by the staff in deter-mining the acceptability of the proposed overpressure mitigating system, you should provioe a thorough evaluation of the effect of these maintenance and testing requirements on the susceptibility of the reactor coolant system to a pressure transient.
You should provide the above recuested information and the proposed Technical Specifications within 45 days of receipt of this letter.
Sincerely.
I.ty f :.'.;:gy Robert W. Reid, Chief Operating Reactors Branch #4 Division of Operating Reactors cc: See next page
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NRC PORM 318 (9-76) NRCLI O240 W ta s.oovumiusar biifwimai o.ricas iets-eos.es3
Metropolitan Edison Company cc:
G. 7. Trowbridge, Esquire 5
Shaw, Pittman, Potts & Trowbridge 1800 M Street, N. W.
Washington, D. C.
20036 GPU Service Corporation Richard W. Heward, Project Manager Mr. T. Gary Broughton, Safety and Licensing !!anager 260 Cherry Hill Road Parsippany, New Jersey 07054 Pennsylvania Electric Company Mr. R. W. Conrad Vice President, Generation 1001 Broad Street Johnstown, Pennsylvania 15907 Mr. Weldon B. Arehart, Chairman Board of Supervisors of Londonderry Township RFD#1, Geyers Church Road Middletown, Pennsylvania 17057 Miss Mary V. Southard, Chairman Citizens for a Safe Environment P. 0."B'ox 405 Harrisburg, Pennsylvania 17108 Government Publications Section State Library of Pennsylvania Box 1601 (Education Building)
Harrisburg, Pennsylvania 17126 I
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