ML20058C295
| ML20058C295 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 11/19/1993 |
| From: | Simpkin T COMMONWEALTH EDISON CO. |
| To: | Murley T Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20058C297 | List: |
| References | |
| NUDOCS 9312020411 | |
| Download: ML20058C295 (7) | |
Text
'9 24.
b,)s Commonwsalth Edison
(\\ ZA 1400 Opus Place -
7 Downers Grove, tihnois 60515 V
November 19, 1993 Dr Thomas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 Attn:
Document Control Desk
Subject:
Zion Station Units 1 and 2 Application for Amendment to Facility Operating License DPR-39 and DPR-48 NRC Docket Nos. 50-295 and 304
Dear Dr. Murley:
Pursuant to 10 CFR 50.90, Commonwealth Edison (CECO) proposes to amend Appendix A, Technica1 Specification of Facility Operating License DPR-39 and DPR-48.
The proposed amer.dment revises specification 3.3.2.G and its associated bases, which address the requirements for low temperature overpressure protection of the reactor vessel.
P A detailed description of the proposed change is' presented in Attachment A.
The revised Technical Specificatioi pages are contained in Attachment B.
The proposed change has been reviewed and approved by both 1
on-site and off-site review in accordance with CECO procedures.
Ceco has reviewed this proposed amendment in accordance with 10 CFR 50.92(c) and has determined that no significant hazards consideration exists.
This evaluation is documented in Attachment C.
An Environmental Assessment has been completted and is contained in Attachment D.
Attachment E describes the methodology utilized in establishing the required setpoint for the power operated relief valves.
"ECo is notifying the State of Illinois of our application for this amendment by transmitting a copy of this letter and its attachments to the designated State Official.
v. i :n v m s:1 9312O20411 931119 PDR ADOCK 05000295 P
PDR gooi
'I R
A.
Dr. Thomas E. Murley November 19, 1993 To the best of my knowledge and belief the statements contained herein are true and correct.
In some respects, these_
statements are not based on my personal knowledge but upon information received from other Commonwealth Edison and contractor employees.
Such information has been reviewed in accordance with Company practice and I believe it to be reliable.
Please direct any questions regarding this matter to this office.
Sincerely, M
T.W.
Simpkin Muclear Licensing Administrator Attachments cc:
C.Y.
Shiraki, Project Manager - NRR J.D.
Smith, Senior Resident Inspector - Braidwood Document Control Desk - URR Region III Office Office of Nuclear Facility Safety - IDNS f.
"d AM amm
.,-s m--
3 ' ' tu
'e f
m n" tot 4G <
'j t,ti AP '
,u
[;{
'l y 'g,_..
j.
d u m3.m r. w:.
i
ua t
i ATTACHMENT A ZION NUCLEAR GENERATING STATION i
DESCRIPTION AND SAFETY ANALYSIS FOR PROPOSED CHANGES TO APPENDIX A TECHNICAL SPECIFICATIONS FACILITY OPERATING LICENSES DPR-39 AND DPR-48 LICENSE AMENDMENT REQUEST 93-12 LOW TEMPERATURE OVERPRESSURE PROTECTION SETPOINT CHANGE t
i 4
s t
t
- k. ; / )):3*'L C T} '. W} Ji 2
4 i
1 DESCRIPTION OF PROPOSED CHANGE This License Amendment Request (LAR) proposes to change the Low Temperature Overpressure Protection (LTOP) setpoint (Technical i
Specification 3.3.2.G.l.a) from 435 psig to less than or equal to
~
414 psig. The setpoint change will also be reflected in the Bases section for Specification 3.3.2. Proposed changes-to the Technical Specifications are noted in the annotated copy of the Technical Specifications in Attachment B.
CURRENT REQUIREMENT AND BASES Specification 3 3.2.G.l.a currently specifies that "Two power operated relief valves (PORVs) with a lift setting of 435 psig i
shall be OPERABLE."
This specification is applicable in MODE 4 (Hot Shutdown with Tavg 13 50" F ) when the temperature of any Reactor Coolant System (RCS)
Cold Leg is less than or equal to 250* F, MODE 5 (Cold Shutdown),
and MODE 6 (Refueling) when the reactor vessel head is on.
Administrative 1y, Zion Station enables the LTOP system prior to the RCS temperature decreasing to less than or equal to 320*.
i The LTOP Specification is based on the need to control RCS i
pressure at low temperatures so that the integrity of the reactor j
coolant pressure boundary is not compromised by violating the pressure and temperature limits of 10CFR50, Appendix G.
There are three means of protecting the RCS from l
overpressurization by a pressure transient at low temperatures.
l The first means of protection is provided by the Power Operated i
Relief Valves (PORVs) with an automatic lift setting that is conservative with-respect to the low temperature overpressure transient analysis. A single PORV will relieve a pressure transient caused by 1) a mass addition into a solid RCS from a i
charging pump or 2) a heat input based on a reactor coolant pump j
(RCP) being started in an idle RCS and circulating water into a j
steam generator whose temperature is 50 F greater than the RCS temperature. The second means of protection is provided by opening one PORV and deactivating its associated block valve in the open 1
position. This method of protection will provide the same l
relieving capabilities as the first. The third means of protection
=!
is provided by limiting pressurizer level to 25% and pressure to
.l 100 psig. A pressure transient caused by the inadvertent mass-l addition from a charging pump running for 10 minutes will be relieved by the large gas volume.and low pressure present in the pressurizer using this method.
l k
k r il::de u n y. mt t 4 l
i i
f i
=.
l The lift setting'of 435 psig current]y given in Specification
'I 3.3.2.G was established in Technical Specification Amendment 54/51
-l which became effective on Aprill28, 1980. The setpoint was determined by Westinghouse using the LOFTRAN code. The analysis performed for that license amendment submittal determined the predicted pressure overshoot given a conservatively assumed PORV i
opening time, mass input, Steam Generator heat-transfer surface
~!
area, and RCS volume. The PORV setpoint was then-reduced by the j
amount of overshoot to ensure that the maximum peak RCS pressure i
did not exceed the Appendix G limit.-The 435 psig setpoint was determined to be conservative for the mass addition and heat input transient.
NEED FOR AMENDING THE REQUIREMENT
i On January 13, 1993, Zion Station was notified by the Commonwealth Edison Nuclear Engineering Department that the LTOP analysis'for i
Zion Station did not account for the correction factors necessary when RCPs or Residual Heat Removal (RHR) pumps are in operation.
l On January 15, 1993, a preliminary operability assessment was completed which concluded that the pump correction factors could-i not be accommodated within the current Technical Specification 4
setpoint of 435 psig without imposing significant restrictions on RCP operation.
i Options were reviewed to increase RCS temperature to a temperature sufficient to allow for the operation of one or two RCPs during RCS venting and heatup operations with the~ current 435 psig setpoint. On January 26, 1993,.after reviewing the means available to raise and maintain RCS temperature, it was concluded that RHd pump heat and reactor decay heat were inadequate. At that time it I
was concluded that relief from the existing Technical Specification setpoint would be necessary to allow heat up from refueling outage Z2R12 utilizing the RCPs.
j On January 28, 1993, a Temporary Waiver of Compliance (TWOC) for the LTOP setpoint in Technical Specifications was approved by NRR,
{
allowing a lower LTOP setpoint for Unit 2. That TWOC expired.on February 22, 1993.
j t
With the TWOC request, Zion Station committed to develop and submit a Technical Specification amendment revising the LTOP requirements.
l License Amendment Request (LAR) 92-03 Revision 1 was submitted which included relocating the LTOP and Pressure & Temperature limitations to the Pressure and Temperature Limits Report (PTLR).
l In October of 1993, the Zion Nuclear Licensing Administrator (NLA) was informed by the NRC that.LAR 92-03 would likely not be approved I
within the timeframe necessary to support startup from the Dual Unit Outage. As a result, this LAR has been prepared which proposes
= to revise only the LTOP setpoint requirement. LAR 92-03 continues.
to be an active license amendment submittal.
k 1 mdar ry wM /'
s i
w e
3 w
r.
PROPOSED REQUIREMENT AND BASES It is requested that PORV actuation setpoints for LTOP in Specification 3.3.2.G.1.a be revised to specify "Two power operated relief valves (PORVs) with a lift setting of 1414 psig shall be OPERABLE..." The proposed changes to Specification 3.2.2.G.1.a and Bases 3.2.2.G and 4.2.2.G are illustrated in the marked up copy of the affected pages of the current Technical Specifications (Attachment B).
The LTOP Specification is based on the need to control RCS pressure at low temperatures so that the integrity of the reactor coolant pressure boundary is not compromised by violating the pressure and temperature limits of 10CFR50, Appendix G. The Pressurizer PORVs are utilized in overpressure event mitigation.
The PORVs respond to fixed pressure setpoints.
The low pressure setpoint of concern is derived from analyses which assume several limiting conditions (i.e.,
RCS temperature, PORV stroke time, system response characteristics, etc.).
The pressure sensors providing input to the LTOP System sense RCS pressure from taps located on the Loop "C" RCS Hot Leg (PT-405) and on the suction piping to the RHR pumps which is connected to the "A" Hot Leg piping (PT-403). The critical weld used in the LTOP System analysis is located in the vessel beltline region (RCS downcomer). Due to the location of the pressure sensing taps relative to the critical weld, a pressure correction factor must be applied to the LTOP setpoints whenever RCPs or RHR pumps are in operation. Based on operational data at Zion and typical four loop' Westinghouse PWR values, these correction factors range from approximately 5 to 50 psig, depuiding on operational pump combination. The current LTOP setpoint specification does not account for these correction factors.
The proposed amendment replaces the fixed setpoint value with a L414 psig limitation, thereby allowing LTOP setpoints to be set at values lower, and more conservative, than currently al'1 owed.
The requested amendment adopts the approach utilized in the Westinghouse Standardized Technical Specifications, NUREG-0452, Revision 4. This approach allows the flexibility to set the LTOP setrcints to any value which is less than or equal-to the value that was assumed in'the LTOP analyses. This approach recognizes that the safety function is to provide relief capability at a pressure which does not exceed the analytical basis for the'LTOP system. It is-not necessary to specify a minimum LTOP setpoint in order to ensure LTOP operability.
i k : /12 dem r p,w; f it 1
The 414 psig setpoint value was determined to be the maximum setpoint that would, when combined with the correction factors, prevent the RCS from exceeding the Appendix G limits during an overpressure transient at low tamperatures. This value was determined using the methodology described in Attachment E of this submittal. The basis for the 414 psig limitation also includes the following:
1)
The plant-is operated up to 15 EFPY 2)
PORV ftroke time is s3.4 seconds There are certain conditions which will necessitate a reanalysis of i
the L70P setpoints. These conditions are described in Attachment E.
1 Should reanalysis be required, the rathodology presented in 1
Attachment E will be' used to detenu. de the new setpoint. Revised l
setpoints will be evaluated in accordance with 10CFR50.59 to ensure that'any reduction in the setpoint is consistent with system
)
operating parameters (i.e. will not result in spurious PORV actuation, will not have adverse impact on RCP seal operation, l
etc). The LTOP setpoints will be set accordingly as a result of any l
reanalysis but will, in no case, exceed the 1414 psig requirement without approval of a separate license amendment submittal.
SCHEDULE REQUIREMENTS It is requested that this amendment be issued by February 1, 1994 to support startup from the Dual Unit Outage.
u n ween:.nt n
_