ML20085G505
| ML20085G505 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 06/15/1995 |
| From: | Dennis Morey SOUTHERN NUCLEAR OPERATING CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9506200238 | |
| Download: ML20085G505 (7) | |
Text
.
...,,z,,,,,
g i
Southem Nucliar Operating Company.
.i-t.
Post Offics Box 1295 -
d
" Birmingham. Alabama 35201 2
Telephone (205) 868 5131 g
Southern Nudear Operating Company o...
,.y Vee President Farley Project
-June 15, 1995 the southem electnc system 9y W
Docket Nos:
50-348 g
50-364
{
Nuclear Regulatory Commission 2
ATEN: D=* Control Desk i
Wrslungton, DC 20555 Joseph M. Farley Nuclear Plant Techmcal Specifications Change Request Elimination of Periodic Pressure Seamar Famaaa-Time Teatin_o Reauirements
{
r, Ladies and Gentlemen-
?
By letter dated August 17,1994, Southern Nuclear Operating Company (SNC) proposed changs to the Farley Unit I and Unit 2 Technical Specifications to eliminate periodic pressure sensor response time testmg requirements. NRC letter dated April 17,1995 requested additional information pertammg to the proposed changes.' 'Ihe requested information is attached Should 3
you have any further questions, please advise.
j A
Respectfully submitted, i
h 7?l f
1N's f
Dave Morey j
MGE:maf RTITTSS4. DOC SWORN TO AND SUBSCRIBED BEFORE ME h[
Attachmeat F
%q THIS /
DAY OF A4M.)
,1995 cc:
Mr. S. D. Ebneter d
a 87xr- '
Mr. Bj L., Siegel Notary Pdflic 7
Mr. T. M. Ross 2
My Commission Expires:
87Mt
/.
h f
(
st h
4$'I$
w 2:
I 3
w 9506200238 950615 PDR ADOCK 05000348 i-P.
PDR j
?
i F. J'
. Q ?}
_.8' }:' ;r }.} ' -[. ?[J } J_ ; 7 y ;. _..[ L '. j." _'.;';.._. y [ j,+_. f.[.Q :l-[ iyy y ( j a j;:( % ?
(
3
+
ATTACHMENT Joseph M. Farley Nuclear Plant Technical Specifications Change Request Elimmation of Periodic R essure Sensor Response Time Testing Requirements NRC Ouestion No. I Section 4 of EPRI Report NP-7243, Revision 1, " Investigation of Response Time Testmg Requiremets," provides the followmg four reco.....cadations when climinating pressure or differential sensor response time testing (RTT):
Perform a hydraulic RTT prior to installation of a new transmitter / switch or following refurbishment of the transmitter / switch to deternune an initial sensor-specific response time value.
For transmitters and switches that use capillary tubes, RTF should be performed aAer initial
%"-4n and aAer any maintenance or modification activity that could damage the capillary tubes.
Perform periodic driR monitormg on all Rosemount pressure and differential pressure transmitters in accordance with the guidelines in Rosemount Technical Bulletins and NRC Bulletin 90-01, Supplement 1.
If vanable damping is used, implement a method to assure that the potentiometer is at the required setting and cannot be inadvertently changed. Otherwise, perform RTT on the transmitter by hydraulic or electronic white noise analysis methods, at a minimum, following each transmitter calibration Please discuss how each of these recommeMations will be implemented since you propose to climinate sensor RTT. How will this be documented?
SNC P~ana-to On~*ina No.1 Consistent with the proposed Technical Specifications changes (Bases 3/4.3.1 and 3/4.3.2) and EPRI Report NP-7243, Revision 1, and as stated in our previous submittal, the applicable plant surveillance test procedures will include revisions which stipulate that pressure sensor response times must be verified by performance of an appropriate response time test (RTT) prior to placing a sensor in operational service and re-verified following maintenance that may adversely affect sensor response time. In addition, the plant procedure revisions (and/or other appropriate administrative controls) will stipulate that pressure sensors (transmitters and switches) utilizing capillary tubes, e.g., containment pressure, must be subjected to RTT aAer initial installation and following any maintenance or modification activity which could damage the transmitter spillary tubes. When sensor RTT is requimd, the resultant pressure sensor response times will be documented in the plant procedure data P' sages.
i a
(
l
' Attachment Page 2 Farley Nuclear Plant (FNP) has no Rosemount passure transmitters installed in any Reactor Trip System (RTS) or Engineering Safety Featun Actuation System (ESFAS) application for which RTT is required; therefore, no FNP procedure changes ar; presently required. However, Westinghouse Owners Group (WOG) plants that utilize Rnemaunt prr sure type transmitters in such applications should continue to perform enhancaA testirg and/or trendmg consistent with their specific commitments to NRC Bulletin 90-01. Should Farley ch ct to install Resemont transmitters in an RTS or ESFAS applicaten which requires periodic RTT it. the future, tMn FNP will pertbnn anhancaA esting and/or t
trendmg consistent with our specific comndtments to tie bulletin.
FNP has no p'ressure transmitters with variable dampingiinstalled ir any RTS or ESFAS application,
for which RTT is required; therefore, no FNP procedure changes or enhanced admmistrative controls are required. For WOG plants using pressvre transmitters equipped with variable damping capability-in RTS or ESFAS applications which require periodic RTT, each plant must provide their own specific response for admmistrative controls to ast,ure the variable damping potentiometer cannot be inadvertently changed. Examples of s= ch admmistrative controls may include use of pressure transmitters that are factory set and hermetically sealed to prohibit tampering or in situ application of a tamper seal (or sealant) on the potentiometer to secure and give a visual indication of the potentiometer
(
position.
NRC Ouestion No. 2 The failure modes and effects analysis (FMEA) resuks contamed in EPRI Report NP-7243 identified the slow loss of fill fluid in Statham and Foxbor.s N-E13 transmitters as a potential failure mode that
\\
could affect response time in a manner that iray or may not result in a detectable, on-line signal error.
Although this failure mechanism has not been observed in these transmitters, EPRI recomnerxled to continue to perform RTF for these transmitters until criteria are developed relating sensor output to loss of fill fluid and potential response time degradation. What criteria will be developed in order to support the elimination of RTF for these transmitters?
SNC Resoonse to Ouestion No. 2 Revision 1 of EPRI Report NP-7243 noted that the only transmitters which experienced a slow loss of
- fill fluid a.e Rosemount pressure transmitters. The revised EPRI report continues to recommend response time testing of these transmitters.
'Ihe Foxboro manufacturer (Weed Instrument Company) noted that failures of this type have not been reported and that the Foxboro N-El1 and N-E13 series of pressure transmitters have no credible failure mode related to a loss of fill fluid. In the unlikely event of a slow loss of fill fluid, this occurrence would be detected by methods other than response time testing, e.g., periodic calibration.
Therefore, Weed requested that Revision 0 of the EPRI report be amended to indicate response testing of the N-El1 and N-E13 transmitters is not required. (Reference 20 of NP-7243, Rev.1)
Statham transmitters have not experienced slow loss of fill oil failures, and the manufactu rer indicates that the Gulton-Statham design precludes the possibility of oil loss by a method similar to the Rosemount fLilure. However, since no Statham transmitters were identified as being installed in any Westinghouse plant in an RTS or ESFAS application which requires periodic RTT, no Statham transmitters were included within the scope of this WOG Program, as docunented in WCAP-13787, Revision 1, Table 9-1, and revisions to the EPRI report were not pursued.
i Attachment Page 3 NRC Ouestion No. 3
'Ihe FMEA results contamed in EPRI Report NP-7243 identified fill fluid leakage to the atmosphere in the Tobar 32DPI differential pressure transmitter as a potential failure mode that could affect sensor response time. What criteria will be developed in order to support the clinunation of RTT for the Tobar 32DPI and the other similar differential pressure transmitters (Tobar 32DP2 and Veritrak 76DPI)? Does the manufacturer assert that other surveillance tests ensure correct function and verify -
response times and, consequently, support the elimmation of RTT for these transmitters?
SNC Ra<nanme to Ouestion No. 3 As requested by the Tobar manufacturer (Camille Bauer) the racM* ion to periodically test i
Tobar transmitters was deleted from the original version of EPRI Report NP-7243 to correct an error j
in the report 'Ihe FMEA for Tobar 32DPI did not show any failures that could degrade the response time and not be detected by other testing. Furthermore, the transmitter manufacturer indicated that Tobar transmitters do not have failure modes which would effect response time but not be detectable by other means EPRI concurred with the manufacturer and revised the report as shown in Revision 1.
(Reference 19 of NP-7243, Rev.1)
With regard to the Tobar 32DP2 and Veritrak 76DPI transmitters, the results of the similarity analyses, evaluations, and testing documented in Sections 5.8 and 5.9 of WCAP-13632, Revision 1, conclude that there exists no significant time response degradation mode that would not also be observed in transmitter operation or calibration. Manufacturers agreed with the FEMA results, which concluded that periodic RTT is not required.
NRC Ouestion No. 4 For those transmitters where the manufacturer recciiwrc.ds periodic RTT as well as calibration to ensure correct function, how will it be ensured that elimmation of RTT is nevertheless acceptable for the particular application involved? Have the manufacturers reviewed and approved the results of all of the similarity analyses and the FMEA performed by Westinghouse as documented in Section 5 of WCAP-13632, Revision 17 SNC Response to Ouestion No. 4 Table 9-1 of WCAP-13632, Revision 1, lists the specific transmitter manufacturers and models included within the scope of WOG Program MUHP-3040. Periodic RTF is not recc.iiiiicr.ded for any of the transmitters listed on Table 9-1. The testing requirements included in WCAP-13632, Revision 1, are consistent with the EPRI Report NP-7243, Revision 1, testing rwi r.cr.dations. The WCAP only expands the applicability of the report to additional transmitter manufacturers and models. Where the EPRI report recommends continued response time testing or other tracking techniques, Westinghouse presently also recc.;;.r.cr.ds periodic testing or other tracking techniques.
The Westinghouse similarity analyses documented in WCAP-13632 were reviewed and agreed to by the transmitter manufacturers.
g Anadunent Page_4
\\
NRC Ouestion No. 5 Secten 8 of WCAP-13632, Revision 1, states, in part: "A maximum incredible response time for each reactor trip function was calculated by increasing the sensor, signal = = % "i and logic each by a factor of five and applying'the root mean square method De results showed that the containment pressure measurement response time matches the TS and that for level and flow functions, the lughest response time calculated was 2.4 seconds."
Please give the basis fbr increasing the response time by a factor of five and describe why this increased loop response time is considered incredible. Could longer pressure sensor response times -
- delays, i.e. several==wwls or more, occur, and, if so, what effect would it have on overall loop 3
. response time with respect to the TS limits'and plant safety analysis hauts for each Reactor Trip'.
System (RTS) function and N= ed Safety Features Actuation System (ESFAS) funcien? :
SNC Resnonse to Ouestion No; 5 Although not part of the justificatens for deleting the requirement to perform perxxhc response time testing, the WOG was r-W by the Staff to evaluate the effect of significant degradaten of response time on the ability of the instrument loop to perform its safety kae*M It was stated that -
better estimate assumptons along with judgment could be used to show that margin may still exist when the time response allowance for the loop might be ~w To address this request, the method discussed in Secten 8 of WCAP-13632, Revision 1, was utilized 6-ee Westmghouse and the WOG believed that the documented assessment satisfied the intent of the request. A factor of 6ve was selected to demonstrate safety' analyses sensitivity to arbitrary increases in response time degradation, and it approached the limit of our ability to justify asfety analyses a-a**= criteria using better estimate evaluatens. However, based on the results documented in the EPRI report and the Westeghouse WCAP, it is not anticipated that time moponn degradariani will occur or go nadetectul; therefore, the safety assessment h-*ad in Sectia 8 should not be considered as part'of the WOG
. justifications for deletag periodic pressure sense RTT.
NRC Ouestion No. 6 Appendix B of WCAP-13632, Revision I, states that any sensor failure that significantly degrades response time will be detectable during surveillance testing such as calibration and channel checks What is the nummum sensor response time delay (in seconds) that can be detected by technicians during the perfbrmance of other surveillance tests assuming that sensor output has not been affected?
If any of the subject pressure or differential pressure sensors experienced a response time delay of this magnitude, would the TS limits or plant safety armlysis limits for any RTS function or ESFAS function be exceeded?
i l
(
Attachment Page 5 1
- SNC P-= to Ouestmn No. 6 The statement ccawinir6 delectability of time response degradation during surveillance testing such as calibration and channel checks was not meant to imply that e-N= would actually be required to ~
' observe a time (w change during these tests. T~ ha' i a= can observe gross degradation but not w
changes of the magnitude required to ensure remaining within the plant safety analysis limits'. Instead, it has beeni demonstrated that pressure sensors response time has not been significantly effected by degradariani 6f pressure sensor components or that calibration will detect such changes because the -
degradation also impacts the accuracy of the instrument. 'Ihis findmg is the basic premise of the EPRI study which contends that the reason that time response degradation has not been detected during performance of response time tests is that the degradation also impacts accuracy and, therefore, has already been sa prior to poifvii. ace of pressure sensor response time testing. 'Ihe EPRI conclusion is that the FMEAs indicate R'IT is redundant to other periodic tests. This result was duplicated by the Westmghouse FMEAs. WCAP-13632, Revision 1, will be modified in the -
appropriate areas (e.g., Appendix B and Section 11) to clarify this point.
NRC Ouestion No. 7 Will applicable surveillance testag procedures be reviewed and revised by the licensee as necessary to assure that:
a)
Techmcians monitor for sensor response time degradation during the performance of calibrations and furweim! tests.
~;
1 b)
Calibrations are being performed using equipment designed to provide a stip function or fast ramp in the process variable, thus allowing, with reasonable assuance, the renwiition of significant sensor response time delays?
c)
Calibrations and functional tests are being performed in a manner that allows simultaneous monitoring of both the input and output response of sensors under test in order tc ensure that the calibration effectively verifies sensor response time performance in lieu of specific R'IT.
SNC Resnonse to Ouestion No. 7 This question implies that plants referencing this WOG program will rely on the technician's ability to detect a &,.dsd response time during a calibration. As np'M in the response to Question 6, EPRI Report NP-7243, Revision 1, and WCAP-13632, Revision 1, demonstrate that pressure transmitter response time will not be significantly impacted by degradation af components and/or that degradation will impact the accuracy of the instrument and therefore would be detected during surveillance procedures directed toward accuracy checks, e.g., calibration c r chsinel checks As such, it is not necessary to revise surveillance test procedures to incorporate the three riw....cadations (a - c) described above for Westinghouse plants.-
p[
Attachment Page 6 NRC Ouestion No. 8 Section 9 of WCAP-13632, Revision 1, states that allocated sensor response times to be used in place of sensor response times obtamed through actual measurement may be obtamed from: (1) the most conservative response time value recorded from historical RTT, (2) manufacturer supplied response times (if available), or (3) Westmghouse engmeering specifications response times (if available), with the latter being the most conservative. For those sensors in which historical response times as well as Westmghouse engineering specification and/or manufacturer supplied response times are available, is it rcw.i ic.ded that the licensee use the most conse.tvative of these response time values as the allocated response time value? Ifnot,'pleasejustify.
SNC Resoonse to Ouestion No. 8 Section 9 of WCAP-13632 Revision 1, listed the attematives by which a plant may determine a response time allocation for a given pressure sensor. The Westinghouse specifications for pressure sensors are inherently conservative to envelop many potential suppliers and generic applications. A plant should not be penalized in the overall time allowance if the installed sensor has a significantly shorter response time which can be defended by site testing or vendor data. The intent lere is for each site tojustify the value used and not to be unnecessarily conservative.
RTITSS4. DOC F.
. _ _ _ _ _ _ - _ _ _ - _ _ _ _