ML17202G580
| ML17202G580 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 08/10/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17202G578 | List: |
| References | |
| NUDOCS 8908250253 | |
| Download: ML17202G580 (6) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON. 0. C. 20555 SAFETY [VALUATION BY THE OFFICE OF ~UCLEAR REACTOR REGULATION RELATI~G TO PROPOSED LICENSE AMENDMENT TO REVISE TESTING REQUIREMENTS
.OF THE EMtRGENCY CORE COOLING SYSTEM (ECCS} AND STANDBY GAS TREATMENT SYSTEMS (SGTS)
COMMONWEALTH EDISON COMPANY DRESDEN NUCLEAR POWER STATION, UNIT NOS. 2 AND 3 DOCKET NOS. 50-237 AND 50-249
1.0 INTRODUCTION
By letter dated Dece~ber 21, 192£, Commonwealth Edison Company (CECc} proposed to amend Appendix A of Provisional Operating License (POL) No. DPR-19 for Dresde~
Cr it 2 and Facility Operating License No. DPR-25 for Dresden Unit 3 to: revise the testing requirements for other systems or subsystems of the Emergency Core Cooling System (ECCS) or Standby Gas Treatment Systems (SGTS) when one system or subsyste:r.is is inoptrable; revise the operability requirements of several ECCS s;*ster.;s; and incorporate svrr.e administrative changes.
By letter dated May 4, 1989, CECo pr0vided supplemental informatio11 to support the proposed amendment and inciu~ed two additional changes.
These proposed changes wh;ch are part of the Dresden Station i~provement pro5ram action plan, are consistent with similar technical specifications approved for more recently licensed BWRs and the BWR Standard Technical Specifications.
- 2. C EVAL UATI O~
A.
Multipl~ Testing of ECCS and SBGT Systems Present Dresden Units 2 and 3 Technical Specification Surveillance Requirements for ECCS and SBGT provide for demonstrating the operabil;ty cf redundant systems or subsysttms when one system or subsystem is inoperable. These requirements are as feillows:
(1)
One Core Spray subsystem inoperable-demonstrate operability inrnediately of the operable core spray subsystem and the LPCI subsystem. Demonstrate daily thereafter operability of the operable core spray subsystem.
(2)
One LPCI inoperable-demonstrate operability immediately of the remaining LPCI subsystem, containment cooling subsystem, and both core spray subsystem. Demcnstrate daily the operability of the operable LPCI pumps.
(3)
Tht LPCI subsystem is inoperable-demonstrate operability im111ediately arid daily thereafter.of both core spray subsystems and the containrr~nt cooling subsystem.
890~250253 890810 PDR ADOCK 05000237 ii p
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- 2
'L' GnE co~t~inrnent cooling subsyst~m service ~ater pump is inoperable-cernonstrcte operability immedictely and daily thereafter the remaining componer.ts uf that subsystem and the other containment cooling subsystem.
(~i Or1£: contair.men.t_ cooling subsystem is inoperable-demonstrate operability immf;ciiately and cc.ily thereafter of the opera-ble containment cooling subsystem.
( f; The HPCI subsystem is inoptrab le-demonstrate oi:.ierabil i ty irrarediate 1.>* of tht LPCI subsystem, both core spray subsystems, the automatic pressure re1ief subsystem and the. motor operated isolation valves and shell side n~~e-up system fer the isolation condenser. Demonstrate operability daily cf the motor operated isolation valves and shell side make-up systeri of the isolation condenser. Daily demonstration of the operability of the*automatic pressure relief subsystem may *be required derer1oing on p"iar.t power leve: l and the number of operating feedwater
- pumps.
(ij Gnt: of the five relief valves of the automatic pressure relief subsystem
- s
~noperable-demonstrate the operability immediately and weekly thered~ter of the HPCI subsyste~.
(B)
More thbn one relief valve of the ~utomatic pressure relief subsystem is i noperab lt:-dernor.s trate opercb i1 i ty immr:cli ate ly of the HPCI subsystem.
( S; The i soi at ion condenser sys tern is il'loperab 1 e-ciemons t ru te operab i1 i ty ir.11;ediateiy and daily thereafter o7 the HPCI subsystem.
(10) The ur.it or shared ciiesel generator is inoperable-demonstrate eiperability irimediate1y and dail} thereafter cf all low pressure core cooling, tht:
containn~~t cooling subsystems, and the operdble diesel generator.
(lli Or.c SBGT sub~ystem is inoperable-demcristrate operability \\o!ithin 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> aric.l cia i ly thereafter of the operable SBGT subsystem.
The purpose vf this proposed dmendment change is to remove the redundant system t~sting requirements from the ECCS and SGTS sections of the Technical Spec.:ifications (Sections 4.5 and 4.7) while maintaining adequate assurance of system operability needed for accident mitigation.
The requirement for demonstrating operability of the redundant systems identified above for Dresden Units 2 and 3 was originally chosen because there was a lack of plant operating history and a lack of sufficient equipment failure data. Since that time, plant operating experience has demonstrated that ttsting of the redundant ECCS and SGTS when one system is inoperable is not necessary to provide adequate assurance of system operability. In fact, taking the redundont system out of service for testing creates the risk of the secor.d system also failins and in some instances it has been observed that failures o* th~ redur.dant systerr: arc related to the test itself and not an.
__ /
- incication that the system would have failed should it have been needed.
Operability of these' systems can be shown by checking reccrds to verify that valve lineups. ~lectrical lineups and instrumentation requirements have not been cha11ged s i nee the last time the system was verified to be operable.
The current Standard Technical Specifications (STS) and more specifically all the technical specifications approved for recently licensed BWR's accept the philosophy of systerr. operability based on satisfactory performance of monthly, quarterly, refueling interval, post maintenance or other specified performance tests without requiring additional testing when another system is inoperable (except for diesel generator testing). The staff reviewed CECo's December 21, 1988 submittal and requested additional information primerily to confirm that the testing requirements for the redundant systems or subsystems contained in the existing Technical Specifications, as modified by the proposed amendments, were tcnsistent with the requir~ments contained in the Standard Technical Specifications.
In Att~chment 2 to CECo's May 4, 1989 submittal, a comparison betwetn the Dresden Technical Specifications and the Standard Technical Specifications was pr0vided.
The staff has reviewed this submittal and cetermin~c the proposed Technical Specifications for Dresden are consistent with the Standard Technical Specifications and those of recently licensed BWR's with regard to the testing requirements for redundant syste_ms.
On this basis, the fact that testing of the redundant system creates the risk of the st,ond syste~ failing and past operational experience, the staff has deter~ined that the revised testing reouirements for the ECCS and SGTS syste~s and subsystems are acceptable.
In additiu~, other cha~9es to Section 3.5 of the Technical Specifications have bee~ proposed which are admir1istrative i~ nature. Since these changes either clarify present requirements or promote consistency in location of requirements within the Technical Specifications (i.e. relocating all diesel generator 0~~rdbility reauirements in one section of the Ttchnical Specifications), the staff finds the8 acceptable.
During the review, o need to revise a footnote in Table 4.5.1, which waived the applicability of Specification 4.0.D and would have permitted the plant to enter into the Startup/Hot Standby Mode provided the required surveillances were successfully completed with 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> after reactor steam pressure is adequate to perform the test, was identified by the staff. The wording of the footnote presumed prior approval of Section 4.0.D which is also part of the Dresden Technical Specification improvement program but has not yet been submitted.
CECo's ~ioy 4, 1989 submittal eliminated any reference to Section 4.0.0 and included an additional footnote pertair1inQ to entry into the Run Mode which is the same as that required for entry into the Startup/Hot Standby Mode.
However, to assure that reactor operation does not continue during startup when the HPCI system testing requirements contained in Table 4.5.1 -cannot be met, a proposed action statement 3.5.C.2.b has been added.
The staff recognizes that some systems cannot be tested until the plant operational mode has been entered and therefore an exception to the normal Technical Specification survei*llance requirements is needed for a limited tim~
to permit the testing. These types of exceptions have been granted in the past and the staff finds them acceptable.
B.
HF'C Operability Requirements Thf:
~resent Technical Specification Sections 3.5.C/4.5.C require the HPCI sub~ystems to bt cperable whenever the reactor pressure is grEater than 90 psig. lf the HPCI is inoperable and cannot be restored within the time limits of Stction 3.5.C, then the plant must be shut down and reactor pressure reduced to 90 psig.
However, this present LCO requirement of 90 psig for operability cf liPCI is net based on HPCI subsystem design or testing requirements.
The present Surveilla~ce Requirement in Section 4.5.C.1 requires HPCI subsystem testing to demor:strate that HPCI can deliver at.least 5000 gpm against a system head corresponding to a reactor vessel pressure of 1150 to 150 psig. Sir1ce the HPCI system is designed to pump 5600 gpm into the reactor vessel within a reactor pres$ure range of about 1120 psig to 150 psig, the operability of the 1-!PCI syster.: cannot be tested at 90 psig in accordar.ce with the current Technical Specific;e:.t icn requirer11f:rits (at prE:Bures be lo~ 150 psig it is estimated that the flow decreases lir*e-c..rly to zero at 50 psig).
In addition, one of the: HPCl a~to~atic isc1ation sigr.als is low steam line pressure (less than 100 psig).
Since the HPCI system is isolated below a steam line pressure 100 p~ig, the presH.t LCD require1T1ent of 90 psig for operability is impractice.1.
CECo has proposec. changing the. liPCI operatility requirement to 150 psig to support syste~ d~sign flow a~o pressure r~quirements of Sectio~ 4.5.C.1 of the Techriical Specifications and to provide an adequatt rnarg1n to the present setpC;int for syste:m automatic isolation on low steam line pressure.
The staff has rEviweo this proposed chonye and determined it is acceptable since it corrects inconsistencies in the curr~nt Technical Specifications related to HPCI operability requirements and does not result ir. a decrease ir. safety.
CECo h~~ also proposed to change the Surveillance Requirements in Section 4.5.C.l to include thf: HPCI testing requirements (Tab1c 4.5.1) rather than provide a reference tc these requfrements in the Core Sproy and LPCI subsystem testing (Secticn 4.5.h.l).
To be consistent with the standard Technical Specifications and curri:nt BWR industry practite, CECo has added a secur:ci low reactor steam
~ressure f 10~1 rate test to the HPCJ pump flow rate testing. This seconc ttst requirement is also idHtified in Table 4.5.1. A test is performed every 3 months to demonstrate HPCI operability when steam is being supplied tu the turbine at rated reactor pressure. The aC:d£d second low pressure test is perform~d appreiximately every 18 months to demonstrate ECt.S design flow when steam is being supplied to the turbine at low pressure~ This proposed low pressure test will be run at a pump C:ischarg~ pressure of 50 psig over reactor pressure when steam is being supplied to the turbi11e at 300 psig. The 350 psig upper allowable limit for testing was selected to conform with the approximate reactor pressure ~orresponding to the shutoff head of the low pressure coolant injection pump.
The staff has reviewed these proposed changes and determined that both.the administrative changes and the additional lcw pressure HPCI operability test are improve~ents over the existing Technical Specificatio~s and are, therefor~,
acceptable.
C.
- ..utomatic Pressure Rtiief and Jsr.~ation Condenser Operability Requirements 1he present Technical Specificdion Sectior1s 3.5.D (Automatic Pressure.Relit:f) ar.d 3.5.E (Isolation Condenser) re~uire their respective systems to be operable whenever the reactor pressure is greater than 90 psig.
CECo has proposed a Ttchnica1 Specification change that would not require the Automatic Pressure Relief and the Isolation Condenser to be operable until the reactor pressure is greater than 150 psig. These changes have been proposed to preserve the consistency between the Technical Specifications for the HPCI, Automatic Depressurization System and the Isolation Condenser. Although the operability requirement is being increased from 90 to 150 psig, sufficient overlap with the low pressure systems tv assure adequate core cooling will still be pro~ided since the injection ir.terlock for the low pressure systems is set bet\\-Jeen 300 to 350 psig.
On this basis and to provide consistency between the operability requirements for tltt::se systems, the staff has c:c.ncluded the proposE:id ct'langes
- ere acceptal1e.
D.
StandbJ' Gas Trea tmHt System ( SCTS)
The proposed chdnges to thE: SGTS Section of the Technical Specifications (Sections 2.7.B and 4.7.B) in adcition to the elimination of the testili9 0of the reaur.dant trair, disc.ussec ir; Secticr f... cf this Saftty Evaluatiori are:
replacing the wurd "circuits" with the wurd 11 subsysterr.s; 11 deletion of OLtdated requirements for special tests in Section 4.7.8.4; and changing the test frequtnc.y for performing Surveillance Requirements 4.7.B.2a and 4.7.B.2.b.
lhf first t~o proposed ch&nges dre administrative in nature and are acceptable.
The word ch~r.ge is editorial. The s~ecial tests are no longer require:c: because the equipr.ient modifications needed to allow verification uf the system periormd.nce requirements are complE-te.
The frequency of perforrr.ing Survei l lanc.e require:r:ients is presen
- stated as 11or.ce per operating cycle but not to exceed 18 mor.ths.
11 The not to xceed lB months requirement excludes al lo"'*ances for use of tht: allowable st:::11dard accepted interval exterisions permitted for other systems in the Technical Specifications (Definition CC).
The proposed change would use the Terminc;,logy 11or every 18 months whichever occurs first" which wuuld permit the use of these interval extensions. The staff has reviewed this proposed chd.nge and, si* ct:: it is consistent with current standard acceptable practices, finds it acceptable.
E.
Secondary Containment Integrity Requirements The proposed changes to Techr,ical Specification Section 3.7.C on Secondary Ccntainment integrity are:
inclusion of a time frame for restoration of Secondary Containr1ient Integrity; clarification of Definition Z on Secondary Containment Integrity; elimir.ation of completed preoperational and first cycle ope-rating tests and a one-time exemption which was used in 1979; and the relocation of core spray and LPCI suLsystem operational requirements to Specification 3.5.A.
The first proposed change will allow 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to restore Secondary Contair.ment integrity ard, if not restored, an orderly shutdown is required to at 1£a~t hot
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L.; ')r'_j,w;.
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- 6 shutciow-r. \\llithin the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and to cold shutdown within the follo\\'ling 24 hrurs.
The staff has determined that these times are consistent with these of othtr operatins n~clear plants including those that have been recently licensed and that operating experienc~ hes demonstr~ted these times support safe opE:ration.
The prof>osec orderly reactor shutdown is also consistent with the requirements of pres~nt Specification 3.0.A.
The staff therefort finds this proposed change acceptable. The remair.ing three changes are administrative in nature and are acceptable.
F.
Additional Proposed Changes in Supplemental Submittal In CECo's May 4, 1989 submittal, two additional changes were proposed.
One change, related to the Containn1ent Coolir1~ Service \\.:ater {CCSW) system, would add a surveillance requirement to verify that each mam;al, power operated or automatic valve in the flow path that is riot locked, *sealed or otherwise s~cure mu~t be verified to be in its correct positiori. Since this propos~d change is tht: san1e as one cf the requirt:ments to demonstrate operabi lit) cf the ECCS ccr.tained in the STS and is a safety enhancement, the staff fir1ds this acceptable.
The second change, which is purely adrr.ir1istrati\\'e: adds the words "r,ot usec" next to Section 3/4.5.G and is acceptable.
3.0 ENVIRONME!aAL CONS1DER.A.TION These amendments ir.volve changes to surveiilance and operabilit.)' requirements for ECCS equipme:r1t located \\a1itt1in the restricted area as defined in 10 CFR Part 2C.
The staff hes determineo that the amendments involve nc significant increase ;,~ the amount~, and no significant 'hange 1n the types, of any tff luents thet may be released offsite and that there is no sigrificant increase in individual or cumulative occupation~l radiation exposure.
The Commission has pr~viously issued a propost:d finding that these ameudments involve no significant hazards consideratio~ a~d ther~ has been no public comment on such finding.
~ccordingly, these amendments 1:1et-t the eligibility criteria for categorical exclusion set forth in 10 CFR Part 51.22(c)(9).
Pursuant to 10 CFR Part s:.22(b) no environmental impact statement nor environmental assessment rited be prepared in connection with the i~suance of these amendments.
4.0 CONCLUSION
" The staff has concluded, based on the considerations discussed above, that: (1) there is r~asonablc assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) suet. activities will be conducted in compliance with the Cornn1ssion's regulations and the issuance of these amendments w111 not be inimical to the common defense and security nor to the health and safety of the public.
Principal Contributor:
Byron L. Siegel Dated: August 10, 1989
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