ML19263A686
| ML19263A686 | |
| Person / Time | |
|---|---|
| Site: | Seabrook, 05000340 |
| Issue date: | 10/28/1978 |
| From: | YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML19263A685 | List: |
| References | |
| FOIA-79-98, TASK-AS, TASK-BN-79-07, TASK-BN-79-7 BN--79-07, BN-79-7, NUDOCS 7811090150 | |
| Download: ML19263A686 (5) | |
Text
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Repo rt on the Seabrock Station Ref ueling Water S:orage Tark Design Deficiency Prepared by: Tackee Atomic Electric Cocpany for Public Service Ceccar:y of New Ha=pshire Oc:obe r 29. 1973 7sllC ?DI5d
i.
In:::due:ien Cn Septe=be r *,1973 Mr. Seth Folson of the Region 1 cf fice of the NRC was inf or=ed by Mr..*cha Hasei:ine of Yankee A::mic Elec: ic Cc=pany, Manage r, of a design deficiency associa:ed vi:h Seab :ck Station Projec:
the :ef ueling va:e s torage :anks (RVST) a: Seabe:ck S:a: ion. The deficiency was reported u=de: LCC FR50.5 5a(e) and was repceted wi:hin 2 hcurs of
- he deficiency was re;c::ed :o Mr. ?:isce
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conf ir=ation cf the def iciency.
as an unde rs ising of the RWST.
The unde rsiaing was discovered in a routine design review f :he Net ?:si:ive Suc:ica Head (3?Sa) f or :he centainmen: spray and resicual hea: removal 1: also shewed :ha: there The design review verified pt:per 4?SH but pu ps.
did net appear to be suf ficient water inche RNST to c =plete :he ::ansfer su=p bef ore i: was e=p:1ed.
of pucp succions from the tack to the contain=ent This report se rves as.t wri::en repor: unde r the 30 day requiremen:s in 10C?R50.5 5a(e)(3) and is arrar.ged :o provide the inf orma: ion :eques:ed in the regulation.
Descristien of Oeficionev The water s torage capacity of the RWST se rves du, purposes in the One is :o ficod :he cavi:y and canal area abeve :he reactor s:a: ion design.
- o the to refuelings and che other is to supply bora:ed wa:e prio:
acciden:.
contain=ent spray and injection pu=ps during a less of coolan:
deficiency concerns As reported to the II inspector on September 23, tha accide :.
the undersiaing of the RUST's useable volume for a less of eccian:
l The :ank was adequately si:ed for :he !!aoding of the reae:or cavi:y and Canal.
The The :ack capaci:y is dependent upon a ma=ber of paraceters.
major pars =eter is the flooding of the centai: ment during a less of c clas:
accident to a heigh: which will provide sufficient $?SH for :he con:ainmen:
spray and residual hea: removal pu=ps and pr:per coc:ain=en: su=p screen S af e ty s ubme rge nce. The 375,000 gallen design subni::ed in the ?relinica:7 Analysis Repor: (?SAK) =e: this requiremen:. Approxi=ately 350,0CC gallecs of the tank was assumed to be isfec:ed a:d :his voicne did ail:v sufficien:
to meet pu=p NPSH requiremen:s and seress flooding of the containment The deficiency arcse in the abilley of the remaining 15,000 cove rage.
the ether design parameters.
3alices in the ta=k :o meet The ether design parameters are ins::u:nent errer, a working The allevance, ::a nsfer allevance, single f ailure, and unuseable ve'ame.
foll: wing is an explana:ica cf wha: :hese para:eters are and hew : hey were sa:isfied is the original design of the 1957.
sa:isfied or set for :he
- !ncreased velame is :ecessary :o acecca:
err::
iss ::uee nt 1.
- ni: tally accuracy of :ne ins:ranenta: ion readiez :he IWST level.
a ne=1:41 1.; full scale ins:rumen: accuracy 4:::: was as sume d wn i:n
' e :aken :vi:e - :nes
- a nsia:es is:o 3500 gallons. This errer has ::
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- o assure that the tank does ini: tally contain 350,000 gallons and a second time to assure that 350,000 gallons has been inf ec:ed. Thus, 7,000 gallons of capaci:y was necessary for ins trument' error.
Recently, we were infor ed by Wes:inghouse, who is responsible for full scale the RWST level instrumentation, that they pref er a 3:
error which causes an increase in the allowance for ins trument ins trument error to 21.000 gallons.
Vorking allowance - Some allowance above the required capacity of 2.
ala rms wt:h only minor wa:er gallons is necessary to prevent 350,000 losses from the tank.
It would not be prac:ical to maintain a level setpoint and thus, a nominal 3,000 gallons ove r and above et the exact
- r., design capacity is desired f or this sargin.
Transfec allowance - Additional RWST capacity cust be provided :o 3.
accemmodate a reasonable delay time associated w1:h the transfer of As stated certain pu=p suctions from the RWST to the containment su=p.
16TfSAR-3) when the proper quantity of water has_ been transferred This to the containment,Jhe_ containment.. sump valves-open.
autonctically shif ts RHR and containment spray pu=p suctions to the However, the saf ety injection and charging p_ umps containment sump.
continue to draw from the RWST.If you assumed a 10 minu.te_realig: ige',nt time, the allevance would be 24,000 gallons since the flow race of the pumps remaining on the RWST is 2,400 gallons ;3r minute (gpm).
Single failure - Because of the automatic transfer of RHR and 4.
co_cainment pumps to the sump, some allowance must be included for The mos t limiting single failure for tank capacity a single f ailure.
if the containment sump valve for one of the trains failed results Should this wors t sing:e to open upon a low level signal from the RWST.
f ailure occur, the associated RHR and containment spray pumps in that If train will continue to,drawjrom theyST. at a rata of 7800 CFM.
the condi: ion, you assume it takes' 5 mioutes. co recognize and correc:
then an addi:ional 39,000 jallocsTwould have to be added to the tank
^
3a compensate for the single failure. ~Q Unuseable volume - Once the gert of the tank pu=p suction pipes are 5.
reached the pu=ps lose suction and any remaining wa:er in the :ank is unusable. This unusable volume must be included in the design calculations and for a 375,000 gallon tank it is approximately 14,000 gallons.
The design para =eters for instrument error, transfer al* owance and The single f ailure have changed since the original s taing of the :ank.
f ollowing :able is a su=ma:7 of required capaci:ies unde r the old and revised design parameters:
Required AWST 'lolum Cid New Oesign Para e:er 350,000 gal 350,000 gal Injec:ica capaci:7 t.
7,000 gal 21,0C0 gal
- 2. Ins::u=ent errer 3,000 gal 3,000 gal
- 3. Working allevance 24,0C0 gal
- 4. Transf er all:vance 39,000 gal
- 5. Single f ailure 14,000 221 14,000 221
- 6. Unusable volu=e 374,000 gal 451,0C0 gal Tocal As shown by the table, the original 375,000 galien tarl would have all the old design parameters bu: is substan:ially unde rsized for the
=e :
new or revised parameters.
f Analvsis of Saf e:-r ! olica: ions If the :ar.k size had remained at 375,000 gallons, i: is pcssible thac the pu=ps taking sue: ion f cm it would have run cut of wa:er and los:
The saf ety injectica and charging pu=ps are =ultistage pu=es and suct ion.
Thus, the path fres upon less cf suction =ay cease and becc=a inoperable.
- he discharge of the residual heat camoval pu=ps :hrough these pu=ps =ay have been lesh Ecwaver, even vi:h wors: single f ailure for tack sizieg,
- he contain=ent spray and residual heat re=cval paths into the reae:cr respectively would have remained operable coolanc sys:em acd contai::=en:
could have been cupplied :o :he :ces and contatames: at=osphere.
and wa:e under No acciden: analysis was made of a isss =f coola=c acciden:
these condi: ions since the design has been changed and :hese condi:ic=s are no icager credible.
Corrective Action The RWST storage capacity has been increased f: o 375,000 galices This larger size is = ore :han adequa:e for all :he to 475,000 gallons.
design considers: ices and leaves scce margin f : possible f u:ure changes.
erec:icn has s:arted and No work on :he tarA founda:icn, piping ::enla rge :he :ack. Mcwever,
- .us, so field :cdifica:ica needs :o be taken ::
design draw 1:.gs for the :ank, piping and f:u::da: ices were c: pie:e and cens::ue:icn and will have :: be -cdified. The spray che- :a1 c e rt if ied f :
the rJ5T addi: ion tank will also have :o increase in size pr:pc :t:nal ::
the ::nce ::2:ica Of :he=1: sis in 1: vill have :a increase :: :::pe sa:e
_].
f f or :he T45T enlargenent. A decision on wha: will be done :s :he spray chemical addi: ion :3ck will be ude in :he near f uture and docu=ea.:ed in the Final Saf e:y Analysis Report.
M*