ML18051A430

Selected Operating Reactors Issues Program Ii,Rcs Vents (NUREG-0737,Item II.B.1), Final Technical Evaluation Rept

ML18051A430
Person / Time
Site:	Palisades
Issue date:	03/02/1983
From:	Held J ENERGY, INC., LAWRENCE LIVERMORE NATIONAL LABORATORY
To:	Alberthal G Office of Nuclear Reactor Regulation
Shared Package
ML18051A432	List: ML18051A430
References
CON-FIN-A-0250, CON-FIN-A-250, RTR-NUREG-0737, RTR-NUREG-737, TASK-2.B.1, TASK-TM TAC-44394, TF-354-0812A, TF-354-812A, NUDOCS 8306020527
Download: ML18051A430 (6)

Text

ATTACHMENT

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• l.Jl.WRENCE LIVEtJv'lORE LABORATORY .

Selected Operating Reactor Issues Program I I

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Reactor Coolant System Vents (NUREG-00737, Item II.B.l.)

NRC FIN A0250 - Project 9

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FINAL TECHNICAL° EVALUATION REPORT FOR PALISADE.$  :

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Docket Number 50-255 NRC TAC Number 44394

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Prepared by J. T. Held of Energy Incorporated - Seattle (Subcontract

• 4324401) for Lawrence Livermore National Laboratory under contract to the

• NR: Office of Nuclear Reactor Regulation,* Division of Licensing.

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NRC Lead Engineer - Gus Alberthal

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NOTICE "This report was prepared as an account of work sponsored by the United States Governr.ient. ~Je~ither the United States nor the United States Department of Energy, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus,

• product *or process disclosed, or represents that its use would not infringe privately-owned rights."

XA Copy Has Been*s~nt . toPDR TF-354/0812a f/ia rch 2. 1983 I '*/l_I;;__ __

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Doc*ket Number 50-255

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- NRC TAC Number 44394 e.

I 1Ea-iNICAL EVALUATION REPORT ON REACTOR COOLANT SYSTEM VENTS FOR PALISADES INTRODUCTlON

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. _,, }he requireme_nts for *reactor coolant system high .point vents are stated in paragraph

• * ~'cc-X3)(iii) *of. ~to..*S.FR.* :5o_~~f' 1Standcirds fo~ Combustible Gas Control Syste~ in. Light

• _ Water. Cool~d P~~e~ R~o;~," ~d ~e further described in St~~d~rd R~~iew. PJon (SP.?)__,--:_-::

• Section 5.4~ 12, - "Reac~or .* C~lant *System High Point *Vents," "and -Item 11.s.*1 of NUREG-0737~ "Clarification of TMI Action Pion Requirements." In response to these and previous requirements, t~ Consumers Power Company has submitted information in

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. i References I and 2 in support of the vent syst'em at the Palisades Plant~

EVALU~TlON j

,1 The function of the high point vent system is to vent noncondensible gases from the high points of the reactor coolant system (RCS) to assure that core cooling durin.g natural I

I Circulation will not be inhibited. The Palisades reactor coolant gas vent system (RCGVS) J i

provides venting capability from the- reactor vessel head and the pressurizer steam space. The noncondensible gases, steam, and/~r liquids vented from the reactor vessel head and pressurizer steom space are piped and discharged to either the containment atmosphere or the pressurizer quench tank. The RCGVS is designed to vent a volume of hydrogen in standard cubic feet approximately equal to one half of the RCS vo!ume in one hour. Flow restriction orifices in the RCGVS paths, however, limit mass loss from a vent pipe break or inadvertent actuation of the RCGVS to less then the makeup capacity of a single charging pump. Hence, the licensee's compliance with 10 CFR 50.46,

".6.cceptcnce Criteria for Emergency Core Cooling Systems for light Water Nuclear Power Reactors," hos not been affected by the addition of the RCGVS. .

The vent poth from the reactor vessel head and the vent path from the pressurizer each contain two independently powered solenoid-operated valves in parallel and connect 1o a common heoder that discharges either to the coniainment atmosphere or to the quench Enclosure 5 Page I of 5

tank. The lines to the containment atmosphere and the quench tank each contain an

)solation valve powered from independent power sources. Thus, a degree of redundancy has been provided by powering RCGVS valves from different emergency power supplies,

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to *ensure that RCS venting capability from both the reactor vessel head and the pressurizer is maintained. Valve c0ntrol switches and positive indication of valve

'position, derived from valve position indicator switches, ore provided in the main control roomo RCGVS. valve seat . leakage is detected by pressure instrumentation with ciss~ioted alar~ in the main control room.

Th~*portion.- of ecic~hRCGVS path up to and includjng the second normally closed valve.... .*' .

_f ~;ms a po*rt*'-~f)~'.' :re~t.or: c~lant pre~ure .boundary and thus must . me~t *rea~t6i): ~ >:-* -

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coolant pressure bOUndary_requirements. ~his portion of the RCGVS is designated Safety*~*~*;/.,:.:..

CloSs 2' (Safety- Cl~~:*.f .Ui>stream of the. fl~~ ~estriction orifice~) in complian~e with IO,:.:*,<:::'_*

CFR 50.55a an~ Reguiatory Guide 1.26, and is designed for* pressures and te~peratures

- correspondin'g to the RCS design pressure and temperature. In additiOn,.the vent system" materials ore compatible with the reactor coolant chemistry and. ore fabricated and -

t~sted in accordance with SRP Section 5.2.3. The RCGVS is also acceptably separated .

and protected from missiles and the dynamic effects_ of postulated piping ruptures.

Furthermore, the entire RCGVS is designed for Seismic Category I. However, SRP Section 3.2.1 requires that structures, systems, and components "that are important to safety be classified as Seismic Category I items and identified in an acceptable manner.

Although the RCGVS is designed to Seismic Category I crit~ria, the licensee has not verified that the portion of the RCGVS that is* part of the reactor coolant pressure boundary has been acceptably identified and cJassified Seismic Category I. We therefore conclude that the design of the portions of the RCGVS up to and including *the second - --- * -

normally closed valve conforms to all reactor coolant pressure boundary requirements, inc::luding I0 CFR 50.SSa and the applicable portions of General Design Criteria I, 2, 4, i 4, 30, *'Jnd 31 contingent on confirmation by the licensee of the classification of this uortion of the RCGVS as 'Seismic Category I. The licensee has further ascertained that the essential operation of other safety-related systems will not be impaired by postulated failures of RCGVS compor.ents.

We hove reviewed the lic~nsee's RCGVS design to assure an acceptably low probability exists for inadvertent or irreversible actuation of the vent system. Each vent path has two solenoid-opera1ed valves in series, and each valve has a separate key locked control switcJ-a. The control swi1ches must be turned to the reset position first, and then to the Enclosure 5 Pqge 2 of 5

OPen position in order to operate the valves. The valves are powered by emergency

• power supplies and foil to the closed position in the event of loss of power. The licensee has also stated that the controls, displays and mimic bus added to the main control room for the vent system will be considered in a human factors analysis in order to reduce the potential for operator error. However, the Palisades RCGVS design may be susceptible to a common mode failure because operation of one solenoid-operated valve may cause other solenoid-operated valves in the system to open temporarily <see Reference 3). The licensee will be required to evaluate this potential problem and present their conclusions including any. design changes necessary to minimize the probability of an inadvertent vent system octuati~ ,,_,We: therefore find that ~o single active component failure or .

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_h~mon error should rf:SlJ~f _in inadvertent opening or irreversible operation (i.e., faiJ.ure to_*_ *

• ~lose *ofter

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i.ntentional_._

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• of th~. RCGvs;~o~tingent on satisf~cto~\~solutio~ of,** ___ ..'* ~

• the above identified potential pr!lblem. -~ "':>:::~--:~-* . '-*

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We hove also examined the locO'tion where the RCGVS discharges* diree;tly *to* *the .

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containment atmosphere. Based on' a- description provided by the licensee (Referenc~ 2),

this location is in an area that will provide good mixing.with the containment atmosphere to prevent the accumulation or pocketing of high concentrations of hydrogen in_

compliance with ID CFR 50.44, "Standards for Combustible Gas Control System in Light Water Cooled Power Reoctors. 11 Additionally, this location is such that the operation of safety-related systems would not be adversely affected by the discharge of the

<;inticipated mixtures of steam, liquids, and noncondensible gases.

The design provides for individual .test and open/closed indication of each valve,--ond the licensee has s1ated 1hat the solenoid-operated valves will be tested for operability during refueling outages in accordance with Subsection IWV of Section XI of the ASME Code for Category B valves.

. co;*.JCLUS!ON --

We conclude that the Palisades RCGVS design is sufficient to effectively vent

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nonconderrsible gases from the reactor coolant system without leading to_ an unacceptable increase in the probability of a LOCA or a challenge to containment integrity, meets the des!gn requirements of NUREG-0737 Item 11.B. I, and conforms to the require::ients of parogroph (cX3Xiii) of 10 CFR 50.44. We therefore recommend that the Palisades RCGVS design be found acceptable with the following two confirmatory items. The

• 1*J(IT::l~--P- ! ? Enclosure 5 Pc;e 3 of 5

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li~cnsee must (I) verify that the portion of the RCGVS piping that is port of the reactor coolant pressure boundary is classified Seisl!1ic Category I and (2) satisfactorily resolve the common mode failure problem noted above concerning the solenoid-operated valves.

In .addition, it should be noted that the following items were excluded from the scope of our review: seismic and environmental qualification of the RCGVS, RCGVS operating

• guidelines and procedures, and required modifications to the plant technical specific:ations and in-service inspection program for the RCGVS.

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REFERENCES I. Letter, D.P. Hoffman (Consumers Power Company) to D.M. Crutchfield (NRC),

"Docket 50-255 - License DPR Palisades Plant - Response to NUREG-0737, Clarification of TMl Action Plan Requirements," dated December 19, 1980.

2. Letter, B.D. Johnson (Consumers Power Company) to D.M. Crutchfield (NRC),

"Docket 50-255- ~icen~e DPR-20 -Palisades Plant-: NUREG 0737, Item 11.B.J

'Reactor -Coolant System Vents,' Response to Request for Additional Information,"

dated June 9, 1982.

3. NRC Memorandum, T.P. Spe_is (Division of Systems Integration) to T.M. Novak (Division of Licensing), "Unintentional Lifting of Solenoid Operated Pilot Valves in RCS Vent System," dated March 9, 1982~

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