ML18058A577

Safety Evaluation Concluding Licensees Confirmation & Commitments to Staff SE Pertaining to SBO Acceptable

ML18058A577
Person / Time
Site:	Palisades
Issue date:	06/25/1992
From:	Office of Nuclear Reactor Regulation
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ML18058A576	List: ML18058A575 ML18058A577
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NUDOCS 9207060139
Download: ML18058A577 (7)

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION 1.0* INTRODUCTION RELATED TO STATION BLACKOUT ANALYSIS CONSUMERS POWER COMPANY PALISADES PLANT DOCKET NO. 50-255 The NRC si~ff's Safety Evaluatiori (SE) pertaining to the* licensee's initial response to. the Station *s1ackout (SBO) *Rule, 10 CFR *50.63, was transmitted' to the licensee by letter dated May 20, 1991.

The staff found the licensee's proposed method of coping with an SBO to be acceptable, subject to the satisfactory resolution of six recommendations which were.itemized fo the.

staff's SE~

Th~ licensee responded to the staff's SE ~nd, specifically, to the recommendations by letter from G.. B. Slade, Consumers Power Company (CPC) * *.

to the Document Control Desk, U.S. Nuclear R_egulatory Commission, August 1, 1991. *Also, there ~as a teleconferenc~ between representatives of the

• • licensee and the NRC staff on July 2, 1991.

. 2. 0 EVALUATION The licensee's response to each of the staff's SE. r.ecommendat ions are evaluated below.*

2.1 Class IE.Battery Capacity (SE 'Section 2.2.2) "

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SE Recomm~ndatibn The licensee sho~ld not ~onsider load stripping to occur until 30 minutes.into*

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the event, verify that the battery load profile envelopes *the resulting load requirements, and confirm the battery_ adequacy for the.4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> coping duration.

and recovery thereafter.. Also, the licens*ee needs to* verify that the correct" aging -~nd temperature factors recommended in IEEE Std-485 have been a~plied.

The revised results should be reflected in the appropriate plant procedures and included in the SBB ~ubmittal supporting documents *.

Licensee Respons~

• --*--The licensee-**st-ated.that the--Pali-sades Battery-Analysi-s*does not assume*lhat*-*

• *manual load stripping *occurs until 30 minutes into the event *. The battery load reduction which occurs between l and 10 minutes on the battery load profile is due to the dropping out of short duratiori loads (e.g., relays which remain energized until a valve strokes to its final position, emergency sirens, etc.). The licensee also stated that these short duration loads are conservatively assumed to be energized for the first 10 minutes of the event.

The manual l o~d shedd_i ng is shown on* the battery load profi 1 e at 30 minutes into the event.

The licensee concludes that plant prricedures for the station blackout event list battery loads to be shed which are consistent with this battery analysis.

Further, the battery analysis for Palisades does use the correct aging and temperature factors recommended in IEEE-STD-485.

Staff Evaluation Based on its review and the licensee's response; the staff accepts the licensee's Class IE battery capacity analysis.

2.2 Effects of Lo~s of Vent~lation CSE Section 2.2.4) 2.2.l Control Room SE Recommendations The licensee should reevaluate the effects of a loss of ventilation for the areas identified in this Section, specifically in the control room where the licensee used a noneonservative initial temperature and used two different values for the thermal conductivity of concret~ in the heat up calculations.

licensee Response Regarding* the contrpl room HVAC, the licens.ee committed to reevaluate the.*.

effects of a loss *of ventilation assuming an initial temperature of 90°F to be consistent* wit~ a Technical Specification (TS) limit on control room temperature which is currently being developed.

This reevaluation will also correct the value of thermal conductivity utilized in the analysis. This reevaluation is expected to show that the control room will remain below 120°F during an SBO event of four hours duration.

Staff Evaluation Based on its review and the licensee's commitment, and providing that the revised peak calculated temperature for this control room during an SBO e~ent will not exceed 120°F (temperature limit described in NUMARC 87-00), the staff finds th~ licensee's response acceptable and considers its concerns of the.

effects of loss of ventilation in the control room resolved.

The feevaluation should. be included as part of the documentatjon supporting the SBO:response.

Note:

Subsequent to issuing the SE for the Palisades plant, the NRC staff has clartfied its position with respect to the assumed initial temperatures used in the heat up evaluations during an SBO.

The staff position is that the licensee should-doeument the basis and justification for th~ assumed initial temperatures used in the heat up analysis for the control room and identified dominant areas of concern. Administrative procedures or other controls should be established to maintain the initial temperatures consistent with those used in the heat up analyses.

While the use of TS is one method of control, it was not the staff's intent that TS should be developed to provide the controls.

The basis and justification should be included in the documentation that is to be maintained by the licensee in support *of the SBO submittals.

2.2.2 Cable Spreading and Battery Rooms*

SE Recommendation The licensee should ensure that, in the cable spreading and battery rooms, at least one DC powered fan will be available to. each area after the load shedding process is complete or perform heat up calculations of these rooms representative of expected room conditions and associated operating equipment during an SBO event.

Licensee Response With regard to the battery rooms and in response to the staff's concern described in the SE, the licensee stated that no detailed evaluation of the effects of the loss of ventilation has been performed for these rooms.

The licensee also states that the battery rooms are located adjacent to the cable spreading room which has been shown to remain below its design temperature of 104°F for a loss of ventilation of up to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> duration.

The licensee further states that the only heat source available in the battery rooms is the heating due to internal battery resistance which is considered to be insignfficant. The licensee concludes.that the battery rooms' temperature is thus expected to follow closely the cable spreading room's temperature and to remain below 104°F for the duration of an SBO event. With regard to the cable*

spreading room, the licensee indicated that a test was*conducted to demonstrate the effects of loss of ventilation. Consequently, it was deter.mined that certain cabinets required forced cooling to m.aintain cabinet internal temper~tures below their design limits. Subsequent to this testing, fans were installed internal to these cabinets to provide this forced cooling capability. These fans are p6wered from DC backed sour~es and will be available to cool the required cabinets and internal eq~ipment during an SBO event.

Staff Evaluations With respect to the battery rooms, the staff finds the licensee's response acceptable and considers its concern of the effects of loss of ventilation in the battery rooms resolved.

With respect'to the cable spreading room, the staff finds the action taken by the licensee to provide forced cooling to the required cabinets and internal*

equipment, acceptable and considers its concern of the effects of loss of ventilation in the cable spreading room r~solved.

-2~2.3 ~eat Tracing SE Recommendation The licensee needs to verify that the loss of heat tracing during an SBO event would not degrade the operation of safe shutdown system.

. *. Licensee Response The licensee indicated that an evaluation with regard to the effects of the loss of heat tracing duririg an SBO of four hours duration has been performed.

The only area of concern is the concentrated.boric acid tanks and associated piping. This heat tracing system would be lost during an SBO event. A calculation has been performed which indicated that the temperature of the fluid in these components will remain above the precipitation temperatur.e of the boric acid for the duration of a four hour SBO event.

• Staff Evaluation Based on its review, the staff finds the licensee's response acceptable*and considers.its concern of the loss of heat tracing d~ring an SBO ~vent

_ resolved.

2.3 Containment Isolation !SE Section 2.2.5)

SE Recommendation The l_icensee should list in an appropriate procedur* all containment i~olaiion* -

valves thc.t (:annot be excluded by tile exclusion criteria outlined ir:i Regul~tory Guide (RG) Ll55 (i.e., valve.s that are. either normally closed or open and fail "a.s is" upon loss of AC power).: The procedure should.identify*

the actions necess.ary*to ensure'that these valves are fully closed,.. if needed.

• The staff's position is that the valve closure needs *to be confirmed by.

po~ition indication (local, mechanical, remote, process information, ett.).

--Thi~ information should also be*included with.the other documentation that. is to be, maintained by the.1 i censee in support of the SBO submittal s.

Licensee Response.

fn its response_*to ihe staff's ~once~n,* the licensee states *that it has*

reviewed.the plant list *of containment isolation valves and verified that these valves eith~r m~et the exclusion criteri~ of RG *1~155 or *are ta~~ble of being closed from the control room und~r SBO conditions.

• The containment isolation valves which are required to be confirmed ~losed:*are addressed in,

• appropriate 'emergency operating procedures. These valves are confirmed to be in. the closed positio~ by procedure 'if containment pressure. begins to increase. 'The licensee also states that the two valves fdentified by Science Appl.ication~ International Cor~oration (SAIC) a~ not meeting the exclusion*'

c.r.iteria of RG 1.155 are normally clbsed and fail *closed during an SBO event.

• The licensee further states'that these valves are.~i~ operated (with a back-up N2 accumulator) with DC-solen~i~san~ ~ls() haye_QC p_qw_ered positi_()tl ~ *-.-- __ -**-* __

ind-icat1on.~--- The.. licensee concludes that these valves are further backed up by..

a ~heck valve or locked closed manual valve ~hich do meet the ~xcl~si~n criteria of RG 1.155.

Staff Evaluation Based on its review, the staff finds that the licensee's rationale meets the intent of *the guidance described in RG 1.155 and is, therefore, acceptable.

The staff considers its concern ~f containment isolation resolved.

2.4 Proposed Modification CSE Section 2.4)

In the SE, the staff noted that the licensee will add back-up compressed air supplies to* support the atm9spheri~ dump valves (ADV) during an. SBO.

SE Recommendation The licensee should include a full description, including the nature and objectives of the required mqdifications identified above, in the documentation that is to be maintained by the licensee in support of the SBO

• submittals.

Licensee Response, The licensee stat~d that th~ des~riptions of the modificati~ns describe~ ab6ve

• .will be <:.,*2ilable as part of. the documentation maintained in support of the.

SBO submittals.

The licensee also stated that the mpdification to add back~up compressed air supplies to the atmospheric dump yalves will b_e completed by the.end of the second refueling outage after January 1, 1992.

The licensee concludes that th.h refueling outage is currently scheduled to begin in May 1993.

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Staff Evaluation Based oh its*review and the licensee's commitment, the staff finds the licensee's response acceptable and considers the above cited issue re~olyed.

2.5 Quality Assur~nce and Technical Specifications CSE Section 2.5)

SE Recommendation The licensee should veri,fy that the SBO equipment is covered by an appropriate QA program consistent with the guidance of RG 1.155. This evaluation should be documented as part of the documentation supporting the 580 rule response.

• .Licensee Response....

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The licensee states that with the exception of the back-up air supp1y to the ADV being installed as part of a future modification, no non-safety related equipment is used to meet the station blackout requirements of 10 CFR 50.63.

The licensee concludes that the design and installation of the ADV back-up air supply modification will be available as part of the documentation supporting the SBO rule response.

.. J Staff Evaluation The licensee should commit to a QA program for the ADV back-up air supply.

Verification that such a program is in place should be included as part of the.

documentation supporting the SBO file for future audit/verification.

2.6 EOG Reliability Program CSE Section 2.6)

• SE Recommendation It is the staff's position that an emergency diesel generator (EOG) reliability program should b~ developed in accordance with the guidance of RG 1.155, Section 1.2. If an EOG reliability program currently exists, the program should be evaluated. and adjusted in accordance with RG 1.155.

Confirmation that such a program is in place or will be implemented should be included in the documentation that is to be maintained by the licensee in support of the SBO submittals.

Licensee Response The licr~see currently has implemented programs which track ~nd maintain EOG reliabi1

~v. The licensee states that these programs incorporate the elements identifieo in RG 1.155, Section 1.2. The licensee concludes th~t details of

. the EOG Reliability Program are subject to change following resolution of Generic Issue B-56, "Diesel Generator Reliability."

Staff Evaluation The staff a*ccepts the licensee's.assurance that all elements required by RG 1.155 for an EOG reliability program are im~lemented at Palisades.

~djustments to the EOG reliability program, if required, may be made to conform to changing requirements subject to the resolution of Generic Issue:B-5~ "Diesel Generator Reliability.*

3.0

SUMMARY

AND CONCLUSION The staff has reviewed the licensee's response to the staff's SE pertaining to the SBO Rule (10 CFR 50.63) in their transmittal letter dated Atigust 1, 1991.

Also there was a teleconference between representatives of the licensee and the NRC staff on July 2, 1991.

The licensee's confirmation and commitments to the staff's SE are acceptabl~ *. Also, a Quality Assurance Program for the back~up compressed air supplies to the atmosph~ric dump valves must be implemented *in-atco"r'dance*with-RGT.155, Appendfx A.-* The licensee has*.

committed to complete the modification during the May 1993 refueling outage.

It is the staff's position, that the licensee must be in full compliance wi~h

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the SBO Rule within two years after receipt by the licensee of thi.s SSE in accordance with 10 CFR 50.63{c){4). Therefore, the above items should be expeditiously implemented to bring the.licensee into full compliance with the SBO Rule. Also, the* licensee should retain all supporting doc~mentation in the SBO file.

Principal 'Contributor:* C. R. Thomas, SELB/DST

• oate:

June25, 1992

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