ML19247A568

Notifies of Status of Rept on Reactor Cavity Annulus Seal. Most PWR Users Remove Ring During Normal Operation.Others Store Seal Ring in Raised Position During Normal Operation

ML19247A568
Person / Time
Site:	Beaver Valley, Millstone, Calvert Cliffs, Salem, Oconee, Point Beach, Prairie Island, Surry, North Anna, Turkey Point, San Onofre, Cook, Yankee Rowe, Maine Yankee, Rancho Seco, Zion, McGuire, 05000256, Trojan, Crane
Issue date:	07/05/1979
From:	Lainas G Office of Nuclear Reactor Regulation
To:	Trammel C Office of Nuclear Reactor Regulation
References
TAC-11846, NUDOCS 7908010339
Download: ML19247A568 (7)

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UNITED STATES j

NUCLEAR REGULATORY COMMISSION 1

WASHINGTON, D. C. 20555 p

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JUL 5 1979 MEMORANDUM FOR:

C. Trammell, Lead Engineer, Operating Reactors Branch fl, Division of Operating Reactors FROM:

G. Lainas, Chief, Plant Systems Branch, Division of Operating Reactors

SUBJECT:

REACTOR CAVITY ANNULUS SEAL RING STATUS (TAC 11846)

REFERENCE:

D. Eisenhut letter to V. Stello, dated June 21, 19781 On February 2,1978, letters were sent to all PWR licensees requesting information related to the potential for the reactor cavity seal ring to become a missile following a LOCA.

The results of a preliminary review Of licensee responses were summarized in Reference (a).

Per your request at our meeting in late March 1979, the Plant Systems Branch has reviewed the status of all licensee responses concerning this issue.

An updated detailed status is provided in the enclosed table, (Enclosure 1). The following summarizes the sgatus:

(1)

The reactor cavity annulus seal ring is removed during normal operation at 27 of the 42 operating units.

(2)

The licensees for 4 of the 42 units (Haddam Neck, San Onofre, and Surry 1 and 2) propose to resolve the above cited problem at the same time as they would resolve the reactor asymmetric load problem.

PSB has no. objections to this proposal.

(3)

The licensees for 5 of the 42 units ( ANO-1, Farley 1, Oconee 1/2/3) store the seal ring in a raised position during nomal operation.

Because AND-1 has determined (letter dated July 14, 1978) that the seal ring could become a missile if it is stored in a raised position during normal operation, we recommend that the licenseer of the five units be required to supply additional analyses addressing this potential for their facilities.

(4)

Licensees for 2 of the 42 units (Fort Calhoun and Rancho Seco) have proposed design modifications which are currently under review.

The proposed modifications are being reviewed by the EB and do not involve cavity pressurization analyses.

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The licensees for the remaining 4 units (Point Beach 1/2, Maine Yankee, Rankee Rowe), which are operated with the seal ring in'

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place, ~have. not performed the analyses needed to demonstrate

.xrc that the missile potential associated with the seal' ring does

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not have safety significance.

Furthermore, these licensees have not proposed to remcve the seal ring during normal operation.

Consistent with the results of our previous review (sumarized in the above referenced letter), we again recomend that additional analyses or comitments be required from the licensees of these 4 units.

Attached are sample letters (Enclosures 2 and 3) which should be sent to the licensees. is a redraft of a letter which was attached to Reference (a).

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G. Lainas, Chief Plarat Systems Branch Division of Operating Reactors

Contact:

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Enclosure:

As stated cc w/ enclosure:

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G. Lainas F:=._2 E. Adensam sir V. Noonan

="E J. Zudans J. Kerrigan B. Grimes W. Gamill A. Schwencer R. Vollmer

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FNCI.0SURE 1 REACTOR CAVITY ANNULUS SEAL RING STATUS PLANTS LICENSEE ACTION REMARKS ANO-1 Analysis has concluded that the seal ring Seal ring raised,3 feet during (although raised 3 feet above refueling normal operation.

floor) can become a missile; proposed a permanent fix in Fall 1980.

Beaver Valley 1 None Seal ring is removed during normal opera tion.

Biological shield consists of hinged benelex segments.

Calvert Cliff 51 & 2 None Seal ring i.s removed during normal operation.

D. C. Cook 1 & 2 None Seal ring is removed during normal operation.

Crystal River 3 Analysis showed that the seal ring could become a missile.

Seal ring removed.

Davis Besse 1 None Seal Ring is removed during normal operation.

Farley 1 Analysis concluded that steal ring could Seal ring raised 5 inches above not become a missile.

reactor vessel flange.

Fort Ca' hour. 1 None CRDM's are protected by missile barrier; under NRC review (TAC 11021)

R. E. Ginna 1 None Inflatable seal ring is not left in place during normal operation.

~f Haddam Neck Analysis will be included as part of Analysis due 12/79.

Asyntatric LOCA loads task.

y Indian Point 2 & 3 Seal rings removed.

M Kewaunee None Seal ring removed during normal operation.

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REACTOR CAVITY ANNULUS SEAL RIf1G STATUS PLANTS LICENSEE ACTION REMARKS Maine Yankee None; AE calculations during design phase of Licensee believes that a current MY showed that shielding could become a analysis would show that missile missile.

generation is not possible.

In addition, the CRDM is assumed inoperau:e during LOCA.

McGuire 1 None Seal ring removed during normal operation.

Millstone 2 New neutron shield proposed.

Seal rina New desion reviewed and remove d.

appre /cd by PSB 4/17/79.

North Anna 1 None Seal ring is removed during normal ope ra tion.

Oconee 1, 2, & 3 None Seal ring raiscd 3-4 feet above installed position.

Palisades None Seal ring is removed during normal operation.

Point Beach 1 & 2 Based on Trojan's analysts, the licensee Licensee contends that missile concluded that the seal ring could become generation would not affect the safe a missile.

shutdown of the plant during a LOCA.

Prairie Island 1 & 2 None Seal ring is removed during normal operation, w-Modification is under review by I Rancho Seco Proposed a modification for storing the IU2020' 4

reactor cavity seal plate.

- Robinson 2 Seal ring removed I

1. S t. Lucie Seal ring removed.

REACTOR CAVITY ANNULUS SEAL RiftG STATUS PLANTS LICENSEE ACTION REMARKS Salem 1 & 2

':eal rings removed.

San Onofre 1 Analysis will be included as part of Analysis is scheduled for Asymmetric LOCA loads task.

completion by 1/1/80.

Surry 1 & 2 Analysis will be included as part of Analysis scheduled for completion Asymmetric LOCA loads task.

iy 12/79.

TMI-l Seal ring removed.

Trojan Seal ring removed.

Turkey Point 3 & 4 Seal rings removed.

Yankee Rowe None Licensee assumes no action is necessary since control rod insertion during a LOCA is not ase :;oed.

Zion 1 & 2 None Seal rings removed during normal operation.

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ENCLOSURE 2 Licensee (Point Beach 1 & 2, Maine Yankee, and Yankee Rowe)

Gentlemen:

We have reviewed your response to our letter dated February 2,1978, in regard to the potential for the re: 'ar cavity annulus seal ring to become a destructive missile in the event of a loss-of-coolant accident pipe break inside the reactor cavity.

In your response, you indicated that in the event of a large coolant pipe rupture the subsequent ECCS analysis takes no credit for control rod insertion.

Therefore, damage to the control rod drive mechanisms (CRDM) would not affect the safe shutdown of the reactor subsequent to a loss-of-coolant accident as previously analyzed.

However, the role of CRDM for the safe shutdown of the reactor for small break LOCA has not been addressed. Moreover, you have not analyzed the effects of the seal ring, should it become a missile, on other safety related components located inside the containment. Therefore, purusarit to 10 CFR 50.54 (f) of the Commission's regulations, you are hereby requested to (a) demonstrate by appropriate analysis that the seal ring cannot become a destructive missile during continued long-term operation and that it poses no threat to the health and safety of the oublic; or (b) furnish a statement that the seal ring will be remo.ed by no later than the next refueling outage.

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ENCLOSURE 3 Licensee (ANO-1, Farley, Oconee 1, 2 & 3)

Gentlemen:

We have reviewed your response to our letter dated February 2,1978, in regard to the potential for the reactor cavity annulus seal ring to become a destructive missile in the event of a loss-of-coolant accident pipe break inside tne reactor cavity.

In your response, you indicated that the seal ring is in a raised position and does not form a seal between the vessel and the cavity during reactor operation.

One licensee nas informed NRC that for their seal ring the raised pos tion does not eliminate the possibility that the seal ring could become a mis 'le following a postulated reactor coolant pipe rupture inside the reactor s ssel cavity.

Therefore, pursuant to 10 CFR 50.54 (f) of the Commission's regulations you are hereby requested to (a) demonstrate by appropriate analysis that the seal ring cannot become a destructive missile during continued'long-term operation and that is poses no threat to the health and safety of the public; or (b) furnish a statement that the seal ring will be removed by no later than the next refueling outage.

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