ML20248L176
| ML20248L176 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 06/03/1998 |
| From: | Rone A GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 1920-98-20283, NUDOCS 9806100479 | |
| Download: ML20248L176 (6) | |
Text
t a
l 1
j j
GPU Nuclear, Inc.
l
(
One Upper Pond Road NUCLEAR Parsippany, NJ 07054-1095 Tel 201-316-7000 ALL PROPRIETARYINFORMATION HAS BEEN REMOVED FROM THIS COPY June 3,1998 1920-98-20283 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington,DC 20555 Gentlemen:
Subject:
Three Mile Island Unit No.1 Nuclear Generating Station (TMI-1)
DocketNo.50g L5'9 Facility Operating License No. DPR-lf/50 AdditionalInformation Requested for License Amendment to Support a Design Change to Permanently Remove the Reactor Vessel Missile Shields at TMl-1
References:
(1) GPU Nuclear Letter,6710-97-2106," Request for License Amendment
/
to Support a Design Change to Permanently Remove the Reactor Vessel j
Missile Shields at TMI-1", dated March 31,1997.
(2) USNRC Letter,"Three Mile Island, Unit 1 Nuclear Generating Station g[.)/
(TMI-1) Request for AdditionalInformation Regarding Permanent Removal of Reactor Vessel Missile Shields (TAC No. M98471)", dated October 3, 1997.
In Reference 1, GPU Nuclear requested a license amendment to support the permanent removal of the R.eactor Vessel (RV) Missile Shields from TMI-1. It is GPU Nuclear's desire to permanently remove the RV Missile Shields prior to restart from the next refueling outage currently scheduled to begin in September 1999. In Reference 2, the USNRC requested GPU Nuclear to clarify and provide additionalinformation with regard to three specific items. Attachments 1 and 2 provide the requested information.
9806100479 980603 i
PDR ADOCK 05000289, P
PDR~1A
1920-98-20283 Page 2 Reference I also provided FTI Document 51-1240140-00," Reactor Vessel Missile Shield Removal Report," dated December 1995. Reference 1 noted that in accordance with 10 CFR 2.790, FTI Document 51-1240140-00 is considered " Proprietary." It was therefore, requested that this information be withheld from public disclosure. An affidavit supporting this classification signed by J. H. Taylor, Manager, Licensing Services, Framatome Technologies,Inc. was included in Reference 1. This " Proprietary"FTI Document referenced BWNT Document 32-1235102-00,"RV.
Missiles (Bolts and Studs)",in support of report Section 1.3.2.1,"CRDM Closure Analyses",
Section 3.1, " Potential Missile Locations", and Section 4.6, FTI Draft 10CFR50.59 Safety Evaluation. In the preparationof the response to Reference 2, Item 3, BWNT 32-1235102-00 w;s revised to become FTI Document 32-1235102-01,"RV-Missiles (CRDM Hold-Down Bolts and RV-Studs)," dated February 1998. The seven revised pages are provided in Attachment 2 to this letter. Since the Attachment 2 pages are an integral supplement to FTI Document 51-1240140-00, they are considered " Proprietary"and covered under the affidavit previously provided in Reference
- 1. It is therefore, requested that this information be withheld from public disclosure.
If you have any questions or comments on this matter, please contact Ron Zak, Corporate Regulatory Affairs at (973) 316-7035.
- Sincemly,
. H. Rone Vice Presidentand Director Engineering Attachments c:
Administrator, Region 1 (Non-Proprietary)
Senior Resident Inspector (Non-Proprietary)
TMI NRC Project Manager (Proprietary and Non-Proprietary Versions) i G
ATTACHMENT 1 l
" Response to Requested Additionallnformation items 1,2 and 3" 0
{
1920-98-20283 l
Attachment I
{
Pag'e 1 of 2 1
1 ResDonse to Reauested Additionallnformation items 1,2 and 3 Item (l)
Clarify and provide information with regard to the scenario or event that causes the reactor vessel stud and nut to become a missile.
Response to item (1)
For miss'ile generation,the RV studs / nuts are conservativelyassumed to be at.the ASME Code stress allowable of 3Sm. The actual RV stud / nut stress is lower than this allowable. The stud / nut failure is assumed to be instantaneous at this stress level for whatever scenario that one could j
postulate (i.e., fabrication defect, corrosion,etc...). As such, this isn't an event driven failure but a j
determination of the consequences resulting from a hypothetical failure.
l l
Item (2)
Identify if the scenarios of similar potential missiles have been previously evaluated in any design basis document.
Response to Item (2)
GPU Nuclear is not aware of a scenario or assumed event of potential missiles that has been
]
previously evalua'.ed in any design basis document. GPU Nuclear submitted,in Reference 1, the evaluations of potential missiles that were performed as basis for the removal of the RV missile l
shields. During original licensing, missile shields were previously reviewed and approved by the USNRC Staff as an acceptable alternative to evaluating the consequences of or probability of missiles from the RV head area. GPU Nuclear believes that the FMEA analysis and other technical data supplied in the Reference I submittal is an acceptable alternative method as described in NUREG 0800.
J
1920-98-20283 I
t Attaclunent I l
Pagie 2 of 2 Response to Reauested Additionallnformation items 1,2 and 3 (con't)
)
Item (3)
If the stud and attached nut were deter-.ed not to be a potential missile based on the approach of -
insufficient kinetic energy to reach the top of the containment building, then discuss the potential impact and safety consequence resulting from the stud and attached nut, after reaching the apex of their trajectory, dropping back down and colliding with other structures, equipment or components importantto safety.
Response to item (3)
FTI Calculation 32-1235102-00 used conservative stress values (ultimate stress) to calculate the height of the missile for the RV studs / nuts. This calculationwas revised (Attachment 2) using a more appropriate stress value of 3 Sm. Using this stress value, it was shown the RV studs / nuts do not reach the top of the D-ring.
The containment building does contain equipment and components important to safety which could be impacted by a potential RV stud and attached nut missile after the apex of trajectory is reached and the missile drops back down. However, the proposed removal of the RV missile shields would not change the safety consequences for this scenario since the apex of the missile trajectory would not exceed the top of the D-ring as is the case with the RV missile shields in place.
I 4
)
3 l
._______.--______A
ATTACHMENT 2 Revision 1 Pages for FTl Document 32-1235102-01,"RV-Missiles (CRDM Hold-Down Bolts and RV-Studs)," dated February 1998.
(i Pages Follow)
This attachment contains Proprietaryinformation as defined in 10 CFR 2.790(a)(4).
l An affidavit as required by 10 CFR 2.790(b)(1),which supports this determination,has previously been submitted to the USNRC in Reference 1.
)
l l
l l
4 e
e
-