ML20128A540
| ML20128A540 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 05/20/1985 |
| From: | Dixon O SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8505240252 | |
| Download: ML20128A540 (2) | |
Text
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g south CAROLINA ELECTRIC & gas COMPANY POST OFFICE 7 4 cotuualA. SOum CAmouMA seal 8 y.
' o. w. omo.-se.
.May 20, 1985
-v.c.s muetean o.seano.
Mr. Harold R.
Denton, Director
- Office.of Nuclear Reactor Regulation U.S.. Nuclear Regulatory Commission Washington,-D.C.
20555
Subject:
Virgil C.
Summer Nuclear Station Docket No. 50/395 Operating License No. NPF-12 Removal of the Boron Injection Tank Dear Mr.LDenton
.In.a letter from Mr.
O.
W.
- Dixon, Jr.,
to Mr.
H.
R.
Denton dated April 9, 1985, South Carolina Electric & Gas Company (SCE&G) requested an amendment to the Virgli C.
Summer Nuclear Station
' Technical Specifications which would allow for the removal of the Boron Injection Tank (BIT). - In subsequent discussions with the NRC Staff, several questions about the submittal were raised. This letter ~is therefore'provided'to supplement and further clarify the April'9,.1985 submittal.
Reactor Coolant System c o old own can be caused by inadvertent depressurisation,;a' loss of coolant-accident or a' steam line ru p tu r e.-
Of these three accidents, the s team line b reak is the only one in'which the analysis depends on boron to terminate a return to power.
The other accid ent scenarios produce boiling in the core, whichfintroduces negative reactivity and assures the reactor'will P
not become critical and r e tu r n to power.
As stated in the April 9, 1985 letter, the re-evaluation of the steam line break (assuming the BIT removed) demonstrates that sufficient negativ e reac tivity exis ts in the system without the BIT to prevent an inadvertant return to-power in the event of this ac c id en t.
, Removal of the BIT was' determined not to decrease the departure from 3
nucleate. boiling ratio (DNBR) below the '!uits allowed in Title 10 L
of the Code of Federal Regulations or to change the source. term for L
. any accid ent.
Re-evaluation of'the s team line b reak supported this r
conclusion for the steam line break scenario.
Removal of the BIT does not affect the other accident scenario conclusions involving DNBR and' fuel damage because ~ the presence of the BIT is not a factor in these resulting accident conditions.
,e\\
~
passa smllp
- _1
, e
- j j - *! '
Mr. Harold R.
Denton N
.Remova1.of Boron-Injection Tank
~
May 20, 1985 Fage.f2-
- The. containment-mass-andLenergy releases for postulated ' asin. steam
. i line' breaks with:the1 BIT removed do not vary significantly from
'the ' original release data available at the time of plant licensing. _This~new containment analysis based on BIT removal
< indicates energy release rates have in fact decreased.
Be cau s e mass and energy release calculationsEfor outside containment are basedion.subcompartmental responses -des crib ed in the Final Safety
'. Analysis Report (F S AR).section 3.6, and because these evaluations are not significantly affected by the-presence or ab sence of'the BIT 'these releaces were not re-evaluated.
- To. remove the BIT requires piping changes which introduce ' new pipe
' fittings and alter the calculated loads of present piping and supports.
Therefore new pipe. break and pipe whip analyses were performed as required of all high energy piping systems.
These new analyses demonstrated that surrounding equipment required to safely shut down'the_ plant is not compromised by'the ad d i t io n of-this new piping.
If you lshould hav e any fu rther que stions, please advise.
Ver tru yours.
'ss i
.0.
W.
ixon r.
AMM/0WD /inw cc:
V. C. - Su mme r T.C.
Nichols,;Jr./0. W. Dixon, Jr.
E.
H.
Crews, Jr E.
C.
Roberts 16 A.- Williams, Jr.
D.
A.
Nauman J.
Nelson-Grace Group-Managers
.0..S..Bradham C.
A. Price
'C.
L. Ligon-(NSRC)
K.
E.
Nodland
'R.
A.
Stough C.
O.
Percival C. W.
Mehl lJ.
B.
Knotts, Jr.
H.
G.
Shealy NFCF' File o".
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