Tech Spec 3.1

Question 1

What is in section 3.1 of TS

Answer 1

Reactivity Control Systems

Question 2

List the requirements, applicability, and actions required for:

3.1.1 SHUTDOWN MARGIN (SDM) - Reactor Trip Breakers Open

Answer 2

LCO 3.1.1 SDM shall be ≥ the value in the COLR.

APPLICABILITY: MODES 3, 4, and 5 with the Reactor Trip Breakers Open or the CEA drive system not capable of CEA withdrawal.

ACTIONS
CONDITION REQUIRED ACTION COMPLETION TIME
A. SDM not within limit. A.1 Initiate boration to restore
SDM to within limit.
15 minutes

Question 3

List the requirements, applicability, and actions required for:

3.1.2 SHUTDOWN MARGIN (SDM) - Reactor Trip Breakers Closed

Answer 3

3.1.2 SHUTDOWN MARGIN (SDM) - Reactor Trip Breakers Closed
LCO 3.1.2 Reactivity shall be controlled by:
a. SDM shall be ≥ the value in the COLR.
b. KN-1 shall be < 0.99 when Tc ≤ 500°F.
c. Reactor criticality shall not be achieved with shutdown group CEA movement.
APPLICABILITY: MODES 3, 4, and 5 with the Reactor Trip Breakers Closed and the CEA drive system capable of CEA withdrawal.

A. SDM not within limit. A.1 Initiate boration to
restore SDM to within limit.
15 minutes
B. KN-1 not within limit when Tc ≤ 500°F.
OR
B.1 Vary CEA position to restore within limits.
AND
15 minutes
Reactor criticality can be achieved by shutdown
group CEA movement.
B.2 Initiate boration to restore within limits.
15 minutes

Question 4

How does required Shutdown Margin change with RCS temperature (3.1.2)

Answer 4

• Required SDM ↓ as Tcold lowers below 500°F
  o Highest SDM required when > 500°F

Question 5

List the requirements, applicability, and actions required for:

3.1.3 Reactivity Balance

Answer 5

LCO 3.1.3 The core reactivity balance shall be within ± 1% ∆k/k of predicted values.
APPLICABILITY: MODE 1

• Reactivity balance typically based on critical boron curve.
  o Provides indication of soluble boron concentration in the RCS versus cycle burnup.
  o Difference between measured and predicted values would be ~ 100 ppm (depending on boron worth) before the limit is reached.
• If not met, re-evaluate or set new limits within 7 days. Or go to Mode 2 in 6 hours.

Question 6

List the requirements, applicability, and actions required for:

3.1.4 Moderator Temperature Coefficient (MTC)

Answer 6

LCO 3.1.4 The MTC shall be maintained within the limits specified in the COLR, and a maximum positive limit that varies linearly from 0.5 E-4 ∆k/k/°F
at 0% RTP to 0.0 ∆k/k/°F at 100% RTP.

APPLICABILITY: MODES 1 and 2.

A. MTC not within limits. A.1 Be in MODE 3. 6 hours

Question 7

How does MTC change over core life?

Answer 7

• Max positive limit varies linearly from 0.5 E-4 ¬Δk/k/°F at 0% RTP to 0.0 Δ¬k/k/°F at 100% RTP.
  o Most limiting event for + MTC: CEA withdrawal accident from subcritical or low (hot zero) power condition (startup accident)
• Max negative MTC: -4.4 Δ¬k/k/°F
  o Most limiting event for – MTC: EOL MSLB

o MTC becomes more negative over core life due to less boron in the RCS

Question 8

List the requirements, applicability, and actions required for:

3.1.5 Control Element Assembly (CEA) Alignment

Answer 8

LCO 3.1.5 CEA Alignment (Modes 1-2)
* Full strength CEAs operable. (movable/trippable/≤ 4 sec drop time)
* Full strength AND Part Strength CEAs aligned within 6.6” (indicated) of CEAs in their groups.

≥ 1 CEA(s) misaligned > 6.6” and ≤ 9.9” OR One CEA > 9.9”:
* Down power starts within 10 minutes (TCA if > 35%)
* Reduce power within 1 hour (per COLR curves).
o Power Reduction from initial power
o > 80%: 20% ↓ (if initially 85%, reduce power to < 65%)
o > 70% - 80%: 15% ↓
o > 45% - 70%: 10% ↓
o > 35% - 45%: 5% ↓
* Restore alignment within 2 hours.

Question 9

How is a loss of PNC different in a unit with ARCH vs. CEDMCS?

Answer 9

CEDMCS:
Only one CEA RPI channel operable for one CEA per Group.
* Restore RPI or verify positions in 6 hours (fully in or out).
* LCO 3.0.3 if >1 RPI affected in a group. (loss of PNC or PND)

if ARCH, no 3.0.3

Question 10

What is the required action if a full strength CEA is NOT trippable (3.1.5 C) ?

Answer 10

Any untrippable Full strength CEA: Mode 3 in 6 hours.
* Operation is allowed with untrippable Part strength CEAs if alignment and insertion limits are met.

Question 11

What is the required action of 3.1.5 D?

Answer 11

Two or more CEAs trippable and misaligned from their group by > 9.9 inches

Immediately open RTBs if ≥ 2 CEAs misaligned > 9.9 inches:
* Loss of power distribution / safety function. Outside of CPC/CEAC design basis and, for some CEA combinations, will not result in automatic protective action.
* Prevents any potential fuel damage.