Feed control scenarios · BR-UP-01

OPT-104AWAITING_TECHNICAL_REVIEWScenario Estimate (Illustrative — Non-Autonomous)

Three ways to respond to late-phase feed attenuation, compared on expected yield effect, risk and practical constraints. Predicted recovery for Candidate A: +5.1 pts normalized yield (range +3.2 to +6.8).

From investigation INV-104 · hypothesis AModel: AN-104 feed-loss regression v1 (3 batches)Demo · read-only

Return to causal case INV-104 Submit for technical & QA review

These are illustrative estimates, not predictions you can bank on

Estimates rest on three batches and on hypothesis A, which is supported but not yet tested. Submitting sends the proposal for human review; it does not change the recipe, DeltaV configuration or equipment.

Parameter deltas

What each scenario changes relative to the current recipe

Parameter	Baseline	Candidate A	Candidate B
Feed control mode	Open-loop RPM	Mass-balance cascade	Open-loop RPM + offset
Feed setpoint (mL/min)	16.90	16.90	16.90
Pump speed (RPM)	184.2 fixed	172–196 (controller)	212 fixed
Gravimetric trim interval (s)	—	2	—
Head-pressure action at 1.20 bar	Alarm only	Alarm + RPM hold	Alarm only
Projected peak head pressure (bar)	1.48 (observed)	≤ 1.15	1.35
Tubing changeout interval (h)	500	400	500 (OEM life shortened)

Risk matrix

Likelihood × severity of an adverse process outcome · team judgement

0 Baseline — feed shortfall likely to recur; moderate yield impact.
A Controller mis-tuning possible but bounded by RPM and pressure limits.
B Tubing rupture or spallation risk; major impact.

Placements are a qualitative MSAT assessment, not a computed probability.

Practical constraints · Candidate A

Pump speed within OEM tubing limit (≤ 200 RPM)
Head pressure stays below the 1.20 bar ceiling
Feed-tote load cell LC-204 installed on BR-UP-01 skid
LC-204 calibration current
DeltaV cascade block available in the current control-system version
Change control raised for recipe and control strategy
Durham recipient loop can be mapped (TT-006 item 2.7)
Operator training on new alarm response

4 met · 3 open · 1 unverified. Open items must close before implementation, not before review.

Assumptions

Feed-loss-to-yield relationship from AN-104 (3 batches) holds for future batches; small sample, wide uncertainty.
Hypothesis A (tubing slip) is the main driver of the feed shortfall. If tests TP-01/TP-02 contradict it, this estimate no longer applies.
Controller holds delivered mass within ±2% of setpoint; tuning not yet tested on this skid.
No change to media, cell line, temperature profile or harvest timing.
Range reflects bootstrap resampling of the 3-batch fit (5th–95th percentile); it is not a probability that the outcome will fall inside it.

Outcome measure after implementation

Primary: |feed PV − SP| ≤ 3% throughout Phase 05 on the next 3 batches.

Secondary: PM-204 head pressure ≤ 1.20 bar; normalized yield index compared against the +3.2 to +6.8 pt estimate.

Review point: after MES-26076 harvest. If yield gain is below +3.2 pts, revisit hypothesis A.

Status tracking

ProposedApproved —Implemented —Effect observed —

Proposal · Candidate A

What reviewers are being asked to evaluate

ProposalProposed · not approved · not executed

Rationale: Feed shortfall tracks head pressure (R² = 0.941, correlation) and the tubing-slip mechanism is plausible. A mass-balance loop corrects delivered feed regardless of tubing condition.
Expected result: +5.1 pts normalized yield (illustrative range +3.2 to +6.8) and feed delivery within ±3% of setpoint.
Constraints: Change control, LC-204 calibration check, operator training and Durham loop mapping (TT-006) remain open.
Owner: Alex Rivera (MSAT Lead) with Automation Engineering
Required approval: Technical review (MSAT + Automation) then QA review with named e-signatures in REV-01.
Would change this proposal: Test TP-01 showing no slip at 0.55 N·m; controller trial showing oscillation or pressure overshoot; a new batch with full feed delivery but persistent yield loss.

Status tracking

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